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md/raid5: release batch_last before waiting for another stripe_head

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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@vger.kernel.org # v6.0+
Signed-off-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231002183422.13047-1-djeffery@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Jeffery 2023-10-02 14:32:29 -04:00 committed by Greg Kroah-Hartman
parent c404d39e77
commit ebf2d9a782
1 changed files with 7 additions and 0 deletions
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7
drivers/md/raid5.c
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@ -854,6 +854,13 @@ struct stripe_head *raid5_get_active_stripe(struct r5conf *conf,
set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state); set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
r5l_wake_reclaim(conf->log, 0); 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, wait_event_lock_irq(conf->wait_for_stripe,
is_inactive_blocked(conf, hash), is_inactive_blocked(conf, hash),
*(conf->hash_locks + hash)); *(conf->hash_locks + hash));