Re: [Crash-utility] [PATCH] display information about "struct page" on SPARSEMEM.
Dave Anderson wrote:
Ken'ichi Ohmichi wrote:
> Hi Dave,
>
> This patch fixes the problem that the crash utility cannot display
> "struct page" information about SPARSEMEM (not SPARSEMEM_EXTREME)
> properly.
>
> The symbol mem_section is defined as the pointer array in
> SPARSEMEM_EXTREME.
> On the other hand, SPARSEMEM's one is defined as the array of structure
> mem_section like the following:
>
> linux-2.6.23/mm/sparse.c:18L
> #ifdef CONFIG_SPARSEMEM_EXTREME
> struct mem_section *mem_section[NR_SECTION_ROOTS]
> ____cacheline_internodealigned_in_smp;
> #else
> struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
> ____cacheline_internodealigned_in_smp;
> #endif
> EXPORT_SYMBOL(mem_section);
>
> The crash utility considers SPARSEMEM's one to be the pointer array,
> but it is wrong. This patch fixes it.
>
Interesting, I've never seen this problem before on any
SPARSEMEM kernels. But perhaps the original contributor
of this patch, and myself, have never run a kernel configured
with CONFIG_SPARSEMEM (i.e., only with CONFIG_SPARSEMEM_EXTREME)?
(I don't have any dumpfiles to check)
Hi Ken'ichi,
I take that back -- I do have several x86_64 RHEL5 dumpfiles, and
as I suspected, all of them are CONFIG_SPARSEMEM_EXTREME. So it
appears that the CONFIG_SPARSEMEM configuration was never tested?
Also, when I was looking at your patch without the full context,
I did not see that the code already has an if-else for the two
configurations, and that you are only changing the CONFIG_SPARSEMEM
section. Sorry for the confusion...
I appreciate your fixing this -- it's queued for the next release.
Thanks again,
Dave
In any case, can you confirm that this patch work for both cases?
In other words, there is a differentiation between the _EXTREME and
the non-EXTREME cases in the crash utility. Should the patch be an
if-else situation?
Dave
> The following results are this patch effects.
>
> * Before applying this patch
> crash> kmem -p
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> 100 0 ------- ----- 0 0
> 120 1000 ------- ----- 0 0
> 140 2000 ------- ----- 0 0
> 160 3000 ------- ----- 0 0
> 180 4000 ------- ----- 0 0
> 1a0 5000 ------- ----- 0 0
> 1c0 6000 ------- ----- 0 0
> 1e0 7000 ------- ----- 0 0
> 200 8000 ------- ----- 0 0
> [snip]
> crash>
>
> * After applying this patch
> crash> kmem -p
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> c5000000 0 ------- ----- 1 400
> c5000020 1000 ------- ----- 1 400
> c5000040 2000 ------- ----- 1 400
> c5000060 3000 ------- ----- 1 400
> c5000080 4000 ------- ----- 1 400
> c50000a0 5000 ------- ----- 1 400
> c50000c0 6000 ------- ----- 1 400
> c50000e0 7000 ------- ----- 1 400
> c5000100 8000 ------- ----- 0 80000
> [snip]
> crash>
>
>
> Thanks
> Ken'ichi Ohmichi
>
> ---
> Signed-off-by: Ken'ichi Ohmichi <oomichi(a)mxs.nes.nec.co.jp>
>
> ---
> diff -rpuN crash-4.0-4.8.org/memory.c crash-4.0-4.8/memory.c
> --- crash-4.0-4.8.org/memory.c 2007-10-31 11:49:16.000000000 +0900
> +++ crash-4.0-4.8/memory.c 2007-11-01 10:28:15.000000000 +0900
> @@ -12229,7 +12229,9 @@ nr_to_section(ulong nr)
> addr = mem_sec[SECTION_NR_TO_ROOT(nr)] + (nr &
> SECTION_ROOT_MASK()) * SIZE(mem_section);
> else
> - addr = mem_sec[0] + (nr & SECTION_ROOT_MASK()) *
> SIZE(mem_section);
> + addr = symbol_value("mem_section") +
> + (SECTIONS_PER_ROOT() * SECTION_NR_TO_ROOT(nr) +
> + (nr & SECTION_ROOT_MASK())) * SIZE(mem_section);
>
> if (!IS_KVADDR(addr))
> return 0;
> _
>
>
>
> --
> Crash-utility mailing list
> Crash-utility(a)redhat.com
> https://www.redhat.com/mailman/listinfo/crash-utility