When the preferred demotion node does not have enough free space, alloc_demote_folio() attempts to allocate from fallback nodes. Currently, it lacks a mechanism to distribute these fallback allocations, which can lead to unbalanced memory pressure across fallback nodes. Balance the allocation by randomly selecting a new preferred node from the fallback nodes if the initial allocation from the old preferred node fails. Signed-off-by: Bing Jiao --- mm/vmscan.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 81828fa625ed..db2413c4bd26 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1009,6 +1009,11 @@ static struct folio *alloc_demote_folio(struct folio *src, if (dst) return dst; + /* Randomly select a node from fallback nodes for balanced allocation */ + if (allowed_mask) { + mtc->nid = node_random(allowed_mask); + node_clear(mtc->nid, *allowed_mask); + } mtc->gfp_mask &= ~__GFP_THISNODE; mtc->nmask = allowed_mask; -- 2.52.0.358.g0dd7633a29-goog