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

[Michael Ellerman]

Minchan Kim <minchan@xxxxxxxxxx> writes:
> 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.

No worries, bugs happen.

>> 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.

Great, thanks all.

cheers