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Fri, 11 Apr 2025 10:26:32 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 11 Apr 2025 12:26:01 +0200 (CEST) Date: Fri, 11 Apr 2025 12:25:56 +0200 From: Oleg Nesterov To: Frederic Weisbecker Cc: LKML , Andrew Morton , Ingo Molnar , Marcelo Tosatti , Michal Hocko , Peter Zijlstra , Thomas Gleixner , Valentin Schneider , Vlastimil Babka , linux-mm@kvack.org Subject: Re: [PATCH 5/6] sched/isolation: Introduce isolated task work Message-ID: <20250411102555.GA5322@redhat.com> References: <20250410152327.24504-1-frederic@kernel.org> <20250410152327.24504-6-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250410152327.24504-6-frederic@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspamd-Queue-Id: 3A4F5160004 X-Stat-Signature: w11jsg571h4p87964aqqrjdwcojfdqa5 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1744367203-901675 X-HE-Meta: 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 AW4U8aB+ Z9mn1Fnlqy5NnnTcjQwgwcs4T/w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: I know nothing about this code so I can't review, but let me ask anyway... On 04/10, Frederic Weisbecker wrote: > > +int __isolated_task_work_queue(void) > +{ > + unsigned long flags; > + int ret; > + > + if (current->flags & PF_KTHREAD) > + return -EINVAL; What about PF_USER_WORKER's ? IIUC, these (in fact kernel) threads never return to userspace and never call task_work_run(). Or PF_IO_WORKER's, they too run only in kernel mode... But iirc they do call task_work_run(). > + local_irq_save(flags); > + if (task_work_queued(¤t->nohz_full_work)) { > + ret = 0; > + goto out; > + } > + > + ret = task_work_add(current, ¤t->nohz_full_work, TWA_RESUME); > +out: > + local_irq_restore(flags); > + return ret; Hmm, why not local_irq_save(flags); if (task_work_queued(...)) ret = 0; else ret = task_work_add(...); ? Oleg.