From e4b92891aaca0d37b5973362dd14747a65406650 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Sun, 20 Sep 2026 16:50:02 +0100 Subject: [PATCH] mm/shmem: don't release a swapin-error marker as a swap entry A failed shmem swapin (eg, EIO) frees the swap slot and leaves a PTE_MARKER_POISONED entry in the page cache. On truncate or eviction shmem_free_swap() passes that marker to swap_put_entries_direct(), which warns because it is not a swap entry. There is nothing left to release either way. Skip the release for non-swap entries, as every other caller already does. Link: https://lore.kernel.org/20260920155002.1030454-1-devnexen@gmail.com Fixes: ac2d3268284b ("mm/swapfile.c: remove the unneeded checking") Signed-off-by: David Carlier Signed-off-by: Andrew Morton Reported-by: syzbot+23b25ba3c6bf971f9c57@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=23b25ba3c6bf971f9c57 Reviewed-by: Baolin Wang Cc: Baoquan he Cc: Barry Song Cc: Chis Li (Google) Cc: Hugh Dickens Cc: Kairui Song Cc: Kemeng Shi Cc: Nhat Pham Cc: --- mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index f2a36a1b5375..07b2855dfb7b 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1184,6 +1184,7 @@ static long shmem_free_swap(struct address_space *mapping, pgoff_t index, pgoff_t end, void *radswap) { XA_STATE(xas, &mapping->i_pages, index); + const softleaf_t swp = radix_to_swp_entry(radswap); unsigned int nr_pages = 0; pgoff_t base; void *entry; @@ -1200,8 +1201,9 @@ static long shmem_free_swap(struct address_space *mapping, } xas_unlock_irq(&xas); - if (nr_pages) - swap_put_entries_direct(radix_to_swp_entry(radswap), nr_pages); + /* A swapin-error marker holds no swap slot, so just drop it. */ + if (nr_pages && softleaf_is_swap(swp)) + swap_put_entries_direct(swp, nr_pages); return nr_pages; }