linux-kernel - [PATCH 5.4 176/178] dm writecache: add cond_resched to loop in persistent_memory

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Date:   Mon, 29 Jun 2020 11:25:21 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mikulas Patocka <mpatocka@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 5.4 176/178] dm writecache: add cond_resched to loop in persistent_memory_claim()

From: Mikulas Patocka <mpatocka@...hat.com>

commit d35bd764e6899a7bea71958f08d16cea5bfa1919 upstream.

Add cond_resched() to a loop that fills in the mapper memory area
because the loop can be executed many times.

Fixes: 48debafe4f2fe ("dm: add writecache target")
Cc: stable@...r.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/md/dm-writecache.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 64d75bbefda11..67eb4e972cc36 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -279,6 +279,8 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 			while (daa-- && i < p) {
 				pages[i++] = pfn_t_to_page(pfn);
 				pfn.val++;
+				if (!(i & 15))
+					cond_resched();
 			}
 		} while (i < p);
 		wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
-- 
2.25.1