From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2856A2111 for ; Fri, 11 Apr 2025 10:26:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744367204; cv=none; b=bMhG2fFg2Vbn7FXjf11B/pUHl0DJvvGfv25q7z+xjoCsiyVsDwXUM7lQXLSPbM3n30KzBmNgXni9vkxxohjGAaJd4I1xB0zazJYp0iiWFzcVz+iEnzJBlun1W5HL3Jf1S0hcPNR3jy722bkOLth1vnRBuix0yayhk6LYZwdIgw4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744367204; c=relaxed/simple; bh=aHuCE/uU7spSprHLf5V5HqSNXI02fPpj/JvVgJEM574=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sGJXboCbCCZS6v1dJJD1sUKmThMEvaUaXx2QHzjU8O2cMBKMn0zkSgLnezr3jSpJi5sZF3IcStHYSR35phA6SMB0I9hE0hAV/7KBOuPr7IAeN2yczQHYuE8rFqk0Bd4RkwOaf3PE+dztuWXQ2i+30+Z/gXYDc9iMFzwk1l1OB8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OHdImQMY; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OHdImQMY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744367202; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JmMufGW94wEMZGWR6BkGZ+0dzdW798fPhJuI4K0fmUQ=; b=OHdImQMY/jBXZLxwIbg+8pjYDKW8wYP6QrvilvZMuotuKiHrprECg6lDAMQHNqMnk4ww56 j4+2mLopMXKOpbQLvVzT1yDGgEc9y31fYlefnr3Tn5A/nk3jGk0icazs82wz5f7SwpvgZW QnHnH2RDZUMsI3ZzhyfNYTpK9lVGZi8= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-614-3-uVoF_uO9y8ccWm1ixl5A-1; Fri, 11 Apr 2025 06:26:38 -0400 X-MC-Unique: 3-uVoF_uO9y8ccWm1ixl5A-1 X-Mimecast-MFC-AGG-ID: 3-uVoF_uO9y8ccWm1ixl5A_1744367197 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0905B1955DC5; Fri, 11 Apr 2025 10:26:37 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.224.222]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id CEBE8180176C; 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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.