Hello HATAYAMA-san,
On Fri, 16 Nov 2012 14:02:13 +0900
HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
> On kernels from v2.6.18 to v2.6.37, buddy page is marked by the
> PG_buddy flag.
>
> kernel version | PG_buddy
> ------------------ +---------------------------------
> v2.6.17 to v2.6.26 | 19
> v2.6.27 to v2.6.37 | 19 if CONFIG_PAGEFLAGS_EXTEND=y
> | 18 otherwise
>
> We don't need to care about CONFIG_PAGEFLAGS_EXTEND because the
> architectures specifying this as y are um and xtensa only. They are
> not included in the supported architectures of makedumpfile.
Sorry for too late point out.
I did regression test for v1.5.1 on x86_64 machine in the last weekend
and found the issue that page_is_buddy_v2() can't exclude free pages
correctly for kernel 2.6.30 to 2.6.37.
I checked the configuration of these kernels, I made sure that
CONFIG_PAGEFLAGS_EXTENDED was set as y, so PG_buddy=18 is invalid for them.
According to this fact, PG_buddy is variable for the supported architectures
of makedumpfile, too.
So, how did you confirm that CONFIG_PAGEFLAGS_EXTENDED is only related with
um and xtensa ?
And why did you test with PG_buddy=19 for 2.6.32 when you posted this patch set?
> - 2.6.32
> NUMBER(PG_slab)=7
> NUMBER(PG_buddy)=19
> OFFSET(page._mapcount)=12
> OFFSET(page.private)=16
> SIZE(pageflags)=4
Thanks
Atsushi Kumagai
> Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
> ---
>
> makedumpfile.c | 24 ++++++++++++++++++++----
> 1 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 7b13dca..4e5d4d3 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -3669,6 +3669,19 @@ exclude_free_page(void)
> }
>
> /*
> + * For the kernel versions from v2.6.17 to v2.6.37.
> + */
> +static int
> +page_is_buddy_v2(unsigned long flags, unsigned int _mapcount,
> + unsigned long private, unsigned int _count)
> +{
> + if (flags & (1UL << NUMBER(PG_buddy)))
> + return TRUE;
> +
> + return FALSE;
> +}
> +
> +/*
> * For v2.6.38 and later kernel versions.
> */
> static int
> @@ -3690,10 +3703,13 @@ setup_page_is_buddy(void)
> if (OFFSET(page.private) == NOT_FOUND_STRUCTURE)
> goto out;
>
> - if (NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) != NOT_FOUND_NUMBER) {
> - if (OFFSET(page._mapcount) != NOT_FOUND_STRUCTURE)
> - info->page_is_buddy = page_is_buddy_v3;
> - }
> + if (NUMBER(PG_buddy) == NOT_FOUND_NUMBER) {
> + if (NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) != NOT_FOUND_NUMBER) {
> + if (OFFSET(page._mapcount) != NOT_FOUND_STRUCTURE)
> + info->page_is_buddy = page_is_buddy_v3;
> + }
> + } else
> + info->page_is_buddy = page_is_buddy_v2;
>
> out:
> if (!info->page_is_buddy)
>
>
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