From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com (pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com [35.155.198.111]) (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 9F3232F5308; Wed, 8 Oct 2025 15:31:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=35.155.198.111 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759937487; cv=none; b=DFsimIG7IieoTqrWHnm4Y8/zKvSc0iPvCA0xe0bd8rZt1PcGEjafV4uHhPK98HqIF2GgeXabVRFAIl1c0DvucHO8h0mtCj2WKIwmSLJMSFSjgpNYLDe4GZweF1agWqge5bqYYh0YgiDjbar29Jdg3fJV3wayOBzV+uJ6iejc2Nk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759937487; c=relaxed/simple; bh=c8CkUW1Wymk66rGG5tsvWtIDgSEWGpXx8+69cD8zAvI=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=u7WQkSqeeXpOQ6P7T7AeQTTO+U27kCM7rsvOTQAkDarDoOovNrgLkuao7iNXoYDd8a0t/aAlS+D6giO1Lsj/6m/31wpFyzmQ5kO+5GOFn8DFH1OzamTJX/B1/v4VQ3R4nl+SSn78AVysv+/By7KKA2xm9Gtn1wn+YDip3y12J6E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=ZapQTduc; arc=none smtp.client-ip=35.155.198.111 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="ZapQTduc" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1759937485; x=1791473485; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jvk2RBzXwrA99Hwxay/jSQlk3gLjsVti9lJHvH/pTPQ=; b=ZapQTducq58w/mblsQienBoqi0LPRoFCt1s+f3L7E74DJGPw2RoZ1KYO GybO8PW4UMbUFmJWE7eYt8C6ACNM4D6Vv6WKMAW8/lEfUQBYQBk14dt3E bYD8fBj0KlxKZ9sJofA7E5YBXVUi/KCdXPZKvWfshqFU1HAgJ4z5Yroff RaSragkWdG/zhKtotPyluGeGSC9TUKezs+XJ70qPFmq/vx7OP91+hCV1F eB/CZtbH3zbLStk6aYKNI4E2O/DdbJXDSBPPj3rtrFZ657JOFjhxPGvfC jtUKqQRbagOnDP4fbqtnUv0fmVSg6zbW8luQcBmRxw23bslWrRbuTZSHR g==; X-CSE-ConnectionGUID: C84d4vrqS4+tQbY5ZX7vPg== X-CSE-MsgGUID: Smt1enfbSGyJRBqUsp38fA== X-IronPort-AV: E=Sophos;i="6.19,213,1754956800"; d="scan'208";a="4410627" Received: from ip-10-5-6-203.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.6.203]) by internal-pdx-out-009.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Oct 2025 15:31:25 +0000 Received: from EX19MTAUWC002.ant.amazon.com [10.0.21.151:44901] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.54.171:2525] with esmtp (Farcaster) id 71b65f11-5afc-47a3-8856-278291bee2e7; Wed, 8 Oct 2025 15:31:24 +0000 (UTC) X-Farcaster-Flow-ID: 71b65f11-5afc-47a3-8856-278291bee2e7 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Wed, 8 Oct 2025 15:31:24 +0000 Received: from dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (172.19.116.181) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Wed, 8 Oct 2025 15:31:11 +0000 From: Eliav Farber To: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , CC: Linus Torvalds , Lorenzo Stoakes , David Laight Subject: [PATCH v3 05/19 5.15.y] minmax: avoid overly complicated constant expressions in VM code Date: Wed, 8 Oct 2025 15:29:30 +0000 Message-ID: <20251008152946.29285-6-farbere@amazon.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251008152946.29285-1-farbere@amazon.com> References: <20251008152946.29285-1-farbere@amazon.com> Precedence: bulk X-Mailing-List: linux-sparse@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D037UWC003.ant.amazon.com (10.13.139.231) To EX19D001UWA001.ant.amazon.com (10.13.138.214) From: Linus Torvalds [ Upstream commit 3a7e02c040b130b5545e4b115aada7bacd80a2b6 ] The minmax infrastructure is overkill for simple constants, and can cause huge expansions because those simple constants are then used by other things. For example, 'pageblock_order' is a core VM constant, but because it was implemented using 'min_t()' and all the type-checking that involves, it actually expanded to something like 2.5kB of preprocessor noise. And when that simple constant was then used inside other expansions: #define pageblock_nr_pages (1UL << pageblock_order) #define pageblock_start_pfn(pfn) ALIGN_DOWN((pfn), pageblock_nr_pages) and we then use that inside a 'max()' macro: case ISOLATE_SUCCESS: update_cached = false; last_migrated_pfn = max(cc->zone->zone_start_pfn, pageblock_start_pfn(cc->migrate_pfn - 1)); the end result was that one statement expanding to 253kB in size. There are probably other cases of this, but this one case certainly stood out. I've added 'MIN_T()' and 'MAX_T()' macros for this kind of "core simple constant with specific type" use. These macros skip the type checking, and as such need to be very sparingly used only for obvious cases that have active issues like this. Reported-by: Lorenzo Stoakes Link: https://lore.kernel.org/all/36aa2cad-1db1-4abf-8dd2-fb20484aabc3@lucifer.local/ Cc: David Laight Signed-off-by: Linus Torvalds Signed-off-by: Eliav Farber --- include/linux/minmax.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 2ec559284a9f..a7ef65f78933 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -270,4 +270,11 @@ static inline bool in_range32(u32 val, u32 start, u32 len) #define swap(a, b) \ do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) +/* + * Use these carefully: no type checking, and uses the arguments + * multiple times. Use for obvious constants only. + */ +#define MIN_T(type,a,b) __cmp(min,(type)(a),(type)(b)) +#define MAX_T(type,a,b) __cmp(max,(type)(a),(type)(b)) + #endif /* _LINUX_MINMAX_H */ -- 2.47.3