Re: [External] Re: [PATCH] mm:zswap: fix zswap entry reclamation failure in two scenarios

[Zhongkun He]

>
> Shameless plug: zswap will much less likely hit the limit (global or
> cgroup) with the shrinker enabled ;) It will proactively reclaim the
> objects way ahead of the limit.

Hi  Nhat，glad to hear from you.
Back to the beginning, the original intention of this patch is to solve
the problem that shrink_work() fails to reclaim memory in two situations.
The zswap_writeback_entry() will failed for !page_was_allocated
because zswap_load will have two copies of the same page in memory
  (compressed and uncompressed) after faulting in a page from zswap when
zswap_exclusive_loads disabled.

A simple test:
1): Turn off  zswap_exclusive_loads_enabled.
2): Run a read-only program and allocate more memory than the limit,
so the limit will be reached and shrinker will fail.

>
> It comes with its own can of worms, of course - it's unlikely to work
> for all workloads in its current form, but perhaps worth experimenting
> with/improved upon?
>