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39680f50ae
linux/fs
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Linus Torvalds 39680f50ae userfaultfd: don't block on the last VM updates at exit time 
The exit path will do some final updates to the VM of an exiting process
to inform others of the fact that the process is going away.

That happens, for example, for robust futex state cleanup, but also if
the parent has asked for a TID update when the process exits (we clear
the child tid field in user space).

However, at the time we do those final VM accesses, we've already
stopped accepting signals, so the usual "stop waiting for userfaults on
signal" code in fs/userfaultfd.c no longer works, and the process can
become an unkillable zombie waiting for something that will never
happen.

To solve this, just make handle_userfault() abort any user fault
handling if we're already in the exit path past the signal handling
state being dead (marked by PF_EXITING).

This VM special case is pretty ugly, and it is possible that we should
look at finalizing signals later (or move the VM final accesses
earlier).  But in the meantime this is a fairly minimally intrusive fix.

Reported-and-tested-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-02 09:03:18 -08:00
..
9p wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
adfs fs/adfs/adfs.h: tidy up comments 2016-01-20 17:09:18 -08:00
affs affs_do_readpage_ofs(): just use kmap_atomic() around memcpy() 2016-02-20 00:15:51 -05:00
afs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
autofs4 switch ->get_link() to delayed_call, kill ->put_link() 2015-12-30 13:01:03 -05:00
befs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
bfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
btrfs Merge branch 'for-linus-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-02-19 13:40:42 -08:00
cachefiles wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ceph ceph: fix snap context leak in error path 2016-02-04 18:25:15 +01:00
cifs cifs: fix erroneous return value 2016-02-10 18:23:31 -06:00
coda Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-01-23 12:24:56 -08:00
configfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
cramfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
debugfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
devpts pty: make sure super_block is still valid in final /dev/tty close 2016-02-06 23:45:46 -08:00
dlm [regression] fix braino in fs/dlm/user.c 2016-01-21 17:45:15 -05:00
ecryptfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
efivarfs efi: Make efivarfs entries immutable by default 2016-02-10 16:25:52 +00:00
efs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
exofs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
exportfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ext2 Merge branch 'akpm' (patches from Andrew) 2016-02-27 12:46:16 -08:00
ext4 Merge branch 'akpm' (patches from Andrew) 2016-02-27 12:46:16 -08:00
f2fs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
fat wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
freevxfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
fscache FS-Cache: Handle a write to the page immediately beyond the EOF marker 2015-11-11 02:11:02 -05:00
fuse wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
gfs2 wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hfsplus wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hostfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
hpfs hpfs: don't truncate the file when delete fails 2016-02-27 19:15:51 -05:00
hugetlbfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
isofs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
jbd2 fs: use block_device name vsprintf helper 2016-01-06 13:03:18 -05:00
jffs2 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-01-23 12:24:56 -08:00
jfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
kernfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
lockd lockd: constify nlmsvc_binding structure 2016-01-07 10:10:50 -05:00
logfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
minix kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
ncpfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
nfs NFSv4.x/pnfs: Fix a race between layoutget and bulk recalls 2016-02-22 17:46:34 -05:00
nfs_common lockd: NLM grace period shouldn't block NFSv4 opens 2015-08-13 10:22:06 -04:00
nfsd wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
nilfs2 wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
nls
notify fsnotify: turn fsnotify reaper thread into a workqueue job 2016-02-18 16:23:24 -08:00
ntfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ocfs2 ocfs2: unlock inode if deleting inode from orphan fails 2016-02-27 10:28:52 -08:00
omfs
openpromfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
overlayfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
proc proc: revert /proc/<pid>/maps [stack:TID] annotation 2016-02-03 08:28:43 -08:00
pstore wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
qnx4 kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
qnx6 kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
