Patch series "mm: fix memory to node bad links in sysfs", v3.
Sometimes, firmware may expose interleaved memory layout like this:
Early memory node ranges
node 1: [mem 0x0000000000000000-0x000000011fffffff]
node 2: [mem 0x0000000120000000-0x000000014fffffff]
node 1: [mem 0x0000000150000000-0x00000001ffffffff]
node 0: [mem 0x0000000200000000-0x000000048fffffff]
node 2: [mem 0x0000000490000000-0x00000007ffffffff]
In that case, we can see memory blocks assigned to multiple nodes in
sysfs:
$ ls -l /sys/devices/system/memory/memory21
total 0
lrwxrwxrwx 1 root root 0 Aug 24 05:27 node1 -> ../../node/node1
lrwxrwxrwx 1 root root 0 Aug 24 05:27 node2 -> ../../node/node2
-rw-r--r-- 1 root root 65536 Aug 24 05:27 online
-r--r--r-- 1 root root 65536 Aug 24 05:27 phys_device
-r--r--r-- 1 root root 65536 Aug 24 05:27 phys_index
drwxr-xr-x 2 root root 0 Aug 24 05:27 power
-r--r--r-- 1 root root 65536 Aug 24 05:27 removable
-rw-r--r-- 1 root root 65536 Aug 24 05:27 state
lrwxrwxrwx 1 root root 0 Aug 24 05:25 subsystem -> ../../../../bus/memory
-rw-r--r-- 1 root root 65536 Aug 24 05:25 uevent
-r--r--r-- 1 root root 65536 Aug 24 05:27 valid_zones
The same applies in the node's directory with a memory21 link in both
the node1 and node2's directory.
This is wrong but doesn't prevent the system to run. However when
later, one of these memory blocks is hot-unplugged and then hot-plugged,
the system is detecting an inconsistency in the sysfs layout and a
BUG_ON() is raised:
kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084!
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4
CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25
Call Trace:
add_memory_resource+0x23c/0x340 (unreliable)
__add_memory+0x5c/0xf0
dlpar_add_lmb+0x1b4/0x500
dlpar_memory+0x1f8/0xb80
handle_dlpar_errorlog+0xc0/0x190
dlpar_store+0x198/0x4a0
kobj_attr_store+0x30/0x50
sysfs_kf_write+0x64/0x90
kernfs_fop_write+0x1b0/0x290
vfs_write+0xe8/0x290
ksys_write+0xdc/0x130
system_call_exception+0x160/0x270
system_call_common+0xf0/0x27c
This has been seen on PowerPC LPAR.
The root cause of this issue is that when node's memory is registered,
the range used can overlap another node's range, thus the memory block
is registered to multiple nodes in sysfs.
There are two issues here:
(a) The sysfs memory and node's layouts are broken due to these
multiple links
(b) The link errors in link_mem_sections() should not lead to a system
panic.
To address (a) register_mem_sect_under_node should not rely on the
system state to detect whether the link operation is triggered by a hot
plug operation or not. This is addressed by the patches 1 and 2 of this
series.
Issue (b) will be addressed separately.
This patch (of 2):
The memmap_context enum is used to detect whether a memory operation is
due to a hot-add operation or happening at boot time.
Make it general to the hotplug operation and rename it as
meminit_context.
There is no functional change introduced by this patch
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200915094143.79181-1-ldufour@linux.ibm.com
Link: https://lkml.kernel.org/r/20200915132624.9723-1-ldufour@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
PageTransHuge returns true for both thp and hugetlb, so thp stats was
counting both thp and hugetlb migrations. Exclude hugetlb migration by
setting is_thp variable right.
Clean up thp handling code too when we are there.
Fixes: 1a5bae25e3 ("mm/vmstat: add events for THP migration without split")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lkml.kernel.org/r/20200917210413.1462975-1-zi.yan@sent.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently to make sure that every page table entry is read just once
gup_fast walks perform READ_ONCE and pass pXd value down to the next
gup_pXd_range function by value e.g.:
static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
unsigned int flags, struct page **pages, int *nr)
...
pudp = pud_offset(&p4d, addr);
This function passes a reference on that local value copy to pXd_offset,
and might get the very same pointer in return. This happens when the
level is folded (on most arches), and that pointer should not be
iterated.
On s390 due to the fact that each task might have different 5,4 or
3-level address translation and hence different levels folded the logic
is more complex and non-iteratable pointer to a local copy leads to
severe problems.
Here is an example of what happens with gup_fast on s390, for a task
with 3-level paging, crossing a 2 GB pud boundary:
// addr = 0x1007ffff000, end = 0x10080001000
static int gup_pud_range(p4d_t p4d, unsigned long addr, unsigned long end,
unsigned int flags, struct page **pages, int *nr)
{
unsigned long next;
pud_t *pudp;
// pud_offset returns &p4d itself (a pointer to a value on stack)
pudp = pud_offset(&p4d, addr);
do {
// on second iteratation reading "random" stack value
pud_t pud = READ_ONCE(*pudp);
// next = 0x10080000000, due to PUD_SIZE/MASK != PGDIR_SIZE/MASK on s390
next = pud_addr_end(addr, end);
...
} while (pudp++, addr = next, addr != end); // pudp++ iterating over stack
return 1;
}
This happens since s390 moved to common gup code with commit
d1874a0c28 ("s390/mm: make the pxd_offset functions more robust") and
commit 1a42010cdc ("s390/mm: convert to the generic
get_user_pages_fast code").
s390 tried to mimic static level folding by changing pXd_offset
primitives to always calculate top level page table offset in pgd_offset
and just return the value passed when pXd_offset has to act as folded.
What is crucial for gup_fast and what has been overlooked is that
PxD_SIZE/MASK and thus pXd_addr_end should also change correspondingly.
And the latter is not possible with dynamic folding.
