v4.19.13 snapshot.
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+What: /sys/block/zram<id>/disksize
+Date: August 2010
+Contact: Nitin Gupta <ngupta@vflare.org>
+Description:
+ The disksize file is read-write and specifies the disk size
+ which represents the limit on the *uncompressed* worth of data
+ that can be stored in this disk.
+ Unit: bytes
+
+What: /sys/block/zram<id>/initstate
+Date: August 2010
+Contact: Nitin Gupta <ngupta@vflare.org>
+Description:
+ The initstate file is read-only and shows the initialization
+ state of the device.
+
+What: /sys/block/zram<id>/reset
+Date: August 2010
+Contact: Nitin Gupta <ngupta@vflare.org>
+Description:
+ The reset file is write-only and allows resetting the
+ device. The reset operation frees all the memory associated
+ with this device.
+
+What: /sys/block/zram<id>/max_comp_streams
+Date: February 2014
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The max_comp_streams file is read-write and specifies the
+ number of backend's zcomp_strm compression streams (number of
+ concurrent compress operations).
+
+What: /sys/block/zram<id>/comp_algorithm
+Date: February 2014
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The comp_algorithm file is read-write and lets to show
+ available and selected compression algorithms, change
+ compression algorithm selection.
+
+What: /sys/block/zram<id>/mem_used_max
+Date: August 2014
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The mem_used_max file is write-only and is used to reset
+ the counter of maximum memory zram have consumed to store
+ compressed data. For resetting the value, you should write
+ "0". Otherwise, you could see -EINVAL.
+ Unit: bytes
+
+What: /sys/block/zram<id>/mem_limit
+Date: August 2014
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The mem_limit file is write-only and specifies the maximum
+ amount of memory ZRAM can use to store the compressed data.
+ The limit could be changed in run time and "0" means disable
+ the limit. No limit is the initial state. Unit: bytes
+
+What: /sys/block/zram<id>/compact
+Date: August 2015
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ The compact file is write-only and trigger compaction for
+ allocator zrm uses. The allocator moves some objects so that
+ it could free fragment space.
+
+What: /sys/block/zram<id>/io_stat
+Date: August 2015
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The io_stat file is read-only and accumulates device's I/O
+ statistics not accounted by block layer. For example,
+ failed_reads, failed_writes, etc. File format is similar to
+ block layer statistics file format.
+
+What: /sys/block/zram<id>/mm_stat
+Date: August 2015
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The mm_stat file is read-only and represents device's mm
+ statistics (orig_data_size, compr_data_size, etc.) in a format
+ similar to block layer statistics file format.
+
+What: /sys/block/zram<id>/debug_stat
+Date: July 2016
+Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+ The debug_stat file is read-only and represents various
+ device's debugging info useful for kernel developers. Its
+ format is not documented intentionally and may change
+ anytime without any notice.
+
+What: /sys/block/zram<id>/backing_dev
+Date: June 2017
+Contact: Minchan Kim <minchan@kernel.org>
+Description:
+ 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.