Return the error returned by ceph_mdsc_do_request(). Otherwise,
r_target_inode ends up being NULL this ends up returning ENOENT
regardless of the error.
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
If an inode has caps from multiple mds's, the following can happen:
- non-auth mds revokes Fsc. Fcb is used, so page writeback is queued.
- when writeback finishes, ceph_check_caps() is called with auth only
flag. ceph_check_caps() invalidates pagecache, but skips checking any
non-auth caps.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Originally, calling ceph_get_fmode() for open files is by thread that
handles request reply. There is a small window between updating caps and
and waking the request initiator. We need to prevent ceph_check_caps()
from releasing wanted caps in the window.
Previous patches made fill_inode() call __ceph_touch_fmode() for open file
requests. This prevented ceph_check_caps() from releasing wanted caps for
'caps_wanted_delay_min' seconds, enough for request initiator to get
woken up and call ceph_get_fmode().
This allows us to now call ceph_get_fmode() in ceph_open() instead.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
__ceph_caps_file_wanted() already checks 'caps_wanted_delay_min' and
'caps_wanted_delay_max'. There is no need to duplicate the logic in
ceph_check_caps() and __send_cap()
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Add i_last_rd and i_last_wr to ceph_inode_info. These fields are
used to track the last time the client acquired read/write caps for
the inode.
If there is no read/write on an inode for 'caps_wanted_delay_max'
seconds, __ceph_caps_file_wanted() does not request caps for read/write
even there are open files.
Call __ceph_touch_fmode() for dir operations. __ceph_caps_file_wanted()
calculates dir's wanted caps according to last dir read/modification. If
there is recent dir read, dir inode wants CEPH_CAP_ANY_SHARED caps. If
there is recent dir modification, also wants CEPH_CAP_FILE_EXCL.
Readdir is a special case. Dir inode wants CEPH_CAP_FILE_EXCL after
readdir, as with that, modifications do not need to release
CEPH_CAP_FILE_SHARED or invalidate all dentry leases issued by readdir.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Original code only renews caps for inodes with CEPH_I_CAP_DROPPED flag,
which indicates that mds has closed the session and caps were dropped.
Remove this flag in preparation for not requesting caps for idle open
files.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Otherwise ceph_d_delete() may return 1 for the dentry, which makes
dput() prune the dentry and clear parent dir's complete flag.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
With the Octopus release, the MDS will hand out directory create caps.
If we have Fxc caps on the directory, and complete directory information
or a known negative dentry, then we can return without waiting on the
reply, allowing the open() call to return very quickly to userland.
We use the normal ceph_fill_inode() routine to fill in the inode, so we
have to gin up some reply inode information with what we'd expect the
newly-created inode to have. The client assumes that it has a full set
of caps on the new inode, and that the MDS will revoke them when there
is conflicting access.
This functionality is gated on the wsync/nowsync mount options.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
If a create is done, then typically we'll end up writing to the file
soon afterward. We don't want to wait for the reply before doing that
when doing an async create, so that means we need the layout for the
new file before we've gotten the response from the MDS.
All files created in a directory will initially inherit the same layout,
so copy off the requisite info from the first synchronous create in the
directory, and save it in a new i_cached_layout field. Zero out the
layout when we lose Dc caps in the dir.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Add new request field to hold the delegated inode number. Encode that
into the message when it's set.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Starting in Octopus, the MDS will hand out caps that allow the client
to do asynchronous file creates under certain conditions. As part of
that, the MDS will delegate ranges of inode numbers to the client.
Add the infrastructure to decode these ranges, and stuff them into an
xarray for later consumption by the async creation code.
Because the xarray code currently only handles unsigned long indexes,
and those are 32-bits on 32-bit arches, we only enable the decoding when
running on a 64-bit arch.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The MDS is getting a new lock-caching facility that will allow it
to cache the necessary locks to allow asynchronous directory operations.
Since the CEPH_CAP_FILE_* caps are currently unused on directories,
we can repurpose those bits for this purpose.