To fix the issue in addition to pXd values pass original pXdp pointers
down to gup_pXd_range functions. And introduce pXd_offset_lockless
helpers, which take an additional pXd entry value parameter. This has
already been discussed in
https://lkml.kernel.org/r/20190418100218.0a4afd51@mschwideX1
Fixes: 1a42010cdc ("s390/mm: convert to the generic get_user_pages_fast code")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: <stable@vger.kernel.org> [5.2+]
Link: https://lkml.kernel.org/r/patch.git-943f1e5dcff2.your-ad-here.call-01599856292-ext-8676@work.hours
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We forget to add the suffix to the workingset_restore string, so fix it.
And also update the documentation of cgroup-v2.rst.
Fixes: 170b04b7ae ("mm/workingset: prepare the workingset detection infrastructure for anon LRU")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/20200916100030.71698-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SWP_FS is used to make swap_{read,write}page() go through the
filesystem, and it's only used for swap files over NFS. So, !SWP_FS
means non NFS for now, it could be either file backed or device backed.
Something similar goes with legacy SWP_FILE.
So in order to achieve the goal of the original patch, SWP_BLKDEV should
be used instead.
FS corruption can be observed with SSD device + XFS + fragmented
swapfile due to CONFIG_THP_SWAP=y.
I reproduced the issue with the following details:
Environment:
QEMU + upstream kernel + buildroot + NVMe (2 GB)
Kernel config:
CONFIG_BLK_DEV_NVME=y
CONFIG_THP_SWAP=y
Some reproducible steps:
mkfs.xfs -f /dev/nvme0n1
mkdir /tmp/mnt
mount /dev/nvme0n1 /tmp/mnt
bs="32k"
sz="1024m" # doesn't matter too much, I also tried 16m
xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
xfs_io -f -c "pwrite -F -S 0 -b $bs 0 $sz" -c "fdatasync" /tmp/mnt/sw
xfs_io -f -c "pwrite -R -b $bs 0 $sz" -c "fsync" /tmp/mnt/sw
mkswap /tmp/mnt/sw
swapon /tmp/mnt/sw
stress --vm 2 --vm-bytes 600M # doesn't matter too much as well
Symptoms:
- FS corruption (e.g. checksum failure)
- memory corruption at: 0xd2808010
- segfault
Fixes: f0eea189e8 ("mm, THP, swap: Don't allocate huge cluster for file backed swap device")
Fixes: 38d8b4e6bd ("mm, THP, swap: delay splitting THP during swap out")
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Carlos Maiolino <cmaiolino@redhat.com>
Cc: Eric Sandeen <esandeen@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200820045323.7809-1-hsiangkao@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 09854ba94c ("mm: do_wp_page() simplification") reorganized all
the code around the page re-use vs copy, but in the process also moved
the final unlock_page() around to after the wp_page_reuse() call.
That normally doesn't matter - but it means that the unlock_page() is
now done after releasing the page table lock. Again, not a big deal,
you'd think.
But it turns out that it's very wrong indeed, because once we've
released the page table lock, we've basically lost our only reference to
the page - the page tables - and it could now be free'd at any time. We
do hold the mmap_sem, so no actual unmap() can happen, but madvise can
come in and a MADV_DONTNEED will zap the page range - and free the page.
So now the page may be free'd just as we're unlocking it, which in turn
will usually trigger a "Bad page state" error in the freeing path. To
make matters more confusing, by the time the debug code prints out the
page state, the unlock has typically completed and everything looks fine
again.
This all doesn't happen in any normal situations, but it does trigger
with the dirtyc0w_child LTP test. And it seems to trigger much more
easily (but not expclusively) on s390 than elsewhere, probably because
s390 doesn't do the "batch pages up for freeing after the TLB flush"
that gives the unlock_page() more time to complete and makes the race
harder to hit.
Fixes: 09854ba94c ("mm: do_wp_page() simplification")
Link: https://lore.kernel.org/lkml/a46e9bbef2ed4e17778f5615e818526ef848d791.camel@redhat.com/
Link: https://lore.kernel.org/linux-mm/c41149a8-211e-390b-af1d-d5eee690fecb@linux.alibaba.com/
Reported-by: Qian Cai <cai@redhat.com>
Reported-by: Alex Shi <alex.shi@linux.alibaba.com>
Bisected-and-analyzed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Tested-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This completes the split of the non-present and present pte cases by
moving the check for the source pte being present into the single
caller, which also means that we clearly separate out the very different
return value case for a non-present pte.
The present pte case currently always succeeds.
This is a pure code re-organization with no semantic change: the intent
is to make it much easier to add a new return case to the present pte
case for when we do early COW at page table copy time.
This was split out from the previous commit simply to make it easy to
visually see that there were no semantic changes from this code
re-organization.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a purely mechanical split of the copy_one_pte() function. It's
not immediately obvious when looking at the diff because of the
indentation change, but the way to see what is going on in this commit
is to use the "-w" flag to not show pure whitespace changes, and you see
how the first part of copy_one_pte() is simply lifted out into a
separate function.
And since the non-present case is marked unlikely, don't make the new
function be inlined. Not that gcc really seems to care, since it looks
like it will inline it anyway due to the whole "single callsite for
static function" logic. In fact, code generation with the function
split is almost identical to before. But not marking it inline is the
right thing to do.
This is pure prep-work and cleanup for subsequent changes.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a race during page offline that can lead to infinite loop:
a page never ends up on a buddy list and __offline_pages() keeps
retrying infinitely or until a termination signal is received.
Thread#1 - a new process:
load_elf_binary
begin_new_exec
exec_mmap
mmput
exit_mmap
tlb_finish_mmu
tlb_flush_mmu
release_pages
free_unref_page_list
free_unref_page_prepare
set_pcppage_migratetype(page, migratetype);
// Set page->index migration type below MIGRATE_PCPTYPES
Thread#2 - hot-removes memory
__offline_pages
start_isolate_page_range
set_migratetype_isolate
set_pageblock_migratetype(page, MIGRATE_ISOLATE);
Set migration type to MIGRATE_ISOLATE-> set
drain_all_pages(zone);
// drain per-cpu page lists to buddy allocator.
