The patch titled
thp: keep highpte mapped until it is no longer needed
has been added to the -mm tree. Its filename is
thp-keep-highpte-mapped-until-it-is-no-longer-needed.patch
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------------------------------------------------------
Subject: thp: keep highpte mapped until it is no longer needed
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Two users reported THP-related crashes on 32-bit x86 machines. Their oops
reports indicated an invalid pte, and subsequent code inspection showed
that the highpte is actually used after unmap.
The fix is to unmap the pte only after all operations against it are
finished.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Reported-by: werner <w.landgraf@xxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Tested-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/huge_memory.c~thp-keep-highpte-mapped-until-it-is-no-longer-needed mm/huge_memory.c
--- a/mm/huge_memory.c~thp-keep-highpte-mapped-until-it-is-no-longer-needed
+++ a/mm/huge_memory.c
@@ -1837,9 +1837,9 @@ static void collapse_huge_page(struct mm
spin_lock(ptl);
isolated = __collapse_huge_page_isolate(vma, address, pte);
spin_unlock(ptl);
- pte_unmap(pte);
if (unlikely(!isolated)) {
+ pte_unmap(pte);
spin_lock(&mm->page_table_lock);
BUG_ON(!pmd_none(*pmd));
set_pmd_at(mm, address, pmd, _pmd);
@@ -1856,6 +1856,7 @@ static void collapse_huge_page(struct mm
anon_vma_unlock(vma->anon_vma);
__collapse_huge_page_copy(pte, new_page, vma, address, ptl);
+ pte_unmap(pte);
__SetPageUptodate(new_page);
pgtable = pmd_pgtable(_pmd);
VM_BUG_ON(page_count(pgtable) != 1);
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
thp-keep-highpte-mapped-until-it-is-no-longer-needed.patch
mm-compaction-prevent-division-by-zero-during-user-requested-compaction.patch
mm-compaction-prevent-division-by-zero-during-user-requested-compaction-fix.patch
mm-compaction-prevent-division-by-zero-during-user-requested-compaction-fix-fix.patch
memcg-modify-accounting-function-for-supporting-thp-better.patch
memcg-fix-used-bit-handling-at-uncharge-in-thp.patch
memcg-fix-used-bit-handling-at-uncharge-in-thp-fix.patch
memcg-fix-lru-accounting-with-thp.patch
memcg-fix-rmdir-force_empty-with-thp.patch
memcg-correctly-order-reading-pcg_used-and-pc-mem_cgroup.patch
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