This is a note to let you know that I've just added the patch titled
md/raid5: release batch_last before waiting for another stripe_head
to the 6.5-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:
md-raid5-release-batch_last-before-waiting-for-another-stripe_head.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2fd7b0f6d5ad655b1d947d3acdd82f687c31465e Mon Sep 17 00:00:00 2001
From: David Jeffery <djeffery@xxxxxxxxxx>
Date: Mon, 2 Oct 2023 14:32:29 -0400
Subject: md/raid5: release batch_last before waiting for another stripe_head
From: David Jeffery <djeffery@xxxxxxxxxx>
commit 2fd7b0f6d5ad655b1d947d3acdd82f687c31465e upstream.
When raid5_get_active_stripe is called with a ctx containing a stripe_head in
its batch_last pointer, it can cause a deadlock if the task sleeps waiting on
another stripe_head to become available. The stripe_head held by batch_last
can be blocking the advancement of other stripe_heads, leading to no
stripe_heads being released so raid5_get_active_stripe waits forever.
Like with the quiesce state handling earlier in the function, batch_last
needs to be released by raid5_get_active_stripe before it waits for another
stripe_head.
Fixes: 3312e6c887fe ("md/raid5: Keep a reference to last stripe_head for batch")
Cc: stable@xxxxxxxxxxxxxxx # v6.0+
Signed-off-by: David Jeffery <djeffery@xxxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231002183422.13047-1-djeffery@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid5.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -854,6 +854,13 @@ struct stripe_head *raid5_get_active_str
set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
r5l_wake_reclaim(conf->log, 0);
+
+ /* release batch_last before wait to avoid risk of deadlock */
+ if (ctx && ctx->batch_last) {
+ raid5_release_stripe(ctx->batch_last);
+ ctx->batch_last = NULL;
+ }
+
wait_event_lock_irq(conf->wait_for_stripe,
is_inactive_blocked(conf, hash),
*(conf->hash_locks + hash));
Patches currently in stable-queue which might be from djeffery@xxxxxxxxxx are
queue-6.5/md-raid5-release-batch_last-before-waiting-for-another-stripe_head.patch
