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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20151124035637.GE3882@blaptop>
Date:	Tue, 24 Nov 2015 12:56:37 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Kyeongdon Kim <kyeongdon.kim@....com>, ngupta@...are.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] zram: try vmalloc() after kmalloc()

On Tue, Nov 24, 2015 at 10:06:22AM +0900, Sergey Senozhatsky wrote:
> On (11/24/15 09:35), Minchan Kim wrote:
> [..]
> > > We can use __GFP_RECLAIM (used to be __GFP_WAIT).  That permits the
> > > allocation to wait for in-flight IO to complete and to reclaim clean
> > > pagecache.
> > 
> > Generally, you're right but in case of zram, it would be unfortunate.
> > 
> > It would be void *most of time* because it is called in reclaim context
> > and reclaim path bails out to avoid recursion of direct reclaim
> > by PF_MEMALLOC without trying reclaim.
> > However, the reason I said *most of time* is we has another context
> > the funcion could be called.
> > 
> >         "disksize_store"->zcomp_create
> > 
> > In the place, we should make sure the successful allocation to work
> > zram at least so that path should use another gfp.
> > I will work for that.
> 
> Hm... is it really worth it? passing a bool to zcomp_strm_alloc() (so
> it can decide what gfp flags to use) or gfp flags directly is just a
> bit complicated. what's the problem with GFP_NOIO (__GFP_RECLAIM) in
> the first place (sorry if I'm missing something terribly obvious)?

No, you didn't miss anything and your question is really proper.
Actually, I was on same page with you but when I think more,
I guess it makes code looks clean and right way for structuring, IMO.
So, I coded now and am preasure with it. I hope you are on same
page when you look at new patchset. :)

> 
> alternatively, we can just remove the 'dynamic' streams allocation part
> and allocate all of the streams via sysfs store path only.

Hmm, I don't think it's really trouble part we cannot fix easily
so let's stay with it!


> 
> 	-ss

-- 
Kind regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/