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[23.128.96.18]) by mx.google.com with ESMTP id j23si8862372ejc.46.2020.11.10.06.19.45; Tue, 10 Nov 2020 06:20:11 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@joelfernandes.org header.s=google header.b="IP/8t6oI"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730524AbgKJOPs (ORCPT + 99 others); Tue, 10 Nov 2020 09:15:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730306AbgKJOPr (ORCPT ); Tue, 10 Nov 2020 09:15:47 -0500 Received: from mail-qt1-x844.google.com (mail-qt1-x844.google.com [IPv6:2607:f8b0:4864:20::844]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90D3DC0613CF for ; Tue, 10 Nov 2020 06:15:47 -0800 (PST) Received: by mail-qt1-x844.google.com with SMTP id g17so8609550qts.5 for ; Tue, 10 Nov 2020 06:15:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=p3WN5JU8sozr2KBLEdmgK30iN6981Pj68syboeSAB+I=; b=IP/8t6oIpA5IcgxnzxGzBrn/TOFFwSd8Yyx6nWnWozca4T7EUUEY8iJHio8imC90rP PORF7vMiiJG7V7Lhieexs9l5K1x5g3/wMCxQvP921o/ADRZ4ju1m8VeE+YrUnUVtXirD 67+2IXLz1slh/caxtJ6BSPH+xoRAWe+jCzBhI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=p3WN5JU8sozr2KBLEdmgK30iN6981Pj68syboeSAB+I=; b=BfMVSuyyX8iPQ2HBWD3bWYFeKG2028zWv6HrhLdgof+ww4DYKVHfYTaWfvJ4JAEZT2 iSCvR+F344PsXvQzLTvLzoi9IG0zmj6dfi3xwyNMmY426bK94+muuQ9j3U1IK5ePeWsA WJJjkNwaLshz1qYAWOIgQsbuf8kYpf7M6ZIVo23Z8vRvP2jqZRgCTZCzWrz180z1X5A9 AU/3pEEMGXBIz9i2/MK6JQfbA5Akmf16HfsdGkw5tk0N1RbaW3MqTUFbB1+uMNJszi1Q 59P4in0A2hSXuRoyygXWsEcsCTsHHxa3SSsCr6ev4+evM8gSRDnJsQ3N2yN+2XDmDu41 V2dw== X-Gm-Message-State: AOAM530oCjFFHBzwPDu9V4oB4sfG3rjOCZD6uhXb15H4KrwcyKTiNFwm CH62VFFNcNUhw/CS7Segzn5W0Q== X-Received: by 2002:ac8:4613:: with SMTP id p19mr18856364qtn.13.1605017746774; Tue, 10 Nov 2020 06:15:46 -0800 (PST) Received: from localhost ([2620:15c:6:411:cad3:ffff:feb3:bd59]) by smtp.gmail.com with ESMTPSA id z11sm2981618qkz.38.2020.11.10.06.15.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2020 06:15:46 -0800 (PST) Date: Tue, 10 Nov 2020 09:15:45 -0500 From: Joel Fernandes To: chris hyser Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 -tip 17/26] sched: Split the cookie and setup per-task cookie on fork Message-ID: <20201110141545.GA559148@google.com> References: <4ff7f030-b797-6711-fb6a-fe39bb02075a@oracle.com> <6e864ca1-d02b-dc56-7ec2-6224eeb0b32d@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6e864ca1-d02b-dc56-7ec2-6224eeb0b32d@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 09, 2020 at 06:23:13PM -0500, chris hyser wrote: [..] > > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > > index fe6f225bfbf9..c6034c00846a 100644 > > > --- a/include/linux/sched.h > > > +++ b/include/linux/sched.h > > > @@ -688,6 +688,8 @@ struct task_struct { > > > #ifdef CONFIG_SCHED_CORE > > > struct rb_node core_node; > > > unsigned long core_cookie; > > > + unsigned long core_task_cookie; > > > + unsigned long core_group_cookie; > > > unsigned int core_occupation; > > > #endif > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > > index bab4ea2f5cd8..30a9e4cb5ce1 100644 > > > --- a/kernel/sched/core.c > > > +++ b/kernel/sched/core.c > > > @@ -346,11 +346,14 @@ void sched_core_put(void) > > > mutex_unlock(&sched_core_mutex); > > > } > > > +static int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2); > > > + > > > #else /* !CONFIG_SCHED_CORE */ > > > static inline void sched_core_enqueue(struct rq *rq, struct task_struct *p) { } > > > static inline void sched_core_dequeue(struct rq *rq, struct task_struct *p) { } > > > static bool sched_core_enqueued(struct task_struct *task) { return false; } > > > +static int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2) { } > > > #endif /* CONFIG_SCHED_CORE */ > > > @@ -3583,6 +3586,20 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) > > > #endif > > > #ifdef CONFIG_SCHED_CORE > > > RB_CLEAR_NODE(&p->core_node); > > > + > > > + /* > > > + * Tag child via per-task cookie only if parent is tagged via per-task > > > + * cookie. This is independent of, but can be additive to the CGroup tagging. > > > + */ > > > + if (current->core_task_cookie) { > > > + > > > + /* If it is not CLONE_THREAD fork, assign a unique per-task tag. */ > > > + if (!(clone_flags & CLONE_THREAD)) { > > > + return sched_core_share_tasks(p, p); > > > + } > > > + /* Otherwise share the parent's per-task tag. */ > > > + return sched_core_share_tasks(p, current); > > > + } > > > #endif > > > return 0; > > > } > > sched_core_share_tasks() looks at the value of the new tasks core_task_cookie which is non-zero on a > process or thread clone and causes underflow for both the enable flag itself and for cookie ref counts. > > So just zero it in __sched_fork(). Nice catch, applying to my v9 staging tree. Thanks! thanks, - Joel > > -chris > > > PATCH] sched: zero out the core scheduling cookie on clone > > From: chris hyser > > As the cookie is reference counted, even if inherited, zero this and allow > explicit sharing. > > Signed-off-by: Chris Hyser > --- > kernel/sched/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index fd3cc03..2af0ea6 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3378,6 +3378,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p) > p->capture_control = NULL; > #endif > init_numa_balancing(clone_flags, p); > +#ifdef CONFIG_SCHED_CORE > + p->core_task_cookie = 0; > +#endif > #ifdef CONFIG_SMP > p->wake_entry.u_flags = CSD_TYPE_TTWU; > #endif > -- > 1.8.3.1 >