linux-kernel - Re: oops in copy_page

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Message-ID: <CAJd=RBAps4Qk9WLYbQhLkJd8d12NLV0CbjPYC6uqH_-L+Vu0VQ@mail.gmail.com>
Date:	Mon, 7 Jan 2013 20:24:12 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	Hugh Dickins <hughd@...gle.com>
Cc:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>
Subject: Re: oops in copy_page_rep()

Hello Hugh

On Mon, Jan 7, 2013 at 3:06 AM, Hugh Dickins <hughd@...gle.com> wrote:
> I don't entirely like your patch (or the original code): shouldn't
> there be a wait_split_huge_page(), rather than hammering back with
> repeated faults until the split has completed?
>
I take another try with waiting added, take a look please.

Hillf
---
--- a/mm/memory.c	Sun Jan  6 19:49:50 2013
+++ b/mm/memory.c	Mon Jan  7 20:16:14 2013
@@ -3710,6 +3710,11 @@ retry:
 				return do_huge_pmd_numa_page(mm, vma, address,
 							     orig_pmd, pmd);

+			/* Check if pmd is stable */
+			if (pmd_trans_splitting(orig_pmd)) {
+				wait_split_huge_page(vma->anon_vma, pmd);
+				goto retry;
+			}
 			if (dirty && !pmd_write(orig_pmd)) {
 				ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
 							  orig_pmd);
--
--
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