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Subject: Re: [RFC PATCH 1/2] ext4: Fix possible deadlock with local interrupts
 disabled and page-draining IPI
To: Hillf Danton <hillf.zj@alibaba-inc.com>
References: <062501d10262$d40d0a50$7c271ef0$@alibaba-inc.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
From: Nikolay Borisov <kernel@kyup.com>
Message-ID: <56176C10.8040709@kyup.com>
Date: Fri, 9 Oct 2015 10:26:08 +0300
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On 10/09/2015 10:19 AM, Hillf Danton wrote:
>> @@ -109,8 +109,8 @@ static void ext4_finish_bio(struct bio *bio)
>>  			if (bio->bi_error)
>>  				buffer_io_error(bh);
>>  		} while ((bh = bh->b_this_page) != head);
>> -		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
>>  		local_irq_restore(flags);
> 
> What if it takes 100ms to unlock after IRQ restored?

I'm not sure I understand in what direction you are going? Care to
elaborate?

>> +		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
>>  		if (!under_io) {
>>  #ifdef CONFIG_EXT4_FS_ENCRYPTION
>>  			if (ctx)
>> --
>> 2.5.0
>