From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758355AbbCDOKF (ORCPT ); Wed, 4 Mar 2015 09:10:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37627 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758307AbbCDOKC (ORCPT ); Wed, 4 Mar 2015 09:10:02 -0500 From: Jes Sorensen To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Manibalan P , NeilBrown Subject: Re: [PATCH 3.10 49/53] md/raid5: Fix livelock when array is both resyncing and degraded. References: <20150304054609.869052846@linuxfoundation.org> <20150304054618.031766167@linuxfoundation.org> Date: Wed, 04 Mar 2015 09:09:52 -0500 In-Reply-To: <20150304054618.031766167@linuxfoundation.org> (Greg Kroah-Hartman's message of "Tue, 3 Mar 2015 22:06:52 -0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg Kroah-Hartman writes: > 3.10-stable review patch. If anyone has any objections, please let me know. > > ------------------ For all 4 stable branches: Acked-by: Jes Sorensen > > From: NeilBrown > > commit 26ac107378c4742978216be1005b7291b799c7b2 upstream. > > Commit a7854487cd7128a30a7f4f5259de9f67d5efb95f: > md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write. > > Causes an RCW cycle to be forced even when the array is degraded. > A degraded array cannot support RCW as that requires reading all data > blocks, and one may be missing. > > Forcing an RCW when it is not possible causes a live-lock and the code > spins, repeatedly deciding to do something that cannot succeed. > > So change the condition to only force RCW on non-degraded arrays. > > Reported-by: Manibalan P > Bisected-by: Jes Sorensen > Tested-by: Jes Sorensen > Signed-off-by: NeilBrown > Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f > Signed-off-by: Greg Kroah-Hartman > > --- > drivers/md/raid5.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -2853,7 +2853,8 @@ static void handle_stripe_dirtying(struc > * generate correct data from the parity. > */ > if (conf->max_degraded == 2 || > - (recovery_cp < MaxSector && sh->sector >= recovery_cp)) { > + (recovery_cp < MaxSector && sh->sector >= recovery_cp && > + s->failed == 0)) { > /* Calculate the real rcw later - for now make it > * look like rcw is cheaper > */