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Author SHA1 Message Date
David Hildenbrand
950b68d917 mm/memory_hotplug: don't check for "all holes" in shrink_zone_span() 
If we have holes, the holes will automatically get detected and removed
once we remove the next bigger/smaller section.  The extra checks can go.

Link: http://lkml.kernel.org/r/20191006085646.5768-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-02-04 03:05:23 +00:00
David Hildenbrand
9b05158f5d mm/memory_hotplug: we always have a zone in find_(smallest|biggest)_section_pfn 
With shrink_pgdat_span() out of the way, we now always have a valid zone.

Link: http://lkml.kernel.org/r/20191006085646.5768-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-02-04 03:05:23 +00:00
David Hildenbrand
d33695b16a mm/memory_hotplug: poison memmap in remove_pfn_range_from_zone() 
Let's poison the pages similar to when adding new memory in
sparse_add_section().  Also call remove_pfn_range_from_zone() from
memunmap_pages(), so we can poison the memmap from there as well.

Link: http://lkml.kernel.org/r/20191006085646.5768-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-02-04 03:05:23 +00:00
David Hildenbrand
bd5c2344f9 mm/memory_hotplug: pass in nid to online_pages() 
Patch series "mm/memory_hotplug: pass in nid to online_pages()".

Simplify onlining code and get rid of find_memory_block().  Pass in the
nid from the memory block we are trying to online directly, instead of
manually looking it up.

This patch (of 2):

No need to lookup the memory block, we can directly pass in the nid.

Link: http://lkml.kernel.org/r/20200113113354.6341-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-01-31 10:30:39 -08:00
David Hildenbrand
fe4c86c916 mm: remove "count" parameter from has_unmovable_pages() 
Now that the memory isolate notifier is gone, the parameter is always 0.
Drop it and cleanup has_unmovable_pages().

Link: http://lkml.kernel.org/r/20191114131911.11783-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-01-31 10:30:38 -08:00
Dan Williams
f1037ec0cc mm/memory_hotplug: fix remove_memory() lockdep splat 
The daxctl unit test for the dax_kmem driver currently triggers the
(false positive) lockdep splat below.  It results from the fact that
remove_memory_block_devices() is invoked under the mem_hotplug_lock()
causing lockdep entanglements with cpu_hotplug_lock() and sysfs (kernfs
active state tracking).  It is a false positive because the sysfs
attribute path triggering the memory remove is not the same attribute
path associated with memory-block device.

sysfs_break_active_protection() is not applicable since there is no real
deadlock conflict, instead move memory-block device removal outside the
lock.  The mem_hotplug_lock() is not needed to synchronize the
memory-block device removal vs the page online state, that is already
handled by lock_device_hotplug().  Specifically, lock_device_hotplug()
is sufficient to allow try_remove_memory() to check the offline state of
the memblocks and be assured that any in progress online attempts are
flushed / blocked by kernfs_drain() / attribute removal.

The add_memory() path safely creates memblock devices under the
mem_hotplug_lock().  There is no kernfs active state synchronization in
the memblock device_register() path, so nothing to fix there.

This change is only possible thanks to the recent change that refactored
memory block device removal out of arch_remove_memory() (commit
4c4b7f9ba9 "mm/memory_hotplug: remove memory block devices before
arch_remove_memory()"), and David's due diligence tracking down the
guarantees afforded by kernfs_drain().  Not flagged for -stable since
this only impacts ongoing development and lockdep validation, not a
runtime issue.

    ======================================================
    WARNING: possible circular locking dependency detected
    5.5.0-rc3+ #230 Tainted: G           OE
    ------------------------------------------------------
    lt-daxctl/6459 is trying to acquire lock:
    ffff99c7f0003510 (kn->count#241){++++}, at: kernfs_remove_by_name_ns+0x41/0x80

    but task is already holding lock:
    ffffffffa76a5450 (mem_hotplug_lock.rw_sem){++++}, at: percpu_down_write+0x20/0xe0

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #2 (mem_hotplug_lock.rw_sem){++++}:
           __lock_acquire+0x39c/0x790
           lock_acquire+0xa2/0x1b0
           get_online_mems+0x3e/0xb0
           kmem_cache_create_usercopy+0x2e/0x260
           kmem_cache_create+0x12/0x20
           ptlock_cache_init+0x20/0x28
           start_kernel+0x243/0x547
           secondary_startup_64+0xb6/0xc0

    -> #1 (cpu_hotplug_lock.rw_sem){++++}:
           __lock_acquire+0x39c/0x790
           lock_acquire+0xa2/0x1b0
           cpus_read_lock+0x3e/0xb0
           online_pages+0x37/0x300
           memory_subsys_online+0x17d/0x1c0
           device_online+0x60/0x80
           state_store+0x65/0xd0
           kernfs_fop_write+0xcf/0x1c0
           vfs_write+0xdb/0x1d0
           ksys_write+0x65/0xe0
           do_syscall_64+0x5c/0xa0
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    -> #0 (kn->count#241){++++}:
           check_prev_add+0x98/0xa40
           validate_chain+0x576/0x860
           __lock_acquire+0x39c/0x790
           lock_acquire+0xa2/0x1b0
           __kernfs_remove+0x25f/0x2e0
           kernfs_remove_by_name_ns+0x41/0x80
           remove_files.isra.0+0x30/0x70
           sysfs_remove_group+0x3d/0x80
           sysfs_remove_groups+0x29/0x40
           device_remove_attrs+0x39/0x70
           device_del+0x16a/0x3f0
           device_unregister+0x16/0x60
           remove_memory_block_devices+0x82/0xb0
           try_remove_memory+0xb5/0x130
           remove_memory+0x26/0x40
           dev_dax_kmem_remove+0x44/0x6a [kmem]
           device_release_driver_internal+0xe4/0x1c0
           unbind_store+0xef/0x120
           kernfs_fop_write+0xcf/0x1c0
           vfs_write+0xdb/0x1d0
           ksys_write+0x65/0xe0
           do_syscall_64+0x5c/0xa0
           entry_SYSCALL_64_after_hwframe+0x49/0xbe

    other info that might help us debug this:

    Chain exists of:
      kn->count#241 --> cpu_hotplug_lock.rw_sem --> mem_hotplug_lock.rw_sem

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(mem_hotplug_lock.rw_sem);
                                   lock(cpu_hotplug_lock.rw_sem);
                                   lock(mem_hotplug_lock.rw_sem);
      lock(kn->count#241);

     *** DEADLOCK ***

No fixes tag as this has been a long standing issue that predated the
addition of kernfs lockdep annotations.

