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From: Andrew Morton <akpm@osdl.org>
To: Dmitriy Monakhov <dmonakhov@openvz.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Memory Management <linux-mm@kvack.org>,
	devel@openvz.org, ext2-devel@lists.sourceforge.net,
	Andrey Savochkin <saw@swsoft.com>
Subject: Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction
Date: Wed, 11 Oct 2006 23:43:30 -0700	[thread overview]
Message-ID: <20061011234330.efae4265.akpm@osdl.org> (raw)
In-Reply-To: <87mz82vzy1.fsf@sw.ru>

On Thu, 12 Oct 2006 09:57:26 +0400
Dmitriy Monakhov <dmonakhov@openvz.org> wrote:

> While reading Andrew's generic_file_buffered_write patches i've remembered
> one more EXT3 issue.journal_start() in prepare_write() causes different ranking
> violations if copy_from_user() triggers a page fault. It could cause 
> GFP_FS allocation, re-entering into ext3 code possibly with a different
> superblock and journal, ranking violation of journalling serialization 
> and mmap_sem and page lock and all other kinds of funny consequences.

With the stuff Nick and I are looking at, we won't take pagefaults inside
prepare_write()/commit_write() any more.

> Our customers complain about this issue.

Really?  How often?

What on earth are they doing to trigger this?  writev() without the 2.6.18
writev() bugfix?

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  reply	other threads:[~2006-10-12  6:43 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-12  5:57 Dmitriy Monakhov
2006-10-12  6:43 ` Andrew Morton [this message]
2006-10-12  7:01   ` Nick Piggin
2006-10-12  7:53   ` Dmitriy Monakhov
2006-10-12  8:31     ` Nick Piggin
2006-10-12  8:37     ` Andrew Morton

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