From de2e5171433126d340573cb7d0d4fcac084ab2a0 Mon Sep 17 00:00:00 2001
From: Kefeng Wang
Date: Mon, 5 Dec 2022 22:03:27 +0800
Subject: mm: add cond_resched() in swapin_walk_pmd_entry()

When handling MADV_WILLNEED in madvise(), a soflockup may occurr in
swapin_walk_pmd_entry() if swapping in lots of memory on a slow device. 
Add a cond_resched() to avoid the possible softlockup.

Link: https://lkml.kernel.org/r/20221205140327.72304-1-wangkefeng.wang@huawei.com
Fixes: 1998cc048901 ("mm: make madvise(MADV_WILLNEED) support swap file prefetch")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Shaohua Li <shli@fusionio.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/madvise.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'mm')

diff --git a/mm/madvise.c b/mm/madvise.c
index 2573ea3ed684..b7d9b1a1c135 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -223,6 +223,7 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
 			put_page(page);
 	}
 	swap_read_unplug(splug);
+	cond_resched();
 
 	return 0;
 }
-- 
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