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From: Tim Chen <tim.c.chen@linux.intel.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.cz>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Ying Huang <ying.huang@intel.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] mm: Fix missing mem cgroup soft limit tree updates
Date: Tue, 9 Feb 2021 14:34:07 -0800	[thread overview]
Message-ID: <3445ebcd-bc69-ec6e-8995-c95753b5c4a7@linux.intel.com> (raw)
In-Reply-To: <YCMLEB/2IscnaGGh@cmpxchg.org>



On 2/9/21 2:22 PM, Johannes Weiner wrote:
> Hello Tim,
> 
> On Tue, Feb 09, 2021 at 12:29:47PM -0800, Tim Chen wrote:
>> @@ -6849,7 +6850,9 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
>>  	 * exclusive access to the page.
>>  	 */
>>  
>> -	if (ug->memcg != page_memcg(page)) {
>> +	if (ug->memcg != page_memcg(page) ||
>> +	    /* uncharge batch update soft limit tree on a node basis */
>> +	    (ug->dummy_page && ug->nid != page_to_nid(page))) {
> 
> The fix makes sense to me.
> 
> However, unconditionally breaking up the batch by node can
> unnecessarily regress workloads in cgroups that do not have a soft
> limit configured, and cgroup2 which doesn't have soft limits at
> all. Consider an interleaving allocation policy for example.
> 
> Can you please further gate on memcg->soft_limit != PAGE_COUNTER_MAX,
> or at least on !cgroup_subsys_on_dfl(memory_cgrp_subsys)?
> 

Sure.  Will fix this.

Tim

  reply	other threads:[~2021-02-10  1:11 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-09 20:29 [PATCH 0/3] Soft limit memory management bug fixes Tim Chen
2021-02-09 20:29 ` [PATCH 1/3] mm: Fix dropped memcg from mem cgroup soft limit tree Tim Chen
2021-02-10  9:47   ` Michal Hocko
2021-02-09 20:29 ` [PATCH 2/3] mm: Force update of mem cgroup soft limit tree on usage excess Tim Chen
2021-02-10  9:51   ` Michal Hocko
2021-02-09 20:29 ` [PATCH 3/3] mm: Fix missing mem cgroup soft limit tree updates Tim Chen
2021-02-09 22:22   ` Johannes Weiner
2021-02-09 22:34     ` Tim Chen [this message]
2021-02-10 10:08   ` Michal Hocko

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