From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@osdl.org>
Cc: Dmitriy Monakhov <dmonakhov@openvz.org>,
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: Thu, 12 Oct 2006 17:01:03 +1000 [thread overview]
Message-ID: <452DE82F.3080803@yahoo.com.au> (raw)
In-Reply-To: <20061011234330.efae4265.akpm@osdl.org>
Andrew Morton wrote:
> 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.
Yep. Because the page is locked, it is too much to deal with even
without a filesystem in the picture.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@osdl.org>
Cc: Dmitriy Monakhov <dmonakhov@openvz.org>,
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: Thu, 12 Oct 2006 17:01:03 +1000 [thread overview]
Message-ID: <452DE82F.3080803@yahoo.com.au> (raw)
In-Reply-To: <20061011234330.efae4265.akpm@osdl.org>
Andrew Morton wrote:
> 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.
Yep. Because the page is locked, it is too much to deal with even
without a filesystem in the picture.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
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next prev parent reply other threads:[~2006-10-12 7:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-12 5:57 [RFC][PATCH] EXT3: problem with page fault inside a transaction Dmitriy Monakhov
2006-10-12 5:57 ` Dmitriy Monakhov
2006-10-12 6:43 ` Andrew Morton
2006-10-12 6:43 ` Andrew Morton
2006-10-12 7:01 ` Nick Piggin [this message]
2006-10-12 7:01 ` Nick Piggin
2006-10-12 7:53 ` Dmitriy Monakhov
2006-10-12 7:53 ` Dmitriy Monakhov
2006-10-12 8:31 ` Nick Piggin
2006-10-12 8:31 ` Nick Piggin
2006-10-12 8:37 ` Andrew Morton
2006-10-12 8:37 ` Andrew Morton
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