[v2 2/3] makedumpfile: use struct cycle to update cyclic region and clean up

[Atsushi Kumagai]

On 2014/01/27 17:56:56, kexec <kexec-bounces at lists.infradead.org> wrote:
> On 01/27/14 at 01:03pm, HATAYAMA Daisuke wrote:
> > (2014/01/23 18:47), Baoquan He wrote:
> > 
> > > @@ -3301,18 +3301,15 @@ set_bitmap(struct dump_bitmap *bitmap, unsigned long long pfn,
> > >   }
> > >   
> > >   int
> > > -set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val)
> > > +set_bitmap_cyclic(char *bitmap, unsigned long long pfn, int val, struct cycle *cycle)
> > >   {
> > >   	int byte, bit;
> > >   
> > > -	if (pfn < info->cyclic_start_pfn || info->cyclic_end_pfn <= pfn)
> > > -		return FALSE;
> > > -
> > 
> > Removing this check changes behaviour, not just clean up, so should be separated into another patch.
> > 
> > Further, this change seems buggy because, in addition to Kumaga-san's comment, memory outside of
> > cycle region can be passed to here. Please look at the below.
> 
> Hi Both,
> 
> I understand your finding. How about put the pfn checking back to
> set_bitmap_cyclic(). Maybe this is simpler and safer. Otherwise each
> case need be taken care and adding the pfn checking.

Agreed, and this simple check may have a small influence on the
performance, so I think it's OK to do it.


Thanks
Atsushi Kumagai

> 
> > 
> > > @@ -4782,10 +4780,10 @@ exclude_unnecessary_pages_cyclic(void)
> > >   			if (mmd->mem_map == NOT_MEMMAP_ADDR)
> > >   				continue;
> > >   
> > > -			if (mmd->pfn_end >= info->cyclic_start_pfn &&
> > > -			    mmd->pfn_start <= info->cyclic_end_pfn) {
> > > +			if (mmd->pfn_end >= cycle->start_pfn &&
> > > +			    mmd->pfn_start <= cycle->end_pfn) {
> > >   				if (!__exclude_unnecessary_pages(mmd->mem_map,
> > > -								 mmd->pfn_start, mmd->pfn_end))
> > > +								 mmd->pfn_start, mmd->pfn_end, cycle))
> > >   					return FALSE;
> > >   			}
> > >   		}
> > 
> > After this clean up, __exclude_unnecessary_pages() processes memory within cycle region only.
> > So, it's necessary to pass adjusted range, like:
> > 
> > if (MAX(mmd->pfn_start, cycle->start_pfn) < MIN(mmd->pfn_end, cycle->end_pfn))
> >   __exclude_unnecessary_pages(mmd->mem_map, MAX(mmd->pfn_start, cycle->start_pfn), MIN(mmd->pfn_end, cycle->end_pfn))
> > 
> > -- 
> > Thanks.
> > HATAYAMA, Daisuke
> > 
> > 
> > _______________________________________________
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> > kexec at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
> 
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