From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A109AC433E0 for ; Sat, 6 Mar 2021 11:43:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7A5916501F for ; Sat, 6 Mar 2021 11:43:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231392AbhCFLnG (ORCPT ); Sat, 6 Mar 2021 06:43:06 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:34368 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230414AbhCFLm0 (ORCPT ); Sat, 6 Mar 2021 06:42:26 -0500 Date: Sat, 06 Mar 2021 11:42:25 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1615030945; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WIvpUyVDIljWNxa2RGDJ6dtq/5Dl6SJlZHC8zYxqgvM=; b=xkCbhp6mr36JjfDkjUlpYXOqursnAsGTzvbgaIVpijR9W/bW4rZ1M+U/waK7g7EtRRvI8x F53L/0Ol0RK98XjV+tuP4vUuig+JRs4yVZ6AETEvxypZMN8evf/YKeEnPIUofj1ukr2fL/ bD7yOydVb0EfseQdVAYUxFOeffX5dskfevX5+IxN4oFiIuE6CDVBwOrcFNL1ll8f/w92k5 PF4CjXAYjMXPC/pleIPvbqLCPHgYSCaKLl4X37+wcsfM0ehbKVqf1u7EG6HXJLCSx7pz+a 0GQT8m1nY2I8nCsWdj+rmAVYANcQTugSk1UECh9Tunq38fqXXdrW+hRXQwbiGw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1615030945; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WIvpUyVDIljWNxa2RGDJ6dtq/5Dl6SJlZHC8zYxqgvM=; b=VhPY8/ti/AuBftKF4fEbTkx/7A95PO9r3EYa0zDwlFjZRCtrqY12RrZyLDLay+SvE0bo6o J+2TbjpmDOsvVYAg== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched: Fix affine_move_task() self-concurrency Cc: stable@kernel.org, "Peter Zijlstra (Intel)" , Ingo Molnar , Valentin Schneider , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210224131355.649146419@infradead.org> References: <20210224131355.649146419@infradead.org> MIME-Version: 1.0 Message-ID: <161503094501.398.7070933133621230778.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 9e81889c7648d48dd5fe13f41cbc99f3c362484a Gitweb: https://git.kernel.org/tip/9e81889c7648d48dd5fe13f41cbc99f3c362484a Author: Peter Zijlstra AuthorDate: Wed, 24 Feb 2021 11:31:09 +01:00 Committer: Ingo Molnar CommitterDate: Sat, 06 Mar 2021 12:40:21 +01:00 sched: Fix affine_move_task() self-concurrency Consider: sched_setaffinity(p, X); sched_setaffinity(p, Y); Then the first will install p->migration_pending = &my_pending; and issue stop_one_cpu_nowait(pending); and the second one will read p->migration_pending and _also_ issue: stop_one_cpu_nowait(pending), the _SAME_ @pending. This causes stopper list corruption. Add set_affinity_pending::stop_pending, to indicate if a stopper is in progress. Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") Cc: stable@kernel.org Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210224131355.649146419@infradead.org --- kernel/sched/core.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ac05afb..4e4d100 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1864,6 +1864,7 @@ struct migration_arg { struct set_affinity_pending { refcount_t refs; + unsigned int stop_pending; struct completion done; struct cpu_stop_work stop_work; struct migration_arg arg; @@ -1982,12 +1983,15 @@ static int migration_cpu_stop(void *data) * determine is_migration_disabled() and so have to chase after * it. */ + WARN_ON_ONCE(!pending->stop_pending); task_rq_unlock(rq, p, &rf); stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop, &pending->arg, &pending->stop_work); return 0; } out: + if (pending) + pending->stop_pending = false; task_rq_unlock(rq, p, &rf); if (complete) @@ -2183,7 +2187,7 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag int dest_cpu, unsigned int flags) { struct set_affinity_pending my_pending = { }, *pending = NULL; - bool complete = false; + bool stop_pending, complete = false; /* Can the task run on the task's current CPU? If so, we're done */ if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) { @@ -2256,14 +2260,19 @@ static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flag * anything else we cannot do is_migration_disabled(), punt * and have the stopper function handle it all race-free. */ + stop_pending = pending->stop_pending; + if (!stop_pending) + pending->stop_pending = true; refcount_inc(&pending->refs); /* pending->{arg,stop_work} */ if (flags & SCA_MIGRATE_ENABLE) p->migration_flags &= ~MDF_PUSH; task_rq_unlock(rq, p, rf); - stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop, - &pending->arg, &pending->stop_work); + if (!stop_pending) { + stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop, + &pending->arg, &pending->stop_work); + } if (flags & SCA_MIGRATE_ENABLE) return 0;