linux-kernel - [PATCH] pagemap: remove remaining unneeded spin

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Date:	Thu, 29 Mar 2012 04:39:39 -0400
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Sasha Levin <levinsasha928@...il.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	stable@...r.kernel.org
Subject: [PATCH] pagemap: remove remaining unneeded spin_lock()

commit: 025c5b2451e4 "thp: optimize away unnecessary page table locking"
moves spin_lock() into pmd_trans_huge_lock() in order to avoid locking
unless pmd is for thp. So this spin_lock() is a bug.

Reported-by: Sasha Levin <levinsasha928@...il.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: stable@...r.kernel.org
---
 fs/proc/task_mmu.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git linux-3.3.0-6658a6991ce.orig/fs/proc/task_mmu.c linux-3.3.0-6658a6991ce/fs/proc/task_mmu.c
index 9694cc2..06d2b70 100644
--- linux-3.3.0-6658a6991ce.orig/fs/proc/task_mmu.c
+++ linux-3.3.0-6658a6991ce/fs/proc/task_mmu.c
@@ -786,7 +786,6 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 
 	/* find the first VMA at or above 'addr' */
 	vma = find_vma(walk->mm, addr);
-	spin_lock(&walk->mm->page_table_lock);
 	if (pmd_trans_huge_lock(pmd, vma) == 1) {
 		for (; addr != end; addr += PAGE_SIZE) {
 			unsigned long offset;
-- 
1.7.7.6

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