Messages in this thread | | | Date | Tue, 1 Feb 2011 08:48:29 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [patch 1/3] memcg: prevent endless loop when charging huge pages |
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On Mon, 31 Jan 2011 15:03:53 +0100 Johannes Weiner <hannes@cmpxchg.org> wrote:
> The charging code can encounter a charge size that is bigger than a > regular page in two situations: one is a batched charge to fill the > per-cpu stocks, the other is a huge page charge. > > This code is distributed over two functions, however, and only the > outer one is aware of huge pages. In case the charging fails, the > inner function will tell the outer function to retry if the charge > size is bigger than regular pages--assuming batched charging is the > only case. And the outer function will retry forever charging a huge > page. > > This patch makes sure the inner function can distinguish between batch > charging and a single huge page charge. It will only signal another > attempt if batch charging failed, and go into regular reclaim when it > is called on behalf of a huge page. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Thank you very much.
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> --- > mm/memcontrol.c | 11 +++++++++-- > 1 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index d572102..73ea323 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1837,8 +1837,15 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask, > flags |= MEM_CGROUP_RECLAIM_NOSWAP; > } else > mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); > - > - if (csize > PAGE_SIZE) /* change csize and retry */ > + /* > + * csize can be either a huge page (HPAGE_SIZE), a batch of > + * regular pages (CHARGE_SIZE), or a single regular page > + * (PAGE_SIZE). > + * > + * Never reclaim on behalf of optional batching, retry with a > + * single page instead. > + */ > + if (csize == CHARGE_SIZE) > return CHARGE_RETRY; > > if (!(gfp_mask & __GFP_WAIT)) > -- > 1.7.3.5 > >
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