The patch titled
Subject: shmem_swapin_page(): fix error processing for get_swap_device()
has been added to the -mm tree. Its filename is
shmem_swapin_page-fix-error-processing-for-get_swap_device.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/shmem_swapin_page-fix-error-processing-for-get_swap_device.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/shmem_swapin_page-fix-error-processing-for-get_swap_device.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: shmem_swapin_page(): fix error processing for get_swap_device()
If we hit this rare race, returning EINVAL (or even -EINVAL) would cause
the page fault to be handled as a SIGBUS. This is not correct; the page
is not missing or unreadable, it has simply changed location. Returning
-EEXIST here will cause the lookup to be retried by the caller.
[willy@xxxxxxxxxxxxx: changelog]
Link: https://lkml.kernel.org/r/20210723080000.93953-1-ying.huang@xxxxxxxxx
Link: https://lkml.kernel.org/r/877dh354vc.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 2efa33fc7f6e ("mm/shmem: fix shmem_swapin() race with swapoff")
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Suggested-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/shmem.c~shmem_swapin_page-fix-error-processing-for-get_swap_device
+++ a/mm/shmem.c
@@ -1708,8 +1708,8 @@ static int shmem_swapin_page(struct inod
/* Prevent swapoff from happening to us. */
si = get_swap_device(swap);
if (!si) {
- error = EINVAL;
- goto failed;
+ error = -EEXIST;
+ goto unlock;
}
/* Look it up and read it in.. */
page = lookup_swap_cache(swap, NULL, 0);
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
shmem_swapin_page-fix-error-processing-for-get_swap_device.patch
mmdo_huge_pmd_numa_page-remove-unnecessary-tlb-flushing-code.patch
mm-migrate-add-sysfs-interface-to-enable-reclaim-migration.patch
