In 'fasync_remove_entry()', prefer 'kfree_rcu()' over 'call_rcu()' with dummy 'fasync_free_rcu()' callback. This is mostly intended in attempt to fix weird https://syzkaller.appspot.com/bug?id=6a64ad907e361e49e92d1c4c114128a1bda2ed7f, where kmemleak may consider 'fa' as unreferenced during RCU grace period. See https://lore.kernel.org/stable/20230930174657.800551-1-joel@xxxxxxxxxxxxxxxxx as well. Comments are highly appreciated. Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> --- fs/fcntl.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index c80a6acad742..c3e342eb74af 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -846,12 +846,6 @@ int send_sigurg(struct fown_struct *fown) static DEFINE_SPINLOCK(fasync_lock); static struct kmem_cache *fasync_cache __ro_after_init; -static void fasync_free_rcu(struct rcu_head *head) -{ - kmem_cache_free(fasync_cache, - container_of(head, struct fasync_struct, fa_rcu)); -} - /* * Remove a fasync entry. If successfully removed, return * positive and clear the FASYNC flag. If no entry exists, @@ -877,7 +871,7 @@ int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) write_unlock_irq(&fa->fa_lock); *fp = fa->fa_next; - call_rcu(&fa->fa_rcu, fasync_free_rcu); + kfree_rcu(fa, fa_rcu); filp->f_flags &= ~FASYNC; result = 1; break; -- 2.43.0
