From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:44679 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922AbaKUNQa (ORCPT ); Fri, 21 Nov 2014 08:16:30 -0500 Date: Fri, 21 Nov 2014 08:16:24 -0500 From: Chris Mason Subject: Re: soft lockup - CPU#0 stuck - Kernel 3.17.2 To: Patrick Schmid CC: Message-ID: <1416575784.24312.0@mail.thefacebook.com> In-Reply-To: <546F379F.8000800@phys.ethz.ch> References: <5464B2DB.7070008@phys.ethz.ch> <1415890157.25389.3@mail.thefacebook.com> <54650166.1090800@phys.ethz.ch> <1415905935.25389.4@mail.thefacebook.com> <54659FDB.6070300@phys.ethz.ch> <1415986775.25389.10@mail.thefacebook.com> <54664884.9010307@phys.ethz.ch> <1415989860.25389.11@mail.thefacebook.com> <1416008854.25389.12@mail.thefacebook.com> <546F379F.8000800@phys.ethz.ch> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Nov 21, 2014 at 8:01 AM, Patrick Schmid wrote: > On 15.11.2014 00:47, Chris Mason wrote: >> >> Ok, I think this is related to the new fair read/writer lock >> implementation in the generic kernel code. >> btrfs_clear_path_blocking() >> will end up taking locks outside of the strict locking order the >> rest >> of Btrfs uses. This used to be fine because we hold the blocking >> lock >> while we do it, but with the new queued locks we're running into >> trouble. We hit a similar bug earlier and I convinced myself the >> problem was only with btrfs_next_leaf and our trylock. But it's a >> bigger problem than I realized. >> >> So for now I've changed btrfs_clear_path_blocking to honor the rules >> and fixed up our trylock to make it faster. >> >> I'm letting a test run on this patch over the weekend, since I don't >> want any surprises with your backup farm. >> >> -chris > > Hi Chris > > Here comes a short feedback.... I applied your patch (Fix lockups from > btrfs_clear_path_blocking) yesterday and my system survived this > night! ;-) > > Thank you for the quick fix. Great to hear, thanks for following up. I'm sending this to Linus for the next 3.18 rc. -chris