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 A72DCEB64DC for ; Thu, 15 Jun 2023 12:59:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245707AbjFOM7a (ORCPT ); Thu, 15 Jun 2023 08:59:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245731AbjFOM72 (ORCPT ); Thu, 15 Jun 2023 08:59:28 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D36DF26B6; Thu, 15 Jun 2023 05:59:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7019663111; Thu, 15 Jun 2023 12:59:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45749C433C8; Thu, 15 Jun 2023 12:59:23 +0000 (UTC) Date: Thu, 15 Jun 2023 08:59:20 -0400 From: Steven Rostedt To: Jiri Olsa Cc: Masami Hiramatsu , Mark Rutland , lkml , linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH] fprobe: Release rethook after the ftrace_ops is unregistered Message-ID: <20230615085920.7dadac74@gandalf.local.home> In-Reply-To: <20230615115236.3476617-1-jolsa@kernel.org> References: <20230615115236.3476617-1-jolsa@kernel.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org Masami, Want to take this via your probes/urgent branch and send it off to Linus? -- Steve On Thu, 15 Jun 2023 13:52:36 +0200 Jiri Olsa wrote: > While running bpf selftests it's possible to get following fault: > > general protection fault, probably for non-canonical address \ > 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI > ... > Call Trace: > > fprobe_handler+0xc1/0x270 > ? __pfx_bpf_testmod_init+0x10/0x10 > ? __pfx_bpf_testmod_init+0x10/0x10 > ? bpf_fentry_test1+0x5/0x10 > ? bpf_fentry_test1+0x5/0x10 > ? bpf_testmod_init+0x22/0x80 > ? do_one_initcall+0x63/0x2e0 > ? rcu_is_watching+0xd/0x40 > ? kmalloc_trace+0xaf/0xc0 > ? do_init_module+0x60/0x250 > ? __do_sys_finit_module+0xac/0x120 > ? do_syscall_64+0x37/0x90 > ? entry_SYSCALL_64_after_hwframe+0x72/0xdc > > > In unregister_fprobe function we can't release fp->rethook while it's > possible there are some of its users still running on another cpu. > > Moving rethook_free call after fp->ops is unregistered with > unregister_ftrace_function call. > > Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support") > Reviewed-by: Steven Rostedt (Google) > Signed-off-by: Jiri Olsa > --- > kernel/trace/fprobe.c | 12 +++--------- > 1 file changed, 3 insertions(+), 9 deletions(-) > > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c > index 18d36842faf5..0121e8c0d54e 100644 > --- a/kernel/trace/fprobe.c > +++ b/kernel/trace/fprobe.c > @@ -364,19 +364,13 @@ int unregister_fprobe(struct fprobe *fp) > fp->ops.saved_func != fprobe_kprobe_handler)) > return -EINVAL; > > - /* > - * rethook_free() starts disabling the rethook, but the rethook handlers > - * may be running on other processors at this point. To make sure that all > - * current running handlers are finished, call unregister_ftrace_function() > - * after this. > - */ > - if (fp->rethook) > - rethook_free(fp->rethook); > - > ret = unregister_ftrace_function(&fp->ops); > if (ret < 0) > return ret; > > + if (fp->rethook) > + rethook_free(fp->rethook); > + > ftrace_free_filter(&fp->ops); > > return ret;