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")
Signed-off-by: David Jeffery <djeffery@xxxxxxxxxx>
---
drivers/md/raid5.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 6383723468e5..0644b83fd3f4 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -854,6 +854,13 @@ struct stripe_head *raid5_get_active_stripe(struct r5conf *conf,
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));
--
2.41.0
