On Thu, 2008-02-07 at 16:04 -0500, Dave Anderson wrote:
> Andrew Hecox wrote:
> > On Thu, 2008-02-07 at 15:38 -0500, Dave Anderson wrote:
> >> Andrew Hecox wrote:
> >>> I get the same:
> >>>
> >>> (/boot/System.map-2.6.9-67.0.1.ELhugemem)
> >>>
> >>> 02323bd8 d log_buf_len
> >>>
> >>> (/usr/lib/debug/lib/modules/2.6.9-67.0.1.ELhugemem/vmlinux)
> >>>
> >>> $1 = (int *) 0x2323bd8
> >>>
> >>> -Andrew
> >> So, as Takao suggested, can you dump the incoming vaddr and
> >> resultant pfn values in diskdumpmsg.c:read_buffer()?
> >>
> >
> > The vaddr value is: 36846552.
> >
> > -Andrew
> >
> >> Dave
> >>
> >>
> >
>
> OK, so the incoming vaddr is 36846552 is which is 0x2323bd8.
> To get a pfn, that hugemem kernel virtual address is passed
> through vtop() and then divided by 4096:
>
> static int read_buffer(DumpFile *dump, addr_t vaddr, size_t len, void *buf)
> {
> addr_t paddr;
> int block_size = get_page_size();
> unsigned long pfn;
> int ret;
> size_t copy_len, offs;
> void *page_data;
>
> paddr = vtop(dump, vaddr);
> pfn = paddr / block_size;
> offs = paddr % block_size;
>
> When 0x2323bd8 is run through vtop(), it simply strips off the
> hugemem unity-map identifier:
>
> addr_t vtop(DumpFile *dump, addr_t vaddr)
> {
> if (strstr("hugemem", dump->utsname->release))
> return vaddr - 0x02000000L;
> else
> return vaddr - 0xc0000000L;
> }
>
> leaving 0x323bd8 -- which gets divided by the page size of 4096, leaving
> a pfn of 0x323.
>
> But you see that the pfn was 271139 (0x42323). If that is expanded
> to a physical address it would be 0x42323000. It looks like it's
> using the non-hugemem value in vtop(), i,e, subtracting c0000000 from
> the incoming vaddr. In other words, 0x2323bd8 - 0xc000000 is
> equal to 0x42323bd8. If that is divided by 4096, you get
> the funky pfn of 271139 (0x42323).
>
> Print out the dump->utsname->release string in vtop(). It must
> not contain "hugemem".
>
Dave,
I get:
(gdb) print dump->utsname->release
$19 = "2.6.9-67.0.1.ELhugemem", '\0' <repeats 42 times>
but then
(gdb) s
16 return vaddr - 0xc0000000L;
! oh uh.
man strstr
...
char *strstr(const char *haystack, const char *needle);
...
It looks like
if (strstr("hugemem", dump->utsname->release))
should be:
if (strstr(dump->utsname->release,"hugemem"))
I patched, recompiled, tested and it works:
[root@ibm-x3455-1 ~]# diskdumpmsg -f -p /var/crash/vmcore
Jan 31 05:43:08 elabhost012 kernel: --- salvaged messages from crash
dump start
Jan 31 05:43:08 elabhost012 kernel: 0218b9c0 0232d363 0232d3e0
0215aff6 df954fac f6db4000 eaa756c0 fffffff7
Jan 31 05:43:08 elabhost012 kernel: f6db4000 df954000 0215b0c0
df954fac 00000000 00000000 00000000 df954fc4
Jan 31 05:43:08 elabhost012 kernel: Call Trace:
Jan 31 05:43:08 elabhost012 kernel: [<0220c46a>] __handle_sysrq
+0x58/0xc6
Jan 31 05:43:08 elabhost012 kernel: [<0218b9c0>] write_sysrq_trigger
+0x37/0x3e
Jan 31 05:43:08 elabhost012 kernel: [<0215aff6>] vfs_write+0xb6/0xe2
Jan 31 05:43:08 elabhost012 kernel: [<0215b0c0>] sys_write+0x3c/0x62
Jan 31 05:43:08 elabhost012 kernel: Code: 11 02 c7 05 10 fd 44 02 00 00
00 00 c7 05 38 fd 44 02 00 00 00 00 c7 05 2c fd 44 02 6e ad 87 4b 89 15
28 fd 44 02 e9 8b 41 f2 ff <c6> 05 00 00 00 00 00 c3 e9 0a ff f4 ff e9
a2 48 f5 ff 85 d2 89
Jan 31 05:43:08 elabhost012 kernel: --- salvaged messages from crash
dump end
Thanks much for all the help! Should I open a bz against the issue? It
looks like all i386 hugemem kernels would be similarly affected.
-Andrew
> Dave
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