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 57AEEC83F21 for ; Thu, 10 Jul 2025 16:46:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EBFEA6B0092; Thu, 10 Jul 2025 12:46:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E69F26B0093; Thu, 10 Jul 2025 12:46:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D58976B0095; Thu, 10 Jul 2025 12:46:54 -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 C284E6B0092 for ; Thu, 10 Jul 2025 12:46:54 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 7B813160154 for ; Thu, 10 Jul 2025 16:46:54 +0000 (UTC) X-FDA: 83648934348.24.CF74079 Received: from mail-ej1-f43.google.com (mail-ej1-f43.google.com [209.85.218.43]) by imf05.hostedemail.com (Postfix) with ESMTP id 8FC9710000C for ; Thu, 10 Jul 2025 16:46:52 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=BOMqVXMq; spf=pass (imf05.hostedemail.com: domain of adobriyan@gmail.com designates 209.85.218.43 as permitted sender) smtp.mailfrom=adobriyan@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=1752166012; 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=j4+b4mC3HT2l2CGi9AAd2/CUQyS9zx3Y/fMcj/u4cU8=; b=bBIYA/T+vwQ7myY+oE1IWRJdCCFa1MBiHAPXzUZhfQrusfkFtokIjeef0UahqOI6WiadVv N7ega6h0beBFtx4j/K7KARBtv9wSiSrbdcpStVZAZ9RzsCuwYGgARhHvzRTmOa1cHAiZfI daOL3rWGnjiknDTeJhYatF5xUDL4O+c= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=BOMqVXMq; spf=pass (imf05.hostedemail.com: domain of adobriyan@gmail.com designates 209.85.218.43 as permitted sender) smtp.mailfrom=adobriyan@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752166012; a=rsa-sha256; cv=none; b=dNMQ2kwST9Ff3QQRR2rh1a70adAcTlOVT1OqswSBmZCHpB0nbZKJFmJ46pX3n3W2Ozg/zp 6MeUazw2T/6/Gnc3J+9KAnwuQejKhgueG/Jzd32mzSjOXHHp8KKW9D2oAULIWuGgBG5hOE UDNhVJyfeL0gcX95gWVP0Hj2yVXH6mE= Received: by mail-ej1-f43.google.com with SMTP id a640c23a62f3a-ade76b8356cso222109766b.2 for ; Thu, 10 Jul 2025 09:46:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1752166011; x=1752770811; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=j4+b4mC3HT2l2CGi9AAd2/CUQyS9zx3Y/fMcj/u4cU8=; b=BOMqVXMqdpN3qoo3C69ElOdECnNygpNm7Ad5PhSuW5HQn+IQRr7sOVboOnIdARq4TJ 0VjS/rXFyQOC4gqYACNIyrwjTibpPgisx0zv5/ZwzWy2iU9L6W+veLGMOeDpBWLARdkt feAOVQ5TPPd5Nq7j6zqWsthWkaRhwhYMUZ8ivG+YdsN+bReMz6W3zEBu4SapWKaX8Uxc NzqPKTRKfPzG+wNwUXqriw8W71gI3rR709B9mx87TdUYHgTBXlEqD0G6pqfcn97NL2xy /t6F6EOWj5u0FjvnFod5qi8ymT0yilP+h16ylrsh6XKpa051RUGYqXWOrjxqwFNt13gC 6+2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752166011; x=1752770811; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=j4+b4mC3HT2l2CGi9AAd2/CUQyS9zx3Y/fMcj/u4cU8=; b=UuSJklgp6LOxsxj4Pru3PGjZLQQCe70/sx5R6SMean59bJNTSl+okB/p8NRnDauwBo OTTFIAK4z3Elgxj3wxiNcSfgnS4BJ/bS6tb+0FSzNvTaWB9uZWCzXbzJm4CcqSZW8KAC SrHHaQ8VJoQLEF6h7Iz2gB2fDfC4L7AHmLcq1xAEy8F5+A18lk6mD1CQ3yrvxwX9Hsg8 p1lSTzAq4z4rzrkXdt8eDIodi3iDHoy6vpdt+rg+/19KLN1Wg2Oos3RMLn/q1WPFswGh XlyCiX4cy13ZaoCByJl+M5RJTDipNq3t46C1Q0HhpoNPrd9jcGJl/etuXLAkPbQG/uxt AZGg== X-Forwarded-Encrypted: i=1; AJvYcCVQaU2RmJS2xtLGEoZ7lLiMPoZ3foJ4AaJXvDs3L90pGoYU93t++b9o+irJuK36smck9W1gx6kQAA==@kvack.org X-Gm-Message-State: AOJu0YzmVov0DxUh1wzhRw5efAX5VTpXB89HA6L3ZFeFwnX76kCG6ppQ Dz87/vZRAbOGJYX3NekKQiJjiNmXuKbVJ7KUULotDlCSDNKJg5VSCAo= X-Gm-Gg: