Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1256548

Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE

Show all headers | View raw

On Tue, Oct 27, 2015 at 03:39:16PM +0800, yalin wang wrote:
> 
> > On Oct 27, 2015, at 15:09, Minchan Kim <minchan@kernel.org> wrote:
> > 
> > Hello Yalin,
> > 
> > Sorry for missing you in Cc list.
> > IIRC, mails to send your previous mail address(Yalin.Wang@sonymobile.com)
> > were returned.
> > 
> > You added comment bottom line so I'm not sure what PageDirty you meant.
> > 
> >> it is wrong here if you only check PageDirty() to decide if the page is freezable or not .
> >> The Anon page are shared by multiple process, _mapcount > 1 ,
> >> so you must check all pt_dirty bit during page_referenced() function,
> >> see this mail thread:
> >> http://ns1.ske-art.com/lists/kernel/msg1934021.html
> > 
> > If one of pte among process sharing the page was dirty, the dirtiness should
> > be propagated from pte to PG_dirty by try_to_unmap_one.
> > IOW, if the page doesn't have PG_dirty flag, it means all of process did
> > MADV_FREE.
> > 
> > Am I missing something from you question?
> > If so, could you show exact scenario I am missing?
> > 
> > Thanks for the interest.
> oh, yeah , that is right , i miss that , pte_dirty will propagate to PG_dirty ,
> so that is correct .
> Generic to say this patch move set_page_dirty() from add_to_swap() to 
> try_to_unmap(), i think can change a little about this patch:
> 
> @@ -1476,6 +1446,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> 				ret = SWAP_FAIL;
> 				goto out_unmap;
> 			}
> +			if (!PageDirty(page))
> +				SetPageDirty(page);
> 			if (list_empty(&mm->mmlist)) {
> 				spin_lock(&mmlist_lock);
> 				if (list_empty(&mm->mmlist))
> 
> i think this 2 lines can be removed ,
> since  pte_dirty have propagated to set_page_dirty() , we don’t need this line here ,
> otherwise you will always dirty a AnonPage, even it is clean,
> then we will page out this clean page to swap partition one more , this is not needed.
> am i understanding correctly ?

Your understanding is correct.
I will fix it in next spin.

> 
> By the way, please change my mail address to yalin.wang2010@gmail.com in CC list .
> Thanks a lot. :) 

Thanks for the review!

> 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim <minchan@kernel.org> - 2015-10-19 08:30 +0200
  [PATCH 2/5] mm: skip huge zero page in MADV_FREE Minchan Kim <minchan@kernel.org> - 2015-10-19 08:30 +0200
  [PATCH 1/5] mm: MADV_FREE trivial clean up Minchan Kim <minchan@kernel.org> - 2015-10-19 08:30 +0200
  [PATCH 5/5] mm: mark stable page dirty in KSM Minchan Kim <minchan@kernel.org> - 2015-10-19 08:30 +0200
    Re: [PATCH 5/5] mm: mark stable page dirty in KSM Hugh Dickins <hughd@google.com> - 2015-10-27 03:30 +0100
      Re: [PATCH 5/5] mm: mark stable page dirty in KSM Minchan Kim <minchan@kernel.org> - 2015-10-27 08:00 +0100
  [PATCH 3/5] mm: clear PG_dirty to mark page freeable Minchan Kim <minchan@kernel.org> - 2015-10-19 08:30 +0200
    Re: [PATCH 3/5] mm: clear PG_dirty to mark page freeable Hugh Dickins <hughd@google.com> - 2015-10-27 02:30 +0100
      Re: [PATCH 3/5] mm: clear PG_dirty to mark page freeable Minchan Kim <minchan@kernel.org> - 2015-10-27 08:00 +0100
  [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Minchan Kim <minchan@kernel.org> - 2015-10-19 08:40 +0200
    Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Hugh Dickins <hughd@google.com> - 2015-10-27 03:10 +0100
      Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE yalin wang <yalin.wang2010@gmail.com> - 2015-10-27 04:50 +0100
        Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Minchan Kim <minchan@kernel.org> - 2015-10-27 08:10 +0100
          Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE yalin wang <yalin.wang2010@gmail.com> - 2015-10-27 08:40 +0100
            Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Minchan Kim <minchan@kernel.org> - 2015-10-27 09:20 +0100
              Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE yalin wang <yalin.wang2010@gmail.com> - 2015-10-27 10:00 +0100
                Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE yalin wang <yalin.wang2010@gmail.com> - 2015-10-28 05:10 +0100
      Re: [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Minchan Kim <minchan@kernel.org> - 2015-10-27 08:00 +0100
  Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim <minchan@kernel.org> - 2015-10-19 12:00 +0200
    Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim <minchan@kernel.org> - 2015-10-20 09:30 +0200
    Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim <minchan@kernel.org> - 2015-10-20 09:30 +0200
      Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page Andrew Morton <akpm@linux-foundation.org> - 2015-10-20 23:40 +0200
        Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-10-21 00:50 +0200
          Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim <minchan@kernel.org> - 2015-10-21 07:20 +0200
            Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page "Kirill A. Shutemov" <kirill@shutemov.name> - 2015-10-21 10:00 +0200

csiph-web