Link: http://lkml.kernel.org/r/157991441887.2763922.4770790047389427325.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-01-31 10:30:36 -08:00
David Hildenbrand
feee6b2989 mm/memory_hotplug: shrink zones when offlining memory 
We currently try to shrink a single zone when removing memory.  We use
the zone of the first page of the memory we are removing.  If that
memmap was never initialized (e.g., memory was never onlined), we will
read garbage and can trigger kernel BUGs (due to a stale pointer):

    BUG: unable to handle page fault for address: 000000000000353d
    #PF: supervisor write access in kernel mode
    #PF: error_code(0x0002) - not-present page
    PGD 0 P4D 0
    Oops: 0002 [#1] SMP PTI
    CPU: 1 PID: 7 Comm: kworker/u8:0 Not tainted 5.3.0-rc5-next-20190820+ #317
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.4
    Workqueue: kacpi_hotplug acpi_hotplug_work_fn
    RIP: 0010:clear_zone_contiguous+0x5/0x10
    Code: 48 89 c6 48 89 c3 e8 2a fe ff ff 48 85 c0 75 cf 5b 5d c3 c6 85 fd 05 00 00 01 5b 5d c3 0f 1f 840
    RSP: 0018:ffffad2400043c98 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000200000000 RCX: 0000000000000000
    RDX: 0000000000200000 RSI: 0000000000140000 RDI: 0000000000002f40
    RBP: 0000000140000000 R08: 0000000000000000 R09: 0000000000000001
    R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000140000
    R13: 0000000000140000 R14: 0000000000002f40 R15: ffff9e3e7aff3680
    FS:  0000000000000000(0000) GS:ffff9e3e7bb00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 000000000000353d CR3: 0000000058610000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     __remove_pages+0x4b/0x640
     arch_remove_memory+0x63/0x8d
     try_remove_memory+0xdb/0x130
     __remove_memory+0xa/0x11
     acpi_memory_device_remove+0x70/0x100
     acpi_bus_trim+0x55/0x90
     acpi_device_hotplug+0x227/0x3a0
     acpi_hotplug_work_fn+0x1a/0x30
     process_one_work+0x221/0x550
     worker_thread+0x50/0x3b0
     kthread+0x105/0x140
     ret_from_fork+0x3a/0x50
    Modules linked in:
    CR2: 000000000000353d

Instead, shrink the zones when offlining memory or when onlining failed.
Introduce and use remove_pfn_range_from_zone(() for that.  We now
properly shrink the zones, even if we have DIMMs whereby

 - Some memory blocks fall into no zone (never onlined)

 - Some memory blocks fall into multiple zones (offlined+re-onlined)

 - Multiple memory blocks that fall into different zones

Drop the zone parameter (with a potential dubious value) from
__remove_pages() and __remove_section().

Link: http://lkml.kernel.org/r/20191006085646.5768-6-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[visible after d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: <stable@vger.kernel.org>	[5.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2020-01-04 13:55:08 -08:00
Souptick Joarder
12cc1c7345 mm/memory_hotplug.c: remove __online_page_set_limits() 
__online_page_set_limits() is a dummy function - remove it and all
callers.

Link: http://lkml.kernel.org/r/8e1bc9d3b492f6bde16e95ebc1dee11d6aefabd7.1567889743.git.jrdr.linux@gmail.com
Link: http://lkml.kernel.org/r/854db2cf8145d9635249c95584d9a91fd774a229.1567889743.git.jrdr.linux@gmail.com
Link: http://lkml.kernel.org/r/9afe6c5a18158f3884a6b302ac2c772f3da49ccc.1567889743.git.jrdr.linux@gmail.com
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:10 -08:00
David Hildenbrand
c5e79ef561 mm/memory_hotplug.c: don't allow to online/offline memory blocks with holes 
Our onlining/offlining code is unnecessarily complicated.  Only memory
blocks added during boot can have holes (a range that is not
IORESOURCE_SYSTEM_RAM).  Hotplugged memory never has holes (e.g., see
add_memory_resource()).  All memory blocks that belong to boot memory
are already online.

Note that boot memory can have holes and the memmap of the holes is
marked PG_reserved.  However, also memory allocated early during boot is
PG_reserved - basically every page of boot memory that is not given to
the buddy is PG_reserved.

Therefore, when we stop allowing to offline memory blocks with holes, we
implicitly no longer have to deal with onlining memory blocks with
holes.  E.g., online_pages() will do a walk_system_ram_range(...,
online_pages_range), whereby online_pages_range() will effectively only
free the memory holes not falling into a hole to the buddy.  The other
pages (holes) are kept PG_reserved (via
move_pfn_range_to_zone()->memmap_init_zone()).

This allows to simplify the code.  For example, we no longer have to
worry about marking pages that fall into memory holes PG_reserved when
onlining memory.  We can stop setting pages PG_reserved completely in
memmap_init_zone().

Offlining memory blocks added during boot is usually not guaranteed to
work either way (unmovable data might have easily ended up on that
memory during boot).  So stopping to do that should not really hurt.
Also, people are not even aware of a setup where onlining/offlining of
memory blocks with holes used to work reliably (see [1] and [2]
especially regarding the hotplug path) - I doubt it worked reliably.

For the use case of offlining memory to unplug DIMMs, we should see no
change.  (holes on DIMMs would be weird).

Please note that hardware errors (PG_hwpoison) are not memory holes and
are not affected by this change when offlining.

[1] https://lkml.org/lkml/2019/10/22/135
[2] https://lkml.org/lkml/2019/8/14/1365

Link: http://lkml.kernel.org/r/20191119115237.6662-1-david@redhat.com
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:05 -08:00
David Hildenbrand
756d25be45 mm/page_isolation.c: convert SKIP_HWPOISON to MEMORY_OFFLINE 
We have two types of users of page isolation:

 1. Memory offlining:  Offline memory so it can be unplugged. Memory
                       won't be touched.

 2. Memory allocation: Allocate memory (e.g., alloc_contig_range()) to
                       become the owner of the memory and make use of
                       it.

For example, in case we want to offline memory, we can ignore (skip
over) PageHWPoison() pages, as the memory won't get used.  We can allow
to offline memory.  In contrast, we don't want to allow to allocate such
memory.

Let's generalize the approach so we can special case other types of
pages we want to skip over in case we offline memory.  While at it, also
pass the same flags to test_pages_isolated().

Link: http://lkml.kernel.org/r/20191021172353.3056-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
David Hildenbrand
0ee5f4f31d mm/page_alloc.c: don't set pages PageReserved() when offlining 
Patch series "mm: Memory offlining + page isolation cleanups", v2.

This patch (of 2):

We call __offline_isolated_pages() from __offline_pages() after all
pages were isolated and are either free (PageBuddy()) or PageHWPoison.
Nothing can stop us from offlining memory at this point.

In __offline_isolated_pages() we first set all affected memory sections
offline (offline_mem_sections(pfn, end_pfn)), to mark the memmap as
invalid (pfn_to_online_page() will no longer succeed), and then walk
over all pages to pull the free pages from the free lists (to the
isolated free lists, to be precise).