When performing an unlink, if we have Fx on the parent directory,
and CEPH_CAP_DIR_UNLINK (aka Fr), and we know that the dentry being
removed is the primary link, then then we can fire off an unlink
request immediately and don't need to wait on reply before returning.
In that situation, just fix up the dcache and link count and return
immediately after issuing the call to the MDS. This does mean that we
need to hold an extra reference to the inode being unlinked, and extra
references to the caps to avoid races. Those references are put and
error handling is done in the r_callback routine.
If the operation ends up failing, then set a writeback error on the
directory inode, and the inode itself that can be fetched later by
an fsync on the dir.
The behavior of dir caps is slightly different from caps on normal
files. Because these are just considered an optimization, if the
session is reconnected, we will not automatically reclaim them. They
are instead considered lost until we do another synchronous op in the
parent directory.
Async dirops are enabled via the "nowsync" mount option, which is
patterned after the xfs "wsync" mount option. For now, the default
is "wsync", but eventually we may flip that.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
If we don't have all of the cap bits for the want mask in
try_get_cap_refs, then just take refs on the need bits.
Signed-off-by: "Yan, Zheng" <ukernel@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Track and correctly handle directory caps for asynchronous operations.
Add aliases for Frc caps that we now designate at Dcu caps (when dealing
with directories).
Unlike file caps, we don't reclaim these when the session goes away, and
instead preemptively release them. In-flight async dirops are instead
handled during reconnect phase. The client needs to re-do a synchronous
operation in order to re-get directory caps.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Rename it to ceph_take_cap_refs and make it available to other files.
Also replace a comment with a lockdep assertion.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
When we issue an async create, we must ensure that any later on-the-wire
requests involving it wait for the create reply.
Expand i_ceph_flags to be an unsigned long, and add a new bit that
MDS requests can wait on. If the bit is set in the inode when sending
caps, then don't send it and just return that it has been delayed.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Newer versions of the MDS will flag a dentry as "primary". In later
patches, we'll need to consult this info, so track it in di->flags.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
...and ensure that such requests are never queued. The MDS has need to
know that a request is asynchronous so add flags and proper
infrastructure for that.
Also, delegated inode numbers and directory caps are associated with the
session, so ensure that async requests are always transmitted on the
first attempt and are never queued to wait for session reestablishment.
If it does end up looking like we'll need to queue the request, then
have it return -EJUKEBOX so the caller can reattempt with a synchronous
request.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The last thing that this function does is release i_ceph_lock, so
have the caller do that instead. Add a lockdep assertion to
ensure that the function is always called with i_ceph_lock held.
Change the prototype to take a ceph_inode_info pointer and drop
the separate mdsc argument as we can get that from the session.
While at it, make it non-static. We'll need this to kick any
flushing caps once the create reply comes in.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Coverity complains about a double write to *p. Don't bother with
osd_instructions and directly skip to the end of redirect reply.
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
ceph_monc_handle_map() confuses static checkers which report a
false use-after-free on monc->monmap, missing that monc->monmap and
client->monc.monmap is the same pointer.
Use monc->monmap consistently and get rid of "old", which is redundant.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
req->r_timeout is only used during mounting, so this error will
be more accurate.
URL: https://tracker.ceph.com/issues/44215
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This patch re-organizes copy_file_range, trying to fix a few issues in the
error handling. Here's the summary:
- Abort copy if initial do_splice_direct() returns fewer bytes than
requested.
- Move the 'size' initialization (with i_size_read()) further down in the
code, after the initial call to do_splice_direct(). This avoids issues
with a possibly stale value if a manual copy is done.
- Move the object copy loop into a separate function. This makes it
easier to handle errors (e.g, dirtying caps and updating the MDS
metadata if only some objects have been copied before an error has
occurred).
- Added calls to ceph_oloc_destroy() to avoid leaking memory with src_oloc
and dst_oloc
- After the object copy loop, the new file size to be reported to the MDS
(if there's file size change) is now the actual file size, and not the
size after an eventual extra manual copy.
- Added a few dout() to show the number of bytes copied in the two manual
copies and in the object copy loop.
