linux-kernel - Re: [PATCH] ubifs: Fix a sleep-in-atomic bug in ubifs_read

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Date:   Mon, 05 Jun 2017 16:43:25 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     Richard Weinberger <richard@....at>
CC:     dedekind1@...il.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ubifs: Fix a sleep-in-atomic bug in ubifs_read_nnode

On 06/05/2017 04:25 PM, Richard Weinberger wrote:
> Jia-Ju Bai,
>
> Am 05.06.2017 um 05:38 schrieb Jia-Ju Bai:
>> The driver may sleep under a spin lock, and the function call path is:
>> ubifs_change_lp (acquire the lock by spin_lock)
>>    change_category
>>      ubifs_remove_from_cat
>>        remove_from_lpt_heap
>>          dbg_check_heap
>>            ubifs_lpt_lookup
>>              ubifs_read_nnode
>>                kzalloc(GFP_NOFS) -->  may sleep
>>
>> To fix it, "GFP_NOFS" is replaced with "GFP_ATOMIC".
> So, this happens only when dbg_check_heap() is activated, right?
>
> Thanks,
> //richard
Yes, I think so.

Thanks,
Jia-Ju Bai