Re: 2.6.22-rc6-mm1 bad_page events.

[Frederik Deweerdt <deweerdt@free.fr>]

On Tue, Jul 03, 2007 at 11:37:47AM -0400, Mathieu Desnoyers wrote:
> Hi Alan,
> 
> I already sent a fix to Andrew and Andi for this (hrm, forget to CC
> lkml on the original message):
> 
> 
> x86_64 mm cpa cache flush fix
> 
> X86_64 and i386 cpa cache flush fix:
> 
> list_del the deferred list entries to poison their pointers.
> clear the flag for every page put in the list.
> 
Hi Mathieu,

I've tried the patch on rc6-mm1, but it doesn't seem to fix the
problem. From what I understood, the bad_page() is called on PG_reserved
being set (flags:0x00000400), not the lru pointer being not NULL or
PG_arch_1 being set.

Regards,
Frederik

> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> CC: Andi Kleen <ak@suse.de>
[...]
>  	flush_map(&l);
>  	list_for_each_entry_safe(pg, next, &l, lru) {
> +		clear_bit(PG_arch_1, &pg->flags);
> +		list_del(&pg->lru);
>  		if (page_private(pg) != 0)
>  			continue;
>  		ClearPagePrivate(pg);
> -		clear_bit(PG_arch_1, &pg->flags);
>  		__free_page(pg);
>  	}
>  }
[...]
> * Alan Cox (alan@lxorguk.ukuu.org.uk) wrote:
> > X86 32bit with lots of debug turned on I get this:
[...]
> > Bad page state in process 'swapper'
> > page:c10000c0 flags:0x00000400 mapping:00000000 mapcount:0 count:0
> > Trying to fix it up, but a reboot is needed
> > Backtrace:
> >  [<c024589c>] bad_page+0x6c/0x100
> >  [<c024648d>] free_hot_cold_page+0x5d/0x140
> >  [<c02116c2>] global_flush_tlb+0x112/0x130
> >  [<c020102d>] init_post+0xd/0xe0
> >  [<c047c876>] kernel_init+0x216/0x220
> >  [<c0214c50>] schedule_tail+0x0/0xe0
> >  [<c047c660>] kernel_init+0x0/0x220
> >  [<c047c660>] kernel_init+0x0/0x220
> >  [<c0204227>] kernel_thread_helper+0x7/0x10
> >  =======================
> > Hexdump:
> > 000: 00 06 00 00 01 00 00 00 ff ff ff ff 0f 00 00 00
> > 010: 00 00 00 00 00 00 00 00 78 00 00 c1 b8 00 00 c1
> > 020: 00 06 00 00 01 00 00 00 ff ff ff ff a7 03 00 00
> > 030: 00 00 00 00 00 00 00 00 98 00 00 c1 d8 00 00 c1
> > 040: 00 04 00 00 00 00 00 00 ff ff ff ff 00 00 00 00
> > 050: 00 00 00 00 00 00 00 00 b8 00 00 c1 f8 00 00 c1
> > 060: 00 06 00 00 01 00 00 00 ff ff ff ff 00 04 00 00
> > 070: 00 00 00 00 00 00 00 00 d8 00 00 c1 18 01 00 c1
> > 080: 00 06 00 00 01 00 00 00 ff ff ff ff 9c 03 00 00
> > 090: 00 00 00 00 00 00 00 00 f8 00 00 c1 38 01 00 c1
> > 0a0: 00 06 00 00 01 00 00 00 ff ff ff ff 00 04 00 00
> > 0b0: 00 00 00 00 00 00 00 00 18 01 00 c1 58 01 00 c1
> > -
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> 
> -- 
> Mathieu Desnoyers
> Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
> OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
> -
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