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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 B1F2DC64E7A for ; Tue, 1 Dec 2020 04:36:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48D21206E3 for ; Tue, 1 Dec 2020 04:36:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YtFuwEFs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728493AbgLAEfs (ORCPT ); Mon, 30 Nov 2020 23:35:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725861AbgLAEfr (ORCPT ); Mon, 30 Nov 2020 23:35:47 -0500 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC749C0613CF; Mon, 30 Nov 2020 20:35:07 -0800 (PST) Received: by mail-pj1-x1043.google.com with SMTP id e5so466440pjt.0; Mon, 30 Nov 2020 20:35:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=BPtWYGD7y8CigqXoE2gXVtOc81D8k8JttMXCbXMY8s0=; b=YtFuwEFsueHt4H+UiwWyjkGT+32Y7ExycKvIjYZJyciw08BO8hcpGs/PW2Up2XUhDV McPNQ4m4mviviDMYzU/W4wBwVDXT+RmBa6V1PeDFDfyHeNKhhkniIu34apuz41AhSzs6 v5FlmRULyJNvR4zG+Mq2y21Hy/R+zftifiFqbLnBCa2ueaPCaYpaPPXHJs5Wy/n4kJ/y r/lxdug5eGLvhr/x+6tdEH8jHqGgs+t9P2boyf/Rrc2IFwElPE3gUVRWMdi0Q0raAMRf Gk5tBWIwjxKz8PqRBg5BdRgWLg424IglcC2I+fsHZX5Yt2LtN0q0p8mPZh7cLK0AMczd IbDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=BPtWYGD7y8CigqXoE2gXVtOc81D8k8JttMXCbXMY8s0=; b=WRjLNXC5P57dTa/Gdkc14MfguUw4XHweeGto3i4b0k98xuuqE/NyrMSUduudytUkjV 5XdI40UlCiU1Ssi8bewwQJA6tG2BjUr6HyYLyIaV4dInlvqnzXFnyuSdBJUxD1z48UZu GPydEyZadceRxnc6PiZULjht+jldICj+tFHLWCnltNmo4zr3M+N61J1DxR6QGKUlOxfg A7LtJbZvE+qk2GwVkEHVTC7tOYRfzPQgnF4+lX/xuR3B/ghM5Ou+B8bfAIe2+MeQ6bx4 o6pjwvD1lqXcrkg+lzSlFLNB71uxZQ0rvyCAPZi09fK/v5t75MyTwFIx/Jatvs25cHRL RMVg== X-Gm-Message-State: AOAM5333UXLa2m7QnHyR55wc2rLIVvRNlymIIvK+DbynlDm22yqRp2qO BGXrJgHqLXRt9mRfuAY06x7wgNG30d2PEYbZLZpol/zRSVg= X-Google-Smtp-Source: ABdhPJyBt3QNzW9OVRkY+oVCY64/AnhKw2iU+cGYjXVyQhP9Bv0zJs3DTlgcK9463VIJADa4k/DRkmH2iag8z8YK/zo= X-Received: by 2002:a17:902:a581:b029:da:d78:7f79 with SMTP id az1-20020a170902a581b02900da0d787f79mr1073866plb.32.1606797307177; Mon, 30 Nov 2020 20:35:07 -0800 (PST) MIME-Version: 1.0 Received: by 2002:a17:90a:7886:0:0:0:0 with HTTP; Mon, 30 Nov 2020 20:35:06 -0800 (PST) In-Reply-To: <20201130112137.587437-1-yili@winhong.com> References: <20201130112137.587437-1-yili@winhong.com> From: Yi Li Date: Tue, 1 Dec 2020 12:35:06 +0800 Message-ID: Subject: Re: [PATCH] bcache: fix panic due to cache_set is null To: Yi Li Cc: colyli@suse.de, kent.overstreet@gmail.com, linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, Guo Chao Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sorry, This patch will cause deadlock, i will check and redo it. On 11/30/20, Yi Li wrote: > bcache_device_detach will release the cache_set after hotunplug cache > disk. update_writeback_rate should check validate of cache_set. > > IP: [] update_writeback_rate+0x59/0x3a0 [bcache] > PGD 879620067 PUD 8755d3067 PMD 0 > Oops: 0000 [#1] SMP > CPU: 8 PID: 1005702 Comm: kworker/8:0 Tainted: G 4.4.0+10 #1 > Hardware name: Intel BIOS SE5C610.86B.01.01.0021.032120170601 03/21/2017 > Workqueue: events update_writeback_rate [bcache] > task: ffff8808786f3800 ti: ffff88077082c000 task.ti: ffff88077082c000 > RIP: e030:[] update_writeback_rate+0x59/0x3a0 [bcache] > RSP: e02b:ffff88077082fde0 EFLAGS: 00010202 > RAX: 0000000000000018 RBX: ffff8808047f0b08 RCX: 0000000000000000 > RDX: 0000000000000001 RSI: ffff88088170dab8 RDI: ffff88088170dab8 > RBP: ffff88077082fe18 R08: 000000000000000a R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000017bc8 R12: 0000000000000000 > R13: ffff8808047f0000 R14: 0000000000000200 R15: ffff8808047f0b08 > FS: 00007f157b6d6700(0000) GS:ffff880881700000(0000) > knlGS:0000000000000000 > CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000368 CR3: 0000000875c05000 CR4: 0000000000040660 > Stack: > 0000000000000001 0000000000007ff0 ffff88085ff600c0 ffff880881714e80 > ffff880881719500 0000000000000200 ffff8808047f0b08 ffff88077082fe60 > ffffffff81088c0c 0000000081714e80 0000000000000000 ffff880881714e80 > Call Trace: > [] process_one_work+0x1fc/0x3b0 > [] worker_thread+0x2a5/0x470 > [] ? __schedule+0x648/0x870 > [] ? rescuer_thread+0x300/0x300 > [] kthread+0xd5/0xe0 > [] ? kthread_stop+0x110/0x110 > [] ret_from_fork+0x3f/0x70 > [] ? kthread_stop+0x110/0x110 > > Reported-by: Guo Chao > Signed-off-by: Guo Chao > Signed-off-by: Yi Li > --- > drivers/md/bcache/writeback.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c > index 3c74996978da..186c4c6e1607 100644 > --- a/drivers/md/bcache/writeback.c > +++ b/drivers/md/bcache/writeback.c > @@ -175,7 +175,15 @@ static void update_writeback_rate(struct work_struct > *work) > struct cached_dev *dc = container_of(to_delayed_work(work), > struct cached_dev, > writeback_rate_update); > - struct cache_set *c = dc->disk.c; > + struct cache_set *c = NULL; > + > + mutex_lock(&bch_register_lock); > + c = dc->disk.c; > + > + if (c == NULL) { > + mutex_unlock(&bch_register_lock); > + return; > + } > > /* > * should check BCACHE_DEV_RATE_DW_RUNNING before calling > @@ -194,6 +202,7 @@ static void update_writeback_rate(struct work_struct > *work) > clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags); > /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */ > smp_mb__after_atomic(); > + mutex_unlock(&bch_register_lock); > return; > } > > @@ -230,6 +239,7 @@ static void update_writeback_rate(struct work_struct > *work) > clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags); > /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */ > smp_mb__after_atomic(); > + mutex_unlock(&bch_register_lock); > } > > static unsigned int writeback_delay(struct cached_dev *dc, > -- > 2.25.3 > > > >