linux-kernel - [PATCH] mm/memory-failure: do pgoff calculation before for_each

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Date:   Tue, 18 Aug 2020 16:26:47 +0800
From:   Xianting Tian <tian.xianting@....com>
To:     <naoya.horiguchi@....com>, <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Xianting Tian <tian.xianting@....com>
Subject: [PATCH] mm/memory-failure: do pgoff calculation before for_each_process()

There is no need to calcaulate pgoff in each loop of for_each_process(),
so move it to the place before for_each_process(), which can save some
CPU cycles.

Signed-off-by: Xianting Tian <tian.xianting@....com>
---
 mm/memory-failure.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 47b8ccb1f..7dc2c9d3b 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -484,11 +484,12 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
 	struct vm_area_struct *vma;
 	struct task_struct *tsk;
 	struct address_space *mapping = page->mapping;
+	pgoff_t pgoff;
 
 	i_mmap_lock_read(mapping);
 	read_lock(&tasklist_lock);
+	pgoff = page_to_pgoff(page);
 	for_each_process(tsk) {
-		pgoff_t pgoff = page_to_pgoff(page);
 		struct task_struct *t = task_early_kill(tsk, force_early);
 
 		if (!t)
-- 
2.17.1