On Thu, 23 May 2013 14:25:24 +0900 HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx> wrote:
> We want to allocate ELF note segment buffer on the 2nd kernel in
> vmalloc space and remap it to user-space in order to reduce the risk
> that memory allocation fails on system with huge number of CPUs and so
> with huge ELF note segment that exceeds 11-order block size.
>
> Although there's already remap_vmalloc_range for the purpose of
> remapping vmalloc memory to user-space, we need to specify user-space
> range via vma. Mmap on /proc/vmcore needs to remap range across
> multiple objects, so the interface that requires vma to cover full
> range is problematic.
>
> This patch introduces remap_vmalloc_range_partial that receives
> user-space range as a pair of base address and size and can be used
> for mmap on /proc/vmcore case.
>
> remap_vmalloc_range is rewritten using remap_vmalloc_range_partial.
>
> ...
>
> +int remap_vmalloc_range_partial(struct vm_area_struct *vma, unsigned long uaddr,
> + void *kaddr, unsigned long size)
> {
> struct vm_struct *area;
> - unsigned long uaddr = vma->vm_start;
> - unsigned long usize = vma->vm_end - vma->vm_start;
>
> - if ((PAGE_SIZE-1) & (unsigned long)addr)
> + size = PAGE_ALIGN(size);
> +
> + if (((PAGE_SIZE-1) & (unsigned long)uaddr) ||
> + ((PAGE_SIZE-1) & (unsigned long)kaddr))
> return -EINVAL;
hm, that's ugly.
Why don't we do this:
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: include/linux/mm.h: add PAGE_ALIGNED() helper
To test whether an address is aligned to PAGE_SIZE.
Cc: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>,
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 3 +++
1 file changed, 3 insertions(+)
diff -puN include/linux/mm.h~a include/linux/mm.h
--- a/include/linux/mm.h~a
+++ a/include/linux/mm.h
@@ -52,6 +52,9 @@ extern unsigned long sysctl_admin_reserv
/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
+/* test whether an address (unsigned long or pointer) is aligned to PAGE_SIZE */
+#define PAGE_ALIGNED(addr) IS_ALIGNED((unsigned long)addr, PAGE_SIZE)
+
/*
* Linux kernel virtual memory manager primitives.
* The idea being to have a "virtual" mm in the same way
_
(I'd have thought we already had such a thing, but we don't seem to)
Then this:
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: vmalloc-introduce-remap_vmalloc_range_partial-fix
use PAGE_ALIGNED()
Cc: Atsushi Kumagai <kumagai-atsushi@xxxxxxxxxxxxxxxxx>
Cc: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Lisa Mitchell <lisa.mitchell@xxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff -puN include/linux/vmalloc.h~vmalloc-introduce-remap_vmalloc_range_partial-fix include/linux/vmalloc.h
diff -puN mm/vmalloc.c~vmalloc-introduce-remap_vmalloc_range_partial-fix mm/vmalloc.c
--- a/mm/vmalloc.c~vmalloc-introduce-remap_vmalloc_range_partial-fix
+++ a/mm/vmalloc.c
@@ -1476,10 +1476,9 @@ static void __vunmap(const void *addr, i
if (!addr)
return;
- if ((PAGE_SIZE-1) & (unsigned long)addr) {
- WARN(1, KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
+ if (WARN(!PAGE_ALIGNED(addr), "Trying to vfree() bad address (%p)\n",
+ addr));
return;
- }
area = remove_vm_area(addr);
if (unlikely(!area)) {
@@ -2170,8 +2169,7 @@ int remap_vmalloc_range_partial(struct v
size = PAGE_ALIGN(size);
- if (((PAGE_SIZE-1) & (unsigned long)uaddr) ||
- ((PAGE_SIZE-1) & (unsigned long)kaddr))
+ if (!PAGE_ALIGNED(uaddr) || !PAGE_ALIGNED(kaddr))
return -EINVAL;
area = find_vm_area(kaddr);
_
--
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