Re: [PATCH v2] zswap: re-check zswap_is_full after do zswap_shrink

From: Li Wang
Date: Mon Jun 25 2018 - 04:08:39 EST


On 30 May 2018 at 20:53, Dan Streetman <ddstreet@xxxxxxxx> wrote:
> On Wed, May 30, 2018 at 6:39 AM, Li Wang <liwang@xxxxxxxxxx> wrote:
>> The '/sys/../zswap/stored_pages:' keep raising in zswap test with
>> "zswap.max_pool_percent=0" parameter. But theoretically, it should
>> not compress or store pages any more since there is no space in
>> compressed pool.
>>
>> Reproduce steps:
>> 1. Boot kernel with "zswap.enabled=1"
>> 2. Set the max_pool_percent to 0
>> # echo 0 > /sys/module/zswap/parameters/max_pool_percent
>> 3. Do memory stress test to see if some pages have been compressed
>> # stress --vm 1 --vm-bytes $mem_available"M" --timeout 60s
>> 4. Watching the 'stored_pages' number increasing or not
>>
>> The root cause is:
>> When zswap_max_pool_percent is setting to 0 via kernel parameter, the
>> zswap_is_full() will always return true to do zswap_shrink(). But if
>> the shinking is able to reclain a page successful, then proceeds to
>> compress/store another page, so the value of stored_pages will keep
>> changing.
>>
>> To solve the issue, this patch adds zswap_is_full() check again after
>> zswap_shrink() to make sure it's now under the max_pool_percent, and
>> not to compress/store if reach its limitaion.
>>
>> Signed-off-by: Li Wang <liwang@xxxxxxxxxx>
>
> Acked-by: Dan Streetman <ddstreet@xxxxxxxx>

ping~

Any possible to merge this in kernel-4.18-rcX? My zswap test always
fails on the upstream kernel.


--
Regards,
Li Wang
Email: wangli.ahau@xxxxxxxxx