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
On my machine (x86_64) this struct is 952 bytes, which gets rounded up
to 1024 by kmalloc. Move this to a dedicated slabcache, so we can
allocate them without the extra 72 bytes of overhead per.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Use the "page has been truncated" logic in page_mkwrite_check_truncate
instead of reimplementing it here. Other than with the existing code,
fail with -EFAULT / VM_FAULT_NOPAGE when page_offset(page) == size here
as well, as should be expected.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Allocate one queue per CPU and get a performance boost from
higher parallelism.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Avoid making allocations for !IMG_REQ_CHILD image requests. Only
IMG_REQ_CHILD image requests need to be freed now.
Move the initial request checks to rbd_queue_rq(). Unfortunately we
can't fill the image request and kick the state machine directly from
rbd_queue_rq() because ->queue_rq() isn't allowed to block.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Currently header_rwsem is acquired twice: once in rbd_dev_parent_get()
when the image request is being created and then in rbd_queue_workfn()
to capture mapping_size and snapc. Introduce rbd_img_capture_header()
and move image request allocation so that header_rwsem can be acquired
just once.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
The reference counter is never increased, so we can as well call
rbd_img_request_destroy() directly and drop the kref.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
When a process exits, kernel closes its files. locks_remove_file()
is called to remove file locks on these files. locks_remove_file()
tries unlocking files even there is no file lock.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Based on the latest code, the default value for wsize/rsize is
64MB and the default value for the mount_timeout is 60 seconds.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Since these helpers are only used by ceph.ko, move them there and
rename them with _sync_ qualifiers.
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
CephFS doesn't set this bit to begin with, so there should be no need
to clear it.
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
IMG_REQ_LAYERED is set in rbd_img_request_create(), and tested and
cleared in rbd_img_request_destroy() when the image request is about to
be destroyed. The barriers are unnecessary.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Although CEPH_DEFINE_SHOW_FUNC is much older, it now duplicates
DEFINE_SHOW_ATTRIBUTE from linux/seq_file.h.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
These bits will have new meaning for directory inodes.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
In future patches we'll be taking and relying on Fx caps. Add proper
refcounting for them.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
When the unsafe reply to a request comes in, the request is put on the
r_unsafe_dir inode's list. In future patches, we're going to need to
wait on requests that may not have gotten an unsafe reply yet.
Change __register_request to put the entry on the dir inode's list when
the pointer is set in the request, and don't check the
CEPH_MDS_R_GOT_UNSAFE flag when unregistering it.
The only place that uses this list today is fsync codepath, and with
the coming changes, we'll want to wait on all operations whether it has
gotten an unsafe reply or not.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Merge vm fixes from Andrew Morton:
"5 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm/sparse: fix kernel crash with pfn_section_valid check
mm: fork: fix kernel_stack memcg stats for various stack implementations
hugetlb_cgroup: fix illegal access to memory
drivers/base/memory.c: indicate all memory blocks as removable
mm/swapfile.c: move inode_lock out of claim_swapfile
actually return nanoseconds and not the virtual clock value which
increments at 10e7 HZ (100ns).
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Merge tag 'timers-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fix from Thomas Gleixner:
"A single fix for the Hyper-V clocksource driver to make sched clock
actually return nanoseconds and not the virtual clock value which
increments at 10e7 HZ (100ns)"
* tag 'timers-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource/drivers/hyper-v: Make sched clock return nanoseconds correctly
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Merge tag 'irq-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq fix from Thomas Gleixner:
"A single bugfix to prevent reference leaks in irq affinity notifiers"
* tag 'irq-urgent-2020-03-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Fix reference leaks on irq affinity notifiers
Fix the crash like this:
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc000000000c3447c
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
CPU: 11 PID: 7519 Comm: lt-ndctl Not tainted 5.6.0-rc7-autotest #1
...
