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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4908CC8303C for ; Mon, 7 Jul 2025 11:32:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D4A378D0003; Mon, 7 Jul 2025 07:32:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D21DF8D0002; Mon, 7 Jul 2025 07:32:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C5F398D0003; Mon, 7 Jul 2025 07:32:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id B26DD8D0002 for ; Mon, 7 Jul 2025 07:32:16 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 37EEE591F8 for ; Mon, 7 Jul 2025 11:32:16 +0000 (UTC) X-FDA: 83637255072.09.7A38132 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf25.hostedemail.com (Postfix) with ESMTP id 8A90AA0006 for ; Mon, 7 Jul 2025 11:32:14 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="ObJ/+U2n"; spf=pass (imf25.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1751887934; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=NLkYDupO23LVLNqsl9Wkjw81oL47cuTemN4/Gn/RcGI=; b=WvKNpPbx4R8rZsc3mBz5ahTv9a79Us8Go6Irf1fZMhwXUMC5g9KIaJefprGD4YOS9CpivX 3Nsd3I/TQ1kshpqz3ka8YIyRzKDMAOhV2wqyjKiAcUOJn6suyIKMXXvKgvD67RzNQDTTu4 rPKYqBhZgbhQ4UMfbZr5gw0iUypdsaI= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="ObJ/+U2n"; spf=pass (imf25.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1751887934; a=rsa-sha256; cv=none; b=jwWn+7rvuIWlV/tQLXtcGrfxdjAWIJP+e9rDpyNyFw8+5G6u5G7z3f/y0SoeCAiXCo7xNH S6IVnjM0WR0PkOhLWjNEaYq9Z4mpZvuofkOn/m1k/UuQOtU6Y41rIgq4S4Jq6gP/dA1hCl 3KX9zGUOSgmpTT1BjH+NS2rnLmv4cLM= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B92F65C4CAE; Mon, 7 Jul 2025 11:32:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95FD5C4CEE3; Mon, 7 Jul 2025 11:32:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751887933; bh=KJ9ivJDcFfm+HtMTDVXkf8LFJkwB6s4Vcp0E0EjRA2c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ObJ/+U2noTTkjAYPn1YG/pdjcVIrO/IOmmZsAYxhvnAnuEEw46VjHz21QdgfI8cKT +7NSFG8lrtgTjmywMa+vSb4IahbVlsmSRAt7+EOguDQ/KXOcN8yLq86WtCfj/iQqjm iMnILzLyLzqgvWZ5zRVkCEoY3pLWijnv0qT9pHeJUcS4/EAG4LuQpQTCw+mOWrmedl aoeDXJgFYb5adTum4hw3gLcZESV5SUWXdTax8l3IIvEL1mxa5h3565ySjNU1Le1ZWW MVAlLNI7a0P/eIN7r3+qI4dWVJBoCnTb9ClSSRXMoxWDHybNjqnWeOkN0VfAVYkCjz dJOZ4soLHExRg== Date: Mon, 7 Jul 2025 14:32:02 +0300 From: Mike Rapoport To: Peter Zijlstra , "Liam R. Howlett" Cc: Andrew Morton , Andy Lutomirski , Borislav Petkov , Daniel Gomez , Dave Hansen , Ingo Molnar , Luis Chamberlain , Mark Rutland , Masami Hiramatsu , "H. Peter Anvin" , Petr Pavlu , Sami Tolvanen , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 3/8] execmem: rework execmem_cache_free() Message-ID: References: <20250704134943.3524829-1-rppt@kernel.org> <20250704134943.3524829-4-rppt@kernel.org> <20250707111102.GF1613200@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250707111102.GF1613200@noisy.programming.kicks-ass.net> X-Stat-Signature: oxjsrn5a77ei4dwxyksspkwd6jibpfyr X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8A90AA0006 X-HE-Tag: 1751887934-477063 X-HE-Meta: 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 XC8hxSQI 4I2dJl1EzODp7nGqoc3VE6RhrekzM1HEET6C74Jit+2QWLtYjAWrgs7txEyzEdE8CWH828HH3tbQMenRlIQfx09hqxlH9fQ8ppkBBQdFumKZEkGYKiydNNCVDOIYzVMNYpmCP24SxidWKBJmjP0LVFdDbqFpKRhB8r5QxXDsOs8+0WnSv2T/qusCXkTlAK7zVRAwsoFH9JHAyj+vDKuy65ZNtbtkyifV7vgf58RiXIY5FRb2M27Ii1JbysTjpjhyVms1t/pm6Ruh2B1BYpWu++0czDsoelW5qZxaN1k4sMGCWxUcc4U5ZGn+yOA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 07, 2025 at 01:11:02PM +0200, Peter Zijlstra wrote: > On Fri, Jul 04, 2025 at 04:49:38PM +0300, Mike Rapoport wrote: > > static bool execmem_cache_free(void *ptr) > > { > > struct maple_tree *busy_areas = &execmem_cache.busy_areas; > > unsigned long addr = (unsigned long)ptr; > > MA_STATE(mas, busy_areas, addr, addr); > > void *area; > > + int err; > > + > > + guard(mutex)(&execmem_cache.mutex); > > > > area = mas_walk(&mas); > > + if (!area) > > return false; > > > > + err = __execmem_cache_free(&mas, ptr, GFP_KERNEL | __GFP_NORETRY); > > + if (err) > > + goto err_slowpath; > > > > schedule_work(&execmem_cache_clean_work); > > > > return true; > > + > > +err_slowpath: > > + mas_store_gfp(&mas, pending_free_set(ptr), GFP_KERNEL); > > + execmem_cache.pending_free_cnt++; > > + schedule_delayed_work(&execmem_cache_free_work, FREE_DELAY); > > + return true; > > } > > This is a bit if an anti-pattern, using guard() and error goto. Since Good to know :) > there is only the one site, its best to write it like so: > > static bool execmem_cache_free(void *ptr) > { > struct maple_tree *busy_areas = &execmem_cache.busy_areas; > unsigned long addr = (unsigned long)ptr; > MA_STATE(mas, busy_areas, addr, addr); > void *area; > int err; > > guard(mutex)(&execmem_cache.mutex); > > area = mas_walk(&mas); > if (!area) > return false; > > err = __execmem_cache_free(&mas, ptr, GFP_KERNEL | __GFP_NORETRY); > if (err) { > mas_store_gfp(&mas, pending_free_set(ptr), GFP_KERNEL); > execmem_cache.pending_free_cnt++; > schedule_delayed_work(&execmem_cache_free_work, FREE_DELAY); > return true; > } > > schedule_work(&execmem_cache_clean_work); > return true; > } > > And now I have to ask what happens if mas_store_gfp() returns an error? AFAIU it won't. mas points to exact slot we've got the area from, nothing else can modify the tree because of the mutex, so that mas_store_gfp() essentially updates the value at an existing entry. I'll add a comment about it. Added @Liam to make sure I'm not saying nonsense :) -- Sincerely yours, Mike.