linux-kernel - Re: [PATCH -mm] rmap: add exclusive page to private anon

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Message-ID: <20100630155506.GV16195@random.random>
Date:	Wed, 30 Jun 2010 17:55:06 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kosaki.motohiro@...fujitsu.com
Subject: Re: [PATCH -mm] rmap: add exclusive page to private anon_vma on
 swapin

On Wed, Jun 30, 2010 at 11:37:10AM -0400, Rik van Riel wrote:
> @@ -2714,10 +2715,11 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
>  	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
>  		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
>  		flags &= ~FAULT_FLAG_WRITE;
> +		exclusive = 1;
>  	}

Agreed. it's something I considered doing too but I deferred until I
figure out all the mess with ksm-copy. I'll test your patch but it
should make no practical difference to my workload.

I also had a patch in my queue that changes this path which I deferred
as well for now.

====
Subject: set VM_FAULT_WRITE in do_swap_page

From: Andrea Arcangeli <aarcange@...hat.com>

Set the flag if do_swap_page is decowing the page the same way do_wp_page would
too.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---

diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2673,6 +2686,7 @@ static int do_swap_page(struct mm_struct
 	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
 		flags &= ~FAULT_FLAG_WRITE;
+		ret |= VM_FAULT_WRITE;
 	}
 	flush_icache_page(vma, page);
 	set_pte_at(mm, address, page_table, pte);
--
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