Re: [Crash-utility] Fix fill_mem_map_cache() to read page-size-or-less size correctly
Hi Kazu,
This seems to be an extrememly rare condition, but in any case, your
patch is the correct thing to do.
However, I do have two dumpfiles where the change causes the warning message
to be displayed unnecessarily, which was only meant to be displayed if the
mem_map cache is *not* virtually-mapped. But the single check for
!(vt->flags & V_MEM_MAP) is not always sufficient, so it should also
check for !(machdep->flags & VMEMMAP) like so:
--- a/memory.c 2019-09-17 14:20:24.586069004 -0400
+++ b/memory.c 2019-09-17 14:36:36.765286602 -0400
@@ -6348,13 +6348,13 @@ fill_mem_map_cache(ulong pp, ulong ppend
if (cnt > size)
cnt = size;
- if (!readmem(addr, KVADDR, bufptr, size,
+ if (!readmem(addr, KVADDR, bufptr, cnt,
"virtual page struct cache", RETURN_ON_ERROR|QUIET)) {
- BZERO(bufptr, size);
- if (!(vt->flags & V_MEM_MAP) && ((addr+size) < ppend))
+ BZERO(bufptr, cnt);
+ if (!((vt->flags & V_MEM_MAP) || (machdep->flags & VMEMMAP)) &&
((addr+cnt) < ppend))
error(WARNING,
"mem_map[] from %lx to %lx not accessible\n",
- addr, addr+size);
+ addr, addr+cnt);
}
addr += cnt;
You OK with that?
Thanks,
Dave
----- Original Message -----
Hi Kazu,
I will be out of the office until Monday September 16th. I will check
out your patch when I get back.
Thanks,
Dave
----- Original Message -----
>
> fill_mem_map_cache() intends to read page-size-or-less size if it cannot
> read the whole cache size, but it seems it doesn't correctly, and shows
> just zero for existing data.
>
> crash> kmem -p 1000
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> ffffea0000000040 1000 0 0 0 0
> crash> rd ffffea0000000040
> ffffea0000000040: 000fffff00000400 ........
>
> I think the size below should be cnt, and confirmed that the patch works
> well with a dump by makedumpfile -e option.
>
> Signed-off-by: Kazuhito Hagio <k-hagio(a)ab.jp.nec.com>
> ---
> memory.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index ac7e73679405..4584673ed0ae 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -6348,13 +6348,13 @@ fill_mem_map_cache(ulong pp, ulong ppend, char
> *page_cache)
> if (cnt > size)
> cnt = size;
>
> - if (!readmem(addr, KVADDR, bufptr, size,
> + if (!readmem(addr, KVADDR, bufptr, cnt,
> "virtual page struct cache", RETURN_ON_ERROR|QUIET))
{
> - BZERO(bufptr, size);
> - if (!(vt->flags & V_MEM_MAP) && ((addr+size)
<
> ppend))
> + BZERO(bufptr, cnt);
> + if (!(vt->flags & V_MEM_MAP) && ((addr+cnt)
<
> ppend))
> error(WARNING,
> "mem_map[] from %lx to %lx not
> accessible\n",
> - addr, addr+size);
> + addr, addr+cnt);
> }
>
> addr += cnt;
> --
> 2.18.1
>
--
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