The patch titled
Subject: userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges
has been added to the -mm tree. Its filename is
userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
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------------------------------------------------------
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Subject: userfaultfd: hugetlbfs: userfaultfd_huge_must_wait for hugepmd ranges
Add routine userfaultfd_huge_must_wait which has the same functionality as
the existing userfaultfd_must_wait routine. Only difference is that new
routine must handle page table structure for hugepmd vmas.
Link: http://lkml.kernel.org/r/20161216144821.5183-24-aarcange@xxxxxxxxxx
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 51 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 49 insertions(+), 2 deletions(-)
diff -puN fs/userfaultfd.c~userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges
+++ a/fs/userfaultfd.c
@@ -195,6 +195,49 @@ static inline struct uffd_msg userfault_
return msg;
}
+#ifdef CONFIG_HUGETLB_PAGE
+/*
+ * Same functionality as userfaultfd_must_wait below with modifications for
+ * hugepmd ranges.
+ */
+static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+ unsigned long address,
+ unsigned long flags,
+ unsigned long reason)
+{
+ struct mm_struct *mm = ctx->mm;
+ pte_t *pte;
+ bool ret = true;
+
+ VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+
+ pte = huge_pte_offset(mm, address);
+ if (!pte)
+ goto out;
+
+ ret = false;
+
+ /*
+ * Lockless access: we're in a wait_event so it's ok if it
+ * changes under us.
+ */
+ if (huge_pte_none(*pte))
+ ret = true;
+ if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP))
+ ret = true;
+out:
+ return ret;
+}
+#else
+static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx,
+ unsigned long address,
+ unsigned long flags,
+ unsigned long reason)
+{
+ return false; /* should never get here */
+}
+#endif /* CONFIG_HUGETLB_PAGE */
+
/*
* Verify the pagetables are still not ok after having reigstered into
* the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any
@@ -368,8 +411,12 @@ int handle_userfault(struct vm_fault *vm
TASK_KILLABLE);
spin_unlock(&ctx->fault_pending_wqh.lock);
- must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
- reason);
+ if (!is_vm_hugetlb_page(vmf->vma))
+ must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags,
+ reason);
+ else
+ must_wait = userfaultfd_huge_must_wait(ctx, vmf->address,
+ vmf->flags, reason);
up_read(&mm->mmap_sem);
if (likely(must_wait && !ACCESS_ONCE(ctx->released) &&
_
Patches currently in -mm which might be from mike.kravetz@xxxxxxxxxx are
userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-hugetlb_mcopy_atomic_pte-for-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-__mcopy_atomic_hugetlb-for-huge-page-uffdio_copy.patch
userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.patch
userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
userfaultfd-hugetlbfs-allow-registration-of-ranges-containing-huge-pages.patch
userfaultfd-hugetlbfs-add-userfaultfd_hugetlb-test.patch
userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
userfaultfd-hugetlbfs-reserve-count-on-error-in-__mcopy_atomic_hugetlb.patch
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