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Date: Tue, 27 Apr 2021 12:13:16 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: Nadav Amit <nadav.amit@...il.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Mike Rapoport <rppt@...ux.vnet.ibm.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Hugh Dickins <hughd@...gle.com>, peterx@...hat.com,
Jerome Glisse <jglisse@...hat.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Matthew Wilcox <willy@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Axel Rasmussen <axelrasmussen@...gle.com>,
"Kirill A . Shutemov" <kirill@...temov.name>
Subject: [PATCH v2 23/24] mm/userfaultfd: Enable write protection for shmem & hugetlbfs
We've had all the necessary changes ready for both shmem and hugetlbfs. Turn
on all the shmem/hugetlbfs switches for userfaultfd-wp.
Now we can remove the flags parameter for vma_can_userfault() since not used
any more. Meanwhile, we can expand UFFD_API_RANGE_IOCTLS_BASIC with
_UFFDIO_WRITEPROTECT too because all existing types now support write
protection mode.
Since vma_can_userfault() will be used elsewhere, move into userfaultfd_k.h.
Signed-off-by: Peter Xu <peterx@...hat.com>
---
fs/userfaultfd.c | 19 -------------------
include/linux/userfaultfd_k.h | 15 +++++++++++++++
include/uapi/linux/userfaultfd.h | 7 +++++--
mm/userfaultfd.c | 10 +++-------
4 files changed, 23 insertions(+), 28 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index a41e0631af512..a436a1feb10db 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1275,25 +1275,6 @@ static __always_inline int validate_range(struct mm_struct *mm,
return 0;
}
-static inline bool vma_can_userfault(struct vm_area_struct *vma,
- unsigned long vm_flags)
-{
- /* FIXME: add WP support to hugetlbfs and shmem */
- if (vm_flags & VM_UFFD_WP) {
- if (is_vm_hugetlb_page(vma) || vma_is_shmem(vma))
- return false;
- }
-
- if (vm_flags & VM_UFFD_MINOR) {
- /* FIXME: Add minor fault interception for shmem. */
- if (!is_vm_hugetlb_page(vma))
- return false;
- }
-
- return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
- vma_is_shmem(vma);
-}
-
static int userfaultfd_register(struct userfaultfd_ctx *ctx,
unsigned long arg)
{
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index fefebe6e96560..95afd4814ab29 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -16,6 +16,7 @@
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <asm-generic/pgtable_uffd.h>
+#include <linux/hugetlb_inline.h>
/* The set of all possible UFFD-related VM flags. */
#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
@@ -132,6 +133,20 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
return vma->vm_flags & __VM_UFFD_FLAGS;
}
+static inline bool vma_can_userfault(struct vm_area_struct *vma,
+ unsigned long vm_flags)
+{
+ if (vm_flags & VM_UFFD_MINOR) {
+ /* FIXME: Add minor fault interception for shmem. */
+ if (!is_vm_hugetlb_page(vma))
+ return false;
+ }
+
+ return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
+ vma_is_shmem(vma);
+}
+
+
extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
extern void dup_userfaultfd_complete(struct list_head *);
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index bafbeb1a26245..298fbd4e2d1d3 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -31,7 +31,8 @@
UFFD_FEATURE_MISSING_SHMEM | \
UFFD_FEATURE_SIGBUS | \
UFFD_FEATURE_THREAD_ID | \
- UFFD_FEATURE_MINOR_HUGETLBFS)
+ UFFD_FEATURE_MINOR_HUGETLBFS | \
+ UFFD_FEATURE_WP_HUGETLBFS_SHMEM)
#define UFFD_API_IOCTLS \
((__u64)1 << _UFFDIO_REGISTER | \
(__u64)1 << _UFFDIO_UNREGISTER | \
@@ -45,7 +46,8 @@
#define UFFD_API_RANGE_IOCTLS_BASIC \
((__u64)1 << _UFFDIO_WAKE | \
(__u64)1 << _UFFDIO_COPY | \
- (__u64)1 << _UFFDIO_CONTINUE)
+ (__u64)1 << _UFFDIO_CONTINUE | \
+ (__u64)1 << _UFFDIO_WRITEPROTECT)
/*
* Valid ioctl command number range with this API is from 0x00 to
@@ -196,6 +198,7 @@ struct uffdio_api {
#define UFFD_FEATURE_SIGBUS (1<<7)
#define UFFD_FEATURE_THREAD_ID (1<<8)
#define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9)
+#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<10)
__u64 features;
__u64 ioctls;
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 2cd6ad5c3d8f8..3930e56aaefd8 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -445,7 +445,6 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
err = mfill_zeropage_pte(dst_mm, dst_pmd,
dst_vma, dst_addr);
} else {
- VM_WARN_ON_ONCE(wp_copy);
if (!zeropage)
err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
dst_vma, dst_addr,
@@ -682,15 +681,12 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start,
err = -ENOENT;
dst_vma = find_dst_vma(dst_mm, start, len);
- /*
- * Make sure the vma is not shared, that the dst range is
- * both valid and fully within a single existing vma.
- */
- if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
+
+ if (!dst_vma)
goto out_unlock;
if (!userfaultfd_wp(dst_vma))
goto out_unlock;
- if (!vma_is_anonymous(dst_vma))
+ if (!vma_can_userfault(dst_vma, dst_vma->vm_flags))
goto out_unlock;
if (is_vm_hugetlb_page(dst_vma)) {
--
2.26.2
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