Thread#1 - continue
free_unref_page_commit
migratetype = get_pcppage_migratetype(page);
// get old migration type
list_add(&page->lru, &pcp->lists[migratetype]);
// add new page to already drained pcp list
Thread#2
Never drains pcp again, and therefore gets stuck in the loop.
The fix is to try to drain per-cpu lists again after
check_pages_isolated_cb() fails.
Fixes: c52e75935f ("mm: remove extra drain pages on pcp list")
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200903140032.380431-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20200904151448.100489-2-pasha.tatashin@soleen.com
Link: http://lkml.kernel.org/r/20200904070235.GA15277@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A migrating transparent huge page has to already be unmapped. Otherwise,
the page could be modified while it is being copied to a new page and data
could be lost. The function __split_huge_pmd() checks for a PMD migration
entry before calling __split_huge_pmd_locked() leading one to think that
__split_huge_pmd_locked() can handle splitting a migrating PMD.
However, the code always increments the page->_mapcount and adjusts the
memory control group accounting assuming the page is mapped.
Also, if the PMD entry is a migration PMD entry, the call to
is_huge_zero_pmd(*pmd) is incorrect because it calls pmd_pfn(pmd) instead
of migration_entry_to_pfn(pmd_to_swp_entry(pmd)). Fix these problems by
checking for a PMD migration entry.
Fixes: 84c3fc4e9c ("mm: thp: check pmd migration entry in common path")
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org> [4.14+]
Link: https://lkml.kernel.org/r/20200903183140.19055-1-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit e809d5f0b5 ("tmpfs: per-superblock i_ino support") made changes
to shmem_reserve_inode() in mm/shmem.c, however the original test for
(sbinfo->max_inodes) got dropped. This causes mounting tmpfs with option
nr_inodes=0 to fail:
# mount -ttmpfs -onr_inodes=0 none /ext0
mount: /ext0: mount(2) system call failed: Cannot allocate memory.
This patch restores the nr_inodes=0 functionality.
Fixes: e809d5f0b5 ("tmpfs: per-superblock i_ino support")
Signed-off-by: Byron Stanoszek <gandalf@winds.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Chris Down <chris@chrisdown.name>
Link: https://lkml.kernel.org/r/20200902035715.16414-1-gandalf@winds.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
5.8 commit 5d91f31faf ("mm: swap: fix vmstats for huge page") has
established that vm_events should count every subpage of a THP, including
unevictable_pgs_culled and unevictable_pgs_rescued; but
lru_cache_add_inactive_or_unevictable() was not doing so for
unevictable_pgs_mlocked, and mm/mlock.c was not doing so for
unevictable_pgs mlocked, munlocked, cleared and stranded.
Fix them; but THPs don't go the pagevec way in mlock.c, so no fixes needed
on that path.
Fixes: 5d91f31faf ("mm: swap: fix vmstats for huge page")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301408230.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
check_move_unevictable_pages() is used in making unevictable shmem pages
evictable: by shmem_unlock_mapping(), drm_gem_check_release_pagevec() and
i915/gem check_release_pagevec(). Those may pass down subpages of a huge
page, when /sys/kernel/mm/transparent_hugepage/shmem_enabled is "force".
That does not crash or warn at present, but the accounting of vmstats
unevictable_pgs_scanned and unevictable_pgs_rescued is inconsistent:
scanned being incremented on each subpage, rescued only on the head (since
tails already appear evictable once the head has been updated).
5.8 commit 5d91f31faf ("mm: swap: fix vmstats for huge page") has
established that vm_events in general (and unevictable_pgs_rescued in
particular) should count every subpage: so follow that precedent here.
Do this in such a way that if mem_cgroup_page_lruvec() is made stricter
(to check page->mem_cgroup is always set), no problem: skip the tails
before calling it, and add thp_nr_pages() to vmstats on the head.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301405000.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hugetlbfs pages do not participate in memcg: so although they do find most
of migrate_page_states() useful, it would be better if they did not call
into mem_cgroup_migrate() - where Qian Cai reported that LTP's
move_pages12 triggers the warning in Alex Shi's prospective commit
"mm/memcg: warning on !memcg after readahead page charged".
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxch.org>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301359460.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm: fixes to past from future testing".
Here's a set of independent fixes against 5.9-rc2: prompted by
testing Alex Shi's "warning on !memcg" and lru_lock series, but
I think fit for 5.9 - though maybe only the first for stable.
This patch (of 5):
In 5.8 some instances of memcg charging in do_swap_page() and unuse_pte()
were removed, on the understanding that swap cache is now already charged
at those points; but a case was missed, when ksm_might_need_to_copy() has
decided it must allocate a substitute page: such pages were never charged.
Fix it inside ksm_might_need_to_copy().
This was discovered by Alex Shi's prospective commit "mm/memcg: warning on
!memcg after readahead page charged".
But there is a another surprise: this also fixes some rarer uncharged
PageAnon cases, when KSM is configured in, but has never been activated.
ksm_might_need_to_copy()'s anon_vma->root and linear_page_index() check
sometimes catches a case which would need to have been copied if KSM were
turned on. Or that's my optimistic interpretation (of my own old code),
but it leaves some doubt as to whether everything is working as intended
there - might it hint at rare anon ptes which rmap cannot find? A
question not easily answered: put in the fix for missed memcg charges.
Cc; Matthew Wilcox <willy@infradead.org>
Fixes: 4c6355b25e ("mm: memcontrol: charge swapin pages on instantiation")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org> [5.8]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301343270.5954@eggly.anvils
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301358020.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull percpu fix from Dennis Zhou:
"This is a fix for the first chunk size calculation where the variable
length array incorrectly used the number of longs instead of bytes of
longs.
