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| author | Janosch Frank <frankja@linux.ibm.com> | 2018-07-03 17:02:39 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-07-03 17:32:18 -0700 |
| commit | 1e2c043628c7736dd56536d16c0ce009bc834ae7 (patch) | |
| tree | e511865feee12b1d6ba326588fb7aa36ada14951 /fs/userfaultfd.c | |
| parent | 410da1e12ffed61129d61df5b7adce4d08c7f17c (diff) | |
| download | lwn-1e2c043628c7736dd56536d16c0ce009bc834ae7.tar.gz lwn-1e2c043628c7736dd56536d16c0ce009bc834ae7.zip | |
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/userfaultfd.c')
| -rw-r--r-- | fs/userfaultfd.c | 12 |
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; |