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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 90728C43141 for ; Thu, 21 Jun 2018 03:03:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4542B20874 for ; Thu, 21 Jun 2018 03:03:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MnGbVMcb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4542B20874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754677AbeFUDDc (ORCPT ); Wed, 20 Jun 2018 23:03:32 -0400 Received: from mail-pl0-f68.google.com ([209.85.160.68]:44561 "EHLO mail-pl0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754451AbeFUDD3 (ORCPT ); Wed, 20 Jun 2018 23:03:29 -0400 Received: by mail-pl0-f68.google.com with SMTP id z9-v6so830419plk.11 for ; Wed, 20 Jun 2018 20:03:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:from:subject:cc:message-id:date:user-agent:mime-version :content-transfer-encoding:content-language; bh=YM0NyBKPrXdxiBVQwYPvyqesju+DKxUVC4RWfFvxMxY=; b=MnGbVMcbCQ1qSFdDjVq+II4ymtIbcbNMVzW6QxSLZwZKM/osggspp5mZ1FSnk3hBPE DnbIQK6+UCGcHruqeK3nNJ/NyU5fFWE0QglBODvKpxtEE0x6b7vaKloELyMhZmd11+KW X3A7LimfOa/GmOFnGSJ7S5ri4AvtxEEmkMykMo//PCeyGmcd4U1KN8Ti5S+vK1DLdEwF XapJNbc6HIz6+p9x0kjjqdHGX5w8vVEebKKUz6RJHKm8W9BzIfZzAPA7e6iHL6tnTCLT cvqYJUnU8SpmQbreQRxrbHAbSF6uSHuXcskNSrGheWKWK0t/NDOzrrNjfyaBami0tgv6 zI+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:from:subject:cc:message-id:date:user-agent :mime-version:content-transfer-encoding:content-language; bh=YM0NyBKPrXdxiBVQwYPvyqesju+DKxUVC4RWfFvxMxY=; b=Gpem+p9lQtFg/SqGpIW+6nyE6NS3C6khiSMBKsQsyJCZ/IQZdtzObp3AtNAPbG0CvT QZ9XmBp+YDgZ2YRUJmaks/3Z2Y/R4vs4X4AfMooz3epUG2uxtLCmrvOgm6Q8g8S+Wt8d PGl0rnegYzeb0z8MTnReHN9zOoqFI2caKECfNemoJSUP9vYQCkjwfBU9wo8eMYlbz/yi Gqt0LdWPQQzNLRmTvfhMHNbL2xkhLFfD8Y7VyflZIjByoOR8zShTPAYLJvxlDugfDMm/ QgInhOpOfQDNyq3X/oGFB77TdqVtIpLztSBGlLZ2xm6EIVimVoB4gqCFPa2N/OZyvZXx cq3Q== X-Gm-Message-State: APt69E2Nqapb/xNVpSbrszp5y5mOWrzy/eCma/FBCdrr7W56gjSCbYUZ +XIgoYOhCYfM9I6U8pJ7ocsbrEco X-Google-Smtp-Source: ADUXVKLz88sACpjalht3UC/VwX2QKhVuiKgvZFxV1fzKlCr0C0ywYP/aL7ffjV6Itu3qNMS5I3TkzQ== X-Received: by 2002:a17:902:2924:: with SMTP id g33-v6mr26870814plb.26.1529550208588; Wed, 20 Jun 2018 20:03:28 -0700 (PDT) Received: from ?IPv6:2402:f000:1:1501:200:5efe:166.111.70.11? ([2402:f000:1:1501:200:5efe:a66f:460b]) by smtp.gmail.com with ESMTPSA id t3-v6sm4990045pgs.91.2018.06.20.20.03.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 20 Jun 2018 20:03:28 -0700 (PDT) To: axboe@kernel.dk, akpm@linux-foundation.or, jack@suse.cz, zhangweiping@didichuxing.com, sergey.senozhatsky@gmail.com, andriy.shevchenko@linux.intel.com, christophe.jaillet@wanadoo.fr, aryabinin@virtuozzo.com From: Jia-Ju Bai Subject: [BUG] mm: backing-dev: a possible sleep-in-atomic-context bug in cgwb_create() Cc: linux-mm@kvack.org, Linux Kernel Mailing List Message-ID: <626acba3-c565-7e05-6c8b-0d100ff645c5@gmail.com> Date: Thu, 21 Jun 2018 11:02:58 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel may sleep with holding a spinlock. The function call path (from bottom to top) in Linux-4.16.7 is: [FUNC] schedule lib/percpu-refcount.c, 222: schedule in __percpu_ref_switch_mode lib/percpu-refcount.c, 339: __percpu_ref_switch_mode in percpu_ref_kill_and_confirm ./include/linux/percpu-refcount.h, 127: percpu_ref_kill_and_confirm in percpu_ref_kill mm/backing-dev.c, 545: percpu_ref_kill in cgwb_kill mm/backing-dev.c, 576: cgwb_kill in cgwb_create mm/backing-dev.c, 573: _raw_spin_lock_irqsave in cgwb_create This bug is found by my static analysis tool (DSAC-2) and checked by my code review. I do not know how to correctly fix this bug, so I just report them. Maybe cgwb_kill() should not be called with holding a spinlock. Best wishes, Jia-Ju Bai