From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout01.his.huawei.com (canpmsgout01.his.huawei.com [113.46.200.216]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C8C025FA29; Sat, 7 Mar 2026 00:16:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.216 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772842619; cv=none; b=iuoKX4+kTLcFhgTbYp6afAJS1jqchqzNBgFRPWFl8kxPbOl7gNgptjWUJejGOeMs+cOJK+62bONphQvTZO3L1Jjk9wh7t3kGr+PEPceIgq012kFlBgfkOV2JF1dF92U09hnDlsC/rWhFNg/VY3Rj3EveT5k/f2NVeGQBg0sFODQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772842619; c=relaxed/simple; bh=bG1lD7YvUm3cXv0rKSPVWhKJ4XrMsusCcd+0FjvB1UU=; h=Subject:To:References:CC:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=RuAxk5hFpzpgNoBIC7BRu9hmttqeEafLmKRjXn8Xn/2+zfMPtzQVaSJvzfus7RdTPREurvtVnAXCQ4I/RBhbN2IVzgQs6BxoxqK9EoI2HKFY32qEu6GoMPMJl5/JxkN+cpCC2c7XQBEL9TCnm7VPjUpF7QaeyDGKOD8fh/xSdIQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=YSS2pQGM; arc=none smtp.client-ip=113.46.200.216 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="YSS2pQGM" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=bG1lD7YvUm3cXv0rKSPVWhKJ4XrMsusCcd+0FjvB1UU=; b=YSS2pQGM6g1NjFDf88+5mLv/95uS0Jp7vl92ZRQXY2FwQWG1NaEJoqE31UQ/m5mo2Mwg14ZWD vsvQTuyTfqOyN2YXLOGJrCbOfaGkEb1YXZRXlidGSsaZ4a9w2hI+pYsInqbm5EKKErX3fRk14yG 9tj+xISN3Kfp65BLdSNmMfE= Received: from mail.maildlp.com (unknown [172.19.163.0]) by canpmsgout01.his.huawei.com (SkyGuard) with ESMTPS id 4fSNxB634jz1T4GS; Sat, 7 Mar 2026 08:11:42 +0800 (CST) Received: from dggemv705-chm.china.huawei.com (unknown [10.3.19.32]) by mail.maildlp.com (Postfix) with ESMTPS id 2B2EB40561; Sat, 7 Mar 2026 08:16:48 +0800 (CST) Received: from kwepemq500016.china.huawei.com (7.202.194.202) by dggemv705-chm.china.huawei.com (10.3.19.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 7 Mar 2026 08:16:47 +0800 Received: from [10.174.178.185] (10.174.178.185) by kwepemq500016.china.huawei.com (7.202.194.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 7 Mar 2026 08:16:47 +0800 Subject: Re: [BUG] kernel BUG in ext4_do_writepages To: Xianying Wang , References: CC: , , From: "yebin (H)" Message-ID: <69AB6E6D.4080007@huawei.com> Date: Sat, 7 Mar 2026 08:16:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemq500016.china.huawei.com (7.202.194.202) On 2026/3/6 13:42, Xianying Wang wrote: > Hi, > > I would like to report a kernel BUG triggered by a syzkaller > reproducer in the ext4 filesystem writeback path. > There was a period when I also noticed block allocation failures during write-back, but after the configuration was changed, it didn't seem to happen again. > The issue was originally observed on Linux 6.19.0-rc8 and can also be > reproduced on Linux 7.0-rc2. The crash occurs in the ext4 writeback Can you identify which patch or which patchset introduced the issue? > routine while the background writeback worker is flushing dirty pages > to disk. > > During the crash, the filesystem reports that no free blocks are > available while dirty pages and reserved blocks still exist. Under > this condition, the writeback worker continues processing pending > writeback operations and eventually reaches an internal consistency > check inside the ext4 writeback routine, which triggers a kernel BUG. > > Based on the execution context, the issue appears to be related to the > interaction between delayed allocation and the writeback mechanism > when the filesystem runs out of available blocks. When the writeback > thread attempts to flush dirty pages in this state, ext4 enters an > unexpected internal state that causes the BUG to be triggered. > > This can be reproduced on: > > HEAD commit: > > 11439c4635edd669ae435eec308f4ab8a0804808 > > report: https://pastebin.com/raw/dNFvCatE > > console output : https://pastebin.com/raw/LAPYKL5P > > kernel config : https://pastebin.com/7hk2cU0G > > C reproducer :https://pastebin.com/raw/v07yFCWP > Can you add these to the email as attachments? > Let me know if you need more details or testing. > > Best regards, > > Xianying > > > . >