From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85D9A2BE034; Sun, 4 Oct 2026 09:09:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791104960; cv=none; b=MblgMMLSuEvMHaL2gC1xRr59QFW27C4kFi1lmnmYmODI58No0JIDGWmlnaL4etN9lbjmpbXRSuRQh/nqsH5ptFtjgldnfrY27Ov+g2NvuFzbcJnCXxIVD7eeIPaGrNhMbKBdjdNDsQh8P/jdvxaB5AJko6tfw0z/QzzGpTa8uUU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791104960; c=relaxed/simple; bh=m3+Muw9xdsKZTlVAFncABHSx/jWeDBFS8lhuxCl+VSI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=V/F1mL6yAYQdwn2p9ffWeLN7dnM9RTm4D7ELvS+sKOPhnGRck2m3teT0wtQf8GOve2gll5D9XABYpQYw0xnLCcarJ3t/07y2mE/fBv+R77i20osBJArLPA4V6rGLQo+Vr4S+tYB14nT6IP6a2Fvh/B8CU/G9ZHzz4qayGCFdF10= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b=FQ4B7c38; arc=none smtp.client-ip=216.40.44.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=goodmis.org header.i=@goodmis.org header.b="FQ4B7c38" Received: from omf18.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7F7FF1C3EFC; Sun, 4 Oct 2026 09:09:16 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf18.hostedemail.com (Postfix) with ESMTPA id 04A4D2F; Sun, 4 Oct 2026 09:09:10 +0000 (UTC) Date: Sun, 4 Oct 2026 05:09:04 -0400 From: Steven Rostedt To: Lawrence Lin via B4 Relay Cc: deduce@gmail.com, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Petr Pavlu , linux-modules@vger.kernel.org, Stanislaw Gruszka , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] ftrace: Avoid quadratic symbol lookups in ftrace_module_enable() Message-ID: <20261004050904.06a5ecab@fedora> In-Reply-To: <20261003-ftrace-mod-bsearch-v1-1-92e2fd2d80ff@gmail.com> References: <20261003-ftrace-mod-bsearch-v1-1-92e2fd2d80ff@gmail.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 04A4D2F X-Stat-Signature: m81cmqzreg8pfymuirdqsgoyryw8zqcz X-Rspamd-Server: rspamout03 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+VFOVb5c40zQRx0NDKTb8yjxVareGzTFI= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=bvNjCPW87QjBuKCrWM9oVuVOnsojI94Ko33jmK4OTFI=; b=FQ4B7c38H3XrdRsSHhYUUWdbqbBTZz3W6qFvEEJPMshrhzhqFltofiv2OS9n8oQyADs4dF2SVZx9Qg+e8egWuZ34p+W9mP4uFZ02KWtFA8Zs4rCF7qQa3LcHZo6Ptbt4TfXVfOql/fKy59WyPcNiHqzl51Aikotucr5spcomrq4= X-HE-Tag: 1791104950-341484 X-HE-Meta: U2FsdGVkX19qD9uqcO2x5VYtOa5WEvoyCKTSfcCZWJ7rv0aMW5eK9mw3LOSfh9evpSPFBWS/zo+m7yramWDNSYyYMS/JMePwmm0clOKPMcklhNvd3o/RwA8DgkXtW52WCsyvvcS2RitLAUM4sXyPBqYHCMPcTNW6Td+0vd830AOKpnQckxSNN5jemqo3o3ixwNWuYLJNen0PTbr2XkZDBFsAmCGnGF2qiwwhIMy1rBXKIq/KZo8tHpc5gIdfadrUANCkxSstzaD6+ew0wIoJvLp6EjtaTR6Sy6/EoHaLG+yOBL/ix0mX8JYk37FDEA8uOkwIrsMtckKS2Yt+LNAzLnKVeXd9JvjDJO5zIrdDqvBf23mRgU3U4Q== On Sat, 03 Oct 2026 11:27:10 -0500 Lawrence Lin via B4 Relay wrote: > From: Lawrence Lin > > Since commit b39181f7c690 ("ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid > adding weak function"), ftrace_module_enable() calls test_for_valid_rec() > for every ftrace record of a module being loaded. test_for_valid_rec() > resolves the record address with kallsyms_lookup(), and for a module > address find_kallsyms_symbol() scans the whole symbol table of the module. > Loading a module therefore costs O(records * symbols), all of it under > ftrace_lock. Honestly, I think we can revert commit b39181f7c690. Since commit ef378c3b823385 ("scripts/sorttable: Zero out weak functions in mcount_loc table"), I believe that commit has become obsolete. I just kept it because I didn't want to add regressions. It would be interesting if it actually triggers (finds something). If it doesn't, then I think we should just remove that code instead of adding more complexity to it. -- Steve