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 B8965C3ABC3 for ; Sat, 10 May 2025 10:24:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 042966B00BC; Sat, 10 May 2025 06:24:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F36256B00BD; Sat, 10 May 2025 06:24:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E21DB6B00BF; Sat, 10 May 2025 06:24:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C186F6B00BC for ; Sat, 10 May 2025 06:24:23 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 2532E161EE9 for ; Sat, 10 May 2025 10:24:24 +0000 (UTC) X-FDA: 83426613648.27.3F84E3D Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) by imf08.hostedemail.com (Postfix) with ESMTP id 2D5AF160003 for ; Sat, 10 May 2025 10:24:21 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=lF+TesPm; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf08.hostedemail.com: domain of david.laight.linux@gmail.com designates 209.85.128.51 as permitted sender) smtp.mailfrom=david.laight.linux@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1746872662; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=X54rWRNLW17tSBvsmAsUPfuEHJyuny1CVhaZpG1ZBXU=; b=78hysg/bGn+bSeTdYKQ/suBPpluPM1u4Yk4vwnfnwkwQjCbgHzkglPbOgkEv2Qp4peIAii StVbiCGQ/xEXsG4d+kJXgLCULufPmSf/uijuuiGV2+obYdiWx1pqdmF/iXiFvtSSlw6r21 WQCF60tNla0H1ixFJvl1iiy5kiZnwBI= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=lF+TesPm; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf08.hostedemail.com: domain of david.laight.linux@gmail.com designates 209.85.128.51 as permitted sender) smtp.mailfrom=david.laight.linux@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1746872662; a=rsa-sha256; cv=none; b=a/MXPkVG2Z/wmY8Fgb62BxCsetLRjHtRIsXSdsooU9DJwfMPPr1GfXKE461u37vAq11cF+ fTHsNbwZDkvJ/Zu9yID51WsFZLa2vzC9v8ltQtJU/VxxTSZVqto0EyKtPyWd4/wHUSnCIk T62bTJTnPyzsYIEFLW5nai2SbCqxBmw= Received: by mail-wm1-f51.google.com with SMTP id 5b1f17b1804b1-43ce70f9afbso30376415e9.0 for ; Sat, 10 May 2025 03:24:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1746872660; x=1747477460; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=X54rWRNLW17tSBvsmAsUPfuEHJyuny1CVhaZpG1ZBXU=; b=lF+TesPm72SeLkLW89+E0KR33oRmQVppxI+Cs5SSmg5ILY3zi8shnQYGtN2ArSORl/ zhlY45L7Mc3JNggA077hkMf9WM6O33bflqKaPQjqmKDQ1hVNlUT9gDStuLP+wnxe4bnq 5bcTeOO6241j2TyT3fGZIPUQcZ21k8xLAyfpQW+NkQ5p8bLPybMWSAf/LbWlZ243auBt OyB2ff4n8HnQchhx0LevrlWPusjchEs3qIcvCL5X+cRqzsGA9L8pygsQ8YEbIlBAW1ux 7sviwkA+pd7/N9mBrj9xm+HITyy9eOvUDMabCjllqNoI/qTNAj/k2YTGfRIFkL26/uLd dLqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746872660; x=1747477460; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=X54rWRNLW17tSBvsmAsUPfuEHJyuny1CVhaZpG1ZBXU=; b=h8Gegxg+5PK/dlPRcF2LQUduRQVlQ38lCU3zqnF1CwGdB17BzC729B38bXmJWFd2VJ wBD82B1Y958mJNWn86su/JDhZE81+TDb6jJ24p1KmsoimZJlM85i5yOvIQTMGOPcHX1O S4mRZ9oh160i61pdaoO8+WxmkMBV5hUi1sliMu0uKQNb42dfDV+iQ03dWDTZ07VLwEZl F5OKWZDKNPuiT0jOqiFXcZi+JBYo7PAZsR5HfWJS3/DSD1wnrVQhsI3y9WoSZtinJfkY sAZIsPdiuPP0UHomHnFUqKsrabmRXPw8NRKsIH77AqFMD449NQD3rpKxOkWdA5kSPhA6 aZSQ== X-Forwarded-Encrypted: i=1; AJvYcCWuZ73ypXo3okeh5tPkzsra6KH1aVSfR6Ekml7snBddz+p4YOkTN9F32lya/W5ztMTV8MiWbZFxIA==@kvack.org X-Gm-Message-State: AOJu0YwgINEYL1JO3QwAZlf2BK5VNZf3e4f0q2kExKVKS30kBqitHYoV 5HsREOSlBCPXtUW8IVnXyl8/Dpy64wa11ElO3dwK7R/MFtz8xdn7 X-Gm-Gg: ASbGncuFmqBDrGOSZL1y/aoOZwqXil858PecFJgH/PqTl0ThVZtXuXezBPst8sW8y7w Pilw2/iOmvC4NA8IjfZUJecPugpjr86KG5m0EyE87aRiRf6RlAtZndqO6tnH9hYQCBR5dZB3laf dUExYXIKB2vx/Alf/v1jT2UjYbnrPYYVuz3+UaXvg+Saa+zMrlbD2g0su4BKTMlyquSEQdjgyAH rlKUTE2DWwfC0zPfHGzoPC4kUMKTg++cAGFx9rBEIBfsnvMu7gLfvFJtekphbGLS2pOYsthsIJY rEm5e5Sk9zB5ZKeur3naF0oPNrc04V9tkeQ7oYqcdpZI5mwmXS0cuhWJZRo/0w2oDXJBNfqEOAL ptZYgMcSfm4gfOA== X-Google-Smtp-Source: AGHT+IHmKjjVR4g+SsPL5UrBT/AEPsB+lNkQ5qQbaRA/6ZQru5xn1OVVVzTDLMZwyDlYYW3az+Mxrg== X-Received: by 2002:a05:600c:37c6:b0:43c:f629:66f3 with SMTP id 5b1f17b1804b1-442d6d517e2mr52696175e9.18.1746872660399; Sat, 10 May 2025 03:24:20 -0700 (PDT) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442d67e138asm57265725e9.10.2025.05.10.03.24.