From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-24.sinamail.sina.com.cn (r3-24.sinamail.sina.com.cn [202.108.3.24]) (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 D036A2FD7D3 for ; Thu, 28 May 2026 05:44:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=202.108.3.24 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779947074; cv=none; b=jez0V4olhmzyyXRWngHv6XLQrlFuwoCDz4hOk9VXh1P0ZlxSSJ2hc3to1ADbCHTjN8OfQleMvqzSLbfwcj6mdskFCuBcITjV4gMi5nxNFkfpMYJzEa8QHFwA1aslaxHJkmexTmsNwaJVSFmgf31vHY01POKzuUoXAuQ6yFgkLYc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779947074; c=relaxed/simple; bh=C7JHlHzPIIDbcrjvTTaZykxa0kwfZ19sATnFMjQgAWY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C07bvw7QD9lrF+OJtaVaTrzlXidQaOWPNJ882MN/Xy0/FyvWa/LZF/w1iuAwvwbBg41YNW/ZZQPzD6eBKfKPQt/sH+qxEz2ozZF92PMrF1usEr8OyHkZefWsG73iD2a5LEsK2XLlbKUgNiPdaeURVdJvR4SvseiJazHOaUrAGn0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=KeHDtnCp; arc=none smtp.client-ip=202.108.3.24 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="KeHDtnCp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1779947071; bh=cx/MeDnSm8Ccc4831CYFK65RBNwl+E+0XHr2pEV7eW0=; h=From:Subject:Date:Message-ID; b=KeHDtnCpMDujKRMnpFc++PjSF13nEn76CT++kiXKvHsbsu+MSsmFANgfswG5xhvJJ z1T9N7IywbTsfBSQg/0e0mWtomFZWjXw1YWiql7njo3r58ItOW5IKlI1luqEjEyudZ oOdvGo/ZqmrkAOI4FVwQ51HSGsalc85qPShKENGU= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.31) with ESMTP id 6A17D60E000062C1; Thu, 28 May 2026 13:43:45 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 9341726816115 X-SMAIL-UIID: 4C03AE2645D34C15B349F3C5E267BA13-20260528-134345-1 From: Hillf Danton To: Ming Lei Cc: Tetsuo Handa , Jens Axboe , Bart Van Assche , Christoph Hellwig , Damien Le Moal , linux-block , LKML , Andrew Morton , Linus Torvalds , linux-btrfs@vger.kernel.org, David Sterba , linux-fsdevel@vger.kernel.org, Christian Brauner Subject: Re: [PATCH v3] loop: Fix NULL pointer dereference in lo_rw_aio() Date: Thu, 28 May 2026 13:43:31 +0800 Message-ID: <20260528054334.1159-1-hdanton@sina.com> In-Reply-To: References: <94076bc9-2c09-4bb6-8468-b6b8af419cb9@I-love.SAKURA.ne.jp> <1ab8c579-eb76-4227-8a72-6ec819135219@I-love.SAKURA.ne.jp> <1a9f53d4-6f48-4df8-a3d8-2b0e442a163a@I-love.SAKURA.ne.jp> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, 26 May 2026 22:00:49 -0500 Ming Lei wrote: >On Wed, May 27, 2026 at 10:35:56AM +0900, Tetsuo Handa wrote: >> On 2026/05/27 10:20, Ming Lei wrote: >> >> Of course we should try to figure out the root cause first, but how can we do? >> > >> > Definitely unexpected write IO(after umount & loop closed) from btrfs is more serious, >> > which may cause data loss, so CC btrfs list and maintainer. >> >> Why do you assume that the culprit is btrfs? >> >> https://syzkaller.appspot.com/bug?extid=bc273027d5643e48e5b3 indicated that >> this similar race is also happening with jfs. > > I just didn't see the above report on jfs. > > It doesn't change anything, the same question still stands: unexpected write IO is issued > or crosses umount & last closing of loop disk. > Given the loop workqueue that triggered the jfs warning, can you specify the reason why the workqueue in question is NOT flushed while closing disk?