Note that re-onlining a memory block will result in the whole memmap
getting reinitialized, overwriting any old state.  We already poision
the memmap when offlining is complete to find any access to
stale/uninitialized memmaps.

So, setting the pages PageReserved() is not helpful.  The memap is
marked offline and all pageblocks are isolated.  As soon as offline, the
memmap is stale either way.

This looks like a leftover from ancient times where we initialized the
memmap when adding memory and not when onlining it (the pages were set
PageReserved so re-onling would work as expected).

Link: http://lkml.kernel.org/r/20191021172353.3056-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
David Hildenbrand
0ec4709743 mm/memory_hotplug: remove __online_page_free() and __online_page_increment_counters() 
Let's drop the now unused functions.

Link: http://lkml.kernel.org/r/20190909114830.662-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
David Hildenbrand
18db149120 mm/memory_hotplug: export generic_online_page() 
Patch series "mm/memory_hotplug: Export generic_online_page()".

Let's replace the __online_page...() functions by generic_online_page().
Hyper-V only wants to delay the actual onlining of un-backed pages, so
we can simpy re-use the generic function.

This patch (of 3):

Let's expose generic_online_page() so online_page_callback users can
simply fall back to the generic implementation when actually deciding to
online the pages.

Link: http://lkml.kernel.org/r/20190909114830.662-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
Alastair D'Silva
dca4436d1c mm/memory_hotplug.c: add a bounds check to __add_pages() 
On PowerPC, the address ranges allocated to OpenCAPI LPC memory are
allocated from firmware.  These address ranges may be higher than what
older kernels permit, as we increased the maximum permissable address in
commit 4ffe713b75 ("powerpc/mm: Increase the max addressable memory to
2PB").  It is possible that the addressable range may change again in
the future.

In this scenario, we end up with a bogus section returned from
__section_nr (see the discussion on the thread "mm: Trigger bug on if a
section is not found in __section_nr").

Adding a check here means that we fail early and have an opportunity to
handle the error gracefully, rather than rumbling on and potentially
accessing an incorrect section.

Further discussion is also on the thread ("powerpc: Perform a bounds
check in arch_add_memory")
  http://lkml.kernel.org/r/20190827052047.31547-1-alastair@au1.ibm.com

Link: http://lkml.kernel.org/r/20191001004617.7536-2-alastair@au1.ibm.com
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
Anshuman Khandual
32d1fe8fcb mm/hotplug: reorder memblock_[free|remove]() calls in try_remove_memory() 
Currently during memory hot add procedure, memory gets into memblock
before calling arch_add_memory() which creates its linear mapping.

  add_memory_resource() {
	..................
	memblock_add_node()
	..................
	arch_add_memory()
	..................
  }

But during memory hot remove procedure, removal from memblock happens
first before its linear mapping gets teared down with
arch_remove_memory() which is not consistent.  Resource removal should
happen in reverse order as they were added.  However this does not pose
any problem for now, unless there is an assumption regarding linear
mapping.  One example was a subtle failure on arm64 platform [1].
Though this has now found a different solution.

  try_remove_memory() {
	..................
	memblock_free()
	memblock_remove()
	..................
	arch_remove_memory()
	..................
  }

This changes the sequence of resource removal including memblock and
linear mapping tear down during memory hot remove which will now be the
reverse order in which they were added during memory hot add.  The
changed removal order looks like the following.

  try_remove_memory() {
	..................
	arch_remove_memory()
	..................
	memblock_free()
	memblock_remove()
	..................
  }

[1] https://patchwork.kernel.org/patch/11127623/

Memory hot remove now works on arm64 without this because a recent
commit 60bb462fc7ad ("drivers/base/node.c: simplify
unregister_memory_block_under_nodes()").

This does not fix a serious problem.  It just removes an inconsistency
while freeing resources during memory hot remove which for now does not
pose a real problem.

David mentioned that re-ordering should still make sense for consistency
purpose (removing stuff in the reverse order they were added).  This
patch is now detached from arm64 hot-remove series.

Michal:

: I would just a note that the inconsistency doesn't pose any problem now
: but if somebody makes any assumptions about linear mappings then it could
: get subtly broken like your example for arm64 which has found a different
: solution in the meantime.

Link: http://lkml.kernel.org/r/1569380273-7708-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-12-01 12:59:04 -08:00
David Hildenbrand
7ce700bf11 mm/memory_hotplug: don't access uninitialized memmaps in shrink_zone_span() 
Let's limit shrinking to !ZONE_DEVICE so we can fix the current code.
We should never try to touch the memmap of offline sections where we
could have uninitialized memmaps and could trigger BUGs when calling
page_to_nid() on poisoned pages.

There is no reliable way to distinguish an uninitialized memmap from an
initialized memmap that belongs to ZONE_DEVICE, as we don't have
anything like SECTION_IS_ONLINE we can use similar to
pfn_to_online_section() for !ZONE_DEVICE memory.

E.g., set_zone_contiguous() similarly relies on pfn_to_online_section()
and will therefore never set a ZONE_DEVICE zone consecutive.  Stopping
to shrink the ZONE_DEVICE therefore results in no observable changes,
besides /proc/zoneinfo indicating different boundaries - something we
can totally live with.

Before commit d0dc12e86b ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized with 0 and the node with the right
value.  So the zone might be wrong but not garbage.  After that commit,
both the zone and the node will be garbage when touching uninitialized
memmaps.

Toshiki reported a BUG (race between delayed initialization of
ZONE_DEVICE memmaps without holding the memory hotplug lock and
concurrent zone shrinking).

  https://lkml.org/lkml/2019/11/14/1040

"Iteration of create and destroy namespace causes the panic as below:

      kernel BUG at mm/page_alloc.c:535!
      CPU: 7 PID: 2766 Comm: ndctl Not tainted 5.4.0-rc4 #6
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014
      RIP: 0010:set_pfnblock_flags_mask+0x95/0xf0
      Call Trace:
       memmap_init_zone_device+0x165/0x17c
       memremap_pages+0x4c1/0x540
       devm_memremap_pages+0x1d/0x60
       pmem_attach_disk+0x16b/0x600 [nd_pmem]
       nvdimm_bus_probe+0x69/0x1c0
       really_probe+0x1c2/0x3e0
       driver_probe_device+0xb4/0x100
       device_driver_attach+0x4f/0x60
       bind_store+0xc9/0x110
       kernfs_fop_write+0x116/0x190
       vfs_write+0xa5/0x1a0
       ksys_write+0x59/0xd0
       do_syscall_64+0x5b/0x180
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

  While creating a namespace and initializing memmap, if you destroy the
  namespace and shrink the zone, it will initialize the memmap outside
  the zone and trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page),
  pfn), page) in set_pfnblock_flags_mask()."

