For the ending vma, there is a check to make sure the end is huge page
aligned.
The *if* check makes sure vm_start < end <= vm_end. While the first half
is not necessary, because the *for* clause makes sure vm_start < end.
This patch just removes it.
Signed-off-by: Wei Yang <[email protected]>
---
fs/userfaultfd.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 653d8f7c453c..9ce09ac619a2 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* 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) {
+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
ret = -EINVAL;
--
2.17.1
When there are several condition check in *if* clause, the check will
stop at the first false one.
Since the for loop iterates vma list, we are sure only the last vma
meets the condition "end <= vm_end". Reorder the check sequence to
reduce some computation.
Signed-off-by: Wei Yang <[email protected]>
---
fs/userfaultfd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 9ce09ac619a2..70c0e0ef01d7 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1402,7 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* If this vma contains ending address, and huge pages
* check alignment.
*/
- if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
+ if (end <= cur->vm_end && is_vm_hugetlb_page(cur)) {
unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
ret = -EINVAL;
--
2.17.1
There are three places checking whether one address is huge page
aligned.
This patch just makes a helper function to wrap it up.
Signed-off-by: Wei Yang <[email protected]>
---
fs/userfaultfd.c | 30 +++++++++++++++---------------
1 file changed, 15 insertions(+), 15 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 70c0e0ef01d7..d8665ffdd576 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1296,6 +1296,16 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma)
vma_is_shmem(vma);
}
+static inline bool addr_huge_page_aligned(unsigned long addr,
+ struct vm_area_struct *vma)
+{
+ unsigned long vma_hpagesize = vma_kernel_pagesize(vma);
+
+ if (addr & (vma_hpagesize - 1))
+ return false;
+ return true;
+}
+
static int userfaultfd_register(struct userfaultfd_ctx *ctx,
unsigned long arg)
{
@@ -1363,12 +1373,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* 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;
- }
+ if (is_vm_hugetlb_page(vma) && !addr_huge_page_aligned(start, vma))
+ goto out_unlock;
/*
* Search for not compatible vmas.
@@ -1403,11 +1409,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
* check alignment.
*/
if (end <= cur->vm_end && is_vm_hugetlb_page(cur)) {
- unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
-
ret = -EINVAL;
- if (end & (vma_hpagesize - 1))
+ if (!addr_huge_page_aligned(end, cur))
goto out_unlock;
}
@@ -1551,12 +1555,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
* 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;
- }
+ if (is_vm_hugetlb_page(vma) && !addr_huge_page_aligned(start, vma))
+ goto out_unlock;
/*
* Search for not compatible vmas.
--
2.17.1
Ping for comment :-)
On Fri, Sep 13, 2019 at 05:31:08AM +0800, Wei Yang wrote:
>For the ending vma, there is a check to make sure the end is huge page
>aligned.
>
>The *if* check makes sure vm_start < end <= vm_end. While the first half
>is not necessary, because the *for* clause makes sure vm_start < end.
>
>This patch just removes it.
>
>Signed-off-by: Wei Yang <[email protected]>
>---
> fs/userfaultfd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
>index 653d8f7c453c..9ce09ac619a2 100644
>--- a/fs/userfaultfd.c
>+++ b/fs/userfaultfd.c
>@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
> * 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) {
>+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
> unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
>
> ret = -EINVAL;
>--
>2.17.1
--
Wei Yang
Help you, Help me
On Fri, Sep 13, 2019 at 05:31:08AM +0800, Wei Yang wrote:
>For the ending vma, there is a check to make sure the end is huge page
>aligned.
>
>The *if* check makes sure vm_start < end <= vm_end. While the first half
>is not necessary, because the *for* clause makes sure vm_start < end.
>
>This patch just removes it.
>
Does this one look good?
>Signed-off-by: Wei Yang <[email protected]>
>---
> fs/userfaultfd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
>index 653d8f7c453c..9ce09ac619a2 100644
>--- a/fs/userfaultfd.c
>+++ b/fs/userfaultfd.c
>@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
> * 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) {
>+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
> unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
>
> ret = -EINVAL;
>--
>2.17.1
--
Wei Yang
Help you, Help me