On Thu, 2024-12-12 at 10:15 +1100, Balbir Singh wrote: > On 12/12/24 02:53, Rik van Riel wrote: > > > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 7b3503d12aaf..03d77e93087e 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -5371,6 +5371,15 @@ bool > > mem_cgroup_zswap_writeback_enabled(struct mem_cgroup *memcg) > > if (!zswap_is_enabled()) > > return true; > > > > + /* > > + * Always allow exiting tasks to push data to swap. A > > process in > > + * the middle of exit cannot get OOM killed, but may need > > to push > > + * uncompressible data to swap in order to get the cgroup > > memory > > + * use below the limit, and make progress with the exit. > > + */ > > + if ((current->flags & PF_EXITING) && memcg == > > mem_cgroup_from_task(current)) > > + return true; > > + > > for (; memcg; memcg = parent_mem_cgroup(memcg)) > > if (!READ_ONCE(memcg->zswap_writeback)) > > return false; > > Rik, > > I am unable to understand the motivation here, so we want > mem_cgroup_zswap_writeback_enabled() to return true, it only > returns false if a memcg in the hierarchy has zswap_writeback > set to 0 (false). In my git-grep I can't seem to find how/why > that may be the case. I can see memcg starts of with the value > set to true, if CONFIG_ZSWAP is enabled. > > Your changelog above makes sense, but I am unable to map it to > the code changes. > Wait, are you asking about the code that I'm adding, or about the code that was already there? I want to add the code that allows zswap writeback if the reclaiming task is exiting, and in the same cgroup as the to be written back memory. -- All Rights Reversed.
