Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932797AbbKLXUJ (ORCPT ); Thu, 12 Nov 2015 18:20:09 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45715 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932778AbbKLXUF (ORCPT ); Thu, 12 Nov 2015 18:20:05 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Roman Gushchin , NeilBrown , Shaohua Li , Luis Henriques , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 150/155] md/raid5: fix locking in handle_stripe_clean_event() Date: Thu, 12 Nov 2015 15:18:24 -0800 Message-Id: <1447370309-357-151-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1447370309-357-1-git-send-email-kamal@canonical.com> References: <1447370309-357-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2567 Lines: 70 3.19.8-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Roman Gushchin 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 Fixes: 566c09c53455 ("raid5: relieve lock contention in get_active_stripe()") Signed-off-by: NeilBrown Cc: Shaohua Li [ luis: backported to 3.16: used Roman's backport to 3.14 ] Signed-off-by: Luis Henriques Signed-off-by: Kamal Mostafa --- 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 e421016..5fa7549 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3060,6 +3060,8 @@ 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) { @@ -3073,9 +3075,9 @@ 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 linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/