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fanotify: use fsnotify group lock helpers 

Direct reclaim from fanotify mark allocation context may try to evict
inodes with evictable marks of the same group and hit this deadlock:

[<0>] fsnotify_destroy_mark+0x1f/0x3a
[<0>] fsnotify_destroy_marks+0x71/0xd9
[<0>] __destroy_inode+0x24/0x7e
[<0>] destroy_inode+0x2c/0x67
[<0>] dispose_list+0x49/0x68
[<0>] prune_icache_sb+0x5b/0x79
[<0>] super_cache_scan+0x11c/0x16f
[<0>] shrink_slab.constprop.0+0x23e/0x40f
[<0>] shrink_node+0x218/0x3e7
[<0>] do_try_to_free_pages+0x12a/0x2d2
[<0>] try_to_free_pages+0x166/0x242
[<0>] __alloc_pages_slowpath.constprop.0+0x30c/0x903
[<0>] __alloc_pages+0xeb/0x1c7
[<0>] cache_grow_begin+0x6f/0x31e
[<0>] fallback_alloc+0xe0/0x12d
[<0>] ____cache_alloc_node+0x15a/0x17e
[<0>] kmem_cache_alloc_trace+0xa1/0x143
[<0>] fanotify_add_mark+0xd5/0x2b2
[<0>] do_fanotify_mark+0x566/0x5eb
[<0>] __x64_sys_fanotify_mark+0x21/0x24
[<0>] do_syscall_64+0x6d/0x80
[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim
from allocations under fanotify group lock and use the safe group lock
helpers.

Link: https://lore.kernel.org/r/20220422120327.3459282-16-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2022-04-22 15:03:26 +03:00 committed by Jan Kara
parent 7d5e005d98
commit e79719a2ca
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
fs/notify/fanotify/fanotify_user.c
View File

@ -1035,10 +1035,10 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
__u32 removed; __u32 removed;
int destroy_mark; int destroy_mark;
mutex_lock(&group->mark_mutex); fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group); fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) { if (!fsn_mark) {
mutex_unlock(&group->mark_mutex); fsnotify_group_unlock(group);
return -ENOENT; return -ENOENT;
} }
@ -1048,7 +1048,7 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
fsnotify_recalc_mask(fsn_mark->connector); fsnotify_recalc_mask(fsn_mark->connector);
if (destroy_mark) if (destroy_mark)
fsnotify_detach_mark(fsn_mark); fsnotify_detach_mark(fsn_mark);
mutex_unlock(&group->mark_mutex); fsnotify_group_unlock(group);
if (destroy_mark) if (destroy_mark)
fsnotify_free_mark(fsn_mark); fsnotify_free_mark(fsn_mark);
@ -1196,13 +1196,13 @@ static int fanotify_add_mark(struct fsnotify_group *group,
bool recalc; bool recalc;
int ret = 0; int ret = 0;
mutex_lock(&group->mark_mutex); fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group); fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) { if (!fsn_mark) {
fsn_mark = fanotify_add_new_mark(group, connp, obj_type, fsn_mark = fanotify_add_new_mark(group, connp, obj_type,
fan_flags, fsid); fan_flags, fsid);
if (IS_ERR(fsn_mark)) { if (IS_ERR(fsn_mark)) {
mutex_unlock(&group->mark_mutex); fsnotify_group_unlock(group);
return PTR_ERR(fsn_mark); return PTR_ERR(fsn_mark);
} }
} }
@ -1231,7 +1231,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
fsnotify_recalc_mask(fsn_mark->connector); fsnotify_recalc_mask(fsn_mark->connector);
out: out:
mutex_unlock(&group->mark_mutex); fsnotify_group_unlock(group);
fsnotify_put_mark(fsn_mark); fsnotify_put_mark(fsn_mark);
return ret; return ret;
@ -1385,7 +1385,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
/* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
group = fsnotify_alloc_group(&fanotify_fsnotify_ops, group = fsnotify_alloc_group(&fanotify_fsnotify_ops,
FSNOTIFY_GROUP_USER); FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS);
if (IS_ERR(group)) { if (IS_ERR(group)) {
return PTR_ERR(group); return PTR_ERR(group);
} }