On Mon, Jun 25, 2018 at 4:08 AM Li Wang [off-list ref] wrote:

On 30 May 2018 at 20:53, Dan Streetman [off-list ref] wrote:

quoted

On Wed, May 30, 2018 at 6:39 AM, Li Wang [off-list ref] wrote:

quoted

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 <redacted>

Acked-by: Dan Streetman <redacted>

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