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From:   Xianting Tian <xianting_tian@126.com>
To:     akpm@linux-foundation.org
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm: use blk_io_schedule() for avoiding task hung in sync io
Date:   Mon,  3 Aug 2020 09:36:47 -0400
Message-Id: <1596461807-21087-1-git-send-email-xianting_tian@126.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

swap_readpage() does the sync io for one page, the io is not big, normally,
the io can be finished quickly, but it may take long time or wait forever
in case of io failure or discard.
This patch is to use blk_io_schedule() instead of io_schedule() to avoid
task hung and crash(when set /proc/sys/kernel/hung_task_panic) in case of
above exception occur.
We have prevented task hung in submit_bio_wait(), blk_execute_rq() and
__blkdev_direct_IO().

Signed-off-by: Xianting Tian <xianting_tian@126.com>
---
 mm/page_io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index e8726f3..5d52f7b 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -424,7 +424,7 @@ int swap_readpage(struct page *page, bool synchronous)
 			break;
 
 		if (!blk_poll(disk->queue, qc, true))
-			io_schedule();
+			blk_io_schedule();
 	}
 	__set_current_state(TASK_RUNNING);
 	bio_put(bio);
-- 
1.8.3.1