Roman Pen a8f324a46f debugfs: fix inode i_nlink references for automount dentry ... Directory inodes should start off with i_nlink == 2 (one extra ref for "." entry). debugfs_create_automount() increases neither the i_nlink reference for current inode nor for parent inode. On attempt to remove the automount dentry, kernel complains: [ 86.288070] WARNING: CPU: 1 PID: 3616 at fs/inode.c:273 drop_nlink+0x3e/0x50() [ 86.288461] Modules linked in: debugfs_example2(O-) [ 86.288745] CPU: 1 PID: 3616 Comm: rmmod Tainted: G O 4.4.0-rc3-next-20151207+ #135 [ 86.289197] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150617_082717-anatol 04/01/2014 [ 86.289696] ffffffff81be05c9 ffff8800b9e6fda0 ffffffff81352e2c 0000000000000000 [ 86.290110] ffff8800b9e6fdd8 ffffffff81065142 ffff8801399175e8 ffff8800bb78b240 [ 86.290507] ffff8801399175e8 ffff8800b73d7898 ffff8800b73d7840 ffff8800b9e6fde8 [ 86.290933] Call Trace: [ 86.291080] [<ffffffff81352e2c>] dump_stack+0x4e/0x82 [ 86.291340] [<ffffffff81065142>] warn_slowpath_common+0x82/0xc0 [ 86.291640] [<ffffffff8106523a>] warn_slowpath_null+0x1a/0x20 [ 86.291932] [<ffffffff811ae62e>] drop_nlink+0x3e/0x50 [ 86.292208] [<ffffffff811ba35b>] simple_unlink+0x4b/0x60 [ 86.292481] [<ffffffff811ba3a7>] simple_rmdir+0x37/0x50 [ 86.292748] [<ffffffff812d9808>] __debugfs_remove.part.16+0xa8/0xd0 [ 86.293082] [<ffffffff812d9a0b>] debugfs_remove_recursive+0xdb/0x1c0 [ 86.293406] [<ffffffffa00004dd>] cleanup_module+0x2d/0x3b [debugfs_example2] [ 86.293762] [<ffffffff810d959b>] SyS_delete_module+0x16b/0x220 [ 86.294077] [<ffffffff818ef857>] entry_SYSCALL_64_fastpath+0x12/0x6a [ 86.294405] ---[ end trace c9fc53353fe14a36 ]--- [ 86.294639] ------------[ cut here ]------------ To reproduce the issue it is enough to invoke these lines: autom = debugfs_create_automount("automount", NULL, vfsmount_cb, data); BUG_ON(IS_ERR_OR_NULL(autom)); debugfs_remove(autom); The issue is fixed by increasing inode i_nlink references for current and parent inodes. Signed-off-by: Roman Pen <r.peniaev@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-03-29 10:11:44 -07:00
..
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	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2016-03-19 18:52:29 -07:00
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-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs	2016-03-21 18:12:42 -07:00
cachefiles	CacheFiles: Provide read-and-reset release counters for cachefilesd	2016-02-01 12:30:10 -05:00
ceph	ceph: use kmem_cache_zalloc	2016-03-25 18:51:56 +01:00
cifs	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2016-03-19 18:52:29 -07:00
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	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2016-03-19 18:52:29 -07:00
cramfs	don't put symlink bodies in pagecache into highmem	2015-12-08 22:41:36 -05:00
crypto	f2fs/crypto: fix xts_tweak initialization	2016-03-26 10:13:05 -07:00
debugfs	debugfs: fix inode i_nlink references for automount dentry	2016-03-29 10:11:44 -07:00
devpts	pty: make sure super_block is still valid in final /dev/tty close	2016-02-06 23:45:46 -08:00
dlm	dlm for 4.6	2016-03-17 16:38:36 -07:00
ecryptfs	Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2016-03-23 06:12:39 -07:00
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	Performance improvements in SEEK_DATA and xattr scalability	2016-03-17 16:31:18 -07:00
ext4	ext4: in ext4_dir_llseek, check syscall bitness directly	2016-03-22 15:36:02 -07:00
f2fs	f2fs: submit node page write bios when really required	2016-03-17 21:19:47 -07:00
fat	fat: add config option to set UTF-8 mount option by default	2016-03-22 15:36:02 -07:00
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	fuse: return patrial success from fuse_direct_io()	2016-03-16 14:38:31 +01:00
gfs2	GFS2: merge window	2016-03-17 16:51:32 -07:00
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	jbd2: do not fail journal because of frozen_buffer allocation failure	2016-03-13 17:38:20 -04:00
jffs2	MTD updates for v4.6	2016-03-24 19:57:15 -07:00
jfs	wrappers for ->i_mutex access	2016-01-22 18:04:28 -05:00
kernfs	Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2016-03-21 10:05:13 -07:00
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	ncpfs: fix a braino in OOM handling in ncp_fill_cache()	2016-03-07 22:25:16 -05:00
nfs	Various bugfixes, a RDMA update from Chuck Lever, and support for a new	2016-03-24 19:50:32 -07:00
nfs_common	lockd: NLM grace period shouldn't block NFSv4 opens	2015-08-13 10:22:06 -04:00
nfsd	Various bugfixes, a RDMA update from Chuck Lever, and support for a new	2016-03-24 19:50:32 -07:00