This BUG is also mitigated by this commit, where we for now stop to
shrink the ZONE_DEVICE zone until we can do it in a safe and clean way.

Link: http://lkml.kernel.org/r/20191006085646.5768-5-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[visible after d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Toshiki Fukasawa <t-fukasawa@vx.jp.nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Damian Tometzki <damian.tometzki@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-11-22 09:11:18 -08:00
David Hildenbrand
2c91f8fc6c mm/memory_hotplug: fix try_offline_node() 
try_offline_node() is pretty much broken right now:

 - The node span is updated when onlining memory, not when adding it. We
   ignore memory that was mever onlined. Bad.

 - We touch possible garbage memmaps. The pfn_to_nid(pfn) can easily
   trigger a kernel panic. Bad for memory that is offline but also bad
   for subsection hotadd with ZONE_DEVICE, whereby the memmap of the
   first PFN of a section might contain garbage.

 - Sections belonging to mixed nodes are not properly considered.

As memory blocks might belong to multiple nodes, we would have to walk
all pageblocks (or at least subsections) within present sections.
However, we don't have a way to identify whether a memmap that is not
online was initialized (relevant for ZONE_DEVICE).  This makes things
more complicated.

Luckily, we can piggy pack on the node span and the nid stored in memory
blocks.  Currently, the node span is grown when calling
move_pfn_range_to_zone() - e.g., when onlining memory, and shrunk when
removing memory, before calling try_offline_node().  Sysfs links are
created via link_mem_sections(), e.g., during boot or when adding
memory.

If the node still spans memory or if any memory block belongs to the
nid, we don't set the node offline.  As memory blocks that span multiple
nodes cannot get offlined, the nid stored in memory blocks is reliable
enough (for such online memory blocks, the node still spans the memory).

Introduce for_each_memory_block() to efficiently walk all memory blocks.

Note: We will soon stop shrinking the ZONE_DEVICE zone and the node span
when removing ZONE_DEVICE memory to fix similar issues (access of
garbage memmaps) - until we have a reliable way to identify whether
these memmaps were properly initialized.  This implies later, that once
a node had ZONE_DEVICE memory, we won't be able to set a node offline -
which should be acceptable.

Since commit f1dd2cd13c ("mm, memory_hotplug: do not associate
hotadded memory to zones until online") memory that is added is not
assoziated with a zone/node (memmap not initialized).  The introducing
commit 60a5a19e74 ("memory-hotplug: remove sysfs file of node")
already missed that we could have multiple nodes for a section and that
the zone/node span is updated when onlining pages, not when adding them.

I tested this by hotplugging two DIMMs to a memory-less and cpu-less
NUMA node.  The node is properly onlined when adding the DIMMs.  When
removing the DIMMs, the node is properly offlined.

Masayoshi Mizuma reported:

: Without this patch, memory hotplug fails as panic:
:
:  BUG: kernel NULL pointer dereference, address: 0000000000000000
:  ...
:  Call Trace:
:   remove_memory_block_devices+0x81/0xc0
:   try_remove_memory+0xb4/0x130
:   __remove_memory+0xa/0x20
:   acpi_memory_device_remove+0x84/0x100
:   acpi_bus_trim+0x57/0x90
:   acpi_bus_trim+0x2e/0x90
:   acpi_device_hotplug+0x2b2/0x4d0
:   acpi_hotplug_work_fn+0x1a/0x30
:   process_one_work+0x171/0x380
:   worker_thread+0x49/0x3f0
:   kthread+0xf8/0x130
:   ret_from_fork+0x35/0x40

[david@redhat.com: v3]
  Link: http://lkml.kernel.org/r/20191102120221.7553-1-david@redhat.com
Link: http://lkml.kernel.org/r/20191028105458.28320-1-david@redhat.com
Fixes: 60a5a19e74 ("memory-hotplug: remove sysfs file of node")
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visiable after d0dc12e86b
Signed-off-by: David Hildenbrand <david@redhat.com>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-11-15 18:34:00 -08:00
David Hildenbrand
656d571193 mm/memory_hotplug: fix updating the node span 
We recently started updating the node span based on the zone span to
avoid touching uninitialized memmaps.

Currently, we will always detect the node span to start at 0, meaning a
node can easily span too many pages.  pgdat_is_empty() will still work
correctly if all zones span no pages.  We should skip over all zones
without spanned pages and properly handle the first detected zone that
spans pages.

Unfortunately, in contrast to the zone span (/proc/zoneinfo), the node
span cannot easily be inspected and tested.  The node span gives no real
guarantees when an architecture supports memory hotplug, meaning it can
easily contain holes or span pages of different nodes.

The node span is not really used after init on architectures that
support memory hotplug.

E.g., we use it in mm/memory_hotplug.c:try_offline_node() and in
mm/kmemleak.c:kmemleak_scan().  These users seem to be fine.

Link: http://lkml.kernel.org/r/20191027222714.5313-1-david@redhat.com
Fixes: 00d6c019b5 ("mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-11-06 08:47:50 -08:00
David Hildenbrand
00d6c019b5 mm/memory_hotplug: don't access uninitialized memmaps in shrink_pgdat_span() 
We might use the nid of memmaps that were never initialized.  For
example, if the memmap was poisoned, we will crash the kernel in
pfn_to_nid() right now.  Let's use the calculated boundaries of the
separate zones instead.  This now also avoids having to iterate over a
whole bunch of subsections again, after shrinking one zone.

Before commit d0dc12e86b ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized to 0 and the node was set to the
right value.  After that commit, the node might be garbage.

We'll have to fix shrink_zone_span() next.

Link: http://lkml.kernel.org/r/20191006085646.5768-4-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Damian Tometzki <damian.tometzki@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Halil Pasic <pasic@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>	[4.13+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-10-19 06:32:31 -04:00
Souptick Joarder
29a90db929 mm/memory_hotplug.c: s/is/if 
Correct typo in comment.

Link: http://lkml.kernel.org/r/1568233954-3913-1-git-send-email-jrdr.linux@gmail.com
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
ca9a46f8a4 mm/memory_hotplug: online_pages cannot be 0 in online_pages() 
walk_system_ram_range() will fail with -EINVAL in case
online_pages_range() was never called (== no resource applicable in the
range).  Otherwise, we will always call online_pages_range() with nr_pages
> 0 and, therefore, have online_pages > 0.

Remove that special handling.

Link: http://lkml.kernel.org/r/20190814154109.3448-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
bd02cc01d3 mm/memory_hotplug: make sure the pfn is aligned to the order when onlining 
Commit a9cd410a3d ("mm/page_alloc.c: memory hotplug: free pages as
higher order") assumed that any PFN we get via memory resources is aligned
to to MAX_ORDER - 1, I am not convinced that is always true.  Let's play
safe, check the alignment and fallback to single pages.

akpm: warn in this situation so we get to find out if and why this ever
occurs.

