Commit cac67329 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

userfaultfd: shmem: allow registration of shared memory ranges 

Expand the userfaultfd_register/unregister routines to allow shared
memory VMAs.

Currently, there is no UFFDIO_ZEROPAGE and write-protection support for
shared memory VMAs, which is reflected in ioctl methods supported by
uffdio_register.

Link: http://lkml.kernel.org/r/20161216144821.5183-34-aarcange@redhat.com


Signed-off-by: default avatarMike Rapoport <rppt@linux.vnet.ibm.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 Kravetz <mike.kravetz@oracle.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 cfda0526

fs/userfaultfd.c

+7 −14
Original line number Diff line number Diff line
@@ -1098,7 +1098,8 @@ static __always_inline int validate_range(struct mm_struct *mm, 


static inline bool vma_can_userfault(struct vm_area_struct *vma)

{

	return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma);

	return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||

		vma_is_shmem(vma);

}



static int userfaultfd_register(struct userfaultfd_ctx *ctx,
@@ -1111,7 +1112,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
	struct uffdio_register __user *user_uffdio_register;

	unsigned long vm_flags, new_flags;

	bool found;

	bool huge_pages;

	bool non_anon_pages;

	unsigned long start, end, vma_end;



	user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -1175,13 +1176,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 


	/*

	 * Search for not compatible vmas.

	 *

	 * FIXME: this shall be relaxed later so that it doesn't fail

	 * on tmpfs backed vmas (in addition to the current allowance

	 * on anonymous vmas).

	 */

	found = false;

	huge_pages = false;

	non_anon_pages = false;

	for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {

		cond_resched();
@@ -1220,8 +1217,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
		/*

		 * Note vmas containing huge pages

		 */

		if (is_vm_hugetlb_page(cur))

			huge_pages = true;

		if (is_vm_hugetlb_page(cur) || vma_is_shmem(cur))

			non_anon_pages = true;



		found = true;

	}
@@ -1292,7 +1289,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
		 * userland which ioctls methods are guaranteed to

		 * succeed on this range.

		 */

		if (put_user(huge_pages ? UFFD_API_RANGE_IOCTLS_HPAGE :

		if (put_user(non_anon_pages ? UFFD_API_RANGE_IOCTLS_BASIC :

			     UFFD_API_RANGE_IOCTLS,

			     &user_uffdio_register->ioctls))

			ret = -EFAULT;
@@ -1352,10 +1349,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, 


	/*

	 * Search for not compatible vmas.

	 *

	 * FIXME: this shall be relaxed later so that it doesn't fail

	 * on tmpfs backed vmas (in addition to the current allowance

	 * on anonymous vmas).

	 */

	found = false;

	ret = -EINVAL;

include/uapi/linux/userfaultfd.h

+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ 
	((__u64)1 << _UFFDIO_WAKE |		\

	 (__u64)1 << _UFFDIO_COPY |		\

	 (__u64)1 << _UFFDIO_ZEROPAGE)

#define UFFD_API_RANGE_IOCTLS_HPAGE		\

#define UFFD_API_RANGE_IOCTLS_BASIC		\

	((__u64)1 << _UFFDIO_WAKE |		\

	 (__u64)1 << _UFFDIO_COPY)

tools/testing/selftests/vm/userfaultfd.c

+1 −1
Original line number Diff line number Diff line
@@ -129,7 +129,7 @@ static void allocate_area(void **alloc_area) 


#else /* HUGETLB_TEST */



#define EXPECTED_IOCTLS		UFFD_API_RANGE_IOCTLS_HPAGE

#define EXPECTED_IOCTLS		UFFD_API_RANGE_IOCTLS_BASIC



static int release_pages(char *rel_area)

{