From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 6088825F984 for ; Fri, 17 Oct 2025 22:07:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760738865; cv=none; b=L/QzMYhwUco4p0Bdq0TK9rnomTTCkxAkjY7bBns6WdWthEbnLeZ8OOmGghihBxE6sCt3Sue5hqCB9fcTwz0gTONjXNHz0n7mfaI2a+C2CxdzofAdjvrXFihyM/S4glLEi/bapbkLUefcfg2ie+QsnalycImEv61TUel62waFxgU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760738865; c=relaxed/simple; bh=eqpJsitnRdx6aHva3Dc7wIOb+y6HI3iRsyO4IhbTutY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=HOtP8KM9LJvNrq+AJc5/MpDUpw8bKR0gHX5VSQE4s9ITC79AfA2pRUNZc4uRk5bhv4fc6OdLUDUYRAebBe0IfsObTG8DkcBW6I9//2Szq9EC8BdheKXOyjPkxWCUYkJwRL0d8Q+jyKmyXJL9GZkwYo6IsMbSSkaxprfUkScvC3A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=tTHdM0DL; arc=none smtp.client-ip=115.124.30.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="tTHdM0DL" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1760738854; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=ZDWp9OTlHYqMcHwYcfdrsc43HFGTcdchKzDpk+oEDpo=; b=tTHdM0DLwFjyJKljvPTWDciuWAEhpuhaN/4/HBZLt32cu6FmiNiT7bJ5uxLGes5gsUwgJBQCtVf3TZPGyyL6HMPccJHPNH077OZIBredHuJNJ9I9wTfA62PzBa+Ks/6RarQnm6Lvla8ItJifcgRnMR00PXRl25zVQ7BWThzYkbI= Received: from 30.180.79.37(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0WqQWfgH_1760738852 cluster:ay36) by smtp.aliyun-inc.com; Sat, 18 Oct 2025 06:07:33 +0800 Message-ID: <9f800c6d-1dc5-42eb-9764-ea7b6830f701@linux.alibaba.com> Date: Sat, 18 Oct 2025 06:07:32 +0800 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/9] iomap: account for unaligned end offsets when truncating read range To: Joanne Koong Cc: Christoph Hellwig , brauner@kernel.org, djwong@kernel.org, bfoster@redhat.com, linux-fsdevel@vger.kernel.org, kernel-team@meta.com References: <20251009225611.3744728-1-joannelkoong@gmail.com> <20251009225611.3744728-2-joannelkoong@gmail.com> <49a63e47-450e-4cda-b372-751946d743b8@linux.alibaba.com> <01f687f6-9e6d-4fb0-9245-577a842b8290@linux.alibaba.com> From: Gao Xiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025/10/18 02:41, Joanne Koong wrote: > On Thu, Oct 16, 2025 at 5:03 PM Gao Xiang wrote: >> >> On 2025/10/17 06:03, Joanne Koong wrote: >>> On Wed, Oct 15, 2025 at 6:58 PM Gao Xiang wrote: >> >> ... >> >>>> >>>>> >>>>> So I don't think this patch should have a fixes: tag for that commit. >>>>> It seems to me like no one was hitting this path before with a >>>>> non-block-aligned position and offset. Though now there will be a use >>>>> case for it, which is fuse. >>>> >>>> To make it simplified, the issue is that: >>>> - Previously, before your fuse iomap read patchset (assuming Christian >>>> is already applied), there was no WARNING out of there; >>>> >>>> - A new WARNING should be considered as a kernel regression. >>> >>> No, the warning was always there. As shown in the syzbot report [1], >>> the warning that triggers is this one in iomap_iter_advance() >>> >>> int iomap_iter_advance(struct iomap_iter *iter, u64 *count) >>> { >>> if (WARN_ON_ONCE(*count > iomap_length(iter))) >>> return -EIO; >>> ... >>> } >>> >>> which was there even prior to the fuse iomap read patchset. >>> >>> Erofs could still trigger this warning even without the fuse iomap >>> read patchset changes. So I don't think this qualifies as a new >>> warning that's caused by the fuse iomap read changes. >> >> No, I'm pretty sure the current Linus upstream doesn't have this >> issue, because: >> >> - I've checked it against v6.17 with the C repro and related >> Kconfig (with make olddefconfig revised); >> >> - IOMAP_INLINE is pretty common for directories and regular >> inodes, if it has such warning syzbot should be reported >> much earlier (d9dc477ff6a2 was commited at Feb 26, 2025; >> and b26816b4e320 was commited at Mar 19, 2025) in the dashboard >> (https://syzkaller.appspot.com/upstream/s/erofs) rather >> than triggered directly by your fuse read patchset. >> >> Could you also check with v6.17 codebase? > > I think we are talking about two different things. By "this issue" > what you're talking about is the syzbot read example program that > triggers the warning on erofs, but by "this issue", what I was talking > about is the iomap_iter_advance() warning being triggerable > generically without the fuse read patchset, not just by erofs. Ah, yes. Sorry the subjects of those two patches are similar, I got them mixed up. I thought you resent the previous patch in this patchset. > > If we're talking about the syzbot erofs warning being triggered, then > this patch is irrelevant to be talking about, because it is this other > patch [1] that fixes that issue. That patch got merged in before any > of the fuse iomap read changes. There is no regression to erofs. Can you confirm this since I can't open the link below: tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs-6.19.iomap [1/1] iomap: adjust read range correctly for non-block-aligned positions https://git.kernel.org/vfs/vfs/c/94b11133d6f6 As you said, if this commit is prior to the iomap read patchset, that would be fine. Otherwise it would be better to add a fixes tag to that commit to point out this patch should be ported together to avoid the new warning. Thanks, Gao Xiang > > Thanks, > Joanne > > [1] https://lore.kernel.org/linux-fsdevel/20250922180042.1775241-1-joannelkoong@gmail.com/ > >> >> Thanks, >> Gao Xiang >>