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Date: Sun, 17 Oct 2004 12:19:12 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Jeff Garzik <jgarzik@pobox.com>
CC: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org, ak@suse.de,
       axboe@suse.de
Subject: Re: Hang on x86-64, 2.6.9-rc3-bk4
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Jeff Garzik wrote:
> Nick Piggin wrote:
> 
>> diff -puN mm/vmscan.c~vm-fix mm/vmscan.c
>> --- linux-2.6/mm/vmscan.c~vm-fix    2004-10-17 11:14:02.000000000 +1000
>> +++ linux-2.6-npiggin/mm/vmscan.c    2004-10-17 11:20:55.000000000 +1000
>> @@ -181,7 +181,7 @@ static int shrink_slab(unsigned long sca
>>      struct shrinker *shrinker;
>>  
>>      if (scanned == 0)
>> -        return 0;
>> +        scanned = 1;
>>  
>>      if (!down_read_trylock(&shrinker_rwsem))
>>          return 0;
>> @@ -1065,7 +1065,8 @@ scan:
>>              total_reclaimed += sc.nr_reclaimed;
>>              if (zone->all_unreclaimable)
>>                  continue;
>> -            if (zone->pages_scanned > zone->present_pages * 2)
>> +            if (zone->pages_scanned > (zone->nr_active +
>> +                            zone->nr_inactive) * 4)
>>                  zone->all_unreclaimable = 1;
>>              /*
>>               * If we've done a decent amount of scanning and
> 
> 
> 
> Nope, this patch does not fix the hang.
> 

Arrgh, sorry that should be
	if (zone->pages_scanned *>=* blah)

If you've got zero LRU pages, both sides of this should be zero, and
we *want* all_unreclaimable to be set.