The patch titled
Subject: mm:fix gup_pud_range
has been added to the -mm tree. Its filename is
mm-fix-gup_pud_range.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-gup_pud_range.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-gup_pud_range.patch
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------------------------------------------------------
From: Qiujun Huang <hqjagain@xxxxxxxxx>
Subject: mm:fix gup_pud_range
sorry for not processing for a long time. I met it again.
patch v1 https://lkml.org/lkml/2019/9/20/656
do_machine_check()
do_memory_failure()
memory_failure()
hw_poison_user_mappings()
try_to_unmap()
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
...and now we have a swap entry that indicates that the page entry
refers to a bad (and poisoned) page of memory, but gup_fast() at this
level of the page table was ignoring swap entries, and incorrectly
assuming that "!pxd_none() == valid and present".
And this was not just a poisoned page problem, but a generaly swap entry
problem. So, any swap entry type (device memory migration, numa migration,
or just regular swapping) could lead to the same problem.
Fix this by checking for pxd_present(), instead of pxd_none().
Link: http://lkml.kernel.org/r/1578479084-15508-1-git-send-email-hqjagain@xxxxxxxxx
Signed-off-by: Qiujun Huang <hqjagain@xxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/gup.c~mm-fix-gup_pud_range
+++ a/mm/gup.c
@@ -2237,7 +2237,7 @@ static int gup_pud_range(p4d_t p4d, unsi
pud_t pud = READ_ONCE(*pudp);
next = pud_addr_end(addr, end);
- if (pud_none(pud))
+ if (unlikely(!pud_present(pud)))
return 0;
if (unlikely(pud_huge(pud))) {
if (!gup_huge_pud(pud, pudp, addr, next, flags,
_
Patches currently in -mm which might be from hqjagain@xxxxxxxxx are
mm-fix-gup_pud_range.patch
