From 9e0d0ddfbc0e3491da7e2db73faa08d8d4f322b2 Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Fri, 20 Mar 2026 06:05:59 +0100 Subject: [PATCH] mm/swap: fix swap cache memcg accounting The swap readahead path was recently refactored and while doing this, the order between the charging of the folio in the memcg and the addition of the folio in the swap cache was inverted. Since the accounting of the folio is done while adding the folio to the swap cache and the folio is not charged in the memcg yet, the accounting is then done at the node level, which is wrong. Fix this by charging the folio in the memcg before adding it to the swap cache. Link: https://lkml.kernel.org/r/20260320050601.1833108-1-alex@ghiti.fr Fixes: 2732acda82c9 ("mm, swap: use swap cache as the swap in synchronize layer") Signed-off-by: Alexandre Ghiti Acked-by: Kairui Song Acked-by: Johannes Weiner Reviewed-by: Nhat Pham Acked-by: Chris Li Cc: Alexandre Ghiti Cc: Baoquan He Cc: Barry Song Cc: Kemeng Shi Cc: Signed-off-by: Andrew Morton --- mm/swap_state.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 6d0eef7470be..48aff2c917c0 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -494,6 +494,10 @@ static struct folio *__swap_cache_prepare_and_add(swp_entry_t entry, __folio_set_locked(folio); __folio_set_swapbacked(folio); + + if (!charged && mem_cgroup_swapin_charge_folio(folio, NULL, gfp, entry)) + goto failed; + for (;;) { ret = swap_cache_add_folio(folio, entry, &shadow); if (!ret) @@ -514,11 +518,6 @@ static struct folio *__swap_cache_prepare_and_add(swp_entry_t entry, goto failed; } - if (!charged && mem_cgroup_swapin_charge_folio(folio, NULL, gfp, entry)) { - swap_cache_del_folio(folio); - goto failed; - } - memcg1_swapin(entry, folio_nr_pages(folio)); if (shadow) workingset_refault(folio, shadow);