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[209.85.219.180]) by smtp.gmail.com with ESMTPSA id bi30-20020a05620a319e00b006b929a56a2bsm652959qkb.3.2022.10.24.13.36.40 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Oct 2022 13:36:40 -0700 (PDT) Received: by mail-yb1-f180.google.com with SMTP id 187so3225115ybe.1 for ; Mon, 24 Oct 2022 13:36:40 -0700 (PDT) X-Received: by 2002:a25:bb44:0:b0:6bb:a336:7762 with SMTP id b4-20020a25bb44000000b006bba3367762mr29619641ybk.501.1666643799980; Mon, 24 Oct 2022 13:36:39 -0700 (PDT) MIME-Version: 1.0 References: <20221022111403.531902164@infradead.org> <20221022114424.515572025@infradead.org> <2c800ed1-d17a-def4-39e1-09281ee78d05@nvidia.com> In-Reply-To: From: Linus Torvalds Date: Mon, 24 Oct 2022 13:36:23 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 01/13] mm: Update ptep_get_lockless()s comment To: Jann Horn Cc: Peter Zijlstra , John Hubbard , x86@kernel.org, willy@infradead.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, aarcange@redhat.com, kirill.shutemov@linux.intel.com, jroedel@suse.de, ubizjak@gmail.com Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666643802; a=rsa-sha256; cv=none; b=pJ8vE4IlMq0axOEVipFM5XDeuqfwzR8p9qvkReGMHiUgmNE9PJAhVoMg/LAik8zd10K1op KZpYYEvwWwzYSlEWa22jnehpDQi2kSW43hLPYjVZE7DaFlt6E5YJISHXpYpuxQwZ3iCPmt MN3iCj9FnoJmDQgbMnV3drgMHk9Sizg= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=EyRs4jkV; dmarc=none; spf=pass (imf28.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.160.170 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666643802; 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=nUgSwI+I3I6ArrFTquHdy3o7OpO0gtexbNIMHahi/Oo=; b=PK6JKHya1jAuOLqmZQbtWcnqsm1aeNz7vdfh0Jn+DNh3G2xOn+/lqRSThqry1S7UDS9VWE LqkQoXiO+/grvaU1/fBbGiGtsbbbOXreXWeyqTBollkKPVqwnHRpGv9cD+NNbl6Lp0dk71 rcCLLmxfGNgHQTtkMvPh69YW2s4cUtw= X-Stat-Signature: rcmddgaxe9rm94f1y5wmp4ptco4xbba1 X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: CA631C001D Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=EyRs4jkV; dmarc=none; spf=pass (imf28.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.160.170 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-HE-Tag: 1666643802-738623 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 24, 2022 at 1:24 PM Jann Horn wrote: > > That's why GUP-fast re-checks the PTE after it has grabbed a reference > to the page. Bah. I should have known that. We got that through the PPC version that never had the whole IPI serialization thing (just the RCU freeing). I haven't looked at that code in much too long. Actually, by "much too long" I really mean "thankfully I haven't needed to" ;) Linus