Re: [zram] ltp inspired explosion - master v4.13-rc1-3-g87b2c3fc6317

[Minchan Kim]

Hi Michael,

On Wed, Aug 02, 2017 at 02:24:20PM +1000, Michael Ellerman wrote:
> Minchan Kim <minchan@xxxxxxxxxx> writes:
> > From 0ffbd3c8769fdf56e2f14908f890f9d1703ed32e Mon Sep 17 00:00:00 2001
> > From: Minchan Kim <minchan@xxxxxxxxxx>
> > Date: Tue, 25 Jul 2017 15:15:18 +0900
> > Subject: [PATCH] zram: do not free pool->size_class
> >
> > Mike reported kernel goes oops with ltp:zram03 testcase.
> ...
> >
> > He bisected the problem is [1].
> >
> > By [1], zram doesn't use double pointer for pool->size_class any more
> > in zs_create_pool so counter function zs_destroy_pool don't need to
> > free it, either. Otherwise, it does kfree wrong address and then,
> > kernel goes Oops.
> >
> > [1] cf8e0fedf078 mm/zsmalloc: simplify zs_max_alloc_size handling
> >
> > Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
> > Reported-by: Mike Galbraith <efault@xxxxxx>
> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> > ---
> >  mm/zsmalloc.c | 1 -
> >  1 file changed, 1 deletion(-)
> 
> I just bisected this too.

Sorry for bothering you.

> 
> How about a fixes tag to help the next chump who hits it?
> 
> Fixes: cf8e0fedf078 ("mm/zsmalloc: simplify zs_max_alloc_size handling")

Thanks for good suggestion.
Andrew already did it and just sent to Linus.

Thanks, Andrew.