I forgot to CC stable on this fix.

Chris

On Thu, Sep 5, 2024 at 1:08 AM Chris Li chrisl@kernel.org wrote:

I found a regression on mm-unstable during my swap stress test, using tmpfs to compile linux. The test OOM very soon after the make spawns many cc processes.

It bisects down to this change: 33dfe9204f29b415bbc0abb1a50642d1ba94f5e9 (mm/gup: clear the LRU flag of a page before adding to LRU batch)

Yu Zhao propose the fix: "I think this is one of the potential side effects -- Huge mentioned earlier about isolate_lru_folios():"

I test that with it the swap stress test no longer OOM.

Link: https://lore.kernel.org/r/CAOUHufYi9h0kz5uW3LHHS3ZrVwEq-kKp8S6N-MZUmErNAXoXm... Fixes: 33dfe9204f29 ("mm/gup: clear the LRU flag of a page before adding to LRU batch") Suggested-by: Yu Zhao yuzhao@google.com Suggested-by: Hugh Dickins hughd@google.com Tested-by: Chris Li chrisl@kernel.org Closes: https://lore.kernel.org/all/CAF8kJuNP5iTj2p07QgHSGOJsiUfYpJ2f4R1Q5-3BN9JiD9W... Signed-off-by: Chris Li chrisl@kernel.org

---

Changes in v2:

• Add Closes tag suggested by Yu and Thorsten.
• Link to v1: https://lore.kernel.org/r/20240904-lru-flag-v1-1-36638d6a524c@kernel.org

---

mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c index a9b6a8196f95..96abf4a52382 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4323,7 +4323,7 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_c }

    /* ineligible */

•   if (zone > sc->reclaim_idx) {
  

•   if (!folio_test_lru(folio) || zone > sc->reclaim_idx) {
            gen = folio_inc_gen(lruvec, folio, false);
            list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
            return true;
  
  

---

base-commit: 756ca36d643324d028b325a170e73e392b9590cd change-id: 20240904-lru-flag-2af2f955740e

Best regards,

Chris Li chrisl@kernel.org