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authorJanosch Frank <frankja@linux.ibm.com>2018-07-03 17:02:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-07-03 17:32:18 -0700
commit1e2c043628c7736dd56536d16c0ce009bc834ae7 (patch)
treee511865feee12b1d6ba326588fb7aa36ada14951 /fs
parent410da1e12ffed61129d61df5b7adce4d08c7f17c (diff)
userfaultfd: hugetlbfs: fix userfaultfd_huge_must_wait() pte access
Use huge_ptep_get() to translate huge ptes to normal ptes so we can check them with the huge_pte_* functions. Otherwise some architectures will check the wrong values and will not wait for userspace to bring in the memory. Link: http://lkml.kernel.org/r/20180626132421.78084-1-frankja@linux.ibm.com Fixes: 369cd2121be4 ("userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges") Signed-off-by: Janosch Frank <frankja@linux.ibm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/userfaultfd.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 123bf7d516fc..594d192b2331 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -222,24 +222,26 @@ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
unsigned long reason)
{
struct mm_struct *mm = ctx->mm;
- pte_t *pte;
+ pte_t *ptep, pte;
bool ret = true;
VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
- pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
- if (!pte)
+ ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
+
+ if (!ptep)
goto out;
ret = false;
+ pte = huge_ptep_get(ptep);
/*
* Lockless access: we're in a wait_event so it's ok if it
* changes under us.
*/
- if (huge_pte_none(*pte))
+ if (huge_pte_none(pte))
ret = true;
- if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP))
+ if (!huge_pte_write(pte) && (reason & VM_UFFD_WP))
ret = true;
out:
return ret;