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=-20.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 0B17BC4320A for ; Thu, 19 Aug 2021 08:05:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF6FC610A6 for ; Thu, 19 Aug 2021 08:05:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237036AbhHSIF5 (ORCPT ); Thu, 19 Aug 2021 04:05:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:42672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237225AbhHSIFa (ORCPT ); Thu, 19 Aug 2021 04:05:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4993261139; Thu, 19 Aug 2021 08:04:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629360258; bh=pu0ysrGHipCPaIG2y6nk/FcaajGch8ROclwW+cPMTlA=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=klGfKQuG0JWx1ts+OWEOYXOrkS6Oe4DTXllQVs/cju6eJFL2fyy6Fp62FPdulqY3n xeKZPojvYrTbdEnqulkazrp+C3ISDA7ArsSrTK0Tkl3Ueg1E1HAbevJaJhotw0eBS8 vuXVfQ9WdVqb+mkK+26sw4mVsGVefWKfrp4BeRC1qzK8BE8MxOTKSr/9D8h1tz3tcI Hkiir9eZuPAZGoVPi+EtixJdfIF5Nhv9/6Yxe04DQr8ikAZs/rVmtzywdsnd348yu3 hfBZ3Asgt4xTr8VNnUFyiNbePbkYFbYOR/ecmb8lXdJYftJwIxVhstgt8fD1Pj0zwl iKh8d/pMqKeYA== Subject: Re: [PATCH v6] f2fs: introduce /sys/fs/f2fs//fsck_stack node To: =?UTF-8?B?5p2O5oms6Z+s?= Cc: jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: From: Chao Yu Message-ID: <492e1c4e-f39c-0460-0459-9c84aeaf407f@kernel.org> Date: Thu, 19 Aug 2021 16:04:15 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/8/16 15:23, 李扬韬 wrote: >>> HI Chao, >>>>> SBI_NEED_FSCK is an indicator that fsck.f2fs needs to be triggered, >>>>> this flag is set in too many places. For some scenes that are not very >>>>> reproducible, adding stack information will help locate the problem. >>>>> >>>>> Let's record all fsck stack history, I added F2FS_FSCK_STACK_TRACE >>>>> configuration options and sysfs nodes. After opening the configuration >>>>> options and enabling the node, it will start recording. The recorded >>>>> stack information will not be clear, and we can get information form >>>>> kernel log. >>>>> >>>>> Signed-off-by: Yangtao Li >>>>> --- >>>>> Documentation/ABI/testing/sysfs-fs-f2fs | 7 ++++ >>>>> fs/f2fs/Kconfig | 10 ++++++ >>>>> fs/f2fs/f2fs.h | 45 +++++++++++++++++++++++++ >>>>> fs/f2fs/sysfs.c | 27 +++++++++++++++ >>>>> 4 files changed, 89 insertions(+) >>>>> >>>>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs >>>>> index ef4b9218ae1e..047c398093cf 100644 >>>>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs >>>>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs >>>>> @@ -493,3 +493,10 @@ Contact: "Chao Yu" >>>>> Description: When ATGC is on, it controls age threshold to bypass GCing young >>>>> candidates whose age is not beyond the threshold, by default it was >>>>> initialized as 604800 seconds (equals to 7 days). >>>>> + >>>>> +What: /sys/fs/f2fs//fsck_stack >>>>> +Date: August 2021 >>>>> +Contact: "Yangtao Li" >>>>> +Description: Controls to enable/disable fsck stack trace, you can get stack >>>>> + information from kernel log. Note that the recorded stack information >>>>> + will not be cleared. >>>> >>>> Again, please don't add this into sysfs. >> >>Oh, I missed to check the details... >> >>> >>> I added this node, part of the idea is to trigger the export of stack information. >>> There is no information transmitted through sysfs here, but the record of the stack is switched on and off. >>> If don't export this information through procfs and sysfs, is there a more appropriate way? >> >>Well, I doubt why we should export stack info via proc/sysfs node or >>sysfs switch. >> >>Those info will always be needed to troubleshoot issues no matter in >>user or eng version of Android, can we just print them directly into >>kernel message... what I concern is we may lost the bug scene due to >>no one can help to trigger dmesg printing via