linux-kernel - [PATCH] mm: add cond_resched() in swapin_walk_pmd

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Message-ID: <20221205140327.72304-1-wangkefeng.wang@huawei.com>
Date:   Mon, 5 Dec 2022 22:03:27 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
CC:     <xialonglong1@...wei.com>, Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH] mm: add cond_resched() in swapin_walk_pmd_entry()

When handle MADV_WILLNEED in madvise(), the soflockup may be occurred
in swapin_walk_pmd_entry() if swapin lots of memory on slow device,
add a cond_resched() into it to avoid the possible softlockup.

Fixes: 1998cc048901 ("mm: make madvise(MADV_WILLNEED) support swap file prefetch")
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 mm/madvise.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/madvise.c b/mm/madvise.c
index b913ba6efc10..fea589d8a2fb 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -226,6 +226,7 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
 			put_page(page);
 	}
 	swap_read_unplug(splug);
+	cond_resched();
 
 	return 0;
 }
-- 
2.35.3