[akpm@linux-foundation.org: add WARN_ON_ONCE()]
Link: http://lkml.kernel.org/r/20190814154109.3448-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
b2c2ab208e mm/memory_hotplug: simplify online_pages_range() 
online_pages always corresponds to nr_pages.  Simplify the code, getting
rid of online_pages_blocks().  Add some comments.

Link: http://lkml.kernel.org/r/20190814154109.3448-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
5ecae6359e mm/memory_hotplug: drop PageReserved() check in online_pages_range() 
move_pfn_range_to_zone() will set all pages to PG_reserved via
memmap_init_zone().  The only way a page could no longer be reserved would
be if a MEM_GOING_ONLINE notifier would clear PG_reserved - which is not
done (the online_page callback is used for that purpose by e.g., Hyper-V
instead).  walk_system_ram_range() will never call online_pages_range()
with duplicate PFNs, so drop the PageReserved() check.

This seems to be a leftover from ancient times where the memmap was
initialized when adding memory and we wanted to check for already onlined
memory.

Link: http://lkml.kernel.org/r/20190814154109.3448-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
Wei Yang
33fce0113d mm/memory_hotplug.c: prevent memory leak when reusing pgdat 
When offlining a node in try_offline_node(), pgdat is not released.  So
that pgdat could be reused in hotadd_new_pgdat().  While we reallocate
pgdat->per_cpu_nodestats if this pgdat is reused.

This patch prevents the memory leak by just allocating per_cpu_nodestats
when it is a new pgdat.

Link: http://lkml.kernel.org/r/20190813020608.10194-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
b6c88d3b9d drivers/base/memory.c: don't store end_section_nr in memory blocks 
Each memory block spans the same amount of sections/pages/bytes.  The size
is determined before the first memory block is created.  No need to store
what we can easily calculate - and the calculations even look simpler now.

Michal brought up the idea of variable-sized memory blocks.  However, if
we ever implement something like this, we will need an API compatibility
switch and reworks at various places (most code assumes a fixed memory
block size).  So let's cleanup what we have right now.

While at it, fix the variable naming in register_mem_sect_under_node() -
we no longer talk about a single section.

Link: http://lkml.kernel.org/r/20190809110200.2746-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
David Hildenbrand
3fccb74cf3 mm/memory_hotplug: remove move_pfn_range() 
Let's remove this indirection.  We need the zone in the caller either way,
so let's just detect it there.  Add some documentation for
move_pfn_range_to_zone() instead.

[akpm@linux-foundation.org: restore newline, per David]
Link: http://lkml.kernel.org/r/20190724142324.3686-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:09 -07:00
Matthew Wilcox (Oracle)
d8c6546b1a mm: introduce compound_nr() 
Replace 1 << compound_order(page) with compound_nr(page).  Minor
improvements in readability.

Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-09-24 15:54:08 -07:00
Weitao Hou
aa4996b3af mm/memory_hotplug.c: remove unneeded return for void function 
return is unneeded in void function

Link: http://lkml.kernel.org/r/20190723130814.21826-1-houweitaoo@gmail.com
Signed-off-by: Weitao Hou <houweitaoo@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-08-03 07:02:01 -07:00
Dan Williams
9a84503042 mm/sparsemem: cleanup 'section number' data types 
David points out that there is a mixture of 'int' and 'unsigned long'
usage for section number data types.  Update the memory hotplug path to
use 'unsigned long' consistently for section numbers.

[akpm@linux-foundation.org: fix printk format]
Link: http://lkml.kernel.org/r/156107543656.1329419.11505835211949439815.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
Dan Williams
ba72b4c8cf mm/sparsemem: support sub-section hotplug 
The libnvdimm sub-system has suffered a series of hacks and broken
workarounds for the memory-hotplug implementation's awkward
section-aligned (128MB) granularity.

For example the following backtrace is emitted when attempting
arch_add_memory() with physical address ranges that intersect 'System
RAM' (RAM) with 'Persistent Memory' (PMEM) within a given section:

    # cat /proc/iomem | grep -A1 -B1 Persistent\ Memory
    100000000-1ffffffff : System RAM
    200000000-303ffffff : Persistent Memory (legacy)
    304000000-43fffffff : System RAM
    440000000-23ffffffff : Persistent Memory
    2400000000-43bfffffff : Persistent Memory
      2400000000-43bfffffff : namespace2.0

    WARNING: CPU: 38 PID: 928 at arch/x86/mm/init_64.c:850 add_pages+0x5c/0x60
    [..]
    RIP: 0010:add_pages+0x5c/0x60
    [..]
    Call Trace:
     devm_memremap_pages+0x460/0x6e0
     pmem_attach_disk+0x29e/0x680 [nd_pmem]
     ? nd_dax_probe+0xfc/0x120 [libnvdimm]
     nvdimm_bus_probe+0x66/0x160 [libnvdimm]

It was discovered that the problem goes beyond RAM vs PMEM collisions as
some platform produce PMEM vs PMEM collisions within a given section.
The libnvdimm workaround for that case revealed that the libnvdimm
section-alignment-padding implementation has been broken for a long
while.

A fix for that long-standing breakage introduces as many problems as it
solves as it would require a backward-incompatible change to the
namespace metadata interpretation.  Instead of that dubious route [1],
address the root problem in the memory-hotplug implementation.

Note that EEXIST is no longer treated as success as that is how
sparse_add_section() reports subsection collisions, it was also obviated
by recent changes to perform the request_region() for 'System RAM'
before arch_add_memory() in the add_memory() sequence.

[1] https://lore.kernel.org/r/155000671719.348031.2347363160141119237.stgit@dwillia2-desk3.amr.corp.intel.com

[osalvador@suse.de: fix deactivate_section for early sections]
  Link: http://lkml.kernel.org/r/20190715081549.32577-2-osalvador@suse.de
Link: http://lkml.kernel.org/r/156092354368.979959.6232443923440952359.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
Dan Williams
7ea6216049 mm/sparsemem: prepare for sub-section ranges 
Prepare the memory hot-{add,remove} paths for handling sub-section
ranges by plumbing the starting page frame and number of pages being
handled through arch_{add,remove}_memory() to
sparse_{add,remove}_one_section().

This is simply plumbing, small cleanups, and some identifier renames.
No intended functional changes.

Link: http://lkml.kernel.org/r/156092353780.979959.9713046515562743194.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
Dan Williams
96da435000 mm/hotplug: kill is_dev_zone() usage in __remove_pages() 
The zone type check was a leftover from the cleanup that plumbed altmap
through the memory hotplug path, i.e.  commit da024512a1 "mm: pass the
vmem_altmap to arch_remove_memory and __remove_pages".