nilfs2	mm: introduce page reference manipulation functions	2016-03-17 15:09:34 -07:00
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: extend enough credits for freeing one truncate record while replaying truncate records	2016-03-25 16:37:42 -07:00
omfs
openpromfs	kmemcg: account certain kmem allocations to memcg	2016-01-14 16:00:49 -08:00
orangefs	orangefs: fix orangefs_superblock locking	2016-03-26 07:22:00 -04:00
overlayfs	ovl: cleanup unused var in rename2	2016-03-21 17:31:46 +01:00
proc	Merge branch 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2016-03-21 10:05:13 -07:00
pstore	pstore: Add support for 64 Bit address space	2016-03-10 09:43:36 -08:00
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	Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs	2016-03-21 12:22:37 -07:00
ramfs	don't put symlink bodies in pagecache into highmem	2015-12-08 22:41:36 -05:00
reiserfs	quota: Add support for ->get_nextdqblk() for VFS quota	2016-02-09 13:05:23 +01:00
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	ubifs: Remove unused header	2016-03-20 21:37:46 +01:00
udf	udf: Merge linux specific translation into CS0 conversion function	2016-02-09 13:05:23 +01:00
ufs	kmemcg: account certain kmem allocations to memcg	2016-01-14 16:00:49 -08:00
xfs	Various bugfixes, a RDMA update from Chuck Lever, and support for a new	2016-03-24 19:50:32 -07:00
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	Merge branch 'for-4.6/core' of git://git.kernel.dk/linux-block	2016-03-18 16:43:11 -07:00
buffer.c	mm: simplify lock_page_memcg()	2016-03-15 16:55:16 -07:00
char_dev.c	chrdev: emit a warning when we go below dynamic major range	2016-03-29 10:11:44 -07:00
compat_binfmt_elf.c
compat_ioctl.c	Merge 4.5-rc4 into char-misc-next	2016-02-14 14:25:59 -08:00
compat.c	saner calling conventions for copy_mount_options()	2016-01-04 10:28:32 -05:00
coredump.c	fs/coredump: prevent fsuid=0 dumps into user-controlled directories	2016-03-22 15:36:02 -07:00
dax.c	xfs: Changes for 4.6-rc1	2016-03-21 11:53:05 -07:00
dcache.c	dcache.c: new helper: __d_add()	2016-03-14 00:17:38 -04:00
dcookies.c
direct-io.c	xfs: Changes for 4.6-rc1	2016-03-21 11:53:05 -07:00
drop_caches.c	inode: convert inode_sb_list_lock to per-sb	2015-08-17 18:39:46 -04:00
eventfd.c	eventfd: document lockless access in eventfd_poll	2016-03-22 15:36:02 -07:00
eventpoll.c	timer: convert timer_slack_ns from unsigned long to u64	2016-03-17 15:09:34 -07:00
exec.c	Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2016-03-20 19:08:56 -07:00
fcntl.c	fcntl: allow to set O_DIRECT flag on pipe	2016-01-09 02:55:37 -05:00
fhandle.c	fs/coredump: prevent fsuid=0 dumps into user-controlled directories	2016-03-22 15:36:02 -07:00
file_table.c	fs, file table: reinit files_stat.max_files after deferred memory initialisation	2015-08-07 04:39:40 +03:00
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, cgroup: fix use of the wrong bdi_writeback which mismatches the inode	2016-03-20 09:44:20 -06:00
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	Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux	2016-03-26 12:59:04 -07:00
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	Merge tag 'ofs-pull-tag-1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux	2016-03-26 12:59:04 -07:00
mbcache.c	mbcache: add reusable flag to cache entries	2016-02-22 22:44:04 -05:00
mount.h
mpage.c	fs/mpage.c:mpage_readpages(): use lru_to_page() helper	2016-03-15 16:55:16 -07:00
namei.c	kill dentry_unhash()	2016-03-14 00:16:33 -04:00
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	fs/coredump: prevent fsuid=0 dumps into user-controlled directories	2016-03-22 15:36:02 -07:00
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: do not ignore errors from show_devname method	2016-03-16 13:09:08 -04:00
read_write.c	Merge branches 'work.lookups', 'work.misc' and 'work.preadv2' into for-next	2016-03-18 16:07:38 -04:00
readdir.c	wrappers for ->i_mutex access	2016-01-22 18:04:28 -05:00
select.c	timer: convert timer_slack_ns from unsigned long to u64	2016-03-17 15:09:34 -07:00
seq_file.c	fs, seqfile: always allow oom killer	2015-11-06 17:50:42 -08:00
signalfd.c	signalfd: fix information leak in signalfd_copyinfo	2015-08-07 04:39:40 +03:00
splice.c	Merge branches 'work.lookups', 'work.misc' and 'work.preadv2' into for-next	2016-03-18 16:07:38 -04:00
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	writeback: flush inode cgroup wb switches instead of pinning super_block	2016-03-03 14:42:50 -07:00
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