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SubjectRe: [RFC][PATCH -mmotm 1/4] memcg: don't trigger oom at page migration
* Daisuke Nishimura <d-nishimura@mtf.biglobe.ne.jp> [2008-12-06 11:47:57]:

> On Fri, 5 Dec 2008 19:09:26 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>
> > * Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> [2008-12-05 21:23:04]:
> >
> > > I think triggering OOM at mem_cgroup_prepare_migration would be just a bit
> > > overkill.
> > > Returning -ENOMEM would be enough for mem_cgroup_prepare_migration.
> > > The caller would handle the case anyway.
> > >
> > > Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> > > ---
> > > mm/memcontrol.c | 2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > > index 4dbce1d..50ee1be 100644
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -1330,7 +1330,7 @@ int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr)
> > > unlock_page_cgroup(pc);
> > >
> > > if (mem) {
> > > - ret = mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem);
> > > + ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
> > > css_put(&mem->css);
> > > }
> > > *ptr = mem;
> > >
> >
> > Seems reasonable to me. A comment indicating or adding a noreclaim
> > wrapper around __mem_cgroup_try_charge to indicate that no reclaim
> > will take place will be nice.
> >
> Ah.. this flag to __mem_cgroup_try_charge doesn't mean "don't reclaim"
> but "don't cause oom after it tried to free memory but couldn't
> free enough memory after all".

Thanks, I mistook the parameter. Thanks for clarifying!

>
> Thanks,
> Daisuke Nishimura.
>
> > Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> >
> > --
> > Balbir
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@kvack.org. For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
> >
>

--
Balbir


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