From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Hugh Dickins <hughd@google.com>, Rik van Riel <riel@redhat.com>,
Mel Gorman <mgorman@suse.de>, Michal Hocko <mhocko@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 0/5] MADV_FREE refactoring and fix KSM page
Date: Tue, 20 Oct 2015 16:27:56 +0900 [thread overview]
Message-ID: <20151020072756.GE2941@bbox> (raw)
In-Reply-To: <20151020072109.GD2941@bbox>
On Tue, Oct 20, 2015 at 04:21:09PM +0900, Minchan Kim wrote:
> On Mon, Oct 19, 2015 at 07:01:50PM +0900, Minchan Kim wrote:
> > On Mon, Oct 19, 2015 at 03:31:42PM +0900, Minchan Kim wrote:
> > > Hello, it's too late since I sent previos patch.
> > > https://lkml.org/lkml/2015/6/3/37
> > >
> > > This patch is alomost new compared to previos approach.
> > > I think this is more simple, clear and easy to review.
> > >
> > > One thing I should notice is that I have tested this patch
> > > and couldn't find any critical problem so I rebased patchset
> > > onto recent mmotm(ie, mmotm-2015-10-15-15-20) to send formal
> > > patchset. Unfortunately, I start to see sudden discarding of
> > > the page we shouldn't do. IOW, application's valid anonymous page
> > > was disappeared suddenly.
> > >
> > > When I look through THP changes, I think we could lose
> > > dirty bit of pte between freeze_page and unfreeze_page
> > > when we mark it as migration entry and restore it.
> > > So, I added below simple code without enough considering
> > > and cannot see the problem any more.
> > > I hope it's good hint to find right fix this problem.
> > >
> > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > > index d5ea516ffb54..e881c04f5950 100644
> > > --- a/mm/huge_memory.c
> > > +++ b/mm/huge_memory.c
> > > @@ -3138,6 +3138,9 @@ static void unfreeze_page_vma(struct vm_area_struct *vma, struct page *page,
> > > if (is_write_migration_entry(swp_entry))
> > > entry = maybe_mkwrite(entry, vma);
> > >
> > > + if (PageDirty(page))
> > > + SetPageDirty(page);
> >
> > The condition of PageDirty was typo. I didn't add the condition.
> > Just added.
> >
> > SetPageDirty(page);
>
> I reviewed THP refcount redesign patch and It seems below patch fixes
> MADV_FREE problem. It works well for hours.
>
> From 104a0940b4c0f97e61de9fee0fd602926ff28312 Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan@kernel.org>
> Date: Tue, 20 Oct 2015 16:00:52 +0900
> Subject: [PATCH] mm: mark head page dirty in split_huge_page
>
> In thp split in old THP refcount, we mappped all of pages
> (ie, head + tails) to pte_mkdirty and mark PG_flags to every
> tail pages.
>
> But with THP refcount redesign, we can lose dirty bit in page table
> and PG_dirty for head page if we want to free the THP page using
typo.
freeze
next prev parent reply other threads:[~2015-10-20 7:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-19 6:31 [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim
2015-10-19 6:31 ` [PATCH 1/5] mm: MADV_FREE trivial clean up Minchan Kim
2015-10-19 6:31 ` [PATCH 2/5] mm: skip huge zero page in MADV_FREE Minchan Kim
2015-10-19 6:31 ` [PATCH 3/5] mm: clear PG_dirty to mark page freeable Minchan Kim
2015-10-27 1:28 ` Hugh Dickins
2015-10-27 6:50 ` Minchan Kim
2015-10-19 6:31 ` [PATCH 4/5] mm: simplify reclaim path for MADV_FREE Minchan Kim
2015-10-27 2:09 ` Hugh Dickins
2015-10-27 3:44 ` yalin wang
2015-10-27 7:09 ` Minchan Kim
2015-10-27 7:39 ` yalin wang
2015-10-27 8:10 ` Minchan Kim
2015-10-27 8:52 ` yalin wang
2015-10-28 4:03 ` yalin wang
2015-10-27 6:54 ` Minchan Kim
2015-10-19 6:31 ` [PATCH 5/5] mm: mark stable page dirty in KSM Minchan Kim
2015-10-27 2:23 ` Hugh Dickins
2015-10-27 6:58 ` Minchan Kim
2015-10-19 10:01 ` [PATCH 0/5] MADV_FREE refactoring and fix KSM page Minchan Kim
2015-10-20 1:38 ` Minchan Kim
2015-10-20 7:21 ` Minchan Kim
2015-10-20 7:27 ` Minchan Kim [this message]
2015-10-20 21:36 ` Andrew Morton
2015-10-20 22:43 ` Kirill A. Shutemov
2015-10-21 5:11 ` Minchan Kim
2015-10-21 7:50 ` Kirill A. Shutemov
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