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 22D77C433EF for ; Mon, 7 Feb 2022 20:40:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 786756B0074; Mon, 7 Feb 2022 15:40:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 735536B0075; Mon, 7 Feb 2022 15:40:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 623F16B0078; Mon, 7 Feb 2022 15:40:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0242.hostedemail.com [216.40.44.242]) by kanga.kvack.org (Postfix) with ESMTP id 52BBB6B0074 for ; Mon, 7 Feb 2022 15:40:09 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0E9F694FDA for ; Mon, 7 Feb 2022 20:40:09 +0000 (UTC) X-FDA: 79117150938.09.82C51FD Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf25.hostedemail.com (Postfix) with ESMTP id 80CBBA0007 for ; Mon, 7 Feb 2022 20:40:08 +0000 (UTC) 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 sin.source.kernel.org (Postfix) with ESMTPS id 5C0C4CE11EF; Mon, 7 Feb 2022 20:40:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A39B2C340EE; Mon, 7 Feb 2022 20:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1644266402; bh=rf8gPOUN5xstVP7dA1npNbWM8q6AFZtBXiHOYtQg9Cc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ZmMoxaILZCQ1Z8+Rw+tECtxqVH+UqOhIRSjRZsplt0uiPd/zUNiEtdFt4AvBx8OAa 6epZplVOVDsfv9ZR9+RP18fVCUjnqHkJtiG6s220QyxssWrhTw4ahDBoN6v4HkHjwY P63xwfuMhcFEYQZQpWATVU/wtKSkiQsuW8ErMmQ4= Date: Mon, 7 Feb 2022 12:40:02 -0800 From: Andrew Morton To: Christophe Leroy Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: Outline copy_overflow() Message-Id: <20220207124002.edd04bf6d2abac8a01e35144@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 80CBBA0007 X-Stat-Signature: xf5185atttjbbjbwy1scjcc8ff8u9rhm Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=ZmMoxaIL; dmarc=none; spf=pass (imf25.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspam-User: nil X-HE-Tag: 1644266408-647450 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: On Mon, 7 Feb 2022 11:55:18 +0100 Christophe Leroy wrote: > While building a small config with CONFIG_CC_OPTIMISE_FOR_SIZE, > I ended up with more than 50 times the following function in vmlinux: > > c00243bc : > c00243bc: 94 21 ff f0 stwu r1,-16(r1) > c00243c0: 7c 85 23 78 mr r5,r4 > c00243c4: 7c 64 1b 78 mr r4,r3 > c00243c8: 3c 60 c0 62 lis r3,-16286 > c00243cc: 7c 08 02 a6 mflr r0 > c00243d0: 38 63 5e e5 addi r3,r3,24293 > c00243d4: 90 01 00 14 stw r0,20(r1) > c00243d8: 4b ff 82 45 bl c001c61c <__warn_printk> > c00243dc: 0f e0 00 00 twui r0,0 > c00243e0: 80 01 00 14 lwz r0,20(r1) > c00243e4: 38 21 00 10 addi r1,r1,16 > c00243e8: 7c 08 03 a6 mtlr r0 > c00243ec: 4e 80 00 20 blr > > That function being a non conditional warning on an error path, > it is not worth inlining. > > Outline it. "uninline" is the conventional term for this. > This reduces the size of vmlinux by almost 4kbytes. Did you consider uninlining check_copy_size() instead?