linux-kernel - Re: [PATCH v2] vmscan: return NODE_RECLAIM_NOSCAN in node_reclaim() when CONFIG

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Date:   Tue, 13 Nov 2018 13:18:18 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Wei Yang <richard.weiyang@...il.com>, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, willy@...radead.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] vmscan: return NODE_RECLAIM_NOSCAN in node_reclaim()
 when CONFIG_NUMA is n

On Tue, Nov 13, 2018 at 01:56:11PM +0100, Michal Hocko wrote:
>On Tue 13-11-18 16:04:36, Wei Yang wrote:
>> Commit fa5e084e43eb ("vmscan: do not unconditionally treat zones that
>> fail zone_reclaim() as full") changed the return value of node_reclaim().
>> The original return value 0 means NODE_RECLAIM_SOME after this commit.
>> 
>> While the return value of node_reclaim() when CONFIG_NUMA is n is not
>> changed. This will leads to call zone_watermark_ok() again.
>> 
>> This patch fix the return value by adjusting to NODE_RECLAIM_NOSCAN. Since
>> node_reclaim() is only called in page_alloc.c, move it to mm/internal.h.
>
>The issue should be cosmetic but the code consistency is definitely an
>improvement. Moving this from swap.h makes a lot of sense as well.
>
>> Signed-off-by: Wei Yang <richard.weiyang@...il.com>
>
>Acked-by: Michal Hocko <mhocko@...e.com>

Thanks.

>
>> ---
>> v2:  move node_reclaim() to mm/internal.h
>> ---
>>  include/linux/swap.h |  6 ------
>>  mm/internal.h        | 10 ++++++++++
>>  2 files changed, 10 insertions(+), 6 deletions(-)
>> 
>> diff --git a/include/linux/swap.h b/include/linux/swap.h
>> index d8a07a4f171d..065988c27373 100644
>> --- a/include/linux/swap.h
>> +++ b/include/linux/swap.h
>> @@ -358,14 +358,8 @@ extern unsigned long vm_total_pages;
>>  extern int node_reclaim_mode;
>>  extern int sysctl_min_unmapped_ratio;
>>  extern int sysctl_min_slab_ratio;
>> -extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
>>  #else
>>  #define node_reclaim_mode 0
>> -static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
>> -				unsigned int order)
>> -{
>> -	return 0;
>> -}
>>  #endif
>>  
>>  extern int page_evictable(struct page *page);
>> diff --git a/mm/internal.h b/mm/internal.h
>> index 291eb2b6d1d8..6a57811ae47d 100644
>> --- a/mm/internal.h
>> +++ b/mm/internal.h
>> @@ -444,6 +444,16 @@ static inline void mminit_validate_memmodel_limits(unsigned long *start_pfn,
>>  #define NODE_RECLAIM_SOME	0
>>  #define NODE_RECLAIM_SUCCESS	1
>>  
>> +#ifdef CONFIG_NUMA
>> +extern int node_reclaim(struct pglist_data *, gfp_t, unsigned int);
>> +#else
>> +static inline int node_reclaim(struct pglist_data *pgdat, gfp_t mask,
>> +				unsigned int order)
>> +{
>> +	return NODE_RECLAIM_NOSCAN;
>> +}
>> +#endif
>> +
>>  extern int hwpoison_filter(struct page *p);
>>  
>>  extern u32 hwpoison_filter_dev_major;
>> -- 
>> 2.15.1
>
>-- 
>Michal Hocko
>SUSE Labs

-- 
Wei Yang
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