From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Ethan Solomita <solo@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org
Subject: Re: NR_UNSTABLE_FS vs. NR_FILE_DIRTY: double counting pages?
Date: Sun, 29 Apr 2007 16:22:15 -0400 [thread overview]
Message-ID: <1177878135.6400.37.camel@heimdal.trondhjem.org> (raw)
In-Reply-To: <4632A1A6.90702@google.com>
On Fri, 2007-04-27 at 18:21 -0700, Ethan Solomita wrote:
> There are several places where we add together NR_UNSTABLE_FS and
> NF_FILE_DIRTY:
>
> sync_inodes_sb()
> balance_dirty_pages()
> wakeup_pdflush()
> wb_kupdate()
> prefetch_suitable()
>
> I can trace a standard codepath where it seems both of these are set
> on the same page:
>
> nfs_file_aops.commit_write ->
> nfs_commit_write
> nfs_updatepages
> nfs_writepage_setup
> nfs_wb_page
> nfs_wb_page_priority
> nfs_writepage_locked
> nfs_flush_mapping
> nfs_flush_list
> nfs_flush_multi
> nfs_write_partial_ops.rpc_call_done
> nfs_writeback_done_partial
> nfs_writepage_release
> nfs_reschedule_unstable_write
> nfs_mark_request_commit
> incr NR_UNSTABLE_NFS
>
> nfs_file_aops.commit_write ->
> nfs_commit_write
> nfs_updatepage
> __set_page_dirty_nobuffers
> incr NF_FILE_DIRTY
>
>
> This is the standard code path that derives from sys_write(). Can
> someone either show how this code sequence can't happen, or confirm for
> me that there's a bug?
> -- Ethan
It should not happen. If the page is on the unstable list, then it will
be committed before nfs_updatepage is allowed to redirty it. See the
recent fixes in 2.6.21-rc7.
Trond
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next prev parent reply other threads:[~2007-04-29 20:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-28 1:21 Ethan Solomita
2007-04-29 20:22 ` Trond Myklebust [this message]
2007-04-30 0:26 ` Ethan Solomita
2007-04-30 1:15 ` Ethan Solomita
2007-04-30 1:51 ` Trond Myklebust
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