ASbGncvgiL7cCg6qVwFkj7aTaTSt1SrZUSyaBvZIwGdR1zCR8eHU1h7UTWudFkfRtzG X3PGtpjGRHU0DqY7tCRGFdSMnGEeyypn1T/bXHXydcTqFC6fdWRgvD9a9KkY74b+2D0mjPzmsd+ d/Mnp0TVvjXw4sBdkOcO/9pkLtVLs9VP5QyuvqhI9onOflUi6kJbJZBNMfiUgIL/TzqJ0iCZAkR J2n9xpwaTweLw/8pJP47hJOVdL0ufamFcU4hM8vfQapv8shtbOUNAa97JCtaouG3SjWtlTUlSBe n5ytTootfRwe2HF71HUesjO2LapFWL1FX05ikpKXDBmIpdsA8yLhF958nts3 X-Google-Smtp-Source: AGHT+IH23nDcXHOGmf5MwTJfBGqbZyv2XIbr7qmXq0Q+P00iobs24hGXwBeOoXDJEXEyxxqayy4n2A== X-Received: by 2002:a17:907:3f89:b0:ae0:5137:fc44 with SMTP id a640c23a62f3a-ae6e6e9323dmr433697366b.18.1752166010589; Thu, 10 Jul 2025 09:46:50 -0700 (PDT) Received: from p183 ([46.53.250.196]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae6e8293ff2sm159477466b.111.2025.07.10.09.46.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Jul 2025 09:46:50 -0700 (PDT) Date: Thu, 10 Jul 2025 19:46:48 +0300 From: Alexey Dobriyan To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Subject: Re: [PATCH] mm: implement "memory.oops_if_bad_pte=1" boot option Message-ID: References: <4e1b7d2d-ed54-4e0a-a0a4-906b14d9cd41@p183> <20250709153751.222ea2d1de1313a22a69e64e@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250709153751.222ea2d1de1313a22a69e64e@linux-foundation.org> X-Rspam-User: X-Stat-Signature: zzkjch63xcdb3mg7myfdymitmgqwqrft X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8FC9710000C X-HE-Tag: 1752166012-705733 X-HE-Meta: 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 LijsAwyZ 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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 Wed, Jul 09, 2025 at 03:37:51PM -0700, Andrew Morton wrote: > On Wed, 9 Jul 2025 21:10:59 +0300 Alexey Dobriyan wrote: > > > Implement > > > > memory.oops_if_bad_pte=1 > > > > boot option which oopses the machine instead of dreadful > > > > BUG: Bad page map in process > > > > message. > > > > This is intended > > for people who want to panic at the slightest provocation and > > for people who ruled out hardware problems which in turn means that > > delaying vmcore collection is counter-productive. > > > > Linux doesn't (never?) panicked on PTE corruption and even implemented > > ratelimited version of the message meaning it can go for minutes and > > even hours without anyone noticing which is exactly the opposite of what > > should be done to facilitate debugging. > > > > Not enabled by default. > > > > Not advertised. > > > > @@ -490,6 +498,13 @@ static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) > > static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, > > pte_t pte, struct page *page) > > { > > + /* > > + * This line is a formality to collect vmcore ASAP. Real bug > > + * (hardware or software) happened earlier, current registers and > > + * backtrace aren't interesting. > > + */ > > + BUG_ON(oops_if_bad_pte); > > + > > Oh. A pretty simple thing to do with bpf? Unless you need to explain how to set it up on QA machines :^) The good thing about boot options -- they are very easy to use. > A script to tell the kernel > "dump vmcore if you get here" would have applications in places other > than print_bad_pte()? Sure! > That's what bpf_panic() was for (https://lwn.net/Articles/901284/) but > it apparently didn't get merged for .