This is a note to let you know that I've just added the patch titled

mm, swap: fix false error message in __swp_swapcount()

to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: mm-swap-fix-false-error-message-in-__swp_swapcount.patch and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From e9a6effa500526e2a19d5ad042cb758b55b1ef93 Mon Sep 17 00:00:00 2001

From: Huang Ying huang.ying.caritas@gmail.com Date: Wed, 15 Nov 2017 17:33:15 -0800 Subject: mm, swap: fix false error message in __swp_swapcount()

From: Huang Ying huang.ying.caritas@gmail.com

commit e9a6effa500526e2a19d5ad042cb758b55b1ef93 upstream.

When a page fault occurs for a swap entry, the physical swap readahead (not the VMA base swap readahead) may readahead several swap entries after the fault swap entry. The readahead algorithm calculates some of the swap entries to readahead via increasing the offset of the fault swap entry without checking whether they are beyond the end of the swap device and it relys on the __swp_swapcount() and swapcache_prepare() to check it. Although __swp_swapcount() checks for the swap entry passed in, it will complain with the error message as follow for the expected invalid swap entry. This may make the end users confused.

swap_info_get: Bad swap offset entry 0200f8a7

To fix the false error message, the swap entry checking is added in swapin_readahead() to avoid to pass the out-of-bound swap entries and the swap entry reserved for the swap header to __swp_swapcount() and swapcache_prepare().

Link: http://lkml.kernel.org/r/20171102054225.22897-1-ying.huang@intel.com Fixes: e8c26ab60598 ("mm/swap: skip readahead for unreferenced swap slots") Signed-off-by: "Huang, Ying" ying.huang@intel.com Reported-by: Christian Kujau lists@nerdbynature.de Acked-by: Minchan Kim minchan@kernel.org Suggested-by: Minchan Kim minchan@kernel.org Cc: Tim Chen tim.c.chen@linux.intel.com Cc: Michal Hocko mhocko@suse.com Cc: Hugh Dickins hughd@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- mm/swap_state.c | 3 +++ 1 file changed, 3 insertions(+)

--- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -506,6 +506,7 @@ struct page *swapin_readahead(swp_entry_ unsigned long offset = entry_offset; unsigned long start_offset, end_offset; unsigned long mask; + struct swap_info_struct *si = swp_swap_info(entry); struct blk_plug plug; bool do_poll = true;

@@ -519,6 +520,8 @@ struct page *swapin_readahead(swp_entry_ end_offset = offset | mask; if (!start_offset) /* First page is swap header. */ start_offset++; + if (end_offset >= si->max) + end_offset = si->max - 1;

blk_start_plug(&plug); for (offset = start_offset; offset <= end_offset ; offset++) {

Patches currently in stable-queue which might be from huang.ying.caritas@gmail.com are

queue-4.13/mm-swap-fix-false-error-message-in-__swp_swapcount.patch