linux-kernel - [PATCH 2/8] mm/memory-failure.c: avoid walking page table when vma

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Date:   Thu, 10 Feb 2022 22:17:27 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <naoya.horiguchi@....com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 2/8] mm/memory-failure.c: avoid walking page table when vma_address() return -EFAULT

It's unnecessary to walk the page table when vma_address() return -EFAULT.
Return early if so to save some cpu cycles.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/memory-failure.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b3ff7e99a421..f86819145ea8 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -315,6 +315,8 @@ static unsigned long dev_pagemap_mapping_shift(struct page *page,
 	pmd_t *pmd;
 	pte_t *pte;
 
+	if (address == -EFAULT)
+		return 0;
 	pgd = pgd_offset(vma->vm_mm, address);
 	if (!pgd_present(*pgd))
 		return 0;
-- 
2.23.0