FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > Redhat > Crash Utility

 
 
LinkBack Thread Tools
 
Old 04-06-2010, 05:01 AM
"Ken'ichi Ohmichi"
 
Default handle !SPARSEMEM_EX properly

Hi Nishimura-san,

Thank you for the patch.

Daisuke Nishimura wrote:
> In !SPARSEMEM_EX case, the symbol mem_section points a array of struct mem_section,
> doesn't point a array of pointer to mem_section[], so I think the check:
>
> if (!is_kvaddr(mem_sec[SECTION_NR_TO_ROOT(nr)]))
> return NOT_KV_ADDR;
>
> in nr_to_section() is not a valid check in this case.
>
> To make the matters worse, if CONFIG_CGROUP_MEM_RES_CTLR is enabled, the end of
> struct mem_section is padded with 0.
>
> So, reading mem_section by "rd" of crash will look like:
>
> crash> rd mem_section 128
> c08b71e0: c9002003 c9001200 f7000000 00000000 . ..............
> c08b71f0: c9002003 c9001260 f6980000 00000000 . ..`...........
> c08b7200: c9002003 c90012c0 f6300000 00000000 . ........0.....
> c08b7210: c9002003 c9001320 f5c80000 00000000 . .. ...........
> ...

I see.

In !SPARSEMEM_EX case, nr_to_section() checked invalid area
(pageblock_flags, page_cgroup, and pad) as section_mem_map.

linux-2.6.33/include/linux/mmzone.h:
struct mem_section {
unsigned long section_mem_map;
unsigned long *pageblock_flags;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
struct page_cgroup *page_cgroup;
unsigned long pad;
#endif
};

> This means nr_to_section() will return 0 when "nr" is 3,7,11,... because it meets
> the condition(mem_sec[SECTION_NR_TO_ROOT(nr)] == mem_sec[nr] == 0 == !is_kvaddr).
>
> As a result, mem_map for section 3,7,11,... cannot be handled properly.
>
> This patch is a fix for this problem. nr_to_section() will check "addr" by
> is_kvaddr() later anyway, so this patch just removes the problematic check.
>
> Signed-off-by: Masayuki Igawa <igawa@mxs.nes.nec.co.jp>
> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> ---
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 855c718..73fa94f 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -3547,9 +3547,6 @@ nr_to_section(unsigned long nr, unsigned long *mem_sec)
> {
> unsigned long addr;
>
> - if (!is_kvaddr(mem_sec[SECTION_NR_TO_ROOT(nr)]))
> - return NOT_KV_ADDR;
> -
> if (is_sparsemem_extreme())
> addr = mem_sec[SECTION_NR_TO_ROOT(nr)] +
> (nr & SECTION_ROOT_MASK()) * SIZE(mem_section);

The patch is good, and it has been merged to git tree of makedumpfile:

http://makedumpfile.git.sourceforge.net/git/gitweb.cgi?p=makedumpfile/makedumpfile;a=commit;h=27b71566ec11128c5b061a350e 467546f2d26be6


Thanks
Ken'ichi Ohmichi

--
Crash-utility mailing list
Crash-utility@redhat.com
https://www.redhat.com/mailman/listinfo/crash-utility
 

Thread Tools




All times are GMT. The time now is 12:28 AM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org