This came in as a code fix and not a bug report, so I don't think it
was widely problematic. I believe it worked out due to it being
memblock memory and alignment requirements working in our favor"
* 'for-5.9-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
percpu: fix first chunk size calculation for populated bitmap
Variable populated, which is a member of struct pcpu_chunk, is used as a
unit of size of unsigned long.
However, size of populated is miscounted. So, I fix this minor part.
Fixes: 8ab16c43ea ("percpu: change the number of pages marked in the first_chunk pop bitmap")
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Sunghyun Jin <mcsmonk@gmail.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Commit 2a9127fcf2 ("mm: rewrite wait_on_page_bit_common() logic") made
the page locking entirely fair, in that if a waiter came in while the
lock was held, the lock would be transferred to the lockers strictly in
order.
That was intended to finally get rid of the long-reported watchdog
failures that involved the page lock under extreme load, where a process
could end up waiting essentially forever, as other page lockers stole
the lock from under it.
It also improved some benchmarks, but it ended up causing huge
performance regressions on others, simply because fair lock behavior
doesn't end up giving out the lock as aggressively, causing better
worst-case latency, but potentially much worse average latencies and
throughput.
Instead of reverting that change entirely, this introduces a controlled
amount of unfairness, with a sysctl knob to tune it if somebody needs
to. But the default value should hopefully be good for any normal load,
allowing a few rounds of lock stealing, but enforcing the strict
ordering before the lock has been stolen too many times.
There is also a hint from Matthieu Baerts that the fair page coloring
may end up exposing an ABBA deadlock that is hidden by the usual
optimistic lock stealing, and while the unfairness doesn't fix the
fundamental issue (and I'm still looking at that), it avoids it in
practice.
The amount of unfairness can be modified by writing a new value to the
'sysctl_page_lock_unfairness' variable (default value of 5, exposed
through /proc/sys/vm/page_lock_unfairness), but that is hopefully
something we'd use mainly for debugging rather than being necessary for
any deep system tuning.
This whole issue has exposed just how critical the page lock can be, and
how contended it gets under certain locks. And the main contention
doesn't really seem to be anything related to IO (which was the origin
of this lock), but for things like just verifying that the page file
mapping is stable while faulting in the page into a page table.
Link: https://lore.kernel.org/linux-fsdevel/ed8442fd-6f54-dd84-cd4a-941e8b7ee603@MichaelLarabel.com/
Link: https://www.phoronix.com/scan.php?page=article&item=linux-50-59&num=1
Link: https://lore.kernel.org/linux-fsdevel/c560a38d-8313-51fb-b1ec-e904bd8836bc@tessares.net/
Reported-and-tested-by: Michael Larabel <Michael@michaellarabel.com>
Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip
Pull xen updates from Juergen Gross:
"A small series for fixing a problem with Xen PVH guests when running
as backends (e.g. as dom0).
Mapping other guests' memory is now working via ZONE_DEVICE, thus not
requiring to abuse the memory hotplug functionality for that purpose"
* tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: add helpers to allocate unpopulated memory
memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC
xen/balloon: add header guard
Merge misc fixes from Andrew Morton:
"19 patches.
Subsystems affected by this patch series: MAINTAINERS, ipc, fork,
checkpatch, lib, and mm (memcg, slub, pagemap, madvise, migration,
hugetlb)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
include/linux/log2.h: add missing () around n in roundup_pow_of_two()
mm/khugepaged.c: fix khugepaged's request size in collapse_file
mm/hugetlb: fix a race between hugetlb sysctl handlers
mm/hugetlb: try preferred node first when alloc gigantic page from cma
mm/migrate: preserve soft dirty in remove_migration_pte()
mm/migrate: remove unnecessary is_zone_device_page() check
mm/rmap: fixup copying of soft dirty and uffd ptes
mm/migrate: fixup setting UFFD_WP flag
mm: madvise: fix vma user-after-free
checkpatch: fix the usage of capture group ( ... )
fork: adjust sysctl_max_threads definition to match prototype
ipc: adjust proc_ipc_sem_dointvec definition to match prototype
mm: track page table modifications in __apply_to_page_range()
MAINTAINERS: IA64: mark Status as Odd Fixes only
MAINTAINERS: add LLVM maintainers
MAINTAINERS: update Cavium/Marvell entries
mm: slub: fix conversion of freelist_corrupted()
mm: memcg: fix memcg reclaim soft lockup
memcg: fix use-after-free in uncharge_batch
collapse_file() in khugepaged passes PAGE_SIZE as the number of pages to
be read to page_cache_sync_readahead(). The intent was probably to read
a single page. Fix it to use the number of pages to the end of the
window instead.
Fixes: 99cb0dbd47 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Eric Biggers <ebiggers@google.com>
Link: https://lkml.kernel.org/r/20200903140844.14194-2-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a race between the assignment of `table->data` and write value
to the pointer of `table->data` in the __do_proc_doulongvec_minmax() on
the other thread.
CPU0: CPU1:
proc_sys_write
hugetlb_sysctl_handler proc_sys_call_handler
hugetlb_sysctl_handler_common hugetlb_sysctl_handler
table->data = &tmp; hugetlb_sysctl_handler_common
table->data = &tmp;
proc_doulongvec_minmax
do_proc_doulongvec_minmax sysctl_head_finish
__do_proc_doulongvec_minmax unuse_table
i = table->data;
*i = val; // corrupt CPU1's stack
Fix this by duplicating the `table`, and only update the duplicate of
it. And introduce a helper of proc_hugetlb_doulongvec_minmax() to
simplify the code.
The following oops was seen:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
Code: Bad RIP value.
...
