On Thu, Mar 23, 2023 at 04:00:36AM +0000, Yosry Ahmed wrote: > In workingset_refault(), we call mem_cgroup_flush_stats_delayed() to > flush stats within an RCU read section and with sleeping disallowed. > Move the call to mem_cgroup_flush_stats_delayed() above the RCU read > section and allow sleeping to avoid unnecessarily performing a lot of > work without sleeping. > > Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > --- > > A lot of code paths call into workingset_refault(), so I am not > generally sure at all whether it's okay to sleep in all contexts or not. > Feedback here would be very helpful. > > --- > mm/workingset.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/mm/workingset.c b/mm/workingset.c > index 042eabbb43f6..410bc6684ea7 100644 > --- a/mm/workingset.c > +++ b/mm/workingset.c > @@ -406,6 +406,8 @@ void workingset_refault(struct folio *folio, void *shadow) > unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset); > eviction <<= bucket_order; > > + /* Flush stats (and potentially sleep) before holding RCU read lock */ > + mem_cgroup_flush_stats_delayed(true); Btw, it might be a good time to rename this while you're in the area. delayed suggests this is using a delayed_work, but this is actually sometimes flushing directly from the callsite. What it's doing is ratelimited calls. A better name would be: mem_cgroup_flush_stats_ratelimited()
