Re: [PATCH v3 13/21] kexec: allocate vmcoreinfo note buffer on page-size boundary

Eric W. Biederman
2013-03-19T22:12:57Z

HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> writes:

> To satisfy mmap()'s page-size boundary requirement, specify aligned
> attribute to vmcoreinfo_note objects to allocate it on page-size
> boundary.

Those requirements don't exist. Making this patch wasteful and wrong.

Eric

> Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
> ---
>
> include/linux/kexec.h | 6 ++++--
> kernel/kexec.c | 2 +-
> 2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index d2e6927..5113570 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -185,8 +185,10 @@ extern struct kimage *kexec_crash_image;
> #define VMCOREINFO_BYTES (4096)
> #define VMCOREINFO_NOTE_NAME "VMCOREINFO"
> #define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
> -#define VMCOREINFO_NOTE_SIZE (KEXEC_NOTE_HEAD_BYTES*2 + VMCOREINFO_BYTES \
> - + VMCOREINFO_NOTE_NAME_BYTES)
> +#define VMCOREINFO_NOTE_SIZE ALIGN(KEXEC_NOTE_HEAD_BYTES*2 \
> + +VMCOREINFO_BYTES \
> + +VMCOREINFO_NOTE_NAME_BYTES, \
> + PAGE_SIZE)
>
> /* Location of a reserved region to hold the crash kernel.
> */
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index d1f365e..195de6d 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -43,7 +43,7 @@ note_buf_t __percpu *crash_notes;
>
> /* vmcoreinfo stuff */
> static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
> -u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
> +u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4] __aligned(PAGE_SIZE);
> size_t vmcoreinfo_size;
> size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);