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); rcu_read_lock(); /* * Look up the memcg associated with the stored ID. It might @@ -461,9 +463,6 @@ void workingset_refault(struct folio *folio, void *shadow) lruvec = mem_cgroup_lruvec(memcg, pgdat); mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr); - - /* Do not sleep with RCU lock held */ - mem_cgroup_flush_stats_delayed(false); /* * Compare the distance to the existing workingset size. We * don't activate pages that couldn't stay resident even if -- 2.40.0.rc1.284.g88254d51c5-goog
