From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Expand the userfaultfd_register/unregister routines to allow VM_HUGETLB
vmas. huge page alignment checking is performed after a VM_HUGETLB
vma is encountered.
Also, since there is no UFFDIO_ZEROPAGE support for huge pages do not
return that as a valid ioctl method for huge page ranges.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
fs/userfaultfd.c | 55 ++++++++++++++++++++++++++++++++++++----
include/uapi/linux/userfaultfd.h | 3 +++
2 files changed, 53 insertions(+), 5 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 9357dcf..a73e999 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -27,6 +27,7 @@
#include <linux/mempolicy.h>
#include <linux/ioctl.h>
#include <linux/security.h>
+#include <linux/hugetlb.h>
static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
@@ -1021,6 +1022,7 @@ 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;
unsigned long start, end, vma_end;
user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -1072,6 +1074,17 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
goto out_unlock;
/*
+ * If the first vma contains huge pages, make sure start address
+ * is aligned to huge page size.
+ */
+ if (is_vm_hugetlb_page(vma)) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
+
+ if (start & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
+
+ /*
* Search for not compatible vmas.
*
* FIXME: this shall be relaxed later so that it doesn't fail
@@ -1079,6 +1092,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* on anonymous vmas).
*/
found = false;
+ huge_pages = false;
for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
cond_resched();
@@ -1087,8 +1101,21 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
/* check not compatible vmas */
ret = -EINVAL;
- if (!vma_is_anonymous(cur))
+ if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
goto out_unlock;
+ /*
+ * If this vma contains ending address, and huge pages
+ * check alignment.
+ */
+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end &&
+ end > cur->vm_start) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
+
+ ret = -EINVAL;
+
+ if (end & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
/*
* Check that this vma isn't already owned by a
@@ -1101,6 +1128,12 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
cur->vm_userfaultfd_ctx.ctx != ctx)
goto out_unlock;
+ /*
+ * Note vmas containing huge pages
+ */
+ if (is_vm_hugetlb_page(cur))
+ huge_pages = true;
+
found = true;
}
BUG_ON(!found);
@@ -1112,7 +1145,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(!vma_is_anonymous(vma));
+ BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
vma->vm_userfaultfd_ctx.ctx != ctx);
@@ -1170,7 +1203,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* userland which ioctls methods are guaranteed to
* succeed on this range.
*/
- if (put_user(UFFD_API_RANGE_IOCTLS,
+ if (put_user(huge_pages ? UFFD_API_RANGE_IOCTLS_HPAGE :
+ UFFD_API_RANGE_IOCTLS,
&user_uffdio_register->ioctls))
ret = -EFAULT;
}
@@ -1217,6 +1251,17 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
goto out_unlock;
/*
+ * If the first vma contains huge pages, make sure start address
+ * is aligned to huge page size.
+ */
+ if (is_vm_hugetlb_page(vma)) {
+ unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
+
+ if (start & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
+
+ /*
* Search for not compatible vmas.
*
* FIXME: this shall be relaxed later so that it doesn't fail
@@ -1238,7 +1283,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
* provides for more strict behavior to notice
* unregistration errors.
*/
- if (!vma_is_anonymous(cur))
+ if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
goto out_unlock;
found = true;
@@ -1252,7 +1297,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(!vma_is_anonymous(vma));
+ BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
/*
* Nothing to do: this vma is already registered into this
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 2bbf323..a3828a9 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -29,6 +29,9 @@
((__u64)1 << _UFFDIO_WAKE | \
(__u64)1 << _UFFDIO_COPY | \
(__u64)1 << _UFFDIO_ZEROPAGE)
+#define UFFD_API_RANGE_IOCTLS_HPAGE \
+ ((__u64)1 << _UFFDIO_WAKE | \
+ (__u64)1 << _UFFDIO_COPY)
/*
* Valid ioctl command number range with this API is from 0x00 to
--
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