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userfaultfd: hugetlbfs: 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.

Link: http://lkml.kernel.org/r/20161216144821.5183-22-aarcange@redhat.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrea 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 Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2017-02-22 15:43:04 -08:00 committed by Linus Torvalds
parent 1a1aad8a9b
commit cab350afcb
2 changed files with 53 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
fs/userfaultfd.c
View File

@ -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;
@ -1058,6 +1059,7 @@ 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;
@ -1108,6 +1110,17 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
if (vma->vm_start >= end)
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.
*
@ -1116,6 +1129,7 @@ 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();
@ -1124,8 +1138,21 @@ 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
@ -1138,6 +1165,12 @@ 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);
@ -1149,7 +1182,7 @@ 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);
@ -1207,7 +1240,8 @@ 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;
}
@ -1253,6 +1287,17 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
if (vma->vm_start >= end)
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.
*
@ -1275,7 +1320,7 @@ 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;
@ -1289,7 +1334,7 @@ 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

3
include/uapi/linux/userfaultfd.h
View File

@ -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