From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
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.
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
fs/userfaultfd.c | 21 +++++++--------------
include/uapi/linux/userfaultfd.h | 2 +-
tools/testing/selftests/vm/userfaultfd.c | 2 +-
3 files changed, 9 insertions(+), 16 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index eccfc18..61c553f 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1065,7 +1065,8 @@ 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,
@@ -1078,7 +1079,7 @@ 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;
@@ -1142,13 +1143,9 @@ 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();
@@ -1187,8 +1184,8 @@ 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;
}
@@ -1259,7 +1256,7 @@ 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;
@@ -1319,10 +1316,6 @@ 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;
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 7293321..10631a4 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -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)
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index 3011711..d753a91 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -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)
{
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>