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=-10.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 40169C04EB8 for ; Thu, 6 Dec 2018 13:20:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0A25F20892 for ; Thu, 6 Dec 2018 13:20:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="NyjpHhvw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A25F20892 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=olEuYb6RPg1bHpXg9saKxv+HWqTzNB/uwFfwvFnSEQg=; b=NyjpHhvwS7+tvJ zYb2NgfZHdDLKQ+tNt0Y18SZBtMAX9T0yvatg1JZh0IteRqFO+lqdH4JI/P+P/2gfggkKX5eGfEEd kTu1Vg3F+atU0kfoFIR3P0296bSvBnGo661F7BxSzAhgwIszeNbF8mAMq/KQqSJ8V8XdQRv7KJCv+ 6lmxEflxirufEo0Vb7jCatkEnBkZO+VS/on23RR8kuDm6RhNgZu3vESobhSlW4tNiIE07CUgD2vNZ yRTxqHytTtsTiT0yjGw6FLEkNX1s3kqrDd4XV7Pdk0WpXkAXHdvLPdUD+Xr/ilQ3FWpKfLbY1IVww 2PBoApeRCX8ukslCc0+g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUtZS-0000iG-Kc; Thu, 06 Dec 2018 13:20:02 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gUtZN-0000WJ-Q0 for linux-arm-kernel@lists.infradead.org; Thu, 06 Dec 2018 13:20:00 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1026EA78; Thu, 6 Dec 2018 05:19:47 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D47853F575; Thu, 6 Dec 2018 05:19:46 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id E7AB51AE0BAD; Thu, 6 Dec 2018 13:20:07 +0000 (GMT) Date: Thu, 6 Dec 2018 13:20:07 +0000 From: Will Deacon To: Steven Rostedt Subject: Re: [PATCH 2/2] arm64: ftrace: Set FTRACE_SCHEDULABLE before ftrace_modify_all_code() Message-ID: <20181206132007.GB27744@arm.com> References: <20181205174852.435233070@goodmis.org> <20181205183304.000714627@goodmis.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181205183304.000714627@goodmis.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181206_051957_849469_7A494FE7 X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anders Roxell , keescook@chromium.org, arnd@arndb.de, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, Ingo Molnar , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Dec 05, 2018 at 12:48:54PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > It has been reported that ftrace_replace_code() which is called by > ftrace_modify_all_code() can cause a soft lockup warning for an > allmodconfig kernel. This is because all the debug options enabled > causes the loop in ftrace_replace_code() (which loops over all the > functions being enabled where there can be 10s of thousands), is too > slow, and never schedules out. > > To solve this, setting FTRACE_SCHEDULABLE to the command passed into > ftrace_replace_code() will make it call cond_resched() in the loop, > which prevents the soft lockup warning from triggering. > > Link: http://lkml.kernel.org/r/20181204192903.8193-1-anders.roxell@linaro.org > > Reported-by: Anders Roxell > Signed-off-by: Steven Rostedt (VMware) > --- > arch/arm64/kernel/ftrace.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c > index 57e962290df3..9a8de0a79f97 100644 > --- a/arch/arm64/kernel/ftrace.c > +++ b/arch/arm64/kernel/ftrace.c > @@ -193,6 +193,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, > > void arch_ftrace_update_code(int command) > { > + command |= FTRACE_SCHEDULABLE; > ftrace_modify_all_code(command); > } Bikeshed: I'd probably go for FTRACE_MAY_SLEEP, but I'm not going to die on that hill so... Acked-by: Will Deacon Thanks, Steve! Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel