Patch "xfs: check that per-cpu inodegc workers actually run on that cpu" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    xfs: check that per-cpu inodegc workers actually run on that cpu

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:
     xfs-check-that-per-cpu-inodegc-workers-actually-run-.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 afd86b3c5e1ab8fc89d632a031839219d31d54b7
Author: Darrick J. Wong <djwong@xxxxxxxxxx>
Date:   Thu Sep 21 18:01:54 2023 -0700

    xfs: check that per-cpu inodegc workers actually run on that cpu
    
    [ Upstream commit b37c4c8339cd394ea6b8b415026603320a185651 ]
    
    Now that we've allegedly worked out the problem of the per-cpu inodegc
    workers being scheduled on the wrong cpu, let's put in a debugging knob
    to let us know if a worker ever gets mis-scheduled again.
    
    Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
    Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
    Signed-off-by: Dave Chinner <david@xxxxxxxxxxxxx>
    Signed-off-by: Leah Rumancik <leah.rumancik@xxxxxxxxx>
    Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index ab8181f8d08a9..02022164772de 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -1856,6 +1856,8 @@ xfs_inodegc_worker(
 	struct llist_node	*node = llist_del_all(&gc->list);
 	struct xfs_inode	*ip, *n;
 
+	ASSERT(gc->cpu == smp_processor_id());
+
 	WRITE_ONCE(gc->items, 0);
 
 	if (!node)
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 3d58938a6f75b..29f35169bf9cf 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -66,6 +66,9 @@ struct xfs_inodegc {
 	/* approximate count of inodes in the list */
 	unsigned int		items;
 	unsigned int		shrinker_hits;
+#if defined(DEBUG) || defined(XFS_WARN)
+	unsigned int		cpu;
+#endif
 };
 
 /*
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 9b3af7611eaa9..569960e4ea3a6 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1062,6 +1062,9 @@ xfs_inodegc_init_percpu(
 
 	for_each_possible_cpu(cpu) {
 		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+#if defined(DEBUG) || defined(XFS_WARN)
+		gc->cpu = cpu;
+#endif
 		init_llist_head(&gc->list);
 		gc->items = 0;
 		INIT_DELAYED_WORK(&gc->work, xfs_inodegc_worker);