Call Trace:
? set_max_huge_pages+0x3da/0x4f0
? alloc_pool_huge_page+0x150/0x150
? proc_doulongvec_minmax+0x46/0x60
? hugetlb_sysctl_handler_common+0x1c7/0x200
? nr_hugepages_store+0x20/0x20
? copy_fd_bitmaps+0x170/0x170
? hugetlb_sysctl_handler+0x1e/0x20
? proc_sys_call_handler+0x2f1/0x300
? unregister_sysctl_table+0xb0/0xb0
? __fd_install+0x78/0x100
? proc_sys_write+0x14/0x20
? __vfs_write+0x4d/0x90
? vfs_write+0xef/0x240
? ksys_write+0xc0/0x160
? __ia32_sys_read+0x50/0x50
? __close_fd+0x129/0x150
? __x64_sys_write+0x43/0x50
? do_syscall_64+0x6c/0x200
? entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: e5ff215941 ("hugetlb: multiple hstates for multiple page sizes")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/20200828031146.43035-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit cf11e85fc0 ("mm: hugetlb: optionally allocate gigantic
hugepages using cma"), the gigantic page would be allocated from node
which is not the preferred node, although there are pages available from
that node. The reason is that the nid parameter has been ignored in
alloc_gigantic_page().
Besides, the __GFP_THISNODE also need be checked if user required to
alloc only from the preferred node.
After this patch, the preferred node is tried first before other allowed
nodes, and don't try to allocate from other nodes if __GFP_THISNODE is
specified. If user don't specify the preferred node, the current node
will be used as preferred node, which makes sure consistent behavior of
allocating gigantic and non-gigantic hugetlb page.
Fixes: cf11e85fc0 ("mm: hugetlb: optionally allocate gigantic hugepages using cma")
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Link: https://lkml.kernel.org/r/20200902025016.697260-1-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The code to remove a migration PTE and replace it with a device private
PTE was not copying the soft dirty bit from the migration entry. This
could lead to page contents not being marked dirty when faulting the page
back from device private memory.
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Link: https://lkml.kernel.org/r/20200831212222.22409-3-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/migrate: preserve soft dirty in remove_migration_pte()".
I happened to notice this from code inspection after seeing Alistair
Popple's patch ("mm/rmap: Fixup copying of soft dirty and uffd ptes").
This patch (of 2):
The check for is_zone_device_page() and is_device_private_page() is
unnecessary since the latter is sufficient to determine if the page is a
device private page. Simplify the code for easier reading.
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Link: https://lkml.kernel.org/r/20200831212222.22409-1-rcampbell@nvidia.com
Link: https://lkml.kernel.org/r/20200831212222.22409-2-rcampbell@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During memory migration a pte is temporarily replaced with a migration
swap pte. Some pte bits from the existing mapping such as the soft-dirty
and uffd write-protect bits are preserved by copying these to the
temporary migration swap pte.
However these bits are not stored at the same location for swap and
non-swap ptes. Therefore testing these bits requires using the
appropriate helper function for the given pte type.
Unfortunately several code locations were found where the wrong helper
function is being used to test soft_dirty and uffd_wp bits which leads to
them getting incorrectly set or cleared during page-migration.
Fix these by using the correct tests based on pte type.
Fixes: a5430dda8a ("mm/migrate: support un-addressable ZONE_DEVICE page in migration")
Fixes: 8c3328f1f3 ("mm/migrate: migrate_vma() unmap page from vma while collecting pages")
Fixes: f45ec5ff16 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Alistair Popple <alistair@popple.id.au>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200825064232.10023-2-alistair@popple.id.au
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit f45ec5ff16 ("userfaultfd: wp: support swap and page migration")
introduced support for tracking the uffd wp bit during page migration.
However the non-swap PTE variant was used to set the flag for zone device
private pages which are a type of swap page.
This leads to corruption of the swap offset if the original PTE has the
uffd_wp flag set.
Fixes: f45ec5ff16 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Link: https://lkml.kernel.org/r/20200825064232.10023-1-alistair@popple.id.au
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 52f2347808 ("mm/slub.c: fix corrupted freechain in
deactivate_slab()") suffered an update when picked up from LKML [1].
Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()'
created a no-op statement. Fix it by sticking to the behavior intended
in the original patch [1]. In addition, make freelist_corrupted()
immune to passing NULL instead of &freelist.
The issue has been spotted via static analysis and code review.
[1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@oracle.com/
Fixes: 52f2347808 ("mm/slub.c: fix corrupted freechain in deactivate_slab()")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dongli Zhang <dongli.zhang@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200824130643.10291-1-erosca@de.adit-jv.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg
doesn't have any reclaimable memory.
It can be easily reproduced as below:
watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204]
CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12
Call Trace:
shrink_lruvec+0x49f/0x640
shrink_node+0x2a6/0x6f0
do_try_to_free_pages+0xe9/0x3e0
try_to_free_mem_cgroup_pages+0xef/0x1f0
try_charge+0x2c1/0x750
mem_cgroup_charge+0xd7/0x240
__add_to_page_cache_locked+0x2fd/0x370
add_to_page_cache_lru+0x4a/0xc0
pagecache_get_page+0x10b/0x2f0
filemap_fault+0x661/0xad0
ext4_filemap_fault+0x2c/0x40
__do_fault+0x4d/0xf9
handle_mm_fault+0x1080/0x1790
It only happens on our 1-vcpu instances, because there's no chance for
oom reaper to run to reclaim the to-be-killed process.
Add a cond_resched() at the upper shrink_node_memcgs() to solve this
issue, this will mean that we will get a scheduling point for each memcg
in the reclaimed hierarchy without any dependency on the reclaimable
memory in that memcg thus making it more predictable.
