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

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Message-ID: <CAE1O6mir7Pco=QRBDFTFh7pkVQtXT=PtJ4R-o1RV9PPoY5-nLQ@mail.gmail.com>
Date:   Mon, 25 Jun 2018 16:08:30 +0800
From:   Li Wang <wangli.ahau@...il.com>
To:     Dan Streetman <ddstreet@...e.org>
Cc:     Li Wang <liwang@...hat.com>, Linux-MM <linux-mm@...ck.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Seth Jennings <sjenning@...hat.com>,
        Huang Ying <huang.ying.caritas@...il.com>,
        Yu Zhao <yuzhao@...gle.com>
Subject: Re: [PATCH v2] zswap: re-check zswap_is_full after do zswap_shrink

On 30 May 2018 at 20:53, Dan Streetman <ddstreet@...e.org> wrote:
> On Wed, May 30, 2018 at 6:39 AM, Li Wang <liwang@...hat.com> 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@...hat.com>
>
> Acked-by: Dan Streetman <ddstreet@...e.org>

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@...il.com