linux-kernel - Re: [RFC PATCH 1/2] ext4: Fix possible deadlock with local interrupts disabled and page-draining IPI

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Message-ID: <062501d10262$d40d0a50$7c271ef0$@alibaba-inc.com>
Date:	Fri, 09 Oct 2015 15:19:25 +0800
From:	"Hillf Danton" <hillf.zj@...baba-inc.com>
To:	"'Nikolay Borisov'" <kernel@...p.com>
Cc:	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] ext4: Fix possible deadlock with local interrupts disabled and page-draining IPI

> @@ -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?

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

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