From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from youngberry.canonical.com ([91.189.89.112]:34671 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751053AbbKKP7C (ORCPT ); Wed, 11 Nov 2015 10:59:02 -0500 Date: Wed, 11 Nov 2015 15:58:59 +0000 From: Luis Henriques To: Roman Gushchin Cc: stable@vger.kernel.org, gregkh@linuxfoundation.org, NeilBrown , Shaohua Li Subject: Re: [PATCH] md/raid5: fix locking in handle_stripe_clean_event() Message-ID: <20151111155859.GE8684@ares> References: <144679211123461@kroah.com> <1446803687-6756-1-git-send-email-klamm@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1446803687-6756-1-git-send-email-klamm@yandex-team.ru> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Nov 06, 2015 at 12:54:47PM +0300, Roman Gushchin wrote: > commit b8a9d66d043ffac116100775a469f05f5158c16f upstream. > Thanks, I'll use this backport for the 3.16 kernel as well. Cheers, -- Lu�s > 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 > Fixes: 566c09c53455 ("raid5: relieve lock contention in get_active_stripe()") > Signed-off-by: NeilBrown > Cc: Shaohua Li > Signed-off-by: Greg Kroah-Hartman > Cc: # 3.13 - 4.2 > --- > 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 b98c70e..1c829a0 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -3029,6 +3029,8 @@ 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) { > @@ -3042,9 +3044,9 @@ 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); > > -- > 2.5.0 > > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html