Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1320960

Re: [PATCH] vmpressure: Fix subtree pressure detection

Show all headers | View raw

On 28.1.2016 16:55, Michal Hocko wrote:
> On Wed 27-01-16 19:28:57, Vladimir Davydov wrote:
>> When vmpressure is called for the entire subtree under pressure we
>> mistakenly use vmpressure->scanned instead of vmpressure->tree_scanned
>> when checking if vmpressure work is to be scheduled. This results in
>> suppressing all vmpressure events in the legacy cgroup hierarchy. Fix
>> it.
>>
>> Fixes: 8e8ae645249b ("mm: memcontrol: hook up vmpressure to socket pressure")
>> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
> 
> a = b += c made me scratch my head for a second but this looks correct

Ugh, it's actually a = b += a

While clever and compact, this will make scratch their head anyone looking at
the code in the future. Is it worth it?

> Acked-by: Michal Hocko <mhocko@suse.com>
> 
>> ---
>>  mm/vmpressure.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
>> index 9a6c0704211c..149fdf6c5c56 100644
>> --- a/mm/vmpressure.c
>> +++ b/mm/vmpressure.c
>> @@ -248,9 +248,8 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
>>  
>>  	if (tree) {
>>  		spin_lock(&vmpr->sr_lock);
>> -		vmpr->tree_scanned += scanned;
>> +		scanned = vmpr->tree_scanned += scanned;
>>  		vmpr->tree_reclaimed += reclaimed;
>> -		scanned = vmpr->scanned;
>>  		spin_unlock(&vmpr->sr_lock);
>>  
>>  		if (scanned < vmpressure_win)
>> -- 
>> 2.1.4
> 

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH] vmpressure: Fix subtree pressure detection Michal Hocko <mhocko@kernel.org> - 2016-01-28 17:00 +0100
  Re: [PATCH] vmpressure: Fix subtree pressure detection Vlastimil Babka <vbabka@suse.cz> - 2016-01-28 20:30 +0100
    Re: [PATCH] vmpressure: Fix subtree pressure detection Vladimir Davydov <vdavydov@virtuozzo.com> - 2016-01-29 09:40 +0100
      Re: [PATCH] vmpressure: Fix subtree pressure detection Andrew Morton <akpm@linux-foundation.org> - 2016-02-02 07:30 +0100

csiph-web