Re: [PATCH 2/2] mm: vmscan: fix node reclaim ignoring swappiness parameter
Ridong Chen <[email protected]>
| Newsgroups | org.kernel.vger.cgroups,org.kernel.vger.linux-kernel,org.kvack.linux-mm |
|---|---|
| Message-ID | <[email protected]> |
On 7/13/2026 11:16 PM, Barry Song wrote: > On Sat, Jul 11, 2026 at 5:12 PM Ridong Chen <[email protected]> wrote: >> >> From: Ridong Chen <[email protected]> >> >> sc_swappiness() had two separate definitions depending on >> CONFIG_MEMCG. The !CONFIG_MEMCG variant simply returned >> vm_swappiness, ignoring the proactive_swappiness value passed >> through scan_control. This caused the swappiness parameter >> written to /sys/devices/system/node/nodeX/reclaim to have no >> effect when CONFIG_MEMCG is disabled. >> >> Fix this by consolidating sc_swappiness() into a single definition >> that checks sc->proactive_swappiness first, then falls back to >> mem_cgroup_swappiness() which already handles both CONFIG_MEMCG >> and !CONFIG_MEMCG. >> >> Before fix (swappiness=max ignored, mostly file pages reclaimed): >> >> # cat /proc/sys/vm/swappiness >> 60 >> # cat /proc/vmstat | grep pgsteal >> pgsteal_kswapd 0 >> pgsteal_direct 0 >> pgsteal_khugepaged 0 >> pgsteal_proactive 1840 >> pgsteal_anon 25 >> pgsteal_file 1815 >> # echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim >> # cat /proc/vmstat | grep pgsteal >> pgsteal_kswapd 0 >> pgsteal_direct 0 >> pgsteal_khugepaged 0 >> pgsteal_proactive 18013 >> pgsteal_anon 337 >> pgsteal_file 17676 >> >> After fix (swappiness=max honored, anon pages reclaimed as expected): >> >> # cat /proc/vmstat | grep pgsteal >> pgsteal_kswapd 0 >> pgsteal_direct 0 >> pgsteal_khugepaged 0 >> pgsteal_proactive 0 >> pgsteal_anon 0 >> pgsteal_file 0 >> # echo "64M swappiness=max" > /sys/devices/system/node/node0/reclaim >> # cat /proc/vmstat | grep pgsteal >> pgsteal_kswapd 0 >> pgsteal_direct 0 >> pgsteal_khugepaged 0 >> pgsteal_proactive 16283 >> pgsteal_anon 16283 >> pgsteal_file 0 >> >> Fixes: 68cd9050d871 ("mm: add swappiness= arg to memory.reclaim") >> Signed-off-by: Ridong Chen <[email protected]> > > Reviewed-by: Barry Song <[email protected]> > > As pointed out by Johannes, the Fixes tag should be > b980077899ea. Hi Johannes and Barry, Thank you for your review. You are right, will update it. -- Best regards Ridong