On 08/04/2016 04:02 PM, zijun_hu wrote:
>>From e40d1066f61394992e0167f259001ae9d2581dc1 Mon Sep 17 00:00:00 2001
> From: zijun_hu <zijun...@htc.com>
> Date: Thu, 4 Aug 2016 14:22:52 +0800
> Subject: [PATCH] mm/vmalloc: fix align value calculation error
>
> it causes double align requirement for __get_vm_area_node() if parameter
> size is power of 2 and VM_IOREMAP is set in parameter flags
>
> it is fixed by using order_base_2 instead of fls_long() due to lack of
> get_count_order() for long parameter
>
> Signed-off-by: zijun_hu <zijun...@htc.com>
> ---
> mm/vmalloc.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 91f44e7..8b17c51 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1357,11 +1357,19 @@ static struct vm_struct *__get_vm_area_node(unsigned
> long size,
> {
> struct vmap_area *va;
> struct vm_struct *area;
> + int ioremap_size_order;
>
> BUG_ON(in_interrupt());
> - if (flags & VM_IOREMAP)
> - align = 1ul << clamp_t(int, fls_long(size),
> - PAGE_SHIFT, IOREMAP_MAX_ORDER);
> + if (flags & VM_IOREMAP) {
> + if (unlikely(size < 2))
> + ioremap_size_order = size;
> + else if (unlikely((signed long)size < 0))
> + ioremap_size_order = sizeof(size) * 8;
> + else
> + ioremap_size_order = order_base_2(size);
> + align = 1ul << clamp_t(int, ioremap_size_order, PAGE_SHIFT,
> + IOREMAP_MAX_ORDER);
> + }
>
> size = PAGE_ALIGN(size);
> if (unlikely(!size))
>
another fix approach is shown as follows
From: zijun_hu <zijun...@htc.com>
Date: Thu, 4 Aug 2016 14:22:52 +0800
Subject: [PATCH] mm/vmalloc: fix align value calculation error
it causes double align requirement for __get_vm_area_node() if parameter
size is power of 2 and VM_IOREMAP is set in parameter flags
it is fixed by handling the specail case manually due to lack of
get_count_order() for long parameter
Signed-off-by: zijun_hu <zijun...@htc.com>
---
mm/vmalloc.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 91f44e7..dbbca8a 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1357,11 +1357,16 @@ static struct vm_struct *__get_vm_area_node(unsigned
long size,
{
struct vmap_area *va;
struct vm_struct *area;
+ int ioremap_size_order;
BUG_ON(in_interrupt());
- if (flags & VM_IOREMAP)
- align = 1ul << clamp_t(int, fls_long(size),
- PAGE_SHIFT, IOREMAP_MAX_ORDER);
+ if (flags & VM_IOREMAP) {
+ ioremap_size_order = fls_long(size);
+ if (is_power_of_2(size) && size != 1)
+ ioremap_size_order--;
+ align = 1ul << clamp_t(int, ioremap_size_order, PAGE_SHIFT,
+ IOREMAP_MAX_ORDER);
+ }
size = PAGE_ALIGN(size);
if (unlikely(!size))
--
1.9.1
