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linux-stable/fs
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Roman Penyaev b8e803cda5 epoll: call final ep_events_available() check under the lock 
commit 65759097d8 upstream.

There is a possible race when ep_scan_ready_list() leaves ->rdllist and
->obflist empty for a short period of time although some events are
pending.  It is quite likely that ep_events_available() observes empty
lists and goes to sleep.

Since commit 339ddb53d3 ("fs/epoll: remove unnecessary wakeups of
nested epoll") we are conservative in wakeups (there is only one place
for wakeup and this is ep_poll_callback()), thus ep_events_available()
must always observe correct state of two lists.

The easiest and correct way is to do the final check under the lock.
This does not impact the performance, since lock is taken anyway for
adding a wait entry to the wait queue.

The discussion of the problem can be found here:

   https://lore.kernel.org/linux-fsdevel/a2f22c3c-c25a-4bda-8339-a7bdaf17849e@akamai.com/

In this patch barrierless __set_current_state() is used.  This is safe
since waitqueue_active() is called under the same lock on wakeup side.

Short-circuit for fatal signals (i.e.  fatal_signal_pending() check) is
moved to the line just before actual events harvesting routine.  This is
fully compliant to what is said in the comment of the patch where the
actual fatal_signal_pending() check was added: c257a340ed ("fs, epoll:
short circuit fetching events if thread has been killed").

