This is a note to let you know that I've just added the patch titled
fanotify: use fsnotify group lock helpers
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fanotify-use-fsnotify-group-lock-helpers.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c6a3510b3227beb7779445e3b68f7d586d8eecd8
Author: Amir Goldstein <amir73il@xxxxxxxxx>
Date: Fri Apr 22 15:03:26 2022 +0300
fanotify: use fsnotify group lock helpers
[ Upstream commit e79719a2ca5c61912c0493bc1367db52759cf6fd ]
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@xxxxxxxxx
Suggested-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@xxxxxxxxxx/
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9bb182dc3f9b3..b4d16caa98d80 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1031,10 +1031,10 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
__u32 removed;
int destroy_mark;
- mutex_lock(&group->mark_mutex);
+ fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) {
- mutex_unlock(&group->mark_mutex);
+ fsnotify_group_unlock(group);
return -ENOENT;
}
@@ -1044,7 +1044,7 @@ static int fanotify_remove_mark(struct fsnotify_group *group,
fsnotify_recalc_mask(fsn_mark->connector);
if (destroy_mark)
fsnotify_detach_mark(fsn_mark);
- mutex_unlock(&group->mark_mutex);
+ fsnotify_group_unlock(group);
if (destroy_mark)
fsnotify_free_mark(fsn_mark);
@@ -1192,13 +1192,13 @@ static int fanotify_add_mark(struct fsnotify_group *group,
bool recalc;
int ret = 0;
- mutex_lock(&group->mark_mutex);
+ fsnotify_group_lock(group);
fsn_mark = fsnotify_find_mark(connp, group);
if (!fsn_mark) {
fsn_mark = fanotify_add_new_mark(group, connp, obj_type,
fan_flags, fsid);
if (IS_ERR(fsn_mark)) {
- mutex_unlock(&group->mark_mutex);
+ fsnotify_group_unlock(group);
return PTR_ERR(fsn_mark);
}
}
@@ -1227,7 +1227,7 @@ static int fanotify_add_mark(struct fsnotify_group *group,
fsnotify_recalc_mask(fsn_mark->connector);
out:
- mutex_unlock(&group->mark_mutex);
+ fsnotify_group_unlock(group);
fsnotify_put_mark(fsn_mark);
return ret;
@@ -1381,7 +1381,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
/* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
group = fsnotify_alloc_group(&fanotify_fsnotify_ops,
- FSNOTIFY_GROUP_USER);
+ FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS);
if (IS_ERR(group)) {
return PTR_ERR(group);
}
