linux-kernel - Re: [PATCH] zram: clear disk io accounting when reset zram device

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: <20150529145418.GG11609@blaptop>
Date:	Fri, 29 May 2015 23:54:19 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Weijie Yang <weijie.yang@...sung.com>,
	'Andrew Morton' <akpm@...ux-foundation.org>, ngupta@...are.org,
	'Weijie Yang' <weijie.yang.kh@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] zram: clear disk io accounting when reset zram device

Hello guys,

On Fri, May 29, 2015 at 12:41:41PM +0900, Sergey Senozhatsky wrote:
> On (05/29/15 11:23), Weijie Yang wrote:
> > This patch clears zram disk io accounting when reset the zram device,
> > if don't do this, the residual io accounting stat will affect the
> > diskstat in the next zram active cycle.

Thanks for the fix.

> > 
> 
> thanks. my bad.
> 
> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Acked-by: Minchan Kim <minchan@...nel.org>

I give my acked-by because it's surely fix so there is no reason to
hesitate.

In future, I hope to change it like below.

I think the problem is caused from weired feature "reset" of zram.
Until a while ago, we didn't have hot_add/del feature so we should
use custom reset function but now we have hot/add feature.
So reset is logically same feature(ie, reset = hot_remove+hot_add
but remains same device id).

If we reuse zram_remove/add for reset, finally it calls del_gendisk
which will do part_stat_set_all for us so we didn't have this kinds
of problems.

It needs more churns and some tweaks of zram_[remove|add] but
it's more clean and consistent between reset and hot_remove.

Just my two cents.

> 
> 	-ss
> 
> > Signed-off-by: Weijie Yang <weijie.yang@...sung.com>
> > ---
> >  drivers/block/zram/zram_drv.c |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index 8dcbced..6e134f4 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -805,7 +805,9 @@ static void zram_reset_device(struct zram *zram)
> >  	memset(&zram->stats, 0, sizeof(zram->stats));
> >  	zram->disksize = 0;
> >  	zram->max_comp_streams = 1;
> > +
> >  	set_capacity(zram->disk, 0);
> > +	part_stat_set_all(&zram->disk->part0, 0);
> >  
> >  	up_write(&zram->init_lock);
> >  	/* I/O operation under all of CPU are done so let's free */
> > -- 
> > 1.7.10.4
> > 
> > 

-- 
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/