Link: http://lkml.kernel.org/r/156092352642.979959.6664333788149363039.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Cc: Michal Hocko <mhocko@suse.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
Dan Williams
49ba3c6b37 mm/hotplug: prepare shrink_{zone, pgdat}_span for sub-section removal 
Sub-section hotplug support reduces the unit of operation of hotplug
from section-sized-units (PAGES_PER_SECTION) to sub-section-sized units
(PAGES_PER_SUBSECTION).  Teach shrink_{zone,pgdat}_span() to consider
PAGES_PER_SUBSECTION boundaries as the points where pfn_valid(), not
valid_section(), can toggle.

[osalvador@suse.de: fix shrink_{zone,node}_span]
  Link: http://lkml.kernel.org/r/20190717090725.23618-3-osalvador@suse.de
Link: http://lkml.kernel.org/r/156092351496.979959.12703722803097017492.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
Dan Williams
f1eca35a0d mm/sparsemem: introduce struct mem_section_usage 
Patch series "mm: Sub-section memory hotplug support", v10.

The memory hotplug section is an arbitrary / convenient unit for memory
hotplug.  'Section-size' units have bled into the user interface
('memblock' sysfs) and can not be changed without breaking existing
userspace.  The section-size constraint, while mostly benign for typical
memory hotplug, has and continues to wreak havoc with 'device-memory'
use cases, persistent memory (pmem) in particular.  Recall that pmem
uses devm_memremap_pages(), and subsequently arch_add_memory(), to
allocate a 'struct page' memmap for pmem.  However, it does not use the
'bottom half' of memory hotplug, i.e.  never marks pmem pages online and
never exposes the userspace memblock interface for pmem.  This leaves an
opening to redress the section-size constraint.

To date, the libnvdimm subsystem has attempted to inject padding to
satisfy the internal constraints of arch_add_memory().  Beyond
complicating the code, leading to bugs [2], wasting memory, and limiting
configuration flexibility, the padding hack is broken when the platform
changes this physical memory alignment of pmem from one boot to the
next.  Device failure (intermittent or permanent) and physical
reconfiguration are events that can cause the platform firmware to
change the physical placement of pmem on a subsequent boot, and device
failure is an everyday event in a data-center.

It turns out that sections are only a hard requirement of the
user-facing interface for memory hotplug and with a bit more
infrastructure sub-section arch_add_memory() support can be added for
kernel internal usages like devm_memremap_pages().  Here is an analysis
of the current design assumptions in the current code and how they are
addressed in the new implementation:

Current design assumptions:

 - Sections that describe boot memory (early sections) are never
   unplugged / removed.

 - pfn_valid(), in the CONFIG_SPARSEMEM_VMEMMAP=y, case devolves to a
   valid_section() check

 - __add_pages() and helper routines assume all operations occur in
   PAGES_PER_SECTION units.

 - The memblock sysfs interface only comprehends full sections

New design assumptions:

 - Sections are instrumented with a sub-section bitmask to track (on
   x86) individual 2MB sub-divisions of a 128MB section.

 - Partially populated early sections can be extended with additional
   sub-sections, and those sub-sections can be removed with
   arch_remove_memory(). With this in place we no longer lose usable
   memory capacity to padding.

 - pfn_valid() is updated to look deeper than valid_section() to also
   check the active-sub-section mask. This indication is in the same
   cacheline as the valid_section() so the performance impact is
   expected to be negligible. So far the lkp robot has not reported any
   regressions.

 - Outside of the core vmemmap population routines which are replaced,
   other helper routines like shrink_{zone,pgdat}_span() are updated to
   handle the smaller granularity. Core memory hotplug routines that
   deal with online memory are not touched.

 - The existing memblock sysfs user api guarantees / assumptions are not
   touched since this capability is limited to !online
   !memblock-sysfs-accessible sections.

Meanwhile the issue reports continue to roll in from users that do not
understand when and how the 128MB constraint will bite them.  The current
implementation relied on being able to support at least one misaligned
namespace, but that immediately falls over on any moderately complex
namespace creation attempt.  Beyond the initial problem of 'System RAM'
colliding with pmem, and the unsolvable problem of physical alignment
changes, Linux is now being exposed to platforms that collide pmem ranges
with other pmem ranges by default [3].  In short, devm_memremap_pages()
has pushed the venerable section-size constraint past the breaking point,
and the simplicity of section-aligned arch_add_memory() is no longer
tenable.

These patches are exposed to the kbuild robot on a subsection-v10 branch
[4], and a preview of the unit test for this functionality is available
on the 'subsection-pending' branch of ndctl [5].

[2]: https://lore.kernel.org/r/155000671719.348031.2347363160141119237.stgit@dwillia2-desk3.amr.corp.intel.com
[3]: https://github.com/pmem/ndctl/issues/76
[4]: https://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm.git/log/?h=subsection-v10
[5]: https://github.com/pmem/ndctl/commit/7c59b4867e1c

This patch (of 13):

Towards enabling memory hotplug to track partial population of a section,
introduce 'struct mem_section_usage'.

A pointer to a 'struct mem_section_usage' instance replaces the existing
pointer to a 'pageblock_flags' bitmap.  Effectively it adds one more
'unsigned long' beyond the 'pageblock_flags' (usemap) allocation to house
a new 'subsection_map' bitmap.  The new bitmap enables the memory
hot{plug,remove} implementation to act on incremental sub-divisions of a
section.

SUBSECTION_SHIFT is defined as global constant instead of per-architecture
value like SECTION_SIZE_BITS in order to allow cross-arch compatibility of
subsection users.  Specifically a common subsection size allows for the
possibility that persistent memory namespace configurations be made
compatible across architectures.

The primary motivation for this functionality is to support platforms that
mix "System RAM" and "Persistent Memory" within a single section, or
multiple PMEM ranges with different mapping lifetimes within a single
section.  The section restriction for hotplug has caused an ongoing saga
of hacks and bugs for devm_memremap_pages() users.

Beyond the fixups to teach existing paths how to retrieve the 'usemap'
from a section, and updates to usemap allocation path, there are no
expected behavior changes.

Link: http://lkml.kernel.org/r/156092349845.979959.73333291612799019.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Qian Cai <cai@lca.pw>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:07 -07:00
David Hildenbrand
ea8846411a mm/memory_hotplug: move and simplify walk_memory_blocks() 
Let's move walk_memory_blocks() to the place where memory block logic
resides and simplify it.  While at it, add a type for the callback
function.

Link: http://lkml.kernel.org/r/20190614100114.311-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
fbcf73ce65 mm/memory_hotplug: rename walk_memory_range() and pass start+size instead of pfns 
walk_memory_range() was once used to iterate over sections.  Now, it
iterates over memory blocks.  Rename the function, fixup the
documentation.

Also, pass start+size instead of PFNs, which is what most callers
already have at hand.  (we'll rework link_mem_sections() most probably
soon)

Follow-up patches will rework, simplify, and move walk_memory_blocks()
to drivers/base/memory.c.

