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Commit 369cd212 authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds
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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@redhat.com


Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9903bd7b

fs/userfaultfd.c

+49 −2
Original line number Diff line number Diff line
@@ -202,6 +202,49 @@ static inline struct uffd_msg userfault_msg(unsigned long address, 
	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
@@ -378,8 +421,12 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason) 
	set_current_state(blocking_state);

	spin_unlock(&ctx->fault_pending_wqh.lock);



	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) &&