Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index c1513c7..14b2bf2 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -98,3 +98,42 @@
 		The backing_dev file is read-write and set up backing
 		device for zram to write incompressible pages.
 		For using, user should enable CONFIG_ZRAM_WRITEBACK.
+
+What:		/sys/block/zram<id>/idle
+Date:		November 2018
+Contact:	Minchan Kim <minchan@kernel.org>
+Description:
+		idle file is write-only and mark zram slot as idle.
+		If system has mounted debugfs, user can see which slots
+		are idle via /sys/kernel/debug/zram/zram<id>/block_state
+
+What:		/sys/block/zram<id>/writeback
+Date:		November 2018
+Contact:	Minchan Kim <minchan@kernel.org>
+Description:
+		The writeback file is write-only and trigger idle and/or
+		huge page writeback to backing device.
+
+What:		/sys/block/zram<id>/bd_stat
+Date:		November 2018
+Contact:	Minchan Kim <minchan@kernel.org>
+Description:
+		The bd_stat file is read-only and represents backing device's
+		statistics (bd_count, bd_reads, bd_writes) in a format
+		similar to block layer statistics file format.
+
+What:		/sys/block/zram<id>/writeback_limit_enable
+Date:		November 2018
+Contact:	Minchan Kim <minchan@kernel.org>
+Description:
+		The writeback_limit_enable file is read-write and specifies
+		eanbe of writeback_limit feature. "1" means eable the feature.
+		No limit "0" is the initial state.
+
+What:		/sys/block/zram<id>/writeback_limit
+Date:		November 2018
+Contact:	Minchan Kim <minchan@kernel.org>
+Description:
+		The writeback_limit file is read-write and specifies the maximum
+		amount of writeback ZRAM can do. The limit could be changed
+		in run time.