linux-kernel - Re: [PATCH 1/2] coredump_filter: add hugepage dumping v3

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Date:	Tue, 30 Sep 2008 21:17:04 +0900
From:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hugh@...itas.com>, Adam Litke <agl@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <satoshi.oshima.fk@...achi.com>
Subject: Re: [PATCH 1/2] coredump_filter: add hugepage dumping v3

Hi Kosaki-san,

KOSAKI Motohiro wrote:
> Index: b/Documentation/filesystems/proc.txt
> ===================================================================
> --- a/Documentation/filesystems/proc.txt	2008-09-25 21:19:13.000000000 +0900
> +++ b/Documentation/filesystems/proc.txt	2008-09-25 21:21:05.000000000 +0900
> @@ -2408,24 +2408,29 @@ will be dumped when the <pid> process is
>  of memory types. If a bit of the bitmask is set, memory segments of the
>  corresponding memory type are dumped, otherwise they are not dumped.
>  
> -The following 4 memory types are supported:
> +The following 7 memory types are supported:
>    - (bit 0) anonymous private memory
>    - (bit 1) anonymous shared memory
>    - (bit 2) file-backed private memory
>    - (bit 3) file-backed shared memory
>    - (bit 4) ELF header pages in file-backed private memory areas (it is
>              effective only if the bit 2 is cleared)
> +  - (bit 5) hugetlb private memory
> +  - (bit 6) hugetlb shared memory
>  
>    Note that MMIO pages such as frame buffer are never dumped and vDSO pages
>    are always dumped regardless of the bitmask status.
>  
> -Default value of coredump_filter is 0x3; this means all anonymous memory
> -segments are dumped.
> +  Note bit 0-4 doesn't effect any hugetlb memory. hugetlb memory are only
> +  effected by bit 5-6.
> +
> +Default value of coredump_filter is 0x23; this means all anonymous memory
> +segments and hugetlb private memory are dumped.
>  
>  If you don't want to dump all shared memory segments attached to pid 1234,
> -write 1 to the process's proc file.
> +write 21 to the process's proc file.

This should be:
write 0x21 to the process's proc file.

Except for this, it seems OK.  Thanks.

Reviewed-by: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
  
> -  $ echo 0x1 > /proc/1234/coredump_filter
> +  $ echo 0x21 > /proc/1234/coredump_filter
>  
>  When a new process is created, the process inherits the bitmask status from its
>  parent. It is useful to set up coredump_filter before the program runs.

-- 
Hidehiro Kawai
Hitachi, Systems Development Laboratory
Linux Technology Center

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