sysfs. >> >>Jaegeuk, thoughts? >> >>> >>>> >>>>> diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig >>>>> index 7669de7b49ce..f451e567e4a8 100644 >>>>> --- a/fs/f2fs/Kconfig >>>>> +++ b/fs/f2fs/Kconfig >>>>> @@ -135,3 +135,13 @@ config F2FS_FS_LZORLE >>>>> default y >>>>> help >>>>> Support LZO-RLE compress algorithm, if unsure, say Y. >>>>> + >>>>> +config F2FS_FSCK_STACK_TRACE >>>> >>>> I don't think we need another config to wrap this functionality, may be we >>>> can use F2FS_CHECK_FS instead. >>> >>> OK. >>> >>>> >>>>> + bool "F2FS fsck stack information record" >>>>> + depends on F2FS_FS >>>>> + depends on STACKDEPOT >>>>> + default y >>>>> + help >>>>> + Support printing out fsck stack history. With this, you have to >>>>> + turn on "fsck_stack" sysfs node. Then you can get information >>>>> + from kernel log. >>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >>>>> index ee8eb33e2c25..b2d1d1a5a3fc 100644 >>>>> --- a/fs/f2fs/f2fs.h >>>>> +++ b/fs/f2fs/f2fs.h >>>>> @@ -24,6 +24,8 @@ >>>>> #include >>>>> #include >>>>> #include >>>>> +#include >>>>> +#include >>>>> >>>>> #include >>>>> #include >>>>> @@ -117,6 +119,8 @@ typedef u32 nid_t; >>>>> >>>>> #define COMPRESS_EXT_NUM 16 >>>>> >>>>> +#define FSCK_STACK_DEPTH 64 >>>> >>>> 16? >>> >>> OK. >>> >>>> >>>>> + >>>>> struct f2fs_mount_info { >>>>> unsigned int opt; >>>>> int write_io_size_bits; /* Write IO size bits */ >>>>> @@ -1748,6 +1752,11 @@ struct f2fs_sb_info { >>>>> unsigned int compress_watermark; /* cache page watermark */ >>>>> atomic_t compress_page_hit; /* cache hit count */ >>>>> #endif >>>>> +#ifdef CONFIG_F2FS_FSCK_STACK_TRACE >>>>> + depot_stack_handle_t *fsck_stack_history; >>>>> + unsigned int fsck_count; >>>>> + bool fsck_stack; >>>> >>>> IMO, all bug_on()s are corner cases, and catching those stacks won't cost >>>> much, so we can just use CONFIG_XXX to enable/disable this feature. >>> >>> F2FS_CHECK_FS ？ >>> >>>> >>>>> +#endif >>>>> }; >>>>> >>>>> struct f2fs_private_dio { >>>>> @@ -1954,6 +1963,38 @@ static inline struct address_space *NODE_MAPPING(struct f2fs_sb_info *sbi) >>>>> return sbi->node_inode->i_mapping; >>>>> } >>>>> >>>>> +#ifdef CONFIG_F2FS_FSCK_STACK_TRACE >>>>> +static void fsck_stack_trace(struct f2fs_sb_info *sbi) >>>>> +{ >>>>> + unsigned long entries[FSCK_STACK_DEPTH]; >>>>> + depot_stack_handle_t stack, *new; >>>>> + unsigned int nr_entries; >>>>> + int i; >>>>> + >>>>> + if (!sbi->fsck_stack) >>>>> + return; >>>>> + >>>>> + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); >>>>> + nr_entries = filter_irq_stacks(entries, nr_entries); >>>>> + stack = stack_depot_save(entries, nr_entries, GFP_KERNEL); >>>>> + if (!stack) >>>>> + return; >>>>> + >>>>> + /* Try to find an existing entry for this backtrace */ >>>>> + for (i = 0; i < sbi->fsck_count; i++) >>>>> + if (sbi->fsck_stack_history[i] == stack) >>>>> + return; >>>>> + >>>>> + new = krealloc(sbi->fsck_stack_history, (sbi->fsck_count + 1) * >>>>> + sizeof(*sbi->fsck_stack_history), GFP_KERNEL); >>>>> + if (!new) >>>>> + return; >>>>> + >>>>> + sbi->fsck_stack_history = new; >>>>> + sbi->fsck_stack_history[sbi->fsck_count++] = stack; >>>> >>>> It will case memory leak after f2fs module exits. >>> >>> So let's enable this feature when f2fs is not a module and enable F2FS_CHECK_FS. >> >>I mean it needs to free .fsck_stack_history during umount(). > > > > So this is a double-edged sword, and the person who uses it must be aware of this issue. > The release seems unrealistic under the current circumstances. This is also the reason You mean the handles allocated from stack_depot_save() should not be released, right? > why I add a switch, instead of enabling it by default after opening the configuration. Well, I still didn't get why we can not release the memory allocated by krealloc(). Thanks, > > Yangtao > >