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From: "Michal Koutný" <mkoutny@suse.com>
To: "Chen, Yu C" <yu.c.chen@intel.com>
Cc: "Jain, Ayush" <ayushjai@amd.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>,
	 Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	 Mel Gorman <mgormanmgorman@suse.de>,
	Michal Hocko <mhocko@kernel.org>,
	 Muchun Song <muchun.song@linux.dev>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	 Shakeel Butt <shakeel.butt@linux.dev>,
	"Chen, Tim C" <tim.c.chen@intel.com>,
	 Aubrey Li <aubrey.li@intel.com>,
	Libo Chen <libo.chen@oracle.com>,
	cgroups@vger.kernel.org,  linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	 K Prateek Nayak <kprateek.nayak@amd.com>,
	Madadi Vineeth Reddy <vineethr@linux.ibm.com>,
	 Neeraj.Upadhyay@amd.com, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3] sched/numa: add statistics of numa balance task migration
Date: Mon, 5 May 2025 19:46:36 +0200	[thread overview]
Message-ID: <tkfh4h5ntl42jc2tnwyj6dhiqouf6mowin7euvrnbs2tyiqlay@bpzdptv3plsf> (raw)
In-Reply-To: <bd936eba-e536-4825-ae64-d1bd23c6eb4c@intel.com>

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On Mon, May 05, 2025 at 11:03:10PM +0800, "Chen, Yu C" <yu.c.chen@intel.com> wrote:
> According to this address,
>    4c 8b af 50 09 00 00    mov    0x950(%rdi),%r13  <--- r13 = p->mm;
>    49 8b bd 98 04 00 00    mov    0x498(%r13),%rdi  <--- p->mm->owner
> It seems that this task to be swapped has NULL mm_struct.

So it's likely a kernel thread. Does it make sense to NUMA balance
those? (I naïvely think it doesn't, please correct me.) ...

>  static void __migrate_swap_task(struct task_struct *p, int cpu)
>  {
>         __schedstat_inc(p->stats.numa_task_swapped);
> -       count_memcg_event_mm(p->mm, NUMA_TASK_SWAP);
> +       if (p->mm)
> +               count_memcg_event_mm(p->mm, NUMA_TASK_SWAP);

... proper fix should likely guard this earlier, like the guard in
task_numa_fault() but for the other swapped task.

Michal

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  parent reply	other threads:[~2025-05-05 17:46 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-30 10:36 Chen Yu
2025-05-01  7:00 ` Libo Chen
2025-05-02  9:30   ` Chen, Yu C
2025-05-05  6:43 ` Jain, Ayush
2025-05-05 15:03   ` Chen, Yu C
2025-05-05 17:25     ` Venkat Rao Bagalkote
2025-05-07 11:36       ` Chen, Yu C
2025-05-05 17:46     ` Michal Koutný [this message]
2025-05-05 18:27       ` Chen, Yu C
2025-05-05 18:49         ` Libo Chen
2025-05-05 21:32           ` Libo Chen
2025-05-05 21:57             ` Libo Chen
2025-05-06  5:06               ` Jain, Ayush
2025-05-06  5:36               ` Chen, Yu C
2025-05-06  7:03                 ` Libo Chen

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