Re: [patch 1/3] mm: fix pageref leak in do_swap_page()

From: Balbir Singh
Date: Mon Apr 20 2009 - 23:15:27 EST


* Johannes Weiner <hannes@xxxxxxxxxxx> [2009-04-20 22:24:43]:

> By the time the memory cgroup code is notified about a swapin we
> already hold a reference on the fault page.
>
> If the cgroup callback fails make sure to unlock AND release the page
> or we leak the reference.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

Seems reasonable to me, could you make the changelog more verbose and
mention that lookup_swap_cache() gets a reference to the page and we
need to release the extra reference.

BTW, have you had any luck reproducing the issue? How did you catch
the problem?

--
Balbir
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