From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f50.google.com (mail-pj1-f50.google.com [209.85.216.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0748D2D0292 for ; Sat, 22 Aug 2026 03:27:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787369277; cv=none; b=kq5GRoqYRm/hSPY8+RzDzGGUI1Orw0QwPzAcZbhBJkteqKb8v6fX9G3qaGlsl3LX3PHxWGppA34BUfwy+i0VgJ9w61fHYd2YDPY5N46rHQ46Df3ASZThNul3WJUCxDoJRgCxFDwJU/QyjBYffmnYXotHSD0HgLvncHMwBeGj+wU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787369277; c=relaxed/simple; bh=r0rZITQKtQ0m93bjcwa195ZSrLZUfdfW1/mQ7LAgKJc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SiwuMsSEJ58PpFRBBIdxpI13vT+x6QyirJmsgLQnXYMPkzlyOjycAfCKoVBh7s4fyi3FifuyzPoAreGbxCQtGW14ymwCBpQ/u4lu19IybPCNkoc2S74RT83Cf8+C3nfKufwbKKcym3Y0ntow64o7K0nQUvHWp23nYfW7KRXg3gU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=DtXZpump; arc=none smtp.client-ip=209.85.216.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DtXZpump" Received: by mail-pj1-f50.google.com with SMTP id 98e67ed59e1d1-38e08baf860so1779710a91.2 for ; Fri, 21 Aug 2026 20:27:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1787369275; x=1787974075; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=LOks5Q+WseXHaYrxJ0Gn8dlCqtIA9nboyxrTjV4SPVE=; b=DtXZpumptNjUFJEcE55AFFDudCjZdeXxsAnkjT7VmJi+uycMOTy5k7ss3R3ElXtmuU GihGsJkn4zQSEvTPUbuugoYt9JqMuGsWCpt19b9611Nafdtv5pxxGPM0jYXXWu9/s2A2 SW8b1Md7PhNJSScJwmdv2tdfOWEfeYS+yLmukTwHcvQwqHYK1ur/7MaViOUg2tz7h6Lh 8eZTgTl/+xxXt/l5YxKF8HVHnqz9QFFH3HysJKEYzOIy77VtFZ8PE/v4UAGKbWvd6JDm D2HgRBbAIohldIHzbcvuMT0Itv5a+53/p3f22FM5JFZpcpLkMZ4hr0Vz2e4QNzyC3wAB Fugg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787369275; x=1787974075; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=LOks5Q+WseXHaYrxJ0Gn8dlCqtIA9nboyxrTjV4SPVE=; b=DImY6bof1UaoUTOwnVM8/VNsZM/KEeqK7k2iw6QE4FQ3vQptJuAQBWSw48ovwQJRjp i4ujkDPxz9n6E9e4tNyb8YHqudgFvO/kVJuKNMSxNYpwQ8YwfsmLqDAynpovd1n/t3DM OnvLw5de0v71BWFV9F/xF3v0G3/Ev0VP5jLtnS49PN90GBVoZQsUtW/81QLtJK0Gb15P j54c6mmayR5N97U3eTQHg1IZWmloxHGzaK6YWn4dhTwf91fPCxCnKMlA5YoE7sgJPHVF 5lZyUJgPFZdateXU2lUB5NDmSlvHgGsKWrHcOu6h8/8mczmmy2qHFupecCPl4155GvIe 9pvQ== X-Forwarded-Encrypted: i=1; AHgh+Ro7+dbxGNl47ot210S37hbwydyvLcyR47voJCyhaHW0QjAVlPz/DTkdiLeKkZffcOfDRXhU3vfh79vv@vger.kernel.org X-Gm-Message-State: AFuF++mXuC/cTLqR8svjyJCmxMrrbHYLVXMNOLGhKTNvm7+arzgcM7K/ ly1p69f6+1RJtOqdc2fF8RdQmpM78iUO0K4ATVi13Gdm0toZ8Fud8nydPrSk3J2GTho= X-Gm-Gg: AR+sD12qJc+FjzrfgDIqtExyPtjZp3PEzaCH1awlHWFWqX8knmw6PP9EFBL77krERwW wS4LrTcWxRI+7nZ8MgGl0hNcf3bCg4YZIDCyMemJbYfZZI7ac0M0y1X0/+QA629XJLldY8FBrCA H4DdsO7vmbNCN7Kf0f1aY6orjfLCW2n/EkgGwaEuyR+rVC5IIAPrS0WIhHydmxTlPh2EgMVZ0ic Hy7jWuLkcVYFNLezwEaIpLMNvYrp06nz+Jo780S4ke9fmEf8dmW0Iueq4qry06Ul8mzO5ewMLuN oCPXJzYFg+FqKSiy9VuZaFLMJmDF7TiX2lZoCV4tqGXZX6ZLAA2+wMKws7cGCea9JRoZDSqQmIc kSGV/7iDo9q0c//RZY0qjcRWLEPR2e5r08TSkQxTdylBBN/gKgdRKfP5B4o7DUbCBLj6dPwU+pb a/I6hL4nDP91h4oonXceNY5bZNfcP766S07N6YVrkjQULXnUc4wjEX1XSlzg6jGgcJnuwEq78GH 20gWp8r X-Received: by 2002:a17:90b:3a8d:b0:395:4de0:b78f with SMTP id 98e67ed59e1d1-395dee528b7mr5092881a91.1.1787369275158; Fri, 21 Aug 2026 20:27:55 -0700 (PDT) Received: from [100.125.248.95] ([124.70.231.46]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-395e4999471sm1154921a91.8.2026.08.21.20.27.