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 May 2025 03:24:20 -0700 (PDT) Date: Sat, 10 May 2025 11:24:19 +0100 From: David Laight To: WangYuli Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, yuzhao@google.com, stevensd@chromium.org, kaleshsingh@google.com, zhanjun@uniontech.com, niecheng1@uniontech.com, guanwentao@uniontech.com, Matthew Wilcox Subject: Re: [PATCH] mm: vmscan: Avoid signedness error for GCC 5.4 Message-ID: <20250510112419.749652a7@pumpkin> In-Reply-To: <74D5BC8AD7E5511A+13242b55-13e5-463a-9422-f863d58b6af6@uniontech.com> References: <85050791B887DC13+20250506160238.799984-1-wangyuli@uniontech.com> <20250506162438.91fffc7ef924d9653ed0f503@linux-foundation.org> <74D5BC8AD7E5511A+13242b55-13e5-463a-9422-f863d58b6af6@uniontech.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 15hg8scpt1fsh6jucobbbf4rjni8u7nw X-Rspamd-Queue-Id: 2D5AF160003 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1746872661-80144 X-HE-Meta: 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 kp32RCbk eiFEx9qLoM4NEHf0xMSC/Hw7Ojt2Zgsov9IeL6EhI5DUKAm22NnyMm5jtj9H0GjaFSX3YzIcpiXvaICDnIS/GBs+ZRHDgJsFpBPY3ZFKw4xF1X3WKZWh1GM9ClFWz9Uq6KvvIeNm40fDDlZopR116YqFMOQMcCZNg9+27jTgkzt0F9lwPk2r07MmMwoF51ibz/QFCFoDp9c8DQ7PGl/30xiCkXZYFO5Uz7OE/NJoS2F5ABH6UGwnkKDdX3H6VqeCiTVYlW63DIAw4NyZJnqqDhOBPirOak65nTC+2cSwRX5LaxLBlJRV6Gv4pnwBSBCvHMndtTd1p8BewRDgQiI2vHxBVXRcvEvd7U72QoKIW6ZdSIktyF96+yZRQmoW1zF3yWOYPZ8ZAKUA7VjxTxazO3hmLJTP623xWkgYZHNAfW16ZWqKV+kqrjrOFT/UbtVh0omXgzr3vk9GaQq83L4r5k35knecL88ArJZmhym4pDunLTsA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000078, 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 Wed, 7 May 2025 12:06:11 +0800 WangYuli wrote: > Hi Andrew Morton, > > On 2025/5/7 07:24, Andrew Morton wrote: > > On Wed, 7 May 2025 00:02:38 +0800 WangYuli wrote: > > > > Make `tier' unsigned? After all, negative tier numbers are nonsensical. > > That point is well taken. > > However, I've noticed that variables named "tier" seem to be commonly > defined as int rather than unsigned int throughout the mm subsystem, and > perhaps even the wider kernel code. > > I was wondering if changing just this one instance might feel a little > inconsistent? > > Perhaps a possible approach for now could be to change this line to for > (i = tier % MAX_NR_TIERS; i <= min_t(int, tier, MAX_NR_TIERS - 1); i++) > {, which would allow us to keep the signed int type for the tier > variable itself. Remember that min_t(int, a, b) is just min((int)a, (int)b) and you really wouldn't put casts like that in code. Even if a cast can't be avoided only one side would normally need it. There really ought to be a 'duck shoot' against min_t(). I'm trying very hard to stop any more being added. David > > Regarding the potential for a more comprehensive change in the future to > redefine all these "tier" variables and related ones as unsigned int, I > would be very grateful for your guidance on whether that's a direction > we should consider. > > But actually, whether it's signed or not likely won't affect its normal > operation... > > Thanks, >