From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from phd-imap.ethz.ch ([129.132.80.51]:55986 "EHLO phd-imap.ethz.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757904AbaKUNBW (ORCPT ); Fri, 21 Nov 2014 08:01:22 -0500 Message-ID: <546F379F.8000800@phys.ethz.ch> Date: Fri, 21 Nov 2014 14:01:19 +0100 From: Patrick Schmid MIME-Version: 1.0 To: Chris Mason CC: linux-btrfs@vger.kernel.org Subject: Re: soft lockup - CPU#0 stuck - Kernel 3.17.2 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> In-Reply-To: <1416008854.25389.12@mail.thefacebook.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: 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. Regards Patrick -- Patrick Schmid support: +41 44 633 2668 IT Services Group, HPT H 8 voice: +41 44 633 3997 Departement Physik, ETH Zurich CH-8093 Zurich, Switzerland