Suggested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
syzbot has reported an use-after-free in the uncharge_batch path
BUG: KASAN: use-after-free in instrument_atomic_write include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic64_sub_return include/asm-generic/atomic-instrumented.h:970 [inline]
BUG: KASAN: use-after-free in atomic_long_sub_return include/asm-generic/atomic-long.h:113 [inline]
BUG: KASAN: use-after-free in page_counter_cancel mm/page_counter.c:54 [inline]
BUG: KASAN: use-after-free in page_counter_uncharge+0x3d/0xc0 mm/page_counter.c:155
Write of size 8 at addr ffff8880371c0148 by task syz-executor.0/9304
CPU: 0 PID: 9304 Comm: syz-executor.0 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1f0/0x31e lib/dump_stack.c:118
print_address_description+0x66/0x620 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report+0x132/0x1d0 mm/kasan/report.c:530
check_memory_region_inline mm/kasan/generic.c:183 [inline]
check_memory_region+0x2b5/0x2f0 mm/kasan/generic.c:192
instrument_atomic_write include/linux/instrumented.h:71 [inline]
atomic64_sub_return include/asm-generic/atomic-instrumented.h:970 [inline]
atomic_long_sub_return include/asm-generic/atomic-long.h:113 [inline]
page_counter_cancel mm/page_counter.c:54 [inline]
page_counter_uncharge+0x3d/0xc0 mm/page_counter.c:155
uncharge_batch+0x6c/0x350 mm/memcontrol.c:6764
uncharge_page+0x115/0x430 mm/memcontrol.c:6796
uncharge_list mm/memcontrol.c:6835 [inline]
mem_cgroup_uncharge_list+0x70/0xe0 mm/memcontrol.c:6877
release_pages+0x13a2/0x1550 mm/swap.c:911
tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
tlb_flush_mmu+0x780/0x910 mm/mmu_gather.c:249
tlb_finish_mmu+0xcb/0x200 mm/mmu_gather.c:328
exit_mmap+0x296/0x550 mm/mmap.c:3185
__mmput+0x113/0x370 kernel/fork.c:1076
exit_mm+0x4cd/0x550 kernel/exit.c:483
do_exit+0x576/0x1f20 kernel/exit.c:793
do_group_exit+0x161/0x2d0 kernel/exit.c:903
get_signal+0x139b/0x1d30 kernel/signal.c:2743
arch_do_signal+0x33/0x610 arch/x86/kernel/signal.c:811
exit_to_user_mode_loop kernel/entry/common.c:135 [inline]
exit_to_user_mode_prepare+0x8d/0x1b0 kernel/entry/common.c:166
syscall_exit_to_user_mode+0x5e/0x1a0 kernel/entry/common.c:241
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Commit 1a3e1f4096 ("mm: memcontrol: decouple reference counting from
page accounting") reworked the memcg lifetime to be bound the the struct
page rather than charges. It also removed the css_put_many from
uncharge_batch and that is causing the above splat.
uncharge_batch() is supposed to uncharge accumulated charges for all
pages freed from the same memcg. The queuing is done by uncharge_page
which however drops the memcg reference after it adds charges to the
batch. If the current page happens to be the last one holding the
reference for its memcg then the memcg is OK to go and the next page to
be freed will trigger batched uncharge which needs to access the memcg
which is gone already.
Fix the issue by taking a reference for the memcg in the current batch.
Fixes: 1a3e1f4096 ("mm: memcontrol: decouple reference counting from page accounting")
Reported-by: syzbot+b305848212deec86eabe@syzkaller.appspotmail.com
Reported-by: syzbot+b5ea6fb6f139c8b9482b@syzkaller.appspotmail.com
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Hugh Dickins <hughd@google.com>
Link: https://lkml.kernel.org/r/20200820090341.GC5033@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge emailed patches from Peter Xu:
"This is a small series that I picked up from Linus's suggestion to
simplify cow handling (and also make it more strict) by checking
against page refcounts rather than mapcounts.
This makes uffd-wp work again (verified by running upmapsort)"
Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:
8 files changed, 29 insertions(+), 120 deletions(-)
The reason for the bad timing is that it turns out that commit
17839856fd ("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.
And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.
Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/
* emailed patches from Peter Xu <peterx@redhat.com>:
mm: Add PGREUSE counter
mm/gup: Remove enfornced COW mechanism
mm/ksm: Remove reuse_ksm_page()
mm: do_wp_page() simplification
This accounts for wp_page_reuse() case, where we reused a page for COW.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the more strict (but greatly simplified) page reuse logic in
do_wp_page(), we can safely go back to the world where cow is not
enforced with writes.
This essentially reverts commit 17839856fd ("gup: document and work
around 'COW can break either way' issue"). There are some context
differences due to some changes later on around it:
2170ecfa76 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03)
376a34efa4 ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03)
Some lines moved back and forth with those, but this revert patch should
have striped out and covered all the enforced cow bits anyways.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the function as the last reference has gone away with the do_wp_page()
changes.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
How about we just make sure we're the only possible valid user fo the
page before we bother to reuse it?
Simplify, simplify, simplify.
And get rid of the nasty serialization on the page lock at the same time.
[peterx: add subject prefix]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is in preparation for the logic behind MEMORY_DEVICE_DEVDAX also
being used by non DAX devices.
No functional change intended.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Link: https://lore.kernel.org/r/20200901083326.21264-3-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Merge gate page refcount fix from Dave Hansen:
"During the conversion over to pin_user_pages(), gate pages were missed.
The fix is pretty simple, and is accompanied by a new test from Andy
which probably would have caught this earlier"
* emailed patches from Dave Hansen <dave.hansen@linux.intel.com>:
selftests/x86/test_vsyscall: Improve the process_vm_readv() test
mm: fix pin vs. gup mismatch with gate pages
Gate pages were missed when converting from get to pin_user_pages().
This can lead to refcount imbalances. This is reliably and quickly
reproducible running the x86 selftests when vsyscall=emulate is enabled
(the default). Fix by using try_grab_page() with appropriate flags
passed.
The long story:
Today, pin_user_pages() and get_user_pages() are similar interfaces for
manipulating page reference counts. However, "pins" use a "bias" value
and manipulate the actual reference count by 1024 instead of 1 used by
plain "gets".
That means that pin_user_pages() must be matched with unpin_user_pages()
and can't be mixed with a plain put_user_pages() or put_page().
