We can set memory.low for cgroups as a soft protection limit. When the kernel cannot reclaim any pages from other cgroups, it retries reclaim while ignoring the memory.low protection of the skipped cgroups. Currently, this retry logic only works in direct reclaim path, but is missing in the kswapd asynchronous reclaim. Typically, a cgroup may contain some cold pages that could be reclaimed even when memory.low is set. This change adds retry logic to kswapd: if the first reclaim attempt fails to reclaim any pages and some cgroups were skipped due to memory.low protection, kswapd will perform a second reclaim pass ignoring memory.low restrictions. This ensures more consistent reclaim behavior between direct reclaim and kswapd. By allowing kswapd to reclaim more proactively from protected cgroups under global memory pressure, this optimization can help reduce the occurrence of direct reclaim, which is more disruptive to application performance. Signed-off-by: Jiayuan Chen --- mm/vmscan.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index c80fcae7f2a1..231c66fcdfd8 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -7147,6 +7147,13 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx) goto restart; } + /* Restart if we skipped the memory low event */ + if (sc.memcg_low_skipped && !sc.memcg_low_reclaim && + sc.priority < 1) { + sc.memcg_low_reclaim = 1; + goto restart; + } + if (!sc.nr_reclaimed) atomic_inc(&pgdat->kswapd_failures); -- 2.43.0