Note: walk_memory_blocks() only works correctly right now if the
start_pfn is aligned to a section start.  This is the case right now,
but we'll generalize the function in a follow up patch so the semantics
match the documentation.

[akpm@linux-foundation.org: remove unused variable]
Link: http://lkml.kernel.org/r/20190614100114.311-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Rashmica Gupta <rashmica.g@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
b9bf8d342d mm/memory_hotplug: remove "zone" parameter from sparse_remove_one_section 
The parameter is unused, so let's drop it.  Memory removal paths should
never care about zones.  This is the job of memory offlining and will
require more refactorings.

Link: http://lkml.kernel.org/r/20190527111152.16324-12-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
4c4b7f9ba9 mm/memory_hotplug: remove memory block devices before arch_remove_memory() 
Let's factor out removing of memory block devices, which is only
necessary for memory added via add_memory() and friends that created
memory block devices.  Remove the devices before calling
arch_remove_memory().

This finishes factoring out memory block device handling from
arch_add_memory() and arch_remove_memory().

Link: http://lkml.kernel.org/r/20190527111152.16324-10-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
05f800a0bd mm/memory_hotplug: drop MHP_MEMBLOCK_API 
No longer needed, the callers of arch_add_memory() can handle this
manually.

Link: http://lkml.kernel.org/r/20190527111152.16324-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
db051a0dac mm/memory_hotplug: create memory block devices after arch_add_memory() 
Only memory to be added to the buddy and to be onlined/offlined by user
space using /sys/devices/system/memory/...  needs (and should have!)
memory block devices.

Factor out creation of memory block devices.  Create all devices after
arch_add_memory() succeeded.  We can later drop the want_memblock
parameter, because it is now effectively stale.

Only after memory block devices have been added, memory can be onlined
by user space.  This implies, that memory is not visible to user space
at all before arch_add_memory() succeeded.

While at it
 - use WARN_ON_ONCE instead of BUG_ON in moved unregister_memory()
 - introduce find_memory_block_by_id() to search via block id
 - Use find_memory_block_by_id() in init_memory_block() to catch
   duplicates

Link: http://lkml.kernel.org/r/20190527111152.16324-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
80ec922dbd mm/memory_hotplug: allow arch_remove_memory() without CONFIG_MEMORY_HOTREMOVE 
We want to improve error handling while adding memory by allowing to use
arch_remove_memory() and __remove_pages() even if
CONFIG_MEMORY_HOTREMOVE is not set to e.g., implement something like:

	arch_add_memory()
	rc = do_something();
	if (rc) {
		arch_remove_memory();
	}

We won't get rid of CONFIG_MEMORY_HOTREMOVE for now, as it will require
quite some dependencies for memory offlining.

Link: http://lkml.kernel.org/r/20190527111152.16324-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
David Hildenbrand
cec3ebd083 mm/memory_hotplug: simplify and fix check_hotplug_memory_range() 
Patch series "mm/memory_hotplug: Factor out memory block devicehandling", v3.

We only want memory block devices for memory to be onlined/offlined
(add/remove from the buddy).  This is required so user space can
online/offline memory and kdump gets notified about newly onlined
memory.

Let's factor out creation/removal of memory block devices.  This helps
to further cleanup arch_add_memory/arch_remove_memory() and to make
implementation of new features easier - especially sub-section memory
hot add from Dan.

Anshuman Khandual is currently working on arch_remove_memory().  I added
a temporary solution via "arm64/mm: Add temporary arch_remove_memory()
implementation", that is sufficient as a firsts tep in the context of
this series.  (we don't cleanup page tables in case anything goes wrong
already)

Did a quick sanity test with DIMM plug/unplug, making sure all devices
and sysfs links properly get added/removed.  Compile tested on s390x and
x86-64.

This patch (of 11):

By converting start and size to page granularity, we actually ignore
unaligned parts within a page instead of properly bailing out with an
error.

Link: http://lkml.kernel.org/r/20190527111152.16324-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jun Yao <yaojun8558363@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-18 17:08:06 -07:00
Pavel Tatashin
eca499ab37 mm/hotplug: make remove_memory() interface usable 
Presently the remove_memory() interface is inherently broken.  It tries
to remove memory but panics if some memory is not offline.  The problem
is that it is impossible to ensure that all memory blocks are offline as
this function also takes lock_device_hotplug that is required to change
memory state via sysfs.

So, between calling this function and offlining all memory blocks there
is always a window when lock_device_hotplug is released, and therefore,
there is always a chance for a panic during this window.

Make this interface to return an error if memory removal fails.  This
way it is safe to call this function without panicking machine, and also
makes it symmetric to add_memory() which already returns an error.

Link: http://lkml.kernel.org/r/20190517215438.6487-3-pasha.tatashin@soleen.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-07-16 19:23:24 -07:00
Christoph Hellwig
514caf23a7 memremap: replace the altmap_valid field with a PGMAP_ALTMAP_VALID flag 
Add a flags field to struct dev_pagemap to replace the altmap_valid
boolean to be a little more extensible.  Also add a pgmap_altmap() helper
to find the optional altmap and clean up the code using the altmap using
it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
 2019-07-02 14:32:44 -03:00
Thomas Gleixner
457c899653 treewide: Add SPDX license identifier for missed files 
Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 2019-05-21 10:50:45 +02:00
Dan Williams
e900a918b0 mm: shuffle initial free memory to improve memory-side-cache utilization 
Patch series "mm: Randomize free memory", v10.

This patch (of 3):

Randomization of the page allocator improves the average utilization of
a direct-mapped memory-side-cache.  Memory side caching is a platform
capability that Linux has been previously exposed to in HPC
(high-performance computing) environments on specialty platforms.  In
that instance it was a smaller pool of high-bandwidth-memory relative to
higher-capacity / lower-bandwidth DRAM.  Now, this capability is going
to be found on general purpose server platforms where DRAM is a cache in
front of higher latency persistent memory [1].

Robert offered an explanation of the state of the art of Linux
interactions with memory-side-caches [2], and I copy it here:

    It's been a problem in the HPC space:
    http://www.nersc.gov/research-and-development/knl-cache-mode-performance-coe/

    A kernel module called zonesort is available to try to help:
    https://software.intel.com/en-us/articles/xeon-phi-software

    and this abandoned patch series proposed that for the kernel:
    https://lkml.kernel.org/r/20170823100205.17311-1-lukasz.daniluk@intel.com

    Dan's patch series doesn't attempt to ensure buffers won't conflict, but
    also reduces the chance that the buffers will. This will make performance
    more consistent, albeit slower than "optimal" (which is near impossible
    to attain in a general-purpose kernel).  That's better than forcing
    users to deploy remedies like:
        "To eliminate this gradual degradation, we have added a Stream
         measurement to the Node Health Check that follows each job;
         nodes are rebooted whenever their measured memory bandwidth
         falls below 300 GB/s."

