This is a note to let you know that I've just added the patch titled
dnotify: 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:
dnotify-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 36cd95521a84234d266f70b0598820de8ff393e4
Author: Amir Goldstein <amir73il@xxxxxxxxx>
Date: Fri Apr 22 15:03:21 2022 +0300
dnotify: use fsnotify group lock helpers
[ Upstream commit aabb45fdcb31f00f1e7cae2bce83e83474a87c03 ]
Before commit 9542e6a643fc6 ("nfsd: Containerise filecache laundrette")
nfsd would close open files in direct reclaim context. There is no
guarantee that others memory shrinkers don't do the same and no
guarantee that future shrinkers won't do that.
For example, if overlayfs implements inode cache of fscache would
keep open files to cached objects, inode shrinkers could end up closing
open files to underlying fs.
Direct reclaim from dnotify mark allocation context may try to close
open files that have dnotify marks of the same group and hit a deadlock
on mark_mutex.
Set the FSNOTIFY_GROUP_NOFS flag to prevent going into direct reclaim
from allocations under dnotify group lock and use the safe group lock
helpers.
Link: https://lore.kernel.org/r/20220422120327.3459282-11-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/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 6c586802c50e6..fa81c59a2ad41 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -150,7 +150,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
return;
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
- mutex_lock(&dnotify_group->mark_mutex);
+ fsnotify_group_lock(dnotify_group);
spin_lock(&fsn_mark->lock);
prev = &dn_mark->dn;
@@ -173,7 +173,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
free = true;
}
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
if (free)
fsnotify_free_mark(fsn_mark);
@@ -306,7 +306,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
new_dn_mark->dn = NULL;
/* this is needed to prevent the fcntl/close race described below */
- mutex_lock(&dnotify_group->mark_mutex);
+ fsnotify_group_lock(dnotify_group);
/* add the new_fsn_mark or find an old one. */
fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, dnotify_group);
@@ -316,7 +316,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
} else {
error = fsnotify_add_inode_mark_locked(new_fsn_mark, inode, 0);
if (error) {
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
goto out_err;
}
spin_lock(&new_fsn_mark->lock);
@@ -365,7 +365,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
if (destroy)
fsnotify_detach_mark(fsn_mark);
- mutex_unlock(&dnotify_group->mark_mutex);
+ fsnotify_group_unlock(dnotify_group);
if (destroy)
fsnotify_free_mark(fsn_mark);
fsnotify_put_mark(fsn_mark);
@@ -383,7 +383,8 @@ static int __init dnotify_init(void)
SLAB_PANIC|SLAB_ACCOUNT);
dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC|SLAB_ACCOUNT);
- dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops, 0);
+ dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops,
+ FSNOTIFY_GROUP_NOFS);
if (IS_ERR(dnotify_group))
panic("unable to allocate fsnotify group for dnotify\n");
return 0;
