[stable] upstream d913897abace8 -stable backport request
From: Sergey Senozhatsky
Date: Mon Jan 25 2016 - 07:52:45 EST
Please add upstream 'commit d913897abace8 ("zram: try vmalloc() after
kmalloc()")' to stable releases.
:Author: Kyeongdon Kim <kyeongdon.kim@xxxxxxx>
: zram: try vmalloc() after kmalloc()
: When we're using LZ4 multi compression streams for zram swap, we found
: out page allocation failure message in system running test. That was
: not only once, but a few(2 - 5 times per test). Also, some failure
: cases were continually occurring to try allocation order 3.
: In order to make parallel compression private data, we should call
: kzalloc() with order 2/3 in runtime(lzo/lz4). But if there is no order
: 2/3 size memory to allocate in that time, page allocation fails. This
: patch makes to use vmalloc() as fallback of kmalloc(), this prevents
: page alloc failure warning.
: After using this, we never found warning message in running test, also
: It could reduce process startup latency about 60-120ms in each case.