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Date: Mon, 6 Jun 2016 10:45:30 -0700
From: Mike Kravetz <mike.kravetz@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: Andrea Arcangeli <aarcange@...hat.com>,
Hugh Dickins <hughd@...gle.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Hillf Danton <hillf.zj@...baba-inc.com>,
Michal Hocko <mhocko@...e.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Kravetz <mike.kravetz@...cle.com>
Subject: [RFC PATCH 5/6] fs/userfaultfd: allow registration of ranges containing huge pages
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@...cle.com>
---
fs/userfaultfd.c | 69 +++++++++++++++++++++++++++++++++++++---
include/uapi/linux/userfaultfd.h | 3 ++
2 files changed, 67 insertions(+), 5 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 2d97952..7a1a345 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -26,6 +26,7 @@
#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;
@@ -728,6 +729,7 @@ 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;
@@ -779,6 +781,17 @@ 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 (vma->vm_flags & VM_HUGETLB) {
+ 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
@@ -786,6 +799,7 @@ 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();
@@ -794,7 +808,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
/* check not compatible vmas */
ret = -EINVAL;
- if (cur->vm_ops)
+ if (cur->vm_ops && !(cur->vm_flags & VM_HUGETLB))
goto out_unlock;
/*
@@ -808,6 +822,25 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
cur->vm_userfaultfd_ctx.ctx != ctx)
goto out_unlock;
+ /*
+ * Note vmas containing huge pages
+ */
+ if (cur->vm_flags & VM_HUGETLB) {
+ huge_pages = true;
+
+ /*
+ * If vma contains end address, check alignment
+ */
+ ret = -EINVAL;
+ if (end <= cur->vm_end && end > cur->vm_start) {
+ unsigned long vma_hpagesize =
+ vma_kernel_pagesize(cur);
+
+ if (end & (vma_hpagesize - 1))
+ goto out_unlock;
+ }
+ }
+
found = true;
}
BUG_ON(!found);
@@ -819,7 +852,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(vma->vm_ops);
+ BUG_ON(vma->vm_ops && !(vma->vm_flags & VM_HUGETLB));
BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
vma->vm_userfaultfd_ctx.ctx != ctx);
@@ -877,7 +910,8 @@ out_unlock:
* 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;
}
@@ -924,6 +958,17 @@ 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 (vma->vm_flags & VM_HUGETLB) {
+ 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
@@ -945,9 +990,23 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
* provides for more strict behavior to notice
* unregistration errors.
*/
- if (cur->vm_ops)
+ if (cur->vm_ops && !(cur->vm_flags & VM_HUGETLB))
goto out_unlock;
+ /*
+ * If this vma contains ending address, and huge pages
+ * check alignment.
+ */
+ if (cur->vm_flags & VM_HUGETLB && 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;
+ }
+
found = true;
}
BUG_ON(!found);
@@ -959,7 +1018,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
do {
cond_resched();
- BUG_ON(vma->vm_ops);
+ BUG_ON(vma->vm_ops && !(vma->vm_flags & VM_HUGETLB));
/*
* 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 9057d7a..751d814 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -26,6 +26,9 @@
((__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
--
2.4.11
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