linux-kernel - Re: [PATCH] fs: f2fs: remove WARN_ON in f2fs_is_valid

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Date:   Sat, 9 Apr 2022 11:46:25 +0800
From:   Chao Yu <chao@...nel.org>
To:     Dongliang Mu <mudongliangabcd@...il.com>
Cc:     Dongliang Mu <dzm91@...t.edu.cn>, Jaegeuk Kim <jaegeuk@...nel.org>,
        syzbot+763ae12a2ede1d99d4dc@...kaller.appspotmail.com,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs: f2fs: remove WARN_ON in f2fs_is_valid_blkaddr

On 2022/4/9 9:34, Dongliang Mu wrote:
> On Sat, Apr 9, 2022 at 8:27 AM Chao Yu <chao@...nel.org> wrote:
>>
>> On 2022/4/8 13:22, Dongliang Mu wrote:
>>> From: Dongliang Mu <mudongliangabcd@...il.com>
>>>
>>> In f2fs_is_valid_blkaddr, if type is DATA_GENERIC_ENHANCE or
>>> DATA_GENERIC_ENHANCE_READ, it invokes WARN_ON(1) not matter
>>> blkaddr is in the range or not.
>>
>> If we run into the path where we invoke WARN_ON(1) in f2fs_is_valid_blkaddr(),
>> It means f2fs image may be broken, or there is a bug in f2fs.
>>
>> So, do you suffer any related issue in your environment?
> 
> related issue? Can you explain a little?
> 
> If you mean if this warning occurs, any other issues or crash

I mean have you seen any warning info printed in the path of
f2fs_is_valid_blkaddr() before applying this patch, and if so, w/ what
reproducer? or you just figure out this patch from perspective of code
review?

Thanks,

> behaviors are generated? I tested on the syzbot. After removing the
> WARN_ON, there is no abnormal issue or crash behaviors followed with
> the corresponding reproducer.
> 
> 
>>
>> Thanks,
>>
>>>
>>> Fix this by removing WARN_ON.
>>>
>>> Note that, syzbot patch testing does not incur any further issues
>>>
>>> Reported-by: syzbot+763ae12a2ede1d99d4dc@...kaller.appspotmail.com
>>> Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
>>> ---
>>>    fs/f2fs/checkpoint.c | 2 --
>>>    1 file changed, 2 deletions(-)
>>>
>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>> index f5366feea82d..521498b2dd8c 100644
>>> --- a/fs/f2fs/checkpoint.c
>>> +++ b/fs/f2fs/checkpoint.c
>>> @@ -158,7 +158,6 @@ static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr,
>>>                f2fs_err(sbi, "Inconsistent error blkaddr:%u, sit bitmap:%d",
>>>                         blkaddr, exist);
>>>                set_sbi_flag(sbi, SBI_NEED_FSCK);
>>> -             WARN_ON(1);
>>>        }
>>>        return exist;
>>>    }
>>> @@ -196,7 +195,6 @@ bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
>>>                        f2fs_warn(sbi, "access invalid blkaddr:%u",
>>>                                  blkaddr);
>>>                        set_sbi_flag(sbi, SBI_NEED_FSCK);
>>> -                     WARN_ON(1);
>>>                        return false;
>>>                } else {
>>>                        return __is_bitmap_valid(sbi, blkaddr, type);