A replacement for zonesort was merged upstream in commit cc9aec03e5
("x86/numa_emulation: Introduce uniform split capability").  With this
numa_emulation capability, memory can be split into cache sized
("near-memory" sized) numa nodes.  A bind operation to such a node, and
disabling workloads on other nodes, enables full cache performance.
However, once the workload exceeds the cache size then cache conflicts
are unavoidable.  While HPC environments might be able to tolerate
time-scheduling of cache sized workloads, for general purpose server
platforms, the oversubscribed cache case will be the common case.

The worst case scenario is that a server system owner benchmarks a
workload at boot with an un-contended cache only to see that performance
degrade over time, even below the average cache performance due to
excessive conflicts.  Randomization clips the peaks and fills in the
valleys of cache utilization to yield steady average performance.

Here are some performance impact details of the patches:

1/ An Intel internal synthetic memory bandwidth measurement tool, saw a
   3X speedup in a contrived case that tries to force cache conflicts.
   The contrived cased used the numa_emulation capability to force an
   instance of the benchmark to be run in two of the near-memory sized
   numa nodes.  If both instances were placed on the same emulated they
   would fit and cause zero conflicts.  While on separate emulated nodes
   without randomization they underutilized the cache and conflicted
   unnecessarily due to the in-order allocation per node.

2/ A well known Java server application benchmark was run with a heap
   size that exceeded cache size by 3X.  The cache conflict rate was 8%
   for the first run and degraded to 21% after page allocator aging.  With
   randomization enabled the rate levelled out at 11%.

3/ A MongoDB workload did not observe measurable difference in
   cache-conflict rates, but the overall throughput dropped by 7% with
   randomization in one case.

4/ Mel Gorman ran his suite of performance workloads with randomization
   enabled on platforms without a memory-side-cache and saw a mix of some
   improvements and some losses [3].

While there is potentially significant improvement for applications that
depend on low latency access across a wide working-set, the performance
may be negligible to negative for other workloads.  For this reason the
shuffle capability defaults to off unless a direct-mapped
memory-side-cache is detected.  Even then, the page_alloc.shuffle=0
parameter can be specified to disable the randomization on those systems.

Outside of memory-side-cache utilization concerns there is potentially
security benefit from randomization.  Some data exfiltration and
return-oriented-programming attacks rely on the ability to infer the
location of sensitive data objects.  The kernel page allocator, especially
early in system boot, has predictable first-in-first out behavior for
physical pages.  Pages are freed in physical address order when first
onlined.

Quoting Kees:
    "While we already have a base-address randomization
     (CONFIG_RANDOMIZE_MEMORY), attacks against the same hardware and
     memory layouts would certainly be using the predictability of
     allocation ordering (i.e. for attacks where the base address isn't
     important: only the relative positions between allocated memory).
     This is common in lots of heap-style attacks. They try to gain
     control over ordering by spraying allocations, etc.

     I'd really like to see this because it gives us something similar
     to CONFIG_SLAB_FREELIST_RANDOM but for the page allocator."

While SLAB_FREELIST_RANDOM reduces the predictability of some local slab
caches it leaves vast bulk of memory to be predictably in order allocated.
However, it should be noted, the concrete security benefits are hard to
quantify, and no known CVE is mitigated by this randomization.

Introduce shuffle_free_memory(), and its helper shuffle_zone(), to perform
a Fisher-Yates shuffle of the page allocator 'free_area' lists when they
are initially populated with free memory at boot and at hotplug time.  Do
this based on either the presence of a page_alloc.shuffle=Y command line
parameter, or autodetection of a memory-side-cache (to be added in a
follow-on patch).

The shuffling is done in terms of CONFIG_SHUFFLE_PAGE_ORDER sized free
pages where the default CONFIG_SHUFFLE_PAGE_ORDER is MAX_ORDER-1 i.e.  10,
4MB this trades off randomization granularity for time spent shuffling.
MAX_ORDER-1 was chosen to be minimally invasive to the page allocator
while still showing memory-side cache behavior improvements, and the
expectation that the security implications of finer granularity
randomization is mitigated by CONFIG_SLAB_FREELIST_RANDOM.  The
performance impact of the shuffling appears to be in the noise compared to
other memory initialization work.

This initial randomization can be undone over time so a follow-on patch is
introduced to inject entropy on page free decisions.  It is reasonable to
ask if the page free entropy is sufficient, but it is not enough due to
the in-order initial freeing of pages.  At the start of that process
putting page1 in front or behind page0 still keeps them close together,
page2 is still near page1 and has a high chance of being adjacent.  As
more pages are added ordering diversity improves, but there is still high
page locality for the low address pages and this leads to no significant
impact to the cache conflict rate.

[1]: https://itpeernetwork.intel.com/intel-optane-dc-persistent-memory-operating-modes/
[2]: https://lkml.kernel.org/r/AT5PR8401MB1169D656C8B5E121752FC0F8AB120@AT5PR8401MB1169.NAMPRD84.PROD.OUTLOOK.COM
[3]: https://lkml.org/lkml/2018/10/12/309

[dan.j.williams@intel.com: fix shuffle enable]
  Link: http://lkml.kernel.org/r/154943713038.3858443.4125180191382062871.stgit@dwillia2-desk3.amr.corp.intel.com
[cai@lca.pw: fix SHUFFLE_PAGE_ALLOCATOR help texts]
  Link: http://lkml.kernel.org/r/20190425201300.75650-1-cai@lca.pw
Link: http://lkml.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Robert Elliott <elliott@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 19:52:48 -07:00
David Hildenbrand
ac5c942645 mm/memory_hotplug: make __remove_pages() and arch_remove_memory() never fail 
All callers of arch_remove_memory() ignore errors.  And we should really
try to remove any errors from the memory removal path.  No more errors are
reported from __remove_pages().  BUG() in s390x code in case
arch_remove_memory() is triggered.  We may implement that properly later.
WARN in case powerpc code failed to remove the section mapping, which is
better than ignoring the error completely right now.

Link: http://lkml.kernel.org/r/20190409100148.24703-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 09:47:50 -07:00
David Hildenbrand
9d1d887d78 mm/memory_hotplug: make __remove_section() never fail 
Let's just warn in case a section is not valid instead of failing to
remove somewhere in the middle of the process, returning an error that
will be mostly ignored by callers.

Link: http://lkml.kernel.org/r/20190409100148.24703-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 09:47:49 -07:00
David Hildenbrand
cb7b3a3685 mm/memory_hotplug: make unregister_memory_section() never fail 
Failing while removing memory is mostly ignored and cannot really be
handled.  Let's treat errors in unregister_memory_section() in a nice way,
warning, but continuing.

Link: http://lkml.kernel.org/r/20190409100148.24703-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2019-05-14 09:47:49 -07:00