[PATCH v3 3/6] block/genhd.c: apply pm_runtime_set_memalloc_noio on block devices

[Ming Lei <ming.lei@canonical.com>]

This patch applyes the introduced pm_runtime_set_memalloc_noio on
block device so that PM core will teach mm to not allocate memory with
GFP_IOFS when calling the runtime_resume callback for block devices.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 block/genhd.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 9e02cd6..c5f10ea 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -18,6 +18,7 @@
 #include <linux/mutex.h>
 #include <linux/idr.h>
 #include <linux/log2.h>
+#include <linux/pm_runtime.h>
 
 #include "blk.h"
 
@@ -519,6 +520,12 @@ static void register_disk(struct gendisk *disk)
 
 	dev_set_name(ddev, disk->disk_name);
 
+	/* avoid probable deadlock caused by allocate memory with
+	 * GFP_KERNEL in runtime_resume callback of its all ancestor
+	 * deivces
+	 */
+	pm_runtime_set_memalloc_noio(ddev, true);
+
 	/* delay uevents, until we scanned partition table */
 	dev_set_uevent_suppress(ddev, 1);
 
@@ -661,6 +668,7 @@ void del_gendisk(struct gendisk *disk)
 	disk->driverfs_dev = NULL;
 	if (!sysfs_deprecated)
 		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
+	pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
 	device_del(disk_to_dev(disk));
 }
 EXPORT_SYMBOL(del_gendisk);
-- 
1.7.9.5

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