swap_cluster_readahead() could race with swapoff and might dereference si->swap_file after it's released by swapoff. Close this race window by using get/put_swap_device() pair. Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> --- mm/swap_state.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 3bf0d0c297bc..eba6b0cf6cf9 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -626,12 +626,17 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, unsigned long offset = entry_offset; unsigned long start_offset, end_offset; unsigned long mask; - struct swap_info_struct *si = swp_swap_info(entry); + struct swap_info_struct *si; struct blk_plug plug; bool do_poll = true, page_allocated; struct vm_area_struct *vma = vmf->vma; unsigned long addr = vmf->address; + si = get_swap_device(entry); + /* In case we raced with swapoff. */ + if (!si) + return NULL; + mask = swapin_nr_pages(offset) - 1; if (!mask) goto skip; @@ -673,7 +678,9 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask, lru_add_drain(); /* Push any new pages onto the LRU now */ skip: - return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll); + page = read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll); + put_swap_device(si); + return page; } int init_swap_address_space(unsigned int type, unsigned long nr_pages) -- 2.19.1
