From: Chao Yu <chao@kernel.org> To: Greg KH <gregkh@linuxfoundation.org> Cc: stable@vger.kernel.org, jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, Yi Zhuang <zhuangyi1@huawei.com> Subject: Re: [PATCH] f2fs: quota: fix potential deadlock Date: Tue, 4 Jan 2022 23:05:36 +0800 [thread overview] Message-ID: <53d75d26-2289-a66a-a7fa-62593bad81c8@kernel.org> (raw) In-Reply-To: <YdRJEBhSg8vlD6cP@kroah.com> On 2022/1/4 21:18, Greg KH wrote: > On Tue, Jan 04, 2022 at 09:05:13PM +0800, Chao Yu wrote: >> commit a5c0042200b28fff3bde6fa128ddeaef97990f8d upstream. >> >> As Yi Zhuang reported in bugzilla: >> >> https://bugzilla.kernel.org/show_bug.cgi?id=214299 >> >> There is potential deadlock during quota data flush as below: >> >> Thread A: Thread B: >> f2fs_dquot_acquire >> down_read(&sbi->quota_sem) >> f2fs_write_checkpoint >> block_operations >> f2fs_look_all >> down_write(&sbi->cp_rwsem) >> f2fs_quota_write >> f2fs_write_begin >> __do_map_lock >> f2fs_lock_op >> down_read(&sbi->cp_rwsem) >> __need_flush_qutoa >> down_write(&sbi->quota_sem) >> >> This patch changes block_operations() to use trylock, if it fails, >> it means there is potential quota data updater, in this condition, >> let's flush quota data first and then trylock again to check dirty >> status of quota data. >> >> The side effect is: in heavy race condition (e.g. multi quota data >> upaters vs quota data flusher), it may decrease the probability of >> synchronizing quota data successfully in checkpoint() due to limited >> retry time of quota flush. >> >> Fixes: db6ec53b7e03 ("f2fs: add a rw_sem to cover quota flag changes") >> Cc: stable@vger.kernel.org # v5.3+ >> Reported-by: Yi Zhuang <zhuangyi1@huawei.com> >> Signed-off-by: Chao Yu <chao@kernel.org> >> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> >> --- >> fs/f2fs/checkpoint.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >> index 83e9bc0f91ff..7b0282724231 100644 >> --- a/fs/f2fs/checkpoint.c >> +++ b/fs/f2fs/checkpoint.c >> @@ -1162,7 +1162,8 @@ static bool __need_flush_quota(struct f2fs_sb_info *sbi) >> if (!is_journalled_quota(sbi)) >> return false; >> >> - down_write(&sbi->quota_sem); >> + if (!down_write_trylock(&sbi->quota_sem)) >> + return true; >> if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) { >> ret = false; >> } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) { >> -- >> 2.32.0 >> > > What stable tree(s) is this for? Oh, please help to try applying to 5.4, 5.10, and 5.15 stable trees, thanks! Let me know if I should send patches for different trees separately. Thanks, > > thanks, > > greg k-h
WARNING: multiple messages have this Message-ID (diff)
From: Chao Yu <chao@kernel.org> To: Greg KH <gregkh@linuxfoundation.org> Cc: jaegeuk@kernel.org, Yi Zhuang <zhuangyi1@huawei.com>, stable@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: quota: fix potential deadlock Date: Tue, 4 Jan 2022 23:05:36 +0800 [thread overview] Message-ID: <53d75d26-2289-a66a-a7fa-62593bad81c8@kernel.org> (raw) In-Reply-To: <YdRJEBhSg8vlD6cP@kroah.com> On 2022/1/4 21:18, Greg KH wrote: > On Tue, Jan 04, 2022 at 09:05:13PM +0800, Chao Yu wrote: >> commit a5c0042200b28fff3bde6fa128ddeaef97990f8d upstream. >> >> As Yi Zhuang reported in bugzilla: >> >> https://bugzilla.kernel.org/show_bug.cgi?id=214299 >> >> There is potential deadlock during quota data flush as below: >> >> Thread A: Thread B: >> f2fs_dquot_acquire >> down_read(&sbi->quota_sem) >> f2fs_write_checkpoint >> block_operations >> f2fs_look_all >> down_write(&sbi->cp_rwsem) >> f2fs_quota_write >> f2fs_write_begin >> __do_map_lock >> f2fs_lock_op >> down_read(&sbi->cp_rwsem) >> __need_flush_qutoa >> down_write(&sbi->quota_sem) >> >> This patch changes block_operations() to use trylock, if it fails, >> it means there is potential quota data updater, in this condition, >> let's flush quota data first and then trylock again to check dirty >> status of quota data. >> >> The side effect is: in heavy race condition (e.g. multi quota data >> upaters vs quota data flusher), it may decrease the probability of >> synchronizing quota data successfully in checkpoint() due to limited >> retry time of quota flush. >> >> Fixes: db6ec53b7e03 ("f2fs: add a rw_sem to cover quota flag changes") >> Cc: stable@vger.kernel.org # v5.3+ >> Reported-by: Yi Zhuang <zhuangyi1@huawei.com> >> Signed-off-by: Chao Yu <chao@kernel.org> >> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> >> --- >> fs/f2fs/checkpoint.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c >> index 83e9bc0f91ff..7b0282724231 100644 >> --- a/fs/f2fs/checkpoint.c >> +++ b/fs/f2fs/checkpoint.c >> @@ -1162,7 +1162,8 @@ static bool __need_flush_quota(struct f2fs_sb_info *sbi) >> if (!is_journalled_quota(sbi)) >> return false; >> >> - down_write(&sbi->quota_sem); >> + if (!down_write_trylock(&sbi->quota_sem)) >> + return true; >> if (is_sbi_flag_set(sbi, SBI_QUOTA_SKIP_FLUSH)) { >> ret = false; >> } else if (is_sbi_flag_set(sbi, SBI_QUOTA_NEED_REPAIR)) { >> -- >> 2.32.0 >> > > What stable tree(s) is this for? Oh, please help to try applying to 5.4, 5.10, and 5.15 stable trees, thanks! Let me know if I should send patches for different trees separately. Thanks, > > thanks, > > greg k-h _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
next prev parent reply other threads:[~2022-01-04 15:05 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-01-04 13:05 [PATCH] f2fs: quota: fix potential deadlock Chao Yu 2022-01-04 13:05 ` [f2fs-dev] " Chao Yu 2022-01-04 13:18 ` Greg KH 2022-01-04 13:18 ` [f2fs-dev] " Greg KH 2022-01-04 15:05 ` Chao Yu [this message] 2022-01-04 15:05 ` Chao Yu 2022-01-04 15:17 ` Greg KH 2022-01-04 15:17 ` [f2fs-dev] " Greg KH 2022-01-04 15:48 ` Chao Yu 2022-01-04 15:48 ` [f2fs-dev] " Chao Yu 2022-01-05 15:01 ` Greg KH 2022-01-05 15:01 ` [f2fs-dev] " Greg KH 2022-01-05 15:25 ` Chao Yu 2022-01-05 15:25 ` [f2fs-dev] " Chao Yu -- strict thread matches above, loose matches on Subject: below -- 2021-09-03 2:38 Chao Yu 2021-07-19 8:46 Chao Yu
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