linux-kernel - Re: [stable] upstream d913897abace8 -stable backport request

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Date:	Mon, 25 Jan 2016 22:00:54 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	stable@...r.kernel.org, Minchan Kim <minchan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kyeongdon Kim <kyeongdon.kim@....com>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [stable] upstream d913897abace8 -stable backport request

On (01/25/16 21:50), Sergey Senozhatsky wrote:
> Hello,
> 
> Please add upstream 'commit d913897abace8 ("zram: try vmalloc() after
> kmalloc()")' to stable releases.
> 

[v3.15+]

	-ss

> :commit d913897abace843bba20249f3190167f7895e9c3
> :Author: Kyeongdon Kim <kyeongdon.kim@....com>
> :
> :    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.
> 
> 	-ss
>