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Subject[PATCH 5.11 563/775] mm/rmap: fix potential pte_unmap on an not mapped pte
Date
From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit 5d5d19eda6b0ee790af89c45e3f678345be6f50f ]

For PMD-mapped page (usually THP), pvmw->pte is NULL. For PTE-mapped THP,
pvmw->pte is mapped. But for HugeTLB pages, pvmw->pte is not mapped and
set to the relevant page table entry. So in page_vma_mapped_walk_done(),
we may do pte_unmap() for HugeTLB pte which is not mapped. Fix this by
checking pvmw->page against PageHuge before trying to do pte_unmap().

Link: https://lkml.kernel.org/r/20210127093349.39081-1-linmiaohe@huawei.com
Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()")
Signed-off-by: Hongxiang Lou <louhongxiang@huawei.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michel Lespinasse <walken@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/rmap.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 70085ca1a3fc9..def5c62c93b3b 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -213,7 +213,8 @@ struct page_vma_mapped_walk {

static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
{
- if (pvmw->pte)
+ /* HugeTLB pte is set to the relevant page table entry without pte_mapped. */
+ if (pvmw->pte && !PageHuge(pvmw->page))
pte_unmap(pvmw->pte);
if (pvmw->ptl)
spin_unlock(pvmw->ptl);
--
2.27.0


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