linux-kernel - Re: [PATCH v3 2/2] zram: try vmalloc() after kmalloc()

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Message-ID: <20151201072438.GC894@swordfish>
Date:	Tue, 1 Dec 2015 16:24:38 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Kyeongdon Kim <kyeongdon.kim@....com>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Minchan Kim <minchan@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH v3 2/2] zram: try vmalloc() after kmalloc()

On (12/01/15 15:35), Kyeongdon Kim wrote:
> Let me give you a simple code of it.
> 
> @test #1 (previous shared log)
>  kmalloc(f | __GFP_NOMEMALLOC)
>   __vmalloc(f | __GFP_NOMEMALLOC)
> // can find failure both
> 
> @test #2 (previous shared log)
>  kmalloc(f | __GFP_NOMEMALLOC)
> __vmalloc(f) 	
> // removed '__GFP_NOMEMALLOC' from vmalloc() only, and cannot find
> failure from vmalloc()
> 
> And like you said, I made a quick check to see a failure about kmalloc()
> without the flag :
> 
> @test #3
>  kmalloc(f)
> __vmalloc(f | __GFP_NOMEMALLOC)
> // removed '__GFP_NOMEMALLOC' from zmalloc() only
> // and cannot find failure from zmalloc(), but in this case, it's hard
> to find failure from vmalloc() because of already allocation mostly from
> zsmalloc()
> 

I assume, that "zsmalloc" and "zmalloc" here are meant to be "kzalloc (kmalloc)"

	-ss

> log message (test #3) :
> <4>[  186.763605][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002030000
> <4>[  186.776652][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc0020f0000
> <4>[  186.811423][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002108000
> <4>[  186.816744][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002000000
> <4>[  186.816796][1] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002008000
> 
> @test #4
>  kmalloc(f)
> __vmalloc(f)
> // cannot find failure both until now
> 
> log message (test #4) :
> <4>[  641.440468][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002190000
> <snip>
> <4>[  922.182980][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002208000
> <snip>
> <4>[  923.197593][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc002020000
> <snip>
> <4>[  939.813499][7] KDKIM: zcomp_lz4_create: 24: ret = ffffffc0020a0000
> 
> So,is there another problem if we remove the flag from both sides?
> 
> Thanks,
> Kyeongdon Kim
> 
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