From: Ted Ts'o <tytso@mit.edu>
To: Jan Kara <jack@suse.cz>
Cc: Manish Katiyar <mkatiyar@gmail.com>,
linux-ext4@vger.kernel.org, mfasheh@suse.com, jlbec@evilplan.org
Subject: Re: [PATCH v2 2/3] jbd2: Add extra parameter in start_this_handle() to control allocation flags.
Date: Sun, 5 Jun 2011 23:21:13 -0400 [thread overview]
Message-ID: <20110606032113.GC7180@thunk.org> (raw)
In-Reply-To: <20110602095424.GA5718@quack.suse.cz>
On Thu, Jun 02, 2011 at 11:54:24AM +0200, Jan Kara wrote:
> What happens is that direct reclaim sometimes does
> wait_on_page_writeback() (e.g. shrink_page_list()) or it explicitely waits
> for NR_WRITEBACK statistics to go below some threshold
> (throttle_vm_writeout()). And that is deadlockable if we hold i_mutex while
> doing this because we may need i_mutex to actually move the page from
> PageWriteback state...
We don't actully call set_page_writeback() until right before we
submit the page for writeback. And we convert the unwritten extents
in a workqueue, which gets submitted after we call
end_page_writeback(). So I'm still not seeing a problem; sorry if I'm
being dense!
- Ted
> As I'm saying this, I've realized ext4 has this problem also with
> stable-pages patches because there we can wait for PageWriteback in
> grab_cache_page_write_begin() when we also hold i_mutex. So I think we'll
> have to come up with a way to convert unwritten extents without having to
> hold i_mutex. That's going to be interesting.
>
> Honza
> --
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR
> --
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next prev parent reply other threads:[~2011-06-06 3:21 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-28 6:16 [PATCH v2 1/3] ext4: Fix missing acl release in error path in acl.c Manish Katiyar
2011-05-28 6:20 ` [PATCH v2 2/3] jbd2: Add extra parameter in start_this_handle() to control allocation flags Manish Katiyar
2011-05-31 11:22 ` Jan Kara
2011-05-31 22:27 ` Ted Ts'o
2011-06-02 9:54 ` Jan Kara
2011-06-06 0:12 ` Manish Katiyar
2011-06-06 3:21 ` Ted Ts'o [this message]
2011-06-08 14:10 ` Ted Ts'o
2011-06-17 6:32 ` Manish Katiyar
2011-06-20 14:32 ` Jan Kara
2011-06-20 14:40 ` Manish Katiyar
2011-06-20 17:57 ` Ted Ts'o
2011-06-20 18:08 ` Manish Katiyar
2011-05-28 6:21 ` [PATCH v2 3/3] ext4: Fix ext4 to use pass jbd allocation flags if they can handle ENOMEM Manish Katiyar
2011-05-31 12:10 ` Jan Kara
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