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SubjectRe: [PATCH] mark_page_accessed() in do_swap_page() move latter than memcg charge
On Thu, 15 Jan 2009 20:08:36 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

>
> sorry for late responce.
>
> > > In this case we've hit a case where the page is valid and the pc is
> > > not. This does fix the problem, but won't this impact us getting
> > > correct reclaim stats and thus indirectly impact the working of
> > > pressure?
> > >
> > - If retruns NULL, only global LRU's status is updated.
> >
> > Because this page is not belongs to any memcg, we cannot update
> > any counters. But yes, your point is a concern.
> >
> > Maybe moving acitvate_page() to
> > ==
> > do_swap_page()
> > {
> >
> > - activate_page()
> > mem_cgroup_try_charge()..
> > ....
> > mem_cgroup_commit_charge()....
> > ....
> > + activate_page()
> > }
> > ==
> > is necessary. How do you think, kosaki ?
>
>
> OK. it makes sense. and my test found no bug.
>
Thank you very much! KOSAKI.

Reviewed-by; KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

-Kame

> ==
>
> mark_page_accessed() update reclaim_stat statics.
> but currently, memcg charge is called after mark_page_accessed().
>
> then, mark_page_accessed() don't update memcg statics correctly.
>
> fixing here.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
>
> ---
> mm/memory.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: b/mm/memory.c
> ===================================================================
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2426,8 +2426,6 @@ static int do_swap_page(struct mm_struct
> count_vm_event(PGMAJFAULT);
> }
>
> - mark_page_accessed(page);
> -
> lock_page(page);
> delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
>
> @@ -2480,6 +2478,8 @@ static int do_swap_page(struct mm_struct
> try_to_free_swap(page);
> unlock_page(page);
>
> + mark_page_accessed(page);
> +
> if (write_access) {
> ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
> if (ret & VM_FAULT_ERROR)
>
>
>
>



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