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SubjectRe: [PATCH v2] zswap: re-check zswap_is_full after do zswap_shrink
On Mon, Jun 25, 2018 at 4:08 AM Li Wang <wangli.ahau@gmail.com> wrote:
>
> On 30 May 2018 at 20:53, Dan Streetman <ddstreet@ieee.org> wrote:
> > On Wed, May 30, 2018 at 6:39 AM, Li Wang <liwang@redhat.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@redhat.com>
> >
> > Acked-by: Dan Streetman <ddstreet@ieee.org>
>
> ping~
>
> Any possible to merge this in kernel-4.18-rcX? My zswap test always
> fails on the upstream kernel.

cc'ing Andrew as he may have missed this.

>
>
> --
> Regards,
> Li Wang
> Email: wangli.ahau@gmail.com

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