6.1-stable review patch. If anyone has any objections, please let me know.
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From: David Jeffery djeffery@redhat.com
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 --- 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));