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Aug 2026 20:27:54 -0700 (PDT) Message-ID: Date: Sat, 22 Aug 2026 11:27:25 +0800 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH -next v5 29/32] ext4: add tracepoints for DISKSIZE_GROW_PENDING set, clear, and wait To: sashiko-reviews@lists.linux.dev, Zhang Yi Cc: tytso@mit.edu, linux-ext4@vger.kernel.org References: <20260814093331.1703882-1-yi.zhang@huaweicloud.com> <20260814093331.1703882-30-yi.zhang@huaweicloud.com> <20260814101826.865151F000E9@smtp.kernel.org> Content-Language: en-US From: Zhang Yi In-Reply-To: <20260814101826.865151F000E9@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/14/2026 6:18 PM, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [High] Sequence counter deadlock in tracepoint when called from softirq context on 32-bit SMP. > -- > > --- Patch [29]: [PATCH -next v5 29/32] ext4: add tracepoints for DISKSIZE_GROW_PENDING set, clear, and wait --- > commit f14aeb9661220b55cf0eeb4ff49da9fa6a2a18ca > Author: Zhang Yi > > ext4: add tracepoints for DISKSIZE_GROW_PENDING set, clear, and wait > > This commit adds trace events ext4_iomap_mark_disksize_pending(), > ext4_iomap_clear_disksize_pending(), and ext4_iomap_wait_disksize_pending(). > These tracepoints track disksize-grow-pending state changes and waiting. > >> diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h >> index 69596a216dcb1..4539ef8e5f86c 100644 >> --- a/include/trace/events/ext4.h >> +++ b/include/trace/events/ext4.h > [ ... ] >> +DECLARE_EVENT_CLASS(ext4_iomap_disksize_pending, >> + TP_PROTO(struct inode *inode), >> + TP_ARGS(inode), >> + TP_STRUCT__entry( >> + __field(dev_t, dev) >> + __field(u64, ino) >> + __field(loff_t, i_size) >> + __field(loff_t, i_disksize) >> + ), >> + TP_fast_assign( >> + __entry->dev = inode->i_sb->s_dev; >> + __entry->ino = inode->i_ino; >> + __entry->i_size = i_size_read(inode); > > [Severity: High] > Could this cause a sequence counter deadlock on 32-bit SMP architectures? > > If a process executing i_size_write() is preempted by a block I/O completion > hardware interrupt, and pending softirqs are executed on return from the > interrupt, the softirq could call ext4_iomap_end_bio() in fs/ext4/page-io.c: > > fs/ext4/page-io.c:ext4_iomap_end_bio() { > ... > if (io_mode == EXT4_IOMAP_IOEND_DISKSIZE_GROW_IO) > ext4_iomap_clear_disksize_pending(ioend->io_inode); > ... > } > > This would trigger trace_ext4_iomap_clear_disksize_pending() which calls > i_size_read() here in TP_fast_assign. > > Since i_size_write() disables preemption but not softirqs, the seqcount > would be odd. This would cause i_size_read() to spin indefinitely waiting > for the interrupted i_size_write() to complete on the same CPU. > Yeah, I'll remove the i_size check in the next version. It doesn't look like we really need it. Thanks, Yi. >> + __entry->i_disksize = READ_ONCE(EXT4_I(inode)->i_disksize); >> + ), >> + TP_printk("dev %d:%d ino %llu i_size %lld i_disksize %lld", >> + MAJOR(__entry->dev), MINOR(__entry->dev), >> + __entry->ino, __entry->i_size, __entry->i_disksize) >> +); >