Re: 2.6.18: Kernel BUG at mm/rmap.c:522

[Michael Harris <googlegroups@mgharris.com>]

> Michael Harris wrote:
> >Hi, I can readily reproduce this with 2.6.18 doing 4 simultanous kernel 
> >compiles on two disks to load test a P4 3.2 HT with 2GB. I have SMP and 
> >SMT scheduling enabled, and the 4GB memory option. Here is output with 
> >CONFIG_DEBUG_VM enabled followed by another crash before CONFIG_DEBUG_VM 
> >was enabled.
> 
> >Oct 11 04:53:35 hen kernel: swap_free: Unused swap offset entry 00004000
> >Oct 11 04:53:35 hen kernel: Eeek! page_mapcount(page) went negative! (-1)
> >Oct 11 04:53:35 hen kernel:   page->flags = c0080014
> >Oct 11 04:53:35 hen kernel:   page->count = 0
> >Oct 11 04:53:35 hen kernel:   page->mapping = 00000000
> 
> Hmm, this is a new one. The page is free and not reserved, wheras we are
> used to seeing them reserved here.
> 
> >Oct 11 04:54:31 hen kernel: Bad page state in process 'tripwire'
> >Oct 11 04:54:31 hen kernel: page:c1b5cd80 flags:0xc0000014 
> >mapping:00000000 mapcount:-1 count:0
> 
> >Another crash from a day earlier before enabling DEBUG_VM
> >Oct 10 05:19:43 hen kernel: VM: killing process cc1
> >Oct 10 05:19:43 hen kernel: swap_free: Unused swap offset entry 00002000
> >Oct 10 05:19:56 hen kernel: swap_free: Unused swap offset entry 00000400
> 
> These unused swap offset entry messages seem to indicate extensive memory
> corruption in your page tables. Probably bad RAM, or system overheating
> when you load it up :(
> 
> Can you run a good memory tester like memtest86+ overnight?


Hi, I think this is the case, a stick of ram gone bad. It had worked 
testing under 2.4 but coincidentally failed about the time I upgraded
to 2.6. memtest86 uncovered it at once. Sorry for the trouble and thanks
for the help.
Mike