Re: [PATCH] page->flags corruption fix

[Matt_Domsch]

On Wed, 2003-10-08 at 09:49, Hugh Dickins wrote:
> On Tue, 7 Oct 2003, Rik van Riel wrote:
> 
> > In the "better safe than sorry" category. Thanks go out to
> > Matt Domsch and Robert Hentosh. A similar fix went into the
> > 2.6 kernel. Please apply.
> 
> Seven atomic ops in a row, isn't that rather inefficient?

Not all arches have atomic_set_mask() and atomic_clear_mask().
asm-arm
asm-arm26
asm-h8300
asm-i386
asm-m68k
asm-m68knommu
asm-ppc
asm-s390
asm-sh
asm-v850
asm-x86_64

do.


> The 2.6 version clears those PG_flags all together in one
> non-atomic op - but elsewhere, in prep_new_page.
>
> Is there an actual test case for why 2.4 now needs this change?

There definitely is when RMAP is present - we've reproduced it
repeatedly in our labs.

We've seen a similar failure with the RHEL2.1 kernel w/o RMAP patches
too.  So we fully believe it's possible in stock 2.4.x.

Thanks,
Matt

-- 
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com

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