From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD6F4C3A5A3 for ; Tue, 27 Aug 2019 07:57:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B063221872 for ; Tue, 27 Aug 2019 07:57:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566892638; bh=mKN8NkU+RhB2RiHZtLiYR0I3+S/6LCmoDMZtQW2ExWk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=a+7JBGWda5VorWRCwu6r6tNINsPK/OiWyWgngO0rXvIg4uslSMRwbzv/xW0n6+q9D dIrThs5+k4tvghhtFJTI3e+AApXX7SKxlFcRglPGC6Cerhffpz9MUyPBXO7lIzXpRc g3OIEpGRCMnR8EQ6sHGk/12X6oafKFSQtIj0V9Dg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730768AbfH0H5O (ORCPT ); Tue, 27 Aug 2019 03:57:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:49432 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729763AbfH0H5N (ORCPT ); Tue, 27 Aug 2019 03:57:13 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5CCCF20828; Tue, 27 Aug 2019 07:57:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566892632; bh=mKN8NkU+RhB2RiHZtLiYR0I3+S/6LCmoDMZtQW2ExWk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZAW/1pNEm2kAe9TNNP8CQs/ECFXj/ndQ2W1J3E7wouVqUlVWTfPn/rUcSNhLhF3DZ DvBlcB15Ur3iEwdM7OZ7tf1mvjCZ6y7Ht524mu8/2FDFLbErMf6z1h9vuqKs8XOLju W6hUx/CkXhomEX2h5ipQsPrX6mPGGg7q7KwgjkSM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Mike Snitzer Subject: [PATCH 4.19 61/98] Revert "dm bufio: fix deadlock with loop device" Date: Tue, 27 Aug 2019 09:50:40 +0200 Message-Id: <20190827072721.522960868@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190827072718.142728620@linuxfoundation.org> References: <20190827072718.142728620@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mikulas Patocka commit cf3591ef832915892f2499b7e54b51d4c578b28c upstream. Revert the commit bd293d071ffe65e645b4d8104f9d8fe15ea13862. The proper fix has been made available with commit d0a255e795ab ("loop: set PF_MEMALLOC_NOIO for the worker thread"). Note that the fix offered by commit bd293d071ffe doesn't really prevent the deadlock from occuring - if we look at the stacktrace reported by Junxiao Bi, we see that it hangs in bit_wait_io and not on the mutex - i.e. it has already successfully taken the mutex. Changing the mutex from mutex_lock to mutex_trylock won't help with deadlocks that happen afterwards. PID: 474 TASK: ffff8813e11f4600 CPU: 10 COMMAND: "kswapd0" #0 [ffff8813dedfb938] __schedule at ffffffff8173f405 #1 [ffff8813dedfb990] schedule at ffffffff8173fa27 #2 [ffff8813dedfb9b0] schedule_timeout at ffffffff81742fec #3 [ffff8813dedfba60] io_schedule_timeout at ffffffff8173f186 #4 [ffff8813dedfbaa0] bit_wait_io at ffffffff8174034f #5 [ffff8813dedfbac0] __wait_on_bit at ffffffff8173fec8 #6 [ffff8813dedfbb10] out_of_line_wait_on_bit at ffffffff8173ff81 #7 [ffff8813dedfbb90] __make_buffer_clean at ffffffffa038736f [dm_bufio] #8 [ffff8813dedfbbb0] __try_evict_buffer at ffffffffa0387bb8 [dm_bufio] #9 [ffff8813dedfbbd0] dm_bufio_shrink_scan at ffffffffa0387cc3 [dm_bufio] #10 [ffff8813dedfbc40] shrink_slab at ffffffff811a87ce #11 [ffff8813dedfbd30] shrink_zone at ffffffff811ad778 #12 [ffff8813dedfbdc0] kswapd at ffffffff811ae92f #13 [ffff8813dedfbec0] kthread at ffffffff810a8428 #14 [ffff8813dedfbf50] ret_from_fork at ffffffff81745242 Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Fixes: bd293d071ffe ("dm bufio: fix deadlock with loop device") Depends-on: d0a255e795ab ("loop: set PF_MEMALLOC_NOIO for the worker thread") Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-bufio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1602,7 +1602,9 @@ dm_bufio_shrink_scan(struct shrinker *sh unsigned long freed; c = container_of(shrink, struct dm_bufio_client, shrinker); - if (!dm_bufio_trylock(c)) + if (sc->gfp_mask & __GFP_FS) + dm_bufio_lock(c); + else if (!dm_bufio_trylock(c)) return SHRINK_STOP; freed = __scan(c, sc->nr_to_scan, sc->gfp_mask);