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 DB62BC3ABDD for ; Tue, 20 May 2025 13:42:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 741F66B0083; Tue, 20 May 2025 09:42:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6F2996B0085; Tue, 20 May 2025 09:42:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 608446B0088; Tue, 20 May 2025 09:42:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 3E3066B0083 for ; Tue, 20 May 2025 09:42:15 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id ED449C031F for ; Tue, 20 May 2025 13:42:14 +0000 (UTC) X-FDA: 83463400188.26.A2B14E5 Received: from mail-ed1-f44.google.com (mail-ed1-f44.google.com [209.85.208.44]) by imf23.hostedemail.com (Postfix) with ESMTP id DC4C014000F for ; Tue, 20 May 2025 13:42:12 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=TZGlSuuE; spf=pass (imf23.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.208.44 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747748533; 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=54KmLxIQehegZFn9M1QJb5N7gg26IMl0qsKo4ufd/T0=; b=AmElO6D8H3iVjBRuhQSXLoylnPG8dTFebivu7d557TQIoeUUpiPDXOhXq5kaPgb7jKDLJC rxYsLZWWJTO/aJK3m8yCfWh6xL/aChoZzKHxBg6vdauVS3AlxwxFYyGARvjnQgfGJMZEZz kF470XBL8ttx2e0LaQtQgL0brmcTPk0= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=TZGlSuuE; spf=pass (imf23.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.208.44 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1747748533; a=rsa-sha256; cv=none; b=jOaG6EeKHf3Z9H73Lo6z1rna0v6kXyLYrdP4U7cKnZVo0Z7cJFYa1fO1GpOkNf1VSkqgy1 j0PvGnvtaNP09lxjj7xvn17YtRxUsyslB8LaC2emX3Sp1krv1GQugupHVKS31hABRk9CHO rEanoZwTw5+YtRlZirmzc0eNHyI5alY= Received: by mail-ed1-f44.google.com with SMTP id 4fb4d7f45d1cf-601f278369bso4047161a12.1 for ; Tue, 20 May 2025 06:42:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1747748531; x=1748353331; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=54KmLxIQehegZFn9M1QJb5N7gg26IMl0qsKo4ufd/T0=; b=TZGlSuuE2kjXV4ZcPoYtdcugH/i5VVX1iO4oOTLr/53k5N+juqAr1UPcU1xnKBNRTT fni4BJeae+5LRnd9kuLV95aZswa+C0Dutl+e4iQfTmgX06TupLWnvPxVpcIjZGeqQdaa J8X1Lf/kC/XngL3Nlg5iuAaujNKPVbv9hAz+S2pgqlzuwKMz1Dc80Mt0n6YgKZ/yCziA z0R9d+Vuqk+1c+aFnftAZDOFe/N2NQzYRcE/wS96r41fxJGX0iUSu/b9hev+dO0e9zSN vFg5o21bws2asYNiAn9DM0BHbiQKesDFVNGKJJIaMcKfbhXU6qaNLdRBVVg/gYqq7tBE CIUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747748531; x=1748353331; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=54KmLxIQehegZFn9M1QJb5N7gg26IMl0qsKo4ufd/T0=; b=C5CwtZDlkfh1JCFgMyMpuDxyAE7WtPt9ePr4OB09tHV4PhDrBlO5JF+6cmSeV2nYMi 3aW0MZaNPcJP1sfwbtRxjvzbekfB/1qbMWpYv+RyhcfWMFjRpX42hPIpx0he1wFrD/tV UgQi6/e1Wiqe7a9VZXlpINLLBXgqgT79YnRgKD7j1cTSD/nB63eoVmxd0TFwsA0bAQZD 3shqVJ4lwtP3ZyxQaaSuUALdX+qlXvq2qIcJWbZjxdDtcpST5jpMhU/5DoYvr54NEA/m wT5SYt6DX1Eg5Q4rhoSpt6M9pF8gn9QyibIU0WMxP2weC8DmSN9YMw9j31+IpAaDJhxq 9Htg== X-Forwarded-Encrypted: i=1; AJvYcCW29NW9d3h6wgUlEUMXbTe7Y+mJODe2yKDOPhoV5PpBYX1X2tIl7BVoUphJauVa4lb1GNXMMQpKcQ==@kvack.org X-Gm-Message-State: AOJu0YxNThOGvZmSENZJd/0L/FPUbIwAf3kNVNLtTeHH6EK4Tnsg6w0Z T9xCuo/O9lU9m4SQTZYnvJkWuirwzwOXX8Z5p+4qvCAF4yzzdXcC/eXk X-Gm-Gg: ASbGnctMb0sqlUkocUgPSs4RIAs+bH+IwiXXN8N7CzZW/D3kHYpcF+H37bVhyz/ip+t JC0pZwYEUeChVma/rYDFa4nhw9/dnAVpRzzNV34m23BXu8lwI1qYHA1uPGhVOudKKZBSVoCriI/ ufzcZrHMt2fsR/8guhN0KqXsfAeeLEO/nsF5sMgyFRG60IJ8R/HzEcuHEhMrin7BdPmfDHDuiK4 gPpQg/Gol3iQaSjtYL3uKj8YTO8o08i44qAGyy2BWXhPA9gaeqgDF2ZPXYaUDATK7CJ2oRQf+1u 7mJXBMncYgzZmuEZJQeQSjfe8nNfRqcNtqbejISd/g5jKyi/qDBHDoWrgMjmJpgHrLyP3oQHipr szsrFhwPOy7HrAipSC9mpCkxzJ8MWg76jskM= X-Google-Smtp-Source: AGHT+IEo9WgQ4J+MDIfx1a+Red90PxVBvCLFP+FVI8c5BkozlwlAKL1rsaRIwhktXihym+t9QLu1dQ== X-Received: by 2002:a17:907:1c91:b0:ad5:5857:ece2 with SMTP id a640c23a62f3a-ad55857f064mr1014595066b.37.1747748530861; Tue, 20 May 2025 06:42:10 -0700 (PDT) Received: from ?IPV6:2a03:83e0:1126:4:1c0a:f3ac:4087:51c8? ([2620:10d:c092:500::7:66a9]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ad52d49656bsm733490866b.136.2025.05.20.06.42.