Fixes: 339ddb53d3 ("fs/epoll: remove unnecessary wakeups of nested epoll")
Reported-by: Jason Baron <jbaron@akamai.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jason Baron <jbaron@akamai.com>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200505145609.1865152-1-rpenyaev@suse.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Rishabh Bhatnagar <risbhat@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-08 11:23:05 +01:00
..
9p 9p: missing chunk of "fs/9p: Don't update file type when updating file attributes" 2022-06-22 14:11:02 +02:00
adfs
affs fs/affs: release old buffer head on error path 2021-03-04 10:26:48 +01:00
afs afs: Fix fileserver probe RTT handling 2022-12-08 11:23:03 +01:00
autofs
befs
bfs bfs: don't use WARNING: string when it's just info. 2021-01-06 14:48:39 +01:00
btrfs btrfs: qgroup: fix sleep from invalid context bug in btrfs_qgroup_inherit() 2022-12-08 11:23:02 +01:00
cachefiles cachefiles: Handle readpage error correctly 2020-11-05 11:43:36 +01:00
ceph ceph: avoid putting the realm twice when decoding snaps fails 2022-12-08 11:23:00 +01:00
cifs cifs: add check for returning value of SMB2_set_info_init 2022-11-25 17:42:16 +01:00
coda
configfs configfs: fix a race in configfs_{,un}register_subsystem() 2022-03-02 11:41:10 +01:00
cramfs
crypto fscrypt: add fscrypt_symlink_getattr() for computing st_size 2021-09-12 08:56:38 +02:00
debugfs debugfs: add debugfs_lookup_and_remove() 2022-09-15 12:04:54 +02:00
devpts fsnotify: fix fsnotify hooks in pseudo filesystems 2022-02-01 17:24:34 +01:00
dlm fs: dlm: handle -EBUSY first in lock arg validation 2022-10-26 13:22:14 +02:00
ecryptfs Revert "ecryptfs: replace BUG_ON with error handling code" 2021-05-26 12:05:19 +02:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-12-02 08:49:53 +01:00
efs
erofs erofs: avoid consecutive detection for Highmem memory 2022-08-25 11:17:36 +02:00
exportfs
ext2 ext2: Add more validity checks for inode counts 2022-08-25 11:17:28 +02:00
ext4 ext4: fix BUG_ON() when directory entry has invalid rec_len 2022-11-10 17:57:56 +01:00
f2fs f2fs: fix race condition on setting FI_NO_EXTENT flag 2022-10-26 13:22:46 +02:00
fat fat: add ratelimit to fat*_ent_bread() 2022-06-14 18:11:30 +02:00
freevxfs
fscache fscache: Fix cookie key hashing 2021-09-22 12:26:25 +02:00
fuse fuse: lock inode unconditionally in fuse_fallocate() 2022-12-08 11:23:01 +01:00
gfs2 gfs2: Switch from strlcpy to strscpy 2022-11-25 17:42:22 +01:00
hfs hfs: add lock nesting notation to hfs_find_init 2021-07-31 08:19:38 +02:00
hfsplus hfsplus: prevent corruption in shrinking truncate 2021-05-19 10:08:29 +02:00
hostfs hostfs: fix memory handling in follow_link() 2021-04-14 08:24:14 +02:00
hpfs
hugetlbfs mm, hugetlb: allow for "high" userspace addresses 2022-05-09 09:03:28 +02:00
iomap iomap: iomap_write_failed fix 2022-06-14 18:11:36 +02:00
isofs isofs: Fix out of bound access for corrupted isofs image 2021-11-12 14:43:03 +01:00
jbd2 jbd2: wake up journal waiters in FIFO order, not LIFO 2022-10-26 13:22:17 +02:00
jffs2 jffs2: fix memory leak in jffs2_do_fill_super 2022-06-14 18:11:55 +02:00
jfs fs: jfs: fix possible NULL pointer dereference in dbFree() 2022-06-14 18:11:29 +02:00
kernfs kernfs: fix use-after-free in __kernfs_remove 2022-11-03 23:56:54 +09:00
lockd lockd: lockd server-side shouldn't set fl_ops 2021-09-22 12:26:34 +02:00
minix minix: fix bug when opening a file with O_DIRECT 2022-04-15 14:18:35 +02:00
nfs NFSv4: Retry LOCK on OLD_STATEID during delegation return 2022-11-25 17:42:12 +01:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-30 11:51:22 +01:00
nfsd NFSD: Return nfserr_serverfault if splice_ok but buf->pages have data 2022-10-26 13:22:47 +02:00
nilfs2 nilfs2: fix NULL pointer dereference in nilfs_palloc_commit_free_entry() 2022-12-08 11:23:04 +01:00
nls
notify fsnotify: fix wrong lockdep annotations 2022-06-14 18:11:34 +02:00
ntfs ntfs: check overflow when iterating ATTR_RECORDs 2022-11-25 17:42:22 +01:00
ocfs2 ocfs2: fix BUG when iput after ocfs2_mknod fails 2022-10-29 10:20:34 +02:00
omfs
openpromfs
orangefs orangefs: Fix the size of a memory allocation in orangefs_bufmap_alloc() 2022-01-20 09:19:17 +01:00
overlayfs ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh() 2022-08-25 11:17:23 +02:00
proc mm: /proc/pid/smaps_rollup: fix no vma's null-deref 2022-10-29 10:20:36 +02:00
pstore pstore: Fix typo in compression option name 2021-03-04 10:26:45 +01:00
qnx4 qnx4: work around gcc false positive warning bug 2021-09-30 10:09:26 +02:00
qnx6
