This is a RFC patch, because current PAGE_SIZE is equal to PAGE_CACHE_SIZE,
there isn't any difference and issue when running.
However, the current code mixes these two aligned_size inconsistently, and if
they are not equal in future mincore_unmapped_range() would check more file
pages than wanted.
According to man-page, mincore uses PAGE_SIZE as its size unit, so this patch
uses PAGE_SIZE instead of PAGE_CACHE_SIZE.
Signed-off-by: Weijie Yang <[email protected]>
---
mm/mincore.c | 19 +++++++++++++------
1 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/mm/mincore.c b/mm/mincore.c
index 725c809..8c19bce 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -102,11 +102,18 @@ static void mincore_unmapped_range(struct vm_area_struct *vma,
int i;
if (vma->vm_file) {
- pgoff_t pgoff;
+ pgoff_t pgoff, pgoff_end;
+ int j, count;
+ unsigned char res;
+ count = 1 << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
pgoff = linear_page_index(vma, addr);
- for (i = 0; i < nr; i++, pgoff++)
- vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+ pgoff_end = linear_page_index(vma, end);
+ for (i = 0; pgoff < pgoff_end; pgoff++) {
+ res = mincore_page(vma->vm_file->f_mapping, pgoff);
+ for (j = 0; j < count; j++)
+ vec[i++] = res;
+ }
} else {
for (i = 0; i < nr; i++)
vec[i] = 0;
@@ -258,7 +265,7 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
* return values:
* zero - success
* -EFAULT - vec points to an illegal address
- * -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
+ * -EINVAL - addr is not a multiple of PAGE_SIZE
* -ENOMEM - Addresses in the range [addr, addr + len] are
* invalid for the address space of this process, or
* specify one or more pages which are not currently
@@ -273,14 +280,14 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
unsigned char *tmp;
/* Check the start address: needs to be page-aligned.. */
- if (start & ~PAGE_CACHE_MASK)
+ if (start & ~PAGE_MASK)
return -EINVAL;
/* ..and we need to be passed a valid user-space range */
if (!access_ok(VERIFY_READ, (void __user *) start, len))
return -ENOMEM;
- /* This also avoids any overflows on PAGE_CACHE_ALIGN */
+ /* This also avoids any overflows on PAGE_ALIGN */
pages = len >> PAGE_SHIFT;
pages += (len & ~PAGE_MASK) != 0;
--
1.7.0.4
ping. Any comments?
On Wed, Nov 12, 2014 at 5:50 PM, Weijie Yang <[email protected]> wrote:
> This is a RFC patch, because current PAGE_SIZE is equal to PAGE_CACHE_SIZE,
> there isn't any difference and issue when running.
>
> However, the current code mixes these two aligned_size inconsistently, and if
> they are not equal in future mincore_unmapped_range() would check more file
> pages than wanted.
>
> According to man-page, mincore uses PAGE_SIZE as its size unit, so this patch
> uses PAGE_SIZE instead of PAGE_CACHE_SIZE.
>
> Signed-off-by: Weijie Yang <[email protected]>
> ---
> mm/mincore.c | 19 +++++++++++++------
> 1 files changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/mm/mincore.c b/mm/mincore.c
> index 725c809..8c19bce 100644
> --- a/mm/mincore.c
> +++ b/mm/mincore.c
> @@ -102,11 +102,18 @@ static void mincore_unmapped_range(struct vm_area_struct *vma,
> int i;
>
> if (vma->vm_file) {
> - pgoff_t pgoff;
> + pgoff_t pgoff, pgoff_end;
> + int j, count;
> + unsigned char res;
>
> + count = 1 << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
> pgoff = linear_page_index(vma, addr);
> - for (i = 0; i < nr; i++, pgoff++)
> - vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
> + pgoff_end = linear_page_index(vma, end);
> + for (i = 0; pgoff < pgoff_end; pgoff++) {
> + res = mincore_page(vma->vm_file->f_mapping, pgoff);
> + for (j = 0; j < count; j++)
> + vec[i++] = res;
> + }
> } else {
> for (i = 0; i < nr; i++)
> vec[i] = 0;
> @@ -258,7 +265,7 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
> * return values:
> * zero - success
> * -EFAULT - vec points to an illegal address
> - * -EINVAL - addr is not a multiple of PAGE_CACHE_SIZE
> + * -EINVAL - addr is not a multiple of PAGE_SIZE
> * -ENOMEM - Addresses in the range [addr, addr + len] are
> * invalid for the address space of this process, or
> * specify one or more pages which are not currently
> @@ -273,14 +280,14 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
> unsigned char *tmp;
>
> /* Check the start address: needs to be page-aligned.. */
> - if (start & ~PAGE_CACHE_MASK)
> + if (start & ~PAGE_MASK)
> return -EINVAL;
>
> /* ..and we need to be passed a valid user-space range */
> if (!access_ok(VERIFY_READ, (void __user *) start, len))
> return -ENOMEM;
>
> - /* This also avoids any overflows on PAGE_CACHE_ALIGN */
> + /* This also avoids any overflows on PAGE_ALIGN */
> pages = len >> PAGE_SHIFT;
> pages += (len & ~PAGE_MASK) != 0;
>
> --
> 1.7.0.4
>
>