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b=kmkN62DE5cKaSONPPCbLG8qhpj6R5MJPh0Se463fV5Sp/k0iRT18qNOEdHKXdI1w8 bbGQVdhLrmn2K7JxbvytZu9FtADvYJODPOK0DgVMtd9I1U9UQMz81MzGn3j98hjod0 uU69N5QObZH40/rmGMa+ecy2P16DM+5vY65M4lmktYCTOLlT7kAKwUsUWyCmVv90xM JvrZMR3IHVm713GrQbKYolMVgg2bm4hICbZ0C3KvrmleqRjQrliGfTIizA0pezXFDS Mi68EliPjpoZuVzSAMTz2XQs0jB9MbCS2L9MHC8S9eH3ma0O7oqfN4mUj+65CpgrUz C6rXBaLo5puaA== Message-ID: <4d2853c9-edf4-4685-b186-7214ed6abd84@kernel.org> Date: Fri, 18 Sep 2026 14:26:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/4] mm: support promotion-only NUMA hinting scans To: Gregory Price , Peter Zijlstra Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, kas@kernel.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, jannh@google.com, pfalcato@suse.de, osalvador@suse.de, hannes@cmpxchg.org, raghavendra.kt@amd.com, stable@vger.kernel.org References: <20260911001826.2109390-1-gourry@gourry.net> <20260911001826.2109390-2-gourry@gourry.net> <20260917160328.GM4121339@noisy.programming.kicks-ass.net> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 5E0B8A0002 X-Stat-Signature: uh9pioxowo8458ei5q5s3h1xpafiwhru X-Rspamd-Server: rspam01 X-HE-Tag: 1789734426-126706 X-HE-Meta: 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 WrPGXO1y kJEloVLWHN9sgXrs5SgQBmYGr8p+Lfc3CI8cURtEZRljvy02BDqdsl6Lm1Hj2SapOyDwGwS6cj0FNAbU3vnE9G3rH27tZL3Er1nmVfvOf/tsi26PHTjUkxPg56B0V14U9TsiSnYE+pAbxU2q89InEdKUG3KLHmsuuZF7F/Pn9/9/lKn9emZMlaErmI8DVUKAKWDd9EXSpJX76frZyKE3YDqLMvhgb3DFvTfxaFsm5mYODeArLpPJ0nBh9C4CVbBB6YkGZeRmex/GivJnRVkW+60xRFaAxVZTH0zr6HQfoKQE4YMqRuhDnkQ3kh6Fsq6YjKfGmPf0WwmgbFw/GBp6yRADmpw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/17/26 18:14, Gregory Price wrote: > On Thu, Sep 17, 2026 at 06:03:28PM +0200, Peter Zijlstra wrote: >> On Thu, Sep 10, 2026 at 08:18:23PM -0400, Gregory Price wrote: >> >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >>> index 8dff37059faf..81359b414947 100644 >>> --- a/kernel/sched/fair.c >>> +++ b/kernel/sched/fair.c >>> @@ -4129,8 +4129,10 @@ static void task_numa_work(struct callback_head *work) >>> unsigned long nr_pte_updates = 0; >>> long pages, virtpages; >>> struct vma_iterator vmi; >>> + unsigned int numab_mode = READ_ONCE(sysctl_numa_balancing_mode); >> >> This thing sticks out like a sort thumb, does that want to be on top? >> Typically reverse xmas is preferred and all that. >> > > oi yeah sorry, should have given this a closer style look. > > will fix it up. > >>> bool vma_pids_skipped; >>> bool vma_pids_forced = false; >>> + bool promo_only; >>> >>> WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work)); >>> >> >>> --- a/mm/internal.h >>> +++ b/mm/internal.h >>> @@ -1237,11 +1237,12 @@ static inline bool vma_is_single_threaded_private(struct vm_area_struct *vma) >>> >>> #ifdef CONFIG_NUMA_BALANCING >>> bool folio_can_map_prot_numa(struct folio *folio, struct vm_area_struct *vma, >>> - bool is_private_single_threaded); >>> + bool is_private_single_threaded, bool promo_only); >> >> Two bools rather than updating the existing bool to a flags? > > every time i've added a flag field someone screeches at me, so I tend > to avoid it now - but i can do that's the preference here. > > Otherwise, i tend to follow rule of 3 for generalizing. The is_private_single_threaded only exists to repeatedly call vma_is_single_threaded_private(). Maybe we don't care about that optimization. So maybe move the vma_is_single_threaded_private() call into folio_can_map_prot_numa() and avoid one bool entirely ... and then maybe just pass the cp_flags? -- Cheers, David