quota quota: Check next/prev free block number after reading from quota file 2022-10-26 13:22:14 +02:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-29 09:57:53 +01:00
reiserfs reiserfs: check directory items on read from disk 2021-08-12 13:21:05 +02:00
romfs
squashfs squashfs: fix divide error in calculate_skip() 2021-05-19 10:08:29 +02:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2021-03-07 12:20:48 +01:00
sysv
tracefs tracefs: Only clobber mode/uid/gid on remount if asked 2022-09-20 12:28:00 +02:00
ubifs ubifs: Rectify space amount budget for mkdir/tmpfile operations 2022-04-15 14:18:31 +02:00
udf udf: Fix a slab-out-of-bounds write bug in udf_find_entry() 2022-11-25 17:42:09 +01:00
ufs
unicode
verity fs-verity: fix signed integer overflow with i_size near S64_MAX 2021-10-06 15:42:30 +02:00
xfs xfs: drain the buf delwri queue before xfsaild idles 2022-11-25 17:42:03 +01:00
aio.c aio: fix use-after-free due to missing POLLFREE handling 2021-12-14 14:49:02 +01:00
anon_inodes.c
attr.c vfs: Check the truncate maximum size in inode_newsize_ok() 2022-08-25 11:17:21 +02:00
bad_inode.c
binfmt_aout.c
binfmt_elf.c elf: don't use MAP_FIXED_NOREPLACE for elf interpreter mappings 2021-10-06 15:42:35 +02:00
binfmt_elf_fdpic.c
binfmt_em86.c
binfmt_flat.c binfmt_flat: do not stop relocating GOT entries prematurely on riscv 2022-06-14 18:11:23 +02:00
binfmt_misc.c binfmt_misc: fix possible deadlock in bm_register_write 2021-03-17 17:03:57 +01:00
binfmt_script.c
block_dev.c block: reexpand iov_iter after read/write 2021-05-22 11:38:29 +02:00
buffer.c mm: fs: initialize fsdata passed to write_begin/write_end interface 2022-11-25 17:42:22 +01:00
char_dev.c
compat.c
compat_binfmt_elf.c
compat_ioctl.c compat_ioctl: remove /dev/random commands 2022-06-22 14:11:03 +02:00
coredump.c coredump: fix core_pattern parse error 2020-12-11 13:23:30 +01:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-29 09:57:45 +01:00
dax.c dax: fix cache flush on PMD-mapped pages 2022-06-14 18:11:41 +02:00
dcache.c
dcookies.c
direct-io.c fs: direct-io: fix missing sdio->boundary 2021-04-14 08:24:11 +02:00
drop_caches.c
eventfd.c
eventpoll.c epoll: call final ep_events_available() check under the lock 2022-12-08 11:23:05 +01:00
exec.c exec: Force single empty string when argv is empty 2022-06-06 08:33:50 +02:00
fcntl.c fcntl: fix potential deadlock for &fasync_struct.fa_lock 2021-09-15 09:47:28 +02:00
fhandle.c
file.c fget: clarify and improve __fget_files() implementation 2022-03-02 11:41:18 +01:00
file_table.c SUNRPC: Ensure we flush any closed sockets before xs_xprt_free() 2022-05-25 09:14:34 +02:00
filesystems.c
fs-writeback.c fs-writeback: writeback_sb_inodes：Recalculate 'wrote' according skipped pages 2022-06-14 18:11:44 +02:00
fs_context.c memcg: charge fs_context and legacy_fs_context 2022-02-08 18:24:29 +01:00
fs_parser.c
fs_pin.c
fs_struct.c
fs_types.c
fsopen.c
inode.c fs: fix UAF/GPF bug in nilfs_mdt_destroy 2022-10-15 07:54:36 +02:00
internal.h cgroup1: fix leaked context root causing sporadic NULL deref in LTP 2021-07-31 08:19:37 +02:00
io_uring.c io_uring/af_unix: defer registered files gc to io_uring release 2022-10-26 13:22:59 +02:00
ioctl.c
Kconfig
Kconfig.binfmt
libfs.c libfs: fix error cast of negative value in simple_attr_write() 2020-11-24 13:29:19 +01:00
locks.c
Makefile
mbcache.c
mount.h
mpage.c
namei.c mm: fs: initialize fsdata passed to write_begin/write_end interface 2022-11-25 17:42:22 +01:00
namespace.c fs: warn about impending deprecation of mandatory locks 2021-08-26 08:36:22 -04:00
no-block.c
nsfs.c
open.c
pipe.c pipe: increase minimum default pipe size to 2 pages 2021-08-12 13:21:02 +02:00
pnode.c
pnode.h mount: fix mounting of detached mounts onto targets that reside on shared mounts 2021-03-17 17:03:33 +01:00
posix_acl.c
proc_namespace.c
read_write.c
readdir.c readdir: make sure to verify directory entry for legacy interfaces too 2021-04-21 12:56:16 +02:00
select.c select: Fix indefinitely sleeping task in poll_schedule_timeout() 2022-01-29 10:25:11 +01:00
seq_file.c seq_file: disallow extremely large seq buffer allocations 2021-07-20 16:10:54 +02:00
signalfd.c io_uring: disable polling pollfree files 2022-09-05 10:27:47 +02:00
splice.c Revert "fs: check FMODE_LSEEK to control internal pipe splicing" 2022-10-17 17:24:32 +02:00
stack.c
stat.c stat: fix inconsistency between struct stat and struct compat_stat 2022-04-27 13:50:48 +02:00
statfs.c
super.c vfs: make freeze_super abort when sync_filesystem returns error 2022-02-23 11:59:55 +01:00
sync.c
timerfd.c
userfaultfd.c userfaultfd: open userfaultfds with O_RDONLY 2022-10-26 13:22:21 +02:00
utimes.c
xattr.c