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Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction [message #7365 is a reply to message #7361]

Thu, 12 October 2006 07:01

Nick Piggin
Messages: 35
Registered: March 2006

Member

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.

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[Message index]

		Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction By: Andrew Morton on Thu, 12 October 2006 06:43
		Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction By: Nick Piggin on Thu, 12 October 2006 07:01
		Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction By: Dmitriy Monakhov on Thu, 12 October 2006 07:53
		Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction By: Andrew Morton on Thu, 12 October 2006 08:37
		Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction By: Nick Piggin on Thu, 12 October 2006 08:31

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