Enter gate pages, like the vsyscall page. They are pages usually in the
kernel image, but which are mapped to userspace. Userspace is allowed
access to them, including interfaces using get/pin_user_pages(). The
refcount of these kernel pages is manipulated just like a normal user
page on the get/pin side so that the put/unpin side can work the same
for normal user pages or gate pages.
get_gate_page() uses try_get_page() which only bumps the refcount by
1, not 1024, even if called in the pin_user_pages() path. If someone
pins a gate page, this happens:
pin_user_pages()
get_gate_page()
try_get_page() // bump refcount +1
... some time later
unpin_user_pages()
page_ref_sub_and_test(page, 1024))
... and boom, we get a refcount off by 1023. This is reliably and
quickly reproducible running the x86 selftests when booted with
vsyscall=emulate (the default). The selftests use ptrace(), but I
suspect anything using pin_user_pages() on gate pages could hit this.
To fix it, simply use try_grab_page() instead of try_get_page(), and
pass 'gup_flags' in so that FOLL_PIN can be respected.
This bug traces back to the very beginning of the FOLL_PIN support in
commit 3faa52c03f ("mm/gup: track FOLL_PIN pages"), which showed up in
the 5.7 release.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: 3faa52c03f ("mm/gup: track FOLL_PIN pages")
Reported-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org
Cc: Jann Horn <jannh@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert our removal of PROT_SAO, at least one user expressed an interest in using
it on Power9. Instead don't allow it to be used in guests unless enabled
explicitly at compile time.
A fix for a crash introduced by a recent change to FP handling.
Revert a change to our idle code that left Power10 with no idle support.
One minor fix for the new scv system call path to set PPR.
Fix a crash in our "generic" PMU if branch stack events were enabled.
A fix for the IMC PMU, to correctly identify host kernel samples.
The ADB_PMU powermac code was found to be incompatible with VMAP_STACK, so make
them incompatible in Kconfig until the code can be fixed.
A build fix in drivers/video/fbdev/controlfb.c, and a documentation fix.
Thanks to:
Alexey Kardashevskiy, Athira Rajeev, Christophe Leroy, Giuseppe Sacco,
Madhavan Srinivasan, Milton Miller, Nicholas Piggin, Pratik Rajesh Sampat,
Randy Dunlap, Shawn Anastasio, Vaidyanathan Srinivasan.
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Merge tag 'powerpc-5.9-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
- Revert our removal of PROT_SAO, at least one user expressed an
interest in using it on Power9. Instead don't allow it to be used in
guests unless enabled explicitly at compile time.
- A fix for a crash introduced by a recent change to FP handling.
- Revert a change to our idle code that left Power10 with no idle
support.
- One minor fix for the new scv system call path to set PPR.
- Fix a crash in our "generic" PMU if branch stack events were enabled.
- A fix for the IMC PMU, to correctly identify host kernel samples.
- The ADB_PMU powermac code was found to be incompatible with
VMAP_STACK, so make them incompatible in Kconfig until the code can
be fixed.
- A build fix in drivers/video/fbdev/controlfb.c, and a documentation
fix.
Thanks to Alexey Kardashevskiy, Athira Rajeev, Christophe Leroy,
Giuseppe Sacco, Madhavan Srinivasan, Milton Miller, Nicholas Piggin,
Pratik Rajesh Sampat, Randy Dunlap, Shawn Anastasio, Vaidyanathan
Srinivasan.
* tag 'powerpc-5.9-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/32s: Disable VMAP stack which CONFIG_ADB_PMU
Revert "powerpc/powernv/idle: Replace CPU feature check with PVR check"
powerpc/perf: Fix reading of MSR[HV/PR] bits in trace-imc
powerpc/perf: Fix crashes with generic_compat_pmu & BHRB
powerpc/64s: Fix crash in load_fp_state() due to fpexc_mode
powerpc/64s: scv entry should set PPR
Documentation/powerpc: fix malformed table in syscall64-abi
video: fbdev: controlfb: Fix build for COMPILE_TEST=y && PPC_PMAC=n
selftests/powerpc: Update PROT_SAO test to skip ISA 3.1
powerpc/64s: Disallow PROT_SAO in LPARs by default
Revert "powerpc/64s: Remove PROT_SAO support"
This reverts commit 5c9fa16e8a.
Since PROT_SAO can still be useful for certain classes of software,
reintroduce it. Concerns about guest migration for LPARs using SAO
will be addressed next.
Signed-off-by: Shawn Anastasio <shawn@anastas.io>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200821185558.35561-2-shawn@anastas.io
The following race is observed with the repeated online, offline and a
delay between two successive online of memory blocks of movable zone.
P1 P2
Online the first memory block in
the movable zone. The pcp struct
values are initialized to default
values,i.e., pcp->high = 0 &
pcp->batch = 1.
Allocate the pages from the
movable zone.
Try to Online the second memory
block in the movable zone thus it
entered the online_pages() but yet
to call zone_pcp_update().
This process is entered into
the exit path thus it tries
to release the order-0 pages
to pcp lists through
free_unref_page_commit().
As pcp->high = 0, pcp->count = 1
proceed to call the function
free_pcppages_bulk().
Update the pcp values thus the
new pcp values are like, say,
pcp->high = 378, pcp->batch = 63.
Read the pcp's batch value using
READ_ONCE() and pass the same to
free_pcppages_bulk(), pcp values
passed here are, batch = 63,
count = 1.
Since num of pages in the pcp
lists are less than ->batch,
then it will stuck in
while(list_empty(list)) loop
with interrupts disabled thus
a core hung.
Avoid this by ensuring free_pcppages_bulk() is called with proper count of
pcp list pages.
The mentioned race is some what easily reproducible without [1] because
pcp's are not updated for the first memory block online and thus there is
a enough race window for P2 between alloc+free and pcp struct values
update through onlining of second memory block.
With [1], the race still exists but it is very narrow as we update the pcp
struct values for the first memory block online itself.
This is not limited to the movable zone, it could also happen in cases
with the normal zone (e.g., hotplug to a node that only has DMA memory, or
no other memory yet).
