From patchwork Mon Sep 17 22:41:02 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 10603541 X-Patchwork-Delegate: agross@codeaurora.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DE1611508 for ; Mon, 17 Sep 2018 23:02:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BB00F2A72C for ; Mon, 17 Sep 2018 23:02:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ACF992A77A; Mon, 17 Sep 2018 23:02:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2E6482A72C for ; Mon, 17 Sep 2018 23:02:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730352AbeIREbg (ORCPT ); Tue, 18 Sep 2018 00:31:36 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48390 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727088AbeIREbf (ORCPT ); Tue, 18 Sep 2018 00:31:35 -0400 Received: from localhost (li1825-44.members.linode.com [172.104.248.44]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id C899EC77; Mon, 17 Sep 2018 23:02:06 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neeraj Upadhyay , Thomas Gleixner , "Peter Zijlstra (Intel)" , josh@joshtriplett.org, peterz@infradead.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org, mojha@codeaurora.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org Subject: [PATCH 4.14 014/126] cpu/hotplug: Adjust misplaced smb() in cpuhp_thread_fun() Date: Tue, 18 Sep 2018 00:41:02 +0200 Message-Id: <20180917211705.614335388@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180917211703.481236999@linuxfoundation.org> References: <20180917211703.481236999@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Neeraj Upadhyay commit f8b7530aa0a1def79c93101216b5b17cf408a70a upstream. The smp_mb() in cpuhp_thread_fun() is misplaced. It needs to be after the load of st->should_run to prevent reordering of the later load/stores w.r.t. the load of st->should_run. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Signed-off-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: mojha@codeaurora.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/1536126727-11629-1-git-send-email-neeraju@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- kernel/cpu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -612,15 +612,15 @@ static void cpuhp_thread_fun(unsigned in bool bringup = st->bringup; enum cpuhp_state state; + if (WARN_ON_ONCE(!st->should_run)) + return; + /* * ACQUIRE for the cpuhp_should_run() load of ->should_run. Ensures * that if we see ->should_run we also see the rest of the state. */ smp_mb(); - if (WARN_ON_ONCE(!st->should_run)) - return; - cpuhp_lock_acquire(bringup); if (st->single) { From patchwork Mon Sep 17 22:41:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 10603561 X-Patchwork-Delegate: agross@codeaurora.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 883615A4 for ; Mon, 17 Sep 2018 23:29:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 787DE2A75A for ; Mon, 17 Sep 2018 23:29:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6C8B02A75F; Mon, 17 Sep 2018 23:29:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DEDA72A75B for ; Mon, 17 Sep 2018 23:29:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730014AbeIREbj (ORCPT ); Tue, 18 Sep 2018 00:31:39 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48412 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727088AbeIREbj (ORCPT ); Tue, 18 Sep 2018 00:31:39 -0400 Received: from localhost (li1825-44.members.linode.com [172.104.248.44]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id F043FC03; Mon, 17 Sep 2018 23:02:09 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Neeraj Upadhyay , Thomas Gleixner , Geert Uytterhoeven , Sudeep Holla , josh@joshtriplett.org, peterz@infradead.org, jiangshanlai@gmail.com, dzickus@redhat.com, brendan.jackman@arm.com, malat@debian.org, sramana@codeaurora.org, linux-arm-msm@vger.kernel.org Subject: [PATCH 4.14 015/126] cpu/hotplug: Prevent state corruption on error rollback Date: Tue, 18 Sep 2018 00:41:03 +0200 Message-Id: <20180917211705.700936708@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180917211703.481236999@linuxfoundation.org> References: <20180917211703.481236999@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 69fa6eb7d6a64801ea261025cce9723d9442d773 upstream. When a teardown callback fails, the CPU hotplug code brings the CPU back to the previous state. The previous state becomes the new target state. The rollback happens in undo_cpu_down() which increments the state unconditionally even if the state is already the same as the target. As a consequence the next CPU hotplug operation will start at the wrong state. This is easily to observe when __cpu_disable() fails. Prevent the unconditional undo by checking the state vs. target before incrementing state and fix up the consequently wrong conditional in the unplug code which handles the failure of the final CPU take down on the control CPU side. Fixes: 4dddfb5faa61 ("smp/hotplug: Rewrite AP state machine core") Reported-by: Neeraj Upadhyay Signed-off-by: Thomas Gleixner Tested-by: Geert Uytterhoeven Tested-by: Sudeep Holla Tested-by: Neeraj Upadhyay Cc: josh@joshtriplett.org Cc: peterz@infradead.org Cc: jiangshanlai@gmail.com Cc: dzickus@redhat.com Cc: brendan.jackman@arm.com Cc: malat@debian.org Cc: sramana@codeaurora.org Cc: linux-arm-msm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1809051419580.1416@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman ---- --- kernel/cpu.