From: Kairui Song The allocator will reclaim cached slots while scanning. Currently, it will try again if the reclaim found a folio that is already removed from the swap cache due to a race. But the following lookup will be using the wrong index. It won't cause any OOB issue since the swap cache index is truncated upon lookup, but it may lead to reclaiming of an irrelevant folio. This should not cause a measurable issue, but we should fix it. Fixes: fae8595505313 ("mm, swap: avoid reclaiming irrelevant swap cache") Signed-off-by: Kairui Song --- mm/swapfile.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 4b8ab2cb49ca..4c63fc62f4cb 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -240,13 +240,13 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si, * Offset could point to the middle of a large folio, or folio * may no longer point to the expected offset before it's locked. */ - entry = folio->swap; - if (offset < swp_offset(entry) || offset >= swp_offset(entry) + nr_pages) { + if (offset < swp_offset(folio->swap) || + offset >= swp_offset(folio->swap) + nr_pages) { folio_unlock(folio); folio_put(folio); goto again; } - offset = swp_offset(entry); + offset = swp_offset(folio->swap); need_reclaim = ((flags & TTRS_ANYWAY) || ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) || -- 2.51.0