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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 2EBD1C433E0 for ; Fri, 19 Feb 2021 06:23:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8AFE64EC0 for ; Fri, 19 Feb 2021 06:23:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229535AbhBSGXW (ORCPT ); Fri, 19 Feb 2021 01:23:22 -0500 Received: from m42-2.mailgun.net ([69.72.42.2]:45749 "EHLO m42-2.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229498AbhBSGXU (ORCPT ); Fri, 19 Feb 2021 01:23:20 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1613715780; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=R8F5SrJMAIGBbO6RxWiqQbg011N71/HoCZ+ew9nIx4Y=; b=DqLDj5OeJ/kl7CmfrSX0AHWIZ0fM12Pm7PtQWeH7OCcuXLkPLl6OlALcv7MmWY8oDbMrboQN IgHsFX+TdSKsA7Pw2JHUza0yEOLk1jYWHnLh4gICM9SoTHJz3ZxQE3yPAeZpolgTSaJhZ0TJ XU7rEmrmP1exSBPmkUiU0lyang8= X-Mailgun-Sending-Ip: 69.72.42.2 X-Mailgun-Sid: WyI0MmE5NyIsICJsaW51eC1ibG9ja0B2Z2VyLmtlcm5lbC5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n01.prod.us-west-2.postgun.com with SMTP id 602f59237237f827dc0b4fa6 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 19 Feb 2021 06:22:27 GMT Sender: pragalla=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id BF5FDC43461; Fri, 19 Feb 2021 06:22:26 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: pragalla) by smtp.codeaurora.org (Postfix) with ESMTPSA id E8AECC433C6; Fri, 19 Feb 2021 06:22:25 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 19 Feb 2021 11:52:25 +0530 From: pragalla@codeaurora.org To: John Garry Cc: Bart Van Assche , axboe@kernel.dk, evgreen@google.com, linux-block@vger.kernel.org, stummala@codeaurora.org, Ming Lei Subject: Re: use-after-free access in bt_iter() In-Reply-To: <9ace4c26c47e84c3c6a1c68ef1a193f8@codeaurora.org> References: <056783fa-a510-2463-f353-c64dd8f37be9@acm.org> <5ab6e628-6c93-618a-a10b-fe0df1ab4a40@huawei.com> <9ace4c26c47e84c3c6a1c68ef1a193f8@codeaurora.org> Message-ID: X-Sender: pragalla@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2021-02-05 21:51, pragalla@codeaurora.org wrote: > On 2021-02-05 21:37, John Garry wrote: >> - bouncing jianchao.w.wang@oracle.com >> >>>> >>>>> Some time ago you replied the following to an email from me with a >>>>> suggestion for a fix: "Please let me consider it a bit more." Are >>>>> you >>>>> still working on a fix? >>>> >>>> Unfortunately I have not had a chance, sorry. But I can look again. >>>> >>>> So I have only seen KASAN use-after-free's myself, but never an >>>> actual >>>> oops. IIRC, someone did report an oops. >>>> >>> Hi John, >>> >>>> @Pradeep, do you have a reliable re-creator? I noticed the timeout >>>> handler stackframe in your mail, so I guess not. However, as an >>>> experiment, could you test: >>>> https://lore.kernel.org/linux-block/1608203273-170555-2-git-send-email-john.garry@huawei.com/ >>> Yes, i don't have a reliable re-creator. The oops was noticed as a >>> part of stability testing and >>> was not an intentional try. This was noticed couple of times. >>> Please share the steps (if any) to easy hit or to exercise this path >>> more frequently. >>> Meanwhile, i will go with the usual stability procedure. i will >>> update the results here later. >>> >> Hi John, we ran the stability with the above patch (https://lore.kernel.org/linux-block/1608203273-170555-2-git-send-email-john.garry@huawei.com/) with switching the io-schedulers in b/w for ~88hrs on 2 devices, we didn't notice any crash/issue. >> Do you have a full kernel log for your crash? > Yes. Attaching the full kernel dmesg log. >> >> So there are different flavors of this issue, and you reported a crash >> from blk_mq_queue_tag_busy_iter(). >> >> If you check: >> https://lore.kernel.org/linux-block/76190c94-c5c1-9553-5509-9969fc323544@huawei.com/ >> >> You can see how I artificially trigger an issue in >> blk_mq_queue_tag_busy_iter(). > Sure, i will go through the steps on the recreation part. Thanks. >> >>>> This should fix the common issue. But no final solution to issues >>>> discussed from patch 2/2, which is more exotic. >>>> >>>> BTW, is this the same Pradeep who reported: >>>> https://lore.kernel.org/linux-block/1606402925-24420-1-git-send-email-ppvk@codeaurora.org/ >> >> Thanks, >> John > > Thanks and Regards, > Pradeep