Re: bad page state under possibly oom situation

[Manfred Spraul]

Hugh Dickins wrote:

> (I don't know that it makes any difference, but was this particular report
> from 2.6.9-rc2 or from 2.6.14 or from something else?  In both 2.6.9 and
> 2.6.14, flags 0x90 mean PG_slab|PG_dirty.)
>
>  
A very odd combination:
- free_pages_check() ensures that neither PG_slab nor PG_dirty are set
- prep_new_page() complains that both PG_slab and PG_dirty are set
- AFAICS slab doesn't set PG_dirty, and noone except slab set PG_slab.

I don't understand how two wrong bits can end up in page->flags.
Dipankar, could you modify bad_page() and hexdump +-128 bytes? Perhaps 
someone overwrites random memory. Or change the value of PG_slab to 20 
and check if page->flags remains 0x90.

--
   Manfred
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