Re: [-mm][PATCH 1/2] mm owner fix race between swap and exit

[Paul Menage]

On Mon, Aug 11, 2008 at 5:31 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>> The fix is to notify the subsystem (via mm_owner_changed callback), if
>> no new owner is found by specifying the new task as NULL.
>
> This patch applies to mainline, 2.6.27-rc2 and even 2.6.26.
>
> Against which kernel/patch is it actually applicable?
>
> (If the answer was "all of the above" then please don't go embedding
> mainline bugfixes in the middle of a -mm-only patch series!)

The main thing this fixes is the memrlimit controller, which is only
in -mm. But there's also a dereference of mm->owner in memcontrol.c -
and I think that needs to be fixed to handle a possible NULL mm->owner
too, since in the case of a swapoff racing with the last user of an mm
exiting, I suspect that the swapoff code could try to pull in a page
that gets charged to the mm after its owner has been set to NULL.

Paul
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