diff options
| author | Jaegeuk Kim <jaegeuk@kernel.org> | 2018-07-15 09:58:08 +0900 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2018-07-27 18:03:59 +0900 |
| commit | a1933c09ef84c2fd187e05b560ddc6e1267d6508 (patch) | |
| tree | 9e9327a6e7debbacccbb92b08dda3232fedd204d /fs/f2fs/sysfs.c | |
| parent | 83a3bfdb5a8a086290dff2c13409c7380b683a96 (diff) | |
f2fs: avoid potential deadlock in f2fs_sbi_store
[ 155.018460] ======================================================
[ 155.021431] WARNING: possible circular locking dependency detected
[ 155.024339] 4.18.0-rc3+ #5 Tainted: G OE
[ 155.026879] ------------------------------------------------------
[ 155.029783] umount/2901 is trying to acquire lock:
[ 155.032187] 00000000c4282f1f (kn->count#130){++++}, at: kernfs_remove+0x1f/0x30
[ 155.035439]
[ 155.035439] but task is already holding lock:
[ 155.038892] 0000000056e4307b (&type->s_umount_key#41){++++}, at: deactivate_super+0x33/0x50
[ 155.042602]
[ 155.042602] which lock already depends on the new lock.
[ 155.042602]
[ 155.047465]
[ 155.047465] the existing dependency chain (in reverse order) is:
[ 155.051354]
[ 155.051354] -> #1 (&type->s_umount_key#41){++++}:
[ 155.054768] f2fs_sbi_store+0x61/0x460 [f2fs]
[ 155.057083] kernfs_fop_write+0x113/0x1a0
[ 155.059277] __vfs_write+0x36/0x180
[ 155.061250] vfs_write+0xbe/0x1b0
[ 155.063179] ksys_write+0x55/0xc0
[ 155.065068] do_syscall_64+0x60/0x1b0
[ 155.067071] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 155.069529]
[ 155.069529] -> #0 (kn->count#130){++++}:
[ 155.072421] __kernfs_remove+0x26f/0x2e0
[ 155.074452] kernfs_remove+0x1f/0x30
[ 155.076342] kobject_del.part.5+0xe/0x40
[ 155.078354] f2fs_put_super+0x12d/0x290 [f2fs]
[ 155.080500] generic_shutdown_super+0x6c/0x110
[ 155.082655] kill_block_super+0x21/0x50
[ 155.084634] kill_f2fs_super+0x9c/0xc0 [f2fs]
[ 155.086726] deactivate_locked_super+0x3f/0x70
[ 155.088826] cleanup_mnt+0x3b/0x70
[ 155.090584] task_work_run+0x93/0xc0
[ 155.092367] exit_to_usermode_loop+0xf0/0x100
[ 155.094466] do_syscall_64+0x162/0x1b0
[ 155.096312] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 155.098603]
[ 155.098603] other info that might help us debug this:
[ 155.098603]
[ 155.102418] Possible unsafe locking scenario:
[ 155.102418]
[ 155.105134] CPU0 CPU1
[ 155.107037] ---- ----
[ 155.108910] lock(&type->s_umount_key#41);
[ 155.110674] lock(kn->count#130);
[ 155.113010] lock(&type->s_umount_key#41);
[ 155.115608] lock(kn->count#130);
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/sysfs.c')
| -rw-r--r-- | fs/f2fs/sysfs.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 2e7e611deaef..d3d0266a49da 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -286,8 +286,10 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, bool gc_entry = (!strcmp(a->attr.name, "gc_urgent") || a->struct_type == GC_THREAD); - if (gc_entry) - down_read(&sbi->sb->s_umount); + if (gc_entry) { + if (!down_read_trylock(&sbi->sb->s_umount)) + return -EAGAIN; + } ret = __sbi_store(a, sbi, buf, count); if (gc_entry) up_read(&sbi->sb->s_umount); |