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[209.85.219.171]) by smtp.gmail.com with ESMTPSA id f11-20020a05620a280b00b006f8665f483fsm5027298qkp.85.2022.10.31.10.28.28 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Oct 2022 10:28:28 -0700 (PDT) Received: by mail-yb1-f171.google.com with SMTP id j2so1345406ybb.6 for ; Mon, 31 Oct 2022 10:28:28 -0700 (PDT) X-Received: by 2002:a05:6902:1352:b0:6bb:3f4b:9666 with SMTP id g18-20020a056902135200b006bb3f4b9666mr12896451ybu.101.1667237307861; Mon, 31 Oct 2022 10:28:27 -0700 (PDT) MIME-Version: 1.0 References: <47678198-C502-47E1-B7C8-8A12352CDA95@gmail.com> <140B437E-B994-45B7-8DAC-E9B66885BEEF@gmail.com> In-Reply-To: From: Linus Torvalds Date: Mon, 31 Oct 2022 10:28:11 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 01/13] mm: Update ptep_get_lockless()s comment To: Peter Zijlstra Cc: Nadav Amit , Jann Horn , John Hubbard , X86 ML , Matthew Wilcox , Andrew Morton , kernel list , Linux-MM , Andrea Arcangeli , "Kirill A . Shutemov" , jroedel@suse.de, ubizjak@gmail.com, Alistair Popple Content-Type: text/plain; charset="UTF-8" ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=RJNXAl4s; spf=pass (imf09.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.222.171 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667237311; a=rsa-sha256; cv=none; b=7kCamGeFb8pLhzeVal+8kPZXbAzqUnWaRdh7Aq19C6FgUj3PlL4WNvRg/JNMvjsPQNpbxz RIGQHjX0Am1NaA4CcVJlN4Q2dOfxbuRwNAEGrhL122r6owpvPR460Y2uzXMO+Hh27rbu/h P9+w5G6bj1NqvqCc5wdUmUrpEvF/fyE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667237311; 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=GiwfLGsYKGKqvxfaUpvxh0ddsH6A8EMDdI1AAfBFwR8=; b=Jf/O9maXkzYrEYHIceyc64gLgYLhoKv4QE6zLfkLn4f1jbf6dvLfhk+4x7iOm33PHcSxoi Ot4wZlcE9g5yUmzVhOU9WuYuHJEFmntkaZK66dPcM3+Db+FlEXkMjb4SsDF53yE1vm1xdT bcZb6HeNoBCXGHx4O3iM1nmkogN8Pug= X-Rspam-User: X-Rspamd-Queue-Id: 1B8BA14001C Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=RJNXAl4s; spf=pass (imf09.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.222.171 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none X-Stat-Signature: r7iuk4kqbs53coezng5pyar4xt6i1ykf X-Rspamd-Server: rspam10 X-HE-Tag: 1667237310-168191 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, Oct 31, 2022 at 2:36 AM Peter Zijlstra wrote: > > > (c) move it to clean_and_free_pages_and_swap_cache() that actually > > does the page_zap_pte_rmap() now. > > I'm leaning towards (c); simply because the error case is so terrifying > I feel we should check for it (and I do have vague memories of us > actually hitting something like this in the very distant past). Ok. At that point we no longer have the pte or the virtual address, so it's not goign to be exactly the same debug output. But I think it ends up being fairly natural to do VM_WARN_ON_ONCE_PAGE(page_mapcount(page) < 0, page); instead, and I've fixed that last patch up to do that. Linus