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=-8.5 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 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 E4949C04EB8 for ; Fri, 30 Nov 2018 15:24:11 +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 B059020868 for ; Fri, 30 Nov 2018 15:24:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="D9HkurDa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B059020868 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org 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:MIME-Version:References:In-Reply-To: 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=P7hc3eDScLGIeLwF6vsxDl9SWsXgJ6ivzlVbC+HjWII=; b=D9HkurDaAGOxua AItuneEXCuE9RUlZ7Nnfb1LYSBnay9UbHGhNH+TR3JSlFzAjqToLprRCQ/TyPQFGmyTcPJFy6AphN GrRboZldFYYFSzTHOV4N8Yf//qu0wTIenMsKwGw13x708IPLTbj30juX150/pYKRvkibhElWL3LPO 1suRswACUIn4RbCCitZxMpIZuNkQHFRpnJUEZ04TEBMZRS8u8VN1To7WuE2SDeel00ybsSW3qiZxR rmpcVyuostUX5x0DufhmmvhmvBWY7yMmWaUQVg4AOA2mucx3IrV2tuIqpkPreAEwiPlTUW395wZNV VbGpG14hCknhyKZ7hsMQ==; 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 1gSkeF-00016D-R7; Fri, 30 Nov 2018 15:24:07 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gSkeC-0000vC-1k for linux-arm-kernel@lists.infradead.org; Fri, 30 Nov 2018 15:24:05 +0000 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E997320868; Fri, 30 Nov 2018 15:23:52 +0000 (UTC) Date: Fri, 30 Nov 2018 10:23:51 -0500 From: Steven Rostedt To: Anders Roxell Subject: Re: [PATCH 3/3] arm64: ftrace: add cond_resched() to func ftrace_make_(call|nop) Message-ID: <20181130102351.61045b21@gandalf.local.home> In-Reply-To: <20181130150956.27620-1-anders.roxell@linaro.org> References: <20181130150956.27620-1-anders.roxell@linaro.org> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181130_072404_105392_097C620F X-CRM114-Status: GOOD ( 16.94 ) 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: keescook@chromium.org, Arnd Bergmann , catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, mingo@redhat.com, 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 Fri, 30 Nov 2018 16:09:56 +0100 Anders Roxell wrote: > Both of those functions end up calling ftrace_modify_code(), which is > expensive because it changes the page tables and flush caches. > Microseconds add up because this is called in a loop for each dyn_ftrace > record, and this triggers the softlockup watchdog unless we let it sleep > occasionally. > Rework so that we call cond_resched() before going into the > ftrace_modify_code() function. > > Co-developed-by: Arnd Bergmann > Signed-off-by: Arnd Bergmann > Signed-off-by: Anders Roxell I'm fine with this patch, but I'm not placing an ack on this patch just because I don't know the repercussions of such a change. I'll let you folks take full responsibility ;-) -- Steve > --- > arch/arm64/kernel/ftrace.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c > index de1a397d2d3f..9da38da58df7 100644 > --- a/arch/arm64/kernel/ftrace.c > +++ b/arch/arm64/kernel/ftrace.c > @@ -130,6 +130,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > old = aarch64_insn_gen_nop(); > new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK); > > + /* This function can take a long time when sanitizers are enabled, so > + * lets make sure we allow RCU processing. > + */ > + cond_resched(); > + > return ftrace_modify_code(pc, old, new, true); > } > > @@ -188,6 +193,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, > > new = aarch64_insn_gen_nop(); > > + /* This function can take a long time when sanitizers are enabled, so > + * lets make sure we allow RCU processing. > + */ > + cond_resched(); > + > return ftrace_modify_code(pc, old, new, validate); > } > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel