From: Jan Kara <jack@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
Jan Kara <jack@suse.cz>, Mel Gorman <mgorman@suse.de>,
Shuge <shugelinux@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-ext4@vger.kernel.org, Kevin <kevin@allwinnertech.com>,
Theodore Ts'o <tytso@mit.edu>, Jens Axboe <axboe@kernel.dk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3] [RESEND] mm: Make snapshotting pages for stable writes a per-bio operation
Date: Tue, 9 Apr 2013 23:11:28 +0200 [thread overview]
Message-ID: <20130409211128.GD15214@quack.suse.cz> (raw)
In-Reply-To: <20130409140432.cd69f999302a02caf73788fc@linux-foundation.org>
On Tue 09-04-13 14:04:32, Andrew Morton wrote:
> On Tue, 9 Apr 2013 11:06:17 -0700 "Darrick J. Wong" <darrick.wong@oracle.com> wrote:
>
> > + * Here we write back pagecache data that may be mmaped. Since
> > + * we cannot afford to clean the page and set PageWriteback
> > + * here due to lock ordering (page lock ranks above transaction
> > + * start), the data can change while IO is in flight. Tell the
> > + * block layer it should bounce the bio pages if stable data
> > + * during write is required.
>
> I think there are already ab/ba deadlocks between lock_page() and
> journal_start(). iirc one path was write(), I forget which was the
> other path. This was 10+ years ago and nobody else noticed and I
> didn't know how to fix it so I didn't tell anyone ;)
Hum, I don't think they are there anymore ;)
> It would be neat to be able to hook things like journal_start() into
> lockdep but I don't think that lockdep has easy provision for wiring
> oddball things into its mechanisms.
Actually if you look at fs/jbd/transaction.c:start_this_handle(), you
will notice that it is wired into lockdep (the lock_map_acquire() call
there). And it works since I've seen quite some reports from it ;)
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
prev parent reply other threads:[~2013-04-09 21:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-09 18:06 [PATCH v3] [RESEND] mm: Make snapshotting pages for stable writes a per-bio operation Darrick J. Wong
2013-04-09 18:47 ` Jan Kara
2013-04-09 21:04 ` Andrew Morton
2013-04-09 21:11 ` Jan Kara [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130409211128.GD15214@quack.suse.cz \
--to=jack@suse.cz \
--cc=akpm@linux-foundation.org \
--cc=axboe@kernel.dk \
--cc=catalin.marinas@arm.com \
--cc=darrick.wong@oracle.com \
--cc=kevin@allwinnertech.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=shugelinux@gmail.com \
--cc=tytso@mit.edu \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).