From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "'Nikolay Borisov'" <kernel@kyup.com>
Cc: "'linux-kernel'" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 1/2] ext4: Fix possible deadlock with local interrupts disabled and page-draining IPI
Date: Fri, 09 Oct 2015 15:37:29 +0800 [thread overview]
Message-ID: <062801d10265$5a749fc0$0f5ddf40$@alibaba-inc.com> (raw)
In-Reply-To: <56176C10.8040709@kyup.com>
> >> @@ -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?
>
Your change introduces extra time cost the lock waiter has to pay in
the case that irq happens before the lock is released.
> >> + bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
> >> if (!under_io) {
> >> #ifdef CONFIG_EXT4_FS_ENCRYPTION
> >> if (ctx)
> >> --
> >> 2.5.0
> >
next prev parent reply other threads:[~2015-10-09 7:37 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-09 7:19 Hillf Danton
2015-10-09 7:26 ` Nikolay Borisov
2015-10-09 7:37 ` Hillf Danton [this message]
2015-10-09 8:03 ` Nikolay Borisov
2015-10-12 13:40 ` Jan Kara
2015-10-12 14:51 ` Nikolay Borisov
2015-10-13 8:15 ` Jan Kara
2015-10-13 10:37 ` Nikolay Borisov
2015-10-13 13:14 ` Jan Kara
2015-10-14 9:02 ` Nikolay Borisov
2015-10-16 8:08 ` Nikolay Borisov
2015-10-16 12:51 ` Jan Kara
-- strict thread matches above, loose matches on Subject: below --
2015-10-08 15:31 Nikolay Borisov
[not found] ` <CAOtvUMcrhq3epOPCEciMGq53S6rTyURAKEWhQ=NwrkF95aJ+_Q@mail.gmail.com>
2015-10-09 8:50 ` Nikolay Borisov
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