3.13.11-ckt30 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Roman Gushchin <[email protected]> commit b8a9d66d043ffac116100775a469f05f5158c16f upstream. After commit 566c09c53455 ("raid5: relieve lock contention in get_active_stripe()") __find_stripe() is called under conf->hash_locks + hash. But handle_stripe_clean_event() calls remove_hash() under conf->device_lock. Under some cirscumstances the hash chain can be circuited, and we get an infinite loop with disabled interrupts and locked hash lock in __find_stripe(). This leads to hard lockup on multiple CPUs and following system crash. I was able to reproduce this behavior on raid6 over 6 ssd disks. The devices_handle_discard_safely option should be set to enable trim support. The following script was used: for i in `seq 1 32`; do dd if=/dev/zero of=large$i bs=10M count=100 & done Signed-off-by: Roman Gushchin <[email protected]> Fixes: 566c09c53455 ("raid5: relieve lock contention in get_active_stripe()") Signed-off-by: NeilBrown <[email protected]> Cc: Shaohua Li <[email protected]> [ luis: backported to 3.16: used Roman's backport to 3.14 ] Signed-off-by: Luis Henriques <[email protected]> Signed-off-by: Kamal Mostafa <[email protected]> --- drivers/md/raid5.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 027f564..bd9f959 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3037,6 +3037,8 @@ static void handle_stripe_clean_event(struct r5conf *conf, } if (!discard_pending && test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) { + int hash = sh->hash_lock_index; + clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags); clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags); if (sh->qd_idx >= 0) { @@ -3050,9 +3052,9 @@ static void handle_stripe_clean_event(struct r5conf *conf, * no updated data, so remove it from hash list and the stripe * will be reinitialized */ - spin_lock_irq(&conf->device_lock); + spin_lock_irq(conf->hash_locks + hash); remove_hash(sh); - spin_unlock_irq(&conf->device_lock); + spin_unlock_irq(conf->hash_locks + hash); if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) set_bit(STRIPE_HANDLE, &sh->state); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