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -932,7 +932,8 @@ static int cpuhp_down_callbacks(unsigned ret = cpuhp_invoke_callback(cpu, st->state, false, NULL, NULL); if (ret) { st->target = prev_state; - undo_cpu_down(cpu, st); + if (st->state < prev_state) + undo_cpu_down(cpu, st); break; } } @@ -985,7 +986,7 @@ static int __ref _cpu_down(unsigned int * to do the further cleanups. */ ret = cpuhp_down_callbacks(cpu, st, target); - if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) { + if (ret && st->state == CPUHP_TEARDOWN_CPU && st->state < prev_state) { cpuhp_reset_state(st, prev_state); __cpuhp_kick_ap(st); } From patchwork Mon Sep 17 22:41:23 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 10603563 X-Patchwork-Delegate: agross@codeaurora.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 651545A4 for ; Mon, 17 Sep 2018 23:29:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 53CF82A75F for ; Mon, 17 Sep 2018 23:29:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 466FC2A765; Mon, 17 Sep 2018 23:29:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1F78C2A75F for ; Mon, 17 Sep 2018 23:29:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729166AbeIREaw (ORCPT ); Tue, 18 Sep 2018 00:30:52 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48274 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728884AbeIREaw (ORCPT ); Tue, 18 Sep 2018 00:30:52 -0400 Received: from localhost (li1825-44.members.linode.com [172.104.248.44]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 9A63CC03; Mon, 17 Sep 2018 23:01:23 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gaurav Kohli , Thomas Gleixner , john.stultz@linaro.org, sboyd@kernel.org, linux-arm-msm@vger.kernel.org, Sasha Levin Subject: [PATCH 4.14 035/126] timers: Clear timer_base::must_forward_clk with timer_base::lock held Date: Tue, 18 Sep 2018 00:41:23 +0200 Message-Id: <20180917211707.091416499@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180917211703.481236999@linuxfoundation.org> References: <20180917211703.481236999@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gaurav Kohli [ Upstream commit 363e934d8811d799c88faffc5bfca782fd728334 ] timer_base::must_forward_clock is indicating that the base clock might be stale due to a long idle sleep. The forwarding of the base clock takes place in the timer softirq or when a timer is enqueued to a base which is idle. If the enqueue of timer to an idle base happens from a remote CPU, then the following race can happen: CPU0 CPU1 run_timer_softirq mod_timer base = lock_timer_base(timer); base->must_forward_clk = false if (base->must_forward_clk) forward(base); -> skipped enqueue_timer(base, timer, idx); -> idx is calculated high due to stale base unlock_timer_base(timer); base = lock_timer_base(timer); forward(base); The root cause is that timer_base::must_forward_clk is cleared outside the timer_base::lock held region, so the remote queuing CPU observes it as cleared, but the base clock is still stale. This can cause large granularity values for timers, i.e. the accuracy of the expiry time suffers. Prevent this by clearing the flag with timer_base::lock held, so that the forwarding takes place before the cleared flag is observable by a remote CPU. Signed-off-by: Gaurav Kohli Signed-off-by: Thomas Gleixner Cc: john.stultz@linaro.org Cc: sboyd@kernel.org Cc: linux-arm-msm@vger.kernel.org Link: https://lkml.kernel.org/r/1533199863-22748-1-git-send-email-gkohli@codeaurora.org Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/time/timer.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1609,6 +1609,22 @@ static inline void __run_timers(struct t raw_spin_lock_irq(&base->lock); + /* + * timer_base::must_forward_clk must be cleared before running + * timers so that any timer functions that call mod_timer() will + * not try to forward the base. Idle tracking / clock forwarding + * logic is only used with BASE_STD timers. + * + * The must_forward_clk flag is cleared unconditionally also for + * the deferrable base. The deferrable base is not affected by idle + * tracking and never forwarded, so clearing the flag is a NOOP. + * + * The fact that the deferrable base is never forwarded can cause + * large variations in granularity for deferrable timers, but they + * can be deferred for long periods due to idle anyway. + */ + base->must_forward_clk = false; + while (time_after_eq(jiffies, base->clk)) { levels = collect_expired_timers(base, heads); @@ -1628,19 +1644,6 @@ static __latent_entropy void run_timer_s { struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); - /* - * must_forward_clk must be cleared before running timers so that any - * timer functions that call mod_timer will not try to forward the - * base. idle trcking / clock forwarding logic is only used with - * BASE_STD timers. - * - * The deferrable base does not do idle tracking at all, so we do - * not forward it. This can result in very large variations in - * granularity for deferrable timers, but they can be deferred for - * long periods due to idle. - */ - base->must_forward_clk = false; - __run_timers(base); if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) __run_timers(this_cpu_ptr(&timer_bases[BASE_DEF]));