FAILED: patch "[PATCH] eventfs: Use list_add_tail_rcu() for SRCU-protected children" failed to apply to 6.18-stable tree

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x f67950b2887fa10df50c4317a1fe98a65bc6875b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051233-marauding-delete-836e@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f67950b2887fa10df50c4317a1fe98a65bc6875b Mon Sep 17 00:00:00 2001
From: David Carlier <[email protected]>
Date: Sat, 18 Apr 2026 16:22:50 +0100
Subject: [PATCH] eventfs: Use list_add_tail_rcu() for SRCU-protected children
list

Commit d2603279c7d6 ("eventfs: Use list_del_rcu() for SRCU protected list variable") converted the removal side to pair with the list_for_each_entry_srcu() walker in eventfs_iterate(). The insertion in eventfs_create_dir() was left as a plain list_add_tail(), which on weakly-ordered architectures can expose a new entry to the SRCU reader before its list pointers and fields are observable.

Use list_add_tail_rcu() so the publication pairs with the existing list_del_rcu() and list_for_each_entry_srcu().

index 81df94038f2e..8dd554508828 100644
@@ -706,7 +706,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
 
 	scoped_guard(mutex, &eventfs_mutex) {
 		if (!parent->is_freed)
-			list_add_tail(&ei->list, &parent->children);
+			list_add_tail_rcu(&ei->list, &parent->children);
 	}
 	/* Was the parent freed? */
 	if (list_empty(&ei->list)) {

From: David Carlier <[email protected]>

[ Upstream commit f67950b2887fa10df50c4317a1fe98a65bc6875b ]

Commit d2603279c7d6 ("eventfs: Use list_del_rcu() for SRCU protected list variable") converted the removal side to pair with the list_for_each_entry_srcu() walker in eventfs_iterate(). The insertion in eventfs_create_dir() was left as a plain list_add_tail(), which on weakly-ordered architectures can expose a new entry to the SRCU reader before its list pointers and fields are observable.

Use list_add_tail_rcu() so the publication pairs with the existing list_del_rcu() and list_for_each_entry_srcu().

---
 fs/tracefs/event_inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 0d2bc92b760f3..02d56ed6ad20e 100644
@@ -732,7 +732,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
 
 	mutex_lock(&eventfs_mutex);
 	if (!parent->is_freed)
-		list_add_tail(&ei->list, &parent->children);
+		list_add_tail_rcu(&ei->list, &parent->children);
 	mutex_unlock(&eventfs_mutex);
 
 	/* Was the parent freed? */

2.53.0