Commit a5cdbe9f authored by Kemeng Shi's avatar Kemeng Shi Committed by Andrew Morton
Browse files

mm: shmem: only remove inode from swaplist when it's swapped page count is 0 

Even if we fail to allocate a swap entry, the inode might have previously
allocated entry and we might take inode containing swap entry off
swaplist.  As a result, try_to_unuse() may enter a potential dead loop to
repeatedly look for inode and clean it's swap entry.  Only take inode off
swaplist when it's swapped page count is 0 to fix the issue.

Link: https://lkml.kernel.org/r/20250516170939.965736-5-shikemeng@huaweicloud.com


Fixes: b487a2da ("mm, swap: simplify folio swap allocation")
Signed-off-by: default avatarKemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarKairui Song <kasong@tencent.com>
Reported-by: default avatarkernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505161438.9009cf47-lkp@intel.com


Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3f778ab1

mm/shmem.c

+2 −2
Original line number Diff line number Diff line
@@ -1651,7 +1651,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) 
		BUG_ON(folio_mapped(folio));

		return swap_writepage(&folio->page, wbc);

	}



	if (!info->swapped)

		list_del_init(&info->swaplist);

	mutex_unlock(&shmem_swaplist_mutex);

	if (nr_pages > 1)