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SubjectRe: [PATCH] mm: mmap: show vm_unmapped_area error log
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Hello

sorry for build warning.
I've changed %d to %ld reported by kbuild.
Let me attach full patch again below.
--------------------------------------------------


Even on 64 bit kernel, the mmap failure can happen for a 32 bit task.
Virtual memory space shortage of a task on mmap is reported to userspace
as -ENOMEM. It can be confused as physical memory shortage of overall
system.

The vm_unmapped_area can be called to by some drivers or other kernel
core system like filesystem. It can be hard to know which code layer
returns the -ENOMEM.

Print error log of vm_unmapped_area with rate limited. Without rate
limited, soft lockup ocurrs on infinite mmap sytem call.

i.e.)
<3>[ 576.024088] [6: mmap_infinite:14251] mmap: vm_unmapped_area err:-12 total_vm:0xfee08 flags:0x1 len:0xa00000 low:0x8000 high:0xf3f63000

Fixed type mismatching on previous patch which is reported by kbuild.
Reported-by: kbuild test robot <lkp@intel.com>

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
---
include/linux/mm.h | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 52269e56c514..ecf9e1fcde79 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2379,10 +2379,19 @@ extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info);
static inline unsigned long
vm_unmapped_area(struct vm_unmapped_area_info *info)
{
+ unsigned long addr;
+
if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
- return unmapped_area_topdown(info);
+ addr = unmapped_area_topdown(info);
else
- return unmapped_area(info);
+ addr = unmapped_area(info);
+
+ if (IS_ERR_VALUE(addr) && printk_ratelimit()) {
+ pr_err("%s err:%ld total_vm:0x%lx flags:0x%lx len:0x%lx low:0x%lx high:0x%lx\n",
+ __func__, addr, current->mm->total_vm, info->flags,
+ info->length, info->low_limit, info->high_limit);
+ }
+ return addr;
}


On 2020년 03월 04일 12:02, Jaewon Kim wrote:
> Even on 64 bit kernel, the mmap failure can happen for a 32 bit task.
> Virtual memory space shortage of a task on mmap is reported to userspace
> as -ENOMEM. It can be confused as physical memory shortage of overall
> system.
>
> The vm_unmapped_area can be called to by some drivers or other kernel
> core system like filesystem. It can be hard to know which code layer
> returns the -ENOMEM.
>
> Print error log of vm_unmapped_area with rate limited. Without rate
> limited, soft lockup ocurrs on infinite mmap sytem call.
>
> i.e.)
> <3>[ 576.024088] [6: mmap_infinite:14251] mmap: vm_unmapped_area err:-12 total_vm:0xfee08 flags:0x1 len:0xa00000 low:0x8000 high:0xf3f63000
>
> Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
> ---
> include/linux/mm.h | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 52269e56c514..ee822d65ebb7 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2379,10 +2379,19 @@ extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info);
> static inline unsigned long
> vm_unmapped_area(struct vm_unmapped_area_info *info)
> {
> + unsigned long addr;
> +
> if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
> - return unmapped_area_topdown(info);
> + addr = unmapped_area_topdown(info);
> else
> - return unmapped_area(info);
> + addr = unmapped_area(info);
> +
> + if (IS_ERR_VALUE(addr) && printk_ratelimit()) {
> + pr_err("%s err:%d total_vm:0x%lx flags:0x%lx len:0x%lx low:0x%lx high:0x%lx\n",
> + __func__, addr, current->mm->total_vm, info->flags,
> + info->length, info->low_limit, info->high_limit);
> + }
> + return addr;
> }
>
> /* truncate.c */

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