[Devel] Re: problem with ZONE_MOVABLE.

[Balbir Singh]

Andrew Morton wrote:
> On Thu, 13 Sep 2007 16:00:06 +0530
> Balbir Singh <balbir at linux.vnet.ibm.com> wrote:
> 
>> KAMEZAWA Hiroyuki wrote:
>>> Hi, 
>>>
>>> While I'm playing with memory controller of 2.6.23-rc4-mm1, I met following.
>>>
>>> ==
>>> [root at drpq test-2.6.23-rc4-mm1]# echo $$ > /opt/mem_control/group_1/tasks
>>> [root at drpq test-2.6.23-rc4-mm1]# cat /opt/mem_control/group_1/memory.limit
>>> 32768
>>> [root at drpq test-2.6.23-rc4-mm1]# cat /opt/mem_control/group_1/memory.usage
>>> 286
>>> // Memory is limited to 512 GiB. try "dd" 1GiB (page size is 16KB)
>>>
>>> [root at drpq test-2.6.23-rc4-mm1]# dd if=/dev/zero of=/tmp/tmpfile bs=1024 count=1048576
>>> Killed
>>> [root at drpq test-2.6.23-rc4-mm1]# ls
>>> Killed
>>> //above are caused by OOM.
>>> [root at drpq test-2.6.23-rc4-mm1]# cat /opt/mem_control/group_1/memory.usage
>>> 32763
>>> [root at drpq test-2.6.23-rc4-mm1]# cat /opt/mem_control/group_1/memory.limit
>>> 32768
>>> // fully filled by page cache. no reclaim run.
>>> ==
>>>
>>> The reason  this happens is  because I used kernelcore= boot option, i.e
>>> ZONE_MOVABLE. Seems try_to_free_mem_container_pages() ignores ZONE_MOVABLE.
>>>
>>> Quick fix is attached, but Mel's one-zonelist-pernode patch may change this.
>>> I'll continue to watch.
>>>
>>> Thanks,
>>> -Kame
>>> ==
>>> Now, there is ZONE_MOVABLE...
>>>
>>> page cache and user pages are allocated from gfp_zone(GFP_HIGHUSER_MOVABLE)
>>>
>>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
>>> ---
>>>  mm/vmscan.c |    9 ++-------
>>>  1 file changed, 2 insertions(+), 7 deletions(-)
>>>
>>> Index: linux-2.6.23-rc4-mm1.bak/mm/vmscan.c
>>> ===================================================================
>>> --- linux-2.6.23-rc4-mm1.bak.orig/mm/vmscan.c
>>> +++ linux-2.6.23-rc4-mm1.bak/mm/vmscan.c
>>> @@ -1351,12 +1351,6 @@ unsigned long try_to_free_pages(struct z
>>>
>>>  #ifdef CONFIG_CONTAINER_MEM_CONT
>>>
>>> -#ifdef CONFIG_HIGHMEM
>>> -#define ZONE_USERPAGES ZONE_HIGHMEM
>>> -#else
>>> -#define ZONE_USERPAGES ZONE_NORMAL
>>> -#endif
>>> -
>>>  unsigned long try_to_free_mem_container_pages(struct mem_container *mem_cont)
>>>  {
>>>  	struct scan_control sc = {
>>> @@ -1371,9 +1365,10 @@ unsigned long try_to_free_mem_container_
>>>  	};
>>>  	int node;
>>>  	struct zone **zones;
>>> +	int target_zone = gfp_zone(GFP_HIGHUSER_MOVABLE);
>>>
>>>  	for_each_online_node(node) {
>>> -		zones = NODE_DATA(node)->node_zonelists[ZONE_USERPAGES].zones;
>>> +		zones = NODE_DATA(node)->node_zonelists[target_zone].zones;
>>>  		if (do_try_to_free_pages(zones, sc.gfp_mask, &sc))
>>>  			return 1;
>>>  	}
>> Mel, has sent out a fix (for the single zonelist) that conflicts with
>> this one. Your fix looks correct to me, but it will be over ridden
>> by Mel's fix (once those patches are in -mm).
>>
> 
> "mel's fix" is rather too imprecise a term for me to make head or tail of this.
> 
> Oh well, the patch basically applied, so I whacked it in there, designated
> as to be folded into memory-controller-make-charging-gfp-mask-aware.patch

I agree that this fix is required and may be over-written by Mel'ls
patches in the future, but for now this is the correct fix. Thanks
for applying it.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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