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 ((mem_sec[SECTION_NR_TO_ROOT(nr)] == 0) ||
!IS_KVADDR(mem_sec[SECTION_NR_TO_ROOT(nr)]))
return 0;
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" 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 . .. ...........
...
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).
As a result, mem_map for section 3,7,11,... cannot be handled properly.
Actually, "kmem -n" doesn't show a mem_map for them.
crash> kmem -n
...
NR SECTION CODED_MEM_MAP MEM_MAP PFN
0 c08b71e0 c9002000 c9002000 0
1 c08b71f0 c9002000 c9402000 131072
2 c08b7200 c9002000 c9802000 262144
4 c08b7220 c9002000 ca002000 524288
5 c08b7230 c9002000 ca402000 655360
6 c08b7240 c9002000 ca802000 786432
8 c08b7260 c8c02000 cac02000 1048576
9 c08b7270 c8c02000 cb002000 1179648
10 c08b7280 c8c02000 cb402000 1310720
12 c08b72a0 c8c02000 cbc02000 1572864
...
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: Daisuke Nishimura <[email protected]>
---
diff -uprN crash-5.0.2.orig/memory.c crash-5.0.2/memory.c
--- crash-5.0.2.orig/memory.c 2010-04-05 16:08:52.000000000 +0900
+++ crash-5.0.2/memory.c 2010-04-06 09:56:43.000000000 +0900
@@ -13030,10 +13030,6 @@ nr_to_section(ulong nr)
}
}
- if ((mem_sec[SECTION_NR_TO_ROOT(nr)] == 0) ||
- !IS_KVADDR(mem_sec[SECTION_NR_TO_ROOT(nr)]))
- return 0;
-
if (IS_SPARSEMEM_EX())
addr = mem_sec[SECTION_NR_TO_ROOT(nr)] +
(nr & SECTION_ROOT_MASK()) * SIZE(mem_section);
--
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