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 May 2025 06:42:10 -0700 (PDT) Message-ID: Date: Tue, 20 May 2025 14:42:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] mm: slub: only warn once when allocating slab obj extensions fails To: Harry Yoo Cc: Andrew Morton , surenb@google.com, hannes@cmpxchg.org, shakeel.butt@linux.dev, vlad.wing@gmail.com, linux-mm@kvack.org, kent.overstreet@linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, vbabka@suse.cz, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev References: <20250520122547.1317050-1-usamaarif642@gmail.com> <20250520122547.1317050-2-usamaarif642@gmail.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: gyigcmhfd5368zh5itqxt1xkaee15wi8 X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: DC4C014000F X-HE-Tag: 1747748532-916936 X-HE-Meta: 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 BOGAv4L4 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 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 20/05/2025 14:34, Harry Yoo wrote: > On Tue, May 20, 2025 at 01:25:47PM +0100, Usama Arif wrote: >> In memory bound systems, a large number of warnings for failing this >> allocation repeatedly may mask any real issues in the system >> during memory pressure being reported in dmesg. Change this to >> WARN_ONCE. >> >> Signed-off-by: Usama Arif >> Reported-by: Vlad Poenaru >> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/ >> --- > > Hi, > > Please Cc SLAB ALLOCATOR folks in MAINTAINERS on patches that touch > slab code ;) > Thanks for adding them to CC! I was just thinking of this as a memory allocation profiling issue and added the maintainers for it, but should have added slab maintainers as well. >> mm/slub.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index bf43c403ead2..97cb3d9e8d00 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2102,7 +2102,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p) >> >> slab = virt_to_slab(p); >> if (!slab_obj_exts(slab) && >> - WARN(alloc_slab_obj_exts(slab, s, flags, false), >> + WARN_ONCE(alloc_slab_obj_exts(slab, s, flags, false), >> "%s, %s: Failed to create slab extension vector!\n", >> __func__, s->name)) > > I think this should be pr_warn_once()? > I'm not sure why this was WARN() in the first place. > Isn't WARN_ONCE the same as pr_warn_once but with needing the condition of the first arg to be true? We only want to warn if alloc_slab_obj_exts returns non-zero. So WARN_ONCE should be ok? > The coding style guide explicitly states that: >> Do not WARN lightly >> =================== >> >> WARN*() is intended for unexpected, this-should-never-happen situations. >> WARN*() macros are not to be used for anything that is expected to happen >> during normal operation. These are not pre- or post-condition asserts, >> for example. Again: WARN*() must not be used for a condition that is >> expected to trigger easily, for example, by user space actions. >> pr_warn_once() is a possible alternative, if you need to notify the user >> of a problem. > > And failing to allocate the extension vector can happen during normal > operations. > > panic_on_warn users will be unhappy if they notice their kernel panicked > just because their kernel failed to allocate slab extension vectors, which is > a totally normal situtation. > >> return NULL; >> -- >> 2.47.1 >> >> >