From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 1B576158A36; Mon, 19 Aug 2024 20:40:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724100060; cv=none; b=Ft6kIjtFY981GNQLnnNuB1/GxMElH1ZBQ6IjsUzz+ojKioNUorzQl/ptVe1GcAHRKKNl53HOyR08F82rtfYsYyIUQJHZvv4fwtWBI6ZpRRwN/jHCQ3GJCHoE04