quota wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ramfs don't put symlink bodies in pagecache into highmem 2015-12-08 22:41:36 -05:00
reiserfs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
romfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
squashfs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
sysfs platform/chrome: Branch for v4.4 2015-11-13 21:53:18 -08:00
sysv kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
tracefs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
ubifs wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
udf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-01-23 12:24:56 -08:00
ufs kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
xfs dax: move writeback calls into the filesystems 2016-02-27 10:28:52 -08:00
aio.c mm: move ->mremap() from file_operations to vm_operations_struct 2015-09-04 16:54:41 -07:00
anon_inodes.c
attr.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
bad_inode.c fs/bad_inode.c: is_bad_inode can be boolean 2015-12-06 21:17:14 -05:00
binfmt_aout.c
binfmt_elf_fdpic.c libnvdimm for 4.4: 2015-11-10 12:07:22 -08:00
binfmt_elf.c mm: ASLR: use get_random_long() 2016-02-27 10:28:52 -08:00
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
binfmt_script.c
block_dev.c dax: move writeback calls into the filesystems 2016-02-27 10:28:52 -08:00
buffer.c fs: use block_device name vsprintf helper 2016-01-06 13:03:18 -05:00
char_dev.c
compat_binfmt_elf.c
compat_ioctl.c Bluetooth: Add missing COMPATIBLE_IOCTL for UART line discipline 2016-01-27 10:48:26 -05:00
compat.c saner calling conventions for copy_mount_options() 2016-01-04 10:28:32 -05:00
coredump.c fs/coredump: prevent "" / "." / ".." core path components 2016-01-20 17:09:18 -08:00
dax.c dax: move writeback calls into the filesystems 2016-02-27 10:28:52 -08:00
dcache.c use ->d_seq to get coherency between ->d_inode and ->d_flags 2016-02-29 12:16:43 -05:00
dcookies.c
direct-io.c block: fix use-after-free in dio_bio_complete 2016-01-30 22:02:10 -07:00
drop_caches.c inode: convert inode_sb_list_lock to per-sb 2015-08-17 18:39:46 -04:00
eventfd.c Documentation: filesystem: Fix typo in fs/eventfd.c 2015-12-08 14:52:03 +01:00
eventpoll.c epoll: restrict EPOLLEXCLUSIVE to POLLIN and POLLOUT 2016-02-05 18:10:40 -08:00
exec.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
fcntl.c fcntl: allow to set O_DIRECT flag on pipe 2016-01-09 02:55:37 -05:00
fhandle.c
file_table.c
file.c kmemcg: account certain kmem allocations to memcg 2016-01-14 16:00:49 -08:00
filesystems.c find_filesystem(): simplify comparison 2016-01-19 12:02:23 -05:00
fs_pin.c
fs_struct.c
fs-writeback.c writeback: keep superblock pinned during cgroup writeback association switches 2016-02-16 11:34:07 -07:00
inode.c writeback: initialize inode members that track writeback history 2016-02-16 14:57:21 -07:00
internal.h Merge branch 'for-linus' into work.misc 2016-01-08 21:20:11 -05:00
ioctl.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Kconfig dax: re-enable dax pmd mappings 2016-01-15 17:56:32 -08:00
Kconfig.binfmt
libfs.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
locks.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
Makefile ext4: promote ext4 over ext2 in the default probe order 2015-10-15 10:33:21 -04:00
mbcache.c
mount.h
mpage.c mm, fs: introduce mapping_gfp_constraint() 2015-11-06 17:50:42 -08:00
namei.c do_last(): ELOOP failure exit should be done after leaving RCU mode 2016-02-27 19:37:37 -05:00
namespace.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
no-block.c
nsfs.c fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void 2015-09-11 15:21:34 -07:00
open.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
pipe.c pipe: limit the per-user amount of pages allocated in pipes 2016-01-19 19:25:21 -05:00
pnode.c fs/pnode.c: treat zero mnt_group_id-s as unequal 2016-02-20 00:15:52 -05:00
pnode.h
posix_acl.c xattr handlers: Simplify list operation 2015-12-13 19:46:12 -05:00
proc_namespace.c vfs: show_vfsstat: remove redundant initialization and check of error code 2015-12-06 21:17:16 -05:00
read_write.c fs: return -EOPNOTSUPP if clone is not supported 2016-02-27 19:15:51 -05:00
readdir.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
select.c poll: plug an unused argument to do_poll 2016-01-06 08:26:52 -05:00
seq_file.c fs, seqfile: always allow oom killer 2015-11-06 17:50:42 -08:00
signalfd.c
splice.c fs: __generic_file_splice_read retry lookup on AOP_TRUNCATED_PAGE 2016-01-09 02:55:35 -05:00
stack.c
stat.c fs/stat.c: drop the last new_valid_dev check 2016-01-16 11:17:23 -08:00
statfs.c
super.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2016-01-14 17:04:19 -08:00
sync.c fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE writeback 2015-11-06 17:50:42 -08:00
timerfd.c timerfd: Handle relative timers with CONFIG_TIME_LOW_RES proper 2016-01-17 11:13:55 +01:00
userfaultfd.c userfaultfd: don't block on the last VM updates at exit time 2016-03-02 09:03:18 -08:00
utimes.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
xattr.c xattr handlers: plug a lock leak in simple_xattr_list 2016-02-20 00:15:51 -05:00