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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8FC8C77B7A for ; Tue, 16 May 2023 16:03:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234162AbjEPQDV (ORCPT ); Tue, 16 May 2023 12:03:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232434AbjEPQDT (ORCPT ); Tue, 16 May 2023 12:03:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D35CAC7; Tue, 16 May 2023 09:03:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7138B6316B; Tue, 16 May 2023 16:03:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A397C433D2; Tue, 16 May 2023 16:03:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684252997; bh=helSsO57tH8dHbFRP7TCi/6hSqDAckI7M3dabJ0ZYsA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sRkEXd4R4P1ulUwx8C82RCmJWGwc8Ste6XlVCpWZvC9Qcc2gYmHA1k6dQ21Zf+Tiy qT8FRgwCIYA2117hVruEKq1bbXpARuD7yg9dDIHvUkcjIprxWMEttCswGjfaODMqXc AbXpR7xi/J1hAdmFn+Qh5gjJ9JxKLjCb3Cof3rc+4o65KBLnERtyx/NaKaoY9mPWbF 3mHNnv6y/Mb2J/lWb+cFvzU15NB9pXvxhSykI2u2DfhhpK+alFr4cBdVnQ9MCZ4kK7 BaZPMq90Cc6L+2Qm7TdMttAPm2F4w1UnWDoohkzsv7EmzaY3M2R0sCCQD8nVffAXI3 WooI/NSCY2bRw== Date: Wed, 17 May 2023 01:03:11 +0900 From: Masami Hiramatsu (Google) To: Ze Gao Cc: Peter Zijlstra , Steven Rostedt , Masami Hiramatsu , Albert Ou , Alexander Gordeev , Alexei Starovoitov , Borislav Petkov , Christian Borntraeger , Dave Hansen , Heiko Carstens , "H. Peter Anvin" , Ingo Molnar , Palmer Dabbelt , Paul Walmsley , Sven Schnelle , Thomas Gleixner , Vasily Gorbik , x86@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Conor Dooley , Jiri Olsa , Yonghong Song , Ze Gao Subject: Re: [PATCH v2 2/4] fprobe: make fprobe_kprobe_handler recursion free Message-Id: <20230517010311.f46db3f78b11cf9d92193527@kernel.org> In-Reply-To: References: <20230516071830.8190-1-zegao@tencent.com> <20230516071830.8190-3-zegao@tencent.com> <20230516091820.GB2587705@hirez.programming.kicks-ass.net> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Tue, 16 May 2023 17:47:52 +0800 Ze Gao wrote: > Precisely, these that are called within kprobe_busy_{begin, end}, > which the previous patch does not resolve. Note that kprobe_busy_{begin,end} don't need to use notrace version because kprobe itself prohibits probing on preempt_count_{add,sub}. Thank you, > I will refine the commit message to make it clear. > > FYI, details can checked out here: > Link: https://lore.kernel.org/linux-trace-kernel/20230516132516.c902edcf21028874a74fb868@kernel.org/ > > Regards, > Ze > > On Tue, May 16, 2023 at 5:18 PM Peter Zijlstra wrote: > > > > On Tue, May 16, 2023 at 03:18:28PM +0800, Ze Gao wrote: > > > Current implementation calls kprobe related functions before doing > > > ftrace recursion check in fprobe_kprobe_handler, which opens door > > > to kernel crash due to stack recursion if preempt_count_{add, sub} > > > is traceable. > > > > Which preempt_count*() are you referring to? The ones you just made > > _notrace in the previous patch? -- Masami Hiramatsu (Google)