[1]: https://patchwork.kernel.org/patch/11696389/
Fixes: 5f8dcc2121 ("page-allocator: split per-cpu list into one-list-per-migrate-type")
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: <stable@vger.kernel.org> [2.6+]
Link: http://lkml.kernel.org/r/1597150703-19003-1-git-send-email-charante@codeaurora.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The lowmem_reserve arrays provide a means of applying pressure against
allocations from lower zones that were targeted at higher zones. Its
values are a function of the number of pages managed by higher zones and
are assigned by a call to the setup_per_zone_lowmem_reserve() function.
The function is initially called at boot time by the function
init_per_zone_wmark_min() and may be called later by accesses of the
/proc/sys/vm/lowmem_reserve_ratio sysctl file.
The function init_per_zone_wmark_min() was moved up from a module_init to
a core_initcall to resolve a sequencing issue with khugepaged.
Unfortunately this created a sequencing issue with CMA page accounting.
The CMA pages are added to the managed page count of a zone when
cma_init_reserved_areas() is called at boot also as a core_initcall. This
makes it uncertain whether the CMA pages will be added to the managed page
counts of their zones before or after the call to
init_per_zone_wmark_min() as it becomes dependent on link order. With the
current link order the pages are added to the managed count after the
lowmem_reserve arrays are initialized at boot.
This means the lowmem_reserve values at boot may be lower than the values
used later if /proc/sys/vm/lowmem_reserve_ratio is accessed even if the
ratio values are unchanged.
In many cases the difference is not significant, but for example
an ARM platform with 1GB of memory and the following memory layout
cma: Reserved 256 MiB at 0x0000000030000000
Zone ranges:
DMA [mem 0x0000000000000000-0x000000002fffffff]
Normal empty
HighMem [mem 0x0000000030000000-0x000000003fffffff]
would result in 0 lowmem_reserve for the DMA zone. This would allow
userspace to deplete the DMA zone easily.
Funnily enough
$ cat /proc/sys/vm/lowmem_reserve_ratio
would fix up the situation because as a side effect it forces
setup_per_zone_lowmem_reserve.
This commit breaks the link order dependency by invoking
init_per_zone_wmark_min() as a postcore_initcall so that the CMA pages
have the chance to be properly accounted in their zone(s) and allowing
the lowmem_reserve arrays to receive consistent values.
Fixes: bc22af74f2 ("mm: update min_free_kbytes from khugepaged after core initialization")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1597423766-27849-1-git-send-email-opendmb@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The compilation with CONFIG_DEBUG_RODATA_TEST set produces the following
warning due to the missing include.
mm/rodata_test.c:15:6: warning: no previous prototype for 'rodata_test' [-Wmissing-prototypes]
15 | void rodata_test(void)
| ^~~~~~~~~~~
Fixes: 2959a5f726 ("mm: add arch-independent testcases for RODATA")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lkml.kernel.org/r/20200819080026.918134-1-leon@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Like zap_pte_range add cond_resched so that we can avoid softlockups as
reported below. On non-preemptible kernel with large I/O map region (like
the one we get when using persistent memory with sector mode), an unmap of
the namespace can report below softlockups.
22724.027334] watchdog: BUG: soft lockup - CPU#49 stuck for 23s! [ndctl:50777]
NIP [c0000000000dc224] plpar_hcall+0x38/0x58
LR [c0000000000d8898] pSeries_lpar_hpte_invalidate+0x68/0xb0
Call Trace:
flush_hash_page+0x114/0x200
hpte_need_flush+0x2dc/0x540
vunmap_page_range+0x538/0x6f0
free_unmap_vmap_area+0x30/0x70
remove_vm_area+0xfc/0x140
__vunmap+0x68/0x270
__iounmap.part.0+0x34/0x60
memunmap+0x54/0x70
release_nodes+0x28c/0x300
device_release_driver_internal+0x16c/0x280
unbind_store+0x124/0x170
drv_attr_store+0x44/0x60
sysfs_kf_write+0x64/0x90
kernfs_fop_write+0x1b0/0x290
__vfs_write+0x3c/0x70
vfs_write+0xd8/0x260
ksys_write+0xdc/0x130
system_call+0x5c/0x70
Reported-by: Harish Sriram <harish@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200807075933.310240-1-aneesh.kumar@linux.ibm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
syzbot crashes on the VM_BUG_ON_MM(khugepaged_test_exit(mm), mm) in
__khugepaged_enter(): yes, when one thread is about to dump core, has set
core_state, and is waiting for others, another might do something calling
__khugepaged_enter(), which now crashes because I lumped the core_state
test (known as "mmget_still_valid") into khugepaged_test_exit(). I still
think it's best to lump them together, so just in this exceptional case,
check mm->mm_users directly instead of khugepaged_test_exit().
Fixes: bbe98f9cad ("khugepaged: khugepaged_test_exit() check mmget_still_valid()")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: <stable@vger.kernel.org> [4.8+]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008141503370.18085@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace a comma between expression statements by a semicolon.
Fixes: faced7e080 ("mm: hugetlb controller for cgroups v2")
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Link: http://lkml.kernel.org/r/20200818064333.21759-1-vulab@iscas.ac.cn
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently we found regression when running will_it_scale/page_fault3 test
on ARM64. Over 70% down for the multi processes cases and over 20% down
for the multi threads cases. It turns out the regression is caused by
commit 89b15332af ("mm: drop mmap_sem before calling
balance_dirty_pages() in write fault").
The test mmaps a memory size file then write to the mapping, this would
make all memory dirty and trigger dirty pages throttle, that upstream
commit would release mmap_sem then retry the page fault. The retried
page fault would see correct PTEs installed then just fall through to
spurious TLB flush. The regression is caused by the excessive spurious
TLB flush. It is fine on x86 since x86's spurious TLB flush is no-op.
We could just skip the spurious TLB flush to mitigate the regression.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Xu Yu <xuyu@linux.alibaba.com>
Debugged-by: Xu Yu <xuyu@linux.alibaba.com>
Tested-by: Xu Yu <xuyu@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