NIP [c000000000c3447c] vmemmap_populated+0x98/0xc0
LR [c000000000088354] vmemmap_free+0x144/0x320
Call Trace:
section_deactivate+0x220/0x240
__remove_pages+0x118/0x170
arch_remove_memory+0x3c/0x150
memunmap_pages+0x1cc/0x2f0
devm_action_release+0x30/0x50
release_nodes+0x2f8/0x3e0
device_release_driver_internal+0x168/0x270
unbind_store+0x130/0x170
drv_attr_store+0x44/0x60
sysfs_kf_write+0x68/0x80
kernfs_fop_write+0x100/0x290
__vfs_write+0x3c/0x70
vfs_write+0xcc/0x240
ksys_write+0x7c/0x140
system_call+0x5c/0x68
The crash is due to NULL dereference at
test_bit(idx, ms->usage->subsection_map);
due to ms->usage = NULL in pfn_section_valid()
With commit d41e2f3bd5 ("mm/hotplug: fix hot remove failure in
SPARSEMEM|!VMEMMAP case") section_mem_map is set to NULL after
depopulate_section_mem(). This was done so that pfn_page() can work
correctly with kernel config that disables SPARSEMEM_VMEMMAP. With that
config pfn_to_page does
__section_mem_map_addr(__sec) + __pfn;
where
static inline struct page *__section_mem_map_addr(struct mem_section *section)
{
unsigned long map = section->section_mem_map;
map &= SECTION_MAP_MASK;
return (struct page *)map;
}
Now with SPASEMEM_VMEMAP enabled, mem_section->usage->subsection_map is
used to check the pfn validity (pfn_valid()). Since section_deactivate
release mem_section->usage if a section is fully deactivated,
pfn_valid() check after a subsection_deactivate cause a kernel crash.
static inline int pfn_valid(unsigned long pfn)
{
...
return early_section(ms) || pfn_section_valid(ms, pfn);
}
where
static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
{
int idx = subsection_map_index(pfn);
return test_bit(idx, ms->usage->subsection_map);
}
Avoid this by clearing SECTION_HAS_MEM_MAP when mem_section->usage is
freed. For architectures like ppc64 where large pages are used for
vmmemap mapping (16MB), a specific vmemmap mapping can cover multiple
sections. Hence before a vmemmap mapping page can be freed, the kernel
needs to make sure there are no valid sections within that mapping.
Clearing the section valid bit before depopulate_section_memap enables
this.
[aneesh.kumar@linux.ibm.com: add comment]
Link: http://lkml.kernel.org/r/20200326133235.343616-1-aneesh.kumar@linux.ibm.comLink: http://lkml.kernel.org/r/20200325031914.107660-1-aneesh.kumar@linux.ibm.com
Fixes: d41e2f3bd5 ("mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case")
Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio the
space for task stacks can be allocated using __vmalloc_node_range(),
alloc_pages_node() and kmem_cache_alloc_node().
In the first and the second cases page->mem_cgroup pointer is set, but
in the third it's not: memcg membership of a slab page should be
determined using the memcg_from_slab_page() function, which looks at
page->slab_cache->memcg_params.memcg . In this case, using
mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
page->mem_cgroup pointer is NULL even for pages charged to a non-root
memory cgroup.
It can lead to kernel_stack per-memcg counters permanently showing 0 on
some architectures (depending on the configuration).
In order to fix it, let's introduce a mod_memcg_obj_state() helper,
which takes a pointer to a kernel object as a first argument, uses
mem_cgroup_from_obj() to get a RCU-protected memcg pointer and calls
mod_memcg_state(). It allows to handle all possible configurations
(CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE values) without
spilling any memcg/kmem specifics into fork.c .
Note: This is a special version of the patch created for stable
backports. It contains code from the following two patches:
- mm: memcg/slab: introduce mem_cgroup_from_obj()
- mm: fork: fix kernel_stack memcg stats for various stack implementations
[guro@fb.com: introduce mem_cgroup_from_obj()]
Link: http://lkml.kernel.org/r/20200324004221.GA36662@carbon.dhcp.thefacebook.com
Fixes: 4d96ba3530 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <guro@fb.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: Michal Hocko <mhocko@kernel.org>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200303233550.251375-1-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
