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Subject: [PING 2] [PATCH] jffs2: Fix use of uninitialized delayed_work,
 lockdep breakage
From:   Daniel Santos <daniel.santos@pobox.com>
To:     Hou Tao <houtao1@huawei.com>, LKML <linux-kernel@vger.kernel.org>
Cc:     David Woodhouse <dwmw2@infradead.org>,
        linux-mtd@lists.infradead.org
References: <20181019083020.14335-1-daniel.santos@pobox.com>
 <d2f16a3a-7237-6c4e-5ff8-43f05bdb7e0f@huawei.com>
 <11f65a20-dfca-0ddc-8c7f-58f29afe8c04@pobox.com>
Message-ID: <436a7243-4a32-40cd-5c40-6cc7f44d26c5@pobox.com>
Date:   Sat, 24 Nov 2018 09:29:44 -0600
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Ping 2!

On 11/05/2018 03:38 PM, Daniel Santos wrote:
> Ping.
>
> Daniel
>
> On 10/21/2018 07:32 PM, Hou Tao wrote:
>> On 2018/10/19 16:30, Daniel Santos wrote:
>>> jffs2_sync_fs makes the assumption that if CONFIG_JFFS2_FS_WRITEBUFFER
>>> is defined then a write buffer is available and has been initialized.
>>> However, this does is not the case when the mtd device has no
>>> out-of-band buffer:
>>>
>>> int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
>>> {
>>>         if (!c->mtd->oobsize)
>>>                 return 0;
>>> ...
>>>
>>> The resulting call to cancel_delayed_work_sync passing a uninitialized
>>> (but zeroed) delayed_work struct forces lockdep to become disabled.
>>>
>>> [   90.050639] overlayfs: upper fs does not support tmpfile.
>>> [   90.652264] INFO: trying to register non-static key.
>>> [   90.662171] the code is fine but needs lockdep annotation.
>>> [   90.673090] turning off the locking correctness validator.
>>> [   90.684021] CPU: 0 PID: 1762 Comm: mount_root Not tainted 4.14.63 #0
>>> [   90.696672] Stack : 00000000 00000000 80d8f6a2 00000038 805f0000 80444600 8fe364f4 805dfbe7
>>> [   90.713349]         80563a30 000006e2 8068370c 00000001 00000000 00000001 8e2fdc48 ffffffff
>>> [   90.730020]         00000000 00000000 80d90000 00000000 00000106 00000000 6465746e 312e3420
>>> [   90.746690]         6b636f6c 03bf0000 f8000000 20676e69 00000000 80000000 00000000 8e2c2a90
>>> [   90.763362]         80d90000 00000001 00000000 8e2c2a90 00000003 80260dc0 08052098 80680000
>>> [   90.780033]         ...
>>> [   90.784902] Call Trace:
>>> [   90.789793] [<8000f0d8>] show_stack+0xb8/0x148
>>> [   90.798659] [<8005a000>] register_lock_class+0x270/0x55c
>>> [   90.809247] [<8005cb64>] __lock_acquire+0x13c/0xf7c
>>> [   90.818964] [<8005e314>] lock_acquire+0x194/0x1dc
>>> [   90.828345] [<8003f27c>] flush_work+0x200/0x24c
>>> [   90.837374] [<80041dfc>] __cancel_work_timer+0x158/0x210
>>> [   90.847958] [<801a8770>] jffs2_sync_fs+0x20/0x54
>>> [   90.857173] [<80125cf4>] iterate_supers+0xf4/0x120
>>> [   90.866729] [<80158fc4>] sys_sync+0x44/0x9c
>>> [   90.875067] [<80014424>] syscall_common+0x34/0x58
>>>
>>> Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
>>> ---
>>>  fs/jffs2/super.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
>>> index 793ad30970ff..cae4ecda3c50 100644
>>> --- a/fs/jffs2/super.c
>>> +++ b/fs/jffs2/super.c
>>> @@ -101,7 +101,8 @@ static int jffs2_sync_fs(struct super_block *sb, int wait)
>>>  	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
>>>  
>>>  #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
>>> -	cancel_delayed_work_sync(&c->wbuf_dwork);
>>> +	if (jffs2_is_writebuffered(c))
>>> +		cancel_delayed_work_sync(&c->wbuf_dwork);
>>>  #endif
>>>  
>>>  	mutex_lock(&c->alloc_sem);
>>>
>> Reviewed-by: Hou Tao <houtao1@huawei.com>
>>
>> And I am curious that why is there NAND Flash without OOB area ? So for them
>> the ECC data must be saved in data area ?
>>
>> Regards,
>>
>> Tao
>>
>>
>>