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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1A7KKpu8iHyelnMvFNOPHpastJBG2S7fqWEYdd55aZM=; b=Xj3F/cK4EVuMEhCNsyH88Dhuc3VAinznhN2fx1XbxS+5tpQwROBdGBE/p+nZjBSehC AVqDRVYOuPuiqjG4P9gvdna6q1efJ+O+kw7WBaVO1Q4KcDKaN+bsKvIOzQ7w5rgSWIwV Xjb+A7gvR+bMU2ZY1cYeXwsfB0V64N7wcTLfr68pn0OsjT7IEJusRbDtTtNSclO6Egy2 bfSxDeIBh+s5iyaaUe3Lm/bRwlgm7dm9TC+aLaZh6poO5KkaRp7dSnfi6aanYfmbLzoO 7rOitAMHJfcwiucwegYz4VF4WRv+q86edR1nXBInpdYYNc8io7myslTLcw6Zl48qLaGW X8IQ== X-Gm-Message-State: AOAM533GIK61euP8gYewPyZJt1KWg4nVWhWNzOBmRO+TfXZs1INV525j TitaCmchKU3tM3LFxx8CAWixeYWKWNpDSjRp+qnZLw== X-Google-Smtp-Source: ABdhPJyLOUdems4JWzS/MRZn8GpPxi1lg+1JMAhEnm9vnRVUPvvsCtolJPvi2h6QcMszn37KmBclhtRFhGzGacKicbs= X-Received: by 2002:a9d:bb2:: with SMTP id 47mr5794824oth.160.1603680985321; Sun, 25 Oct 2020 19:56:25 -0700 (PDT) MIME-Version: 1.0 References: <20201021073839.43935-1-zong.li@sifive.com> <50bdca78-0cbb-5c62-f241-ed50737131b2@canonical.com> In-Reply-To: <50bdca78-0cbb-5c62-f241-ed50737131b2@canonical.com> From: Zong Li Date: Mon, 26 Oct 2020 10:56:16 +0800 Message-ID: Subject: Re: [PATCH] stop_machine: Mark functions as notrace To: Colin Ian King X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201025_225628_620887_46B9A400 X-CRM114-Status: GOOD ( 22.21 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: rcu@vger.kernel.org, Palmer Dabbelt , paulmck@kernel.org, vincent.whitchurch@axis.com, jiangshanlai@gmail.com, josh@joshtriplett.org, Steven Rostedt , "linux-kernel@vger.kernel.org List" , Atish Patra , linux-riscv , mathieu.desnoyers@efficios.com, Masami Hiramatsu , Paul Walmsley , joel@joelfernandes.org, Guo Ren , tglx@linutronix.de, Greentime Hu Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Sat, Oct 24, 2020 at 3:29 AM Colin Ian King wrote: > > On 21/10/2020 08:38, Zong Li wrote: > > Like the commit cb9d7fd51d9f ("watchdog: Mark watchdog touch functions > > as notrace"), some architectures assume that the stopped CPUs don't make > > function calls to traceable functions when they are in the stopped > > state. For example, it causes unexpected kernel crashed when switching > > tracer on RISC-V. > > > > The following patches added calls to these two functions, fix it by > > adding the notrace annotations. > > > > Fixes: 4ecf0a43e729 ("processor: get rid of cpu_relax_yield") > > Fixes: 366237e7b083 ("stop_machine: Provide RCU quiescent state in > > multi_cpu_stop()") > > > > Signed-off-by: Zong Li > > --- > > kernel/rcu/tree.c | 2 +- > > kernel/stop_machine.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 06895ef85d69..2a52f42f64b6 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -409,7 +409,7 @@ bool rcu_eqs_special_set(int cpu) > > * > > * The caller must have disabled interrupts and must not be idle. > > */ > > -void rcu_momentary_dyntick_idle(void) > > +notrace void rcu_momentary_dyntick_idle(void) > > { > > int special; > > > > diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c > > index 865bb0228ab6..890b79cf0e7c 100644 > > --- a/kernel/stop_machine.c > > +++ b/kernel/stop_machine.c > > @@ -178,7 +178,7 @@ static void ack_state(struct multi_stop_data *msdata) > > set_state(msdata, msdata->state + 1); > > } > > > > -void __weak stop_machine_yield(const struct cpumask *cpumask) > > +notrace void __weak stop_machine_yield(const struct cpumask *cpumask) > > { > > cpu_relax(); > > } > > > > Apologies for taking so long to reply, I needed to test this on several > devices. > > This not only fixes the ftrace issue I see on RISC-V but also a ftrace > hang issue on ARM64 in 5.8 too. > > Tested-by: Colin Ian King > > Many thanks! Many thanks all for reviewing and testing. Hi Palmer, As Steven suggested, could you help to pick up this patch in RISC-V tree? _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv