The patch titled
Subject: mm, swap: fix false error message in __swp_swapcount()
has been added to the -mm tree. Its filename is
mm-swap-fix-false-error-message-in-__swp_swapcount.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-swap-fix-false-error-message-in-__swp_swapcount.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-swap-fix-false-error-message-in-__swp_swapcount.patch
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From: Huang Ying <huang.ying.caritas@xxxxxxxxx>
Subject: mm, swap: fix false error message in __swp_swapcount()
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@xxxxxxxxx
Fixes: e8c26ab60598 ("mm/swap: skip readahead for unreferenced swap slots")
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reported-by: Christian Kujau <lists@xxxxxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Suggested-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.11+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swap_state.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN mm/swap_state.c~mm-swap-fix-false-error-message-in-__swp_swapcount mm/swap_state.c
--- a/mm/swap_state.c~mm-swap-fix-false-error-message-in-__swp_swapcount
+++ a/mm/swap_state.c
@@ -559,6 +559,7 @@ 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, page_allocated;
@@ -572,6 +573,8 @@ 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 -mm which might be from huang.ying.caritas@xxxxxxxxx are
mm-swap-fix-false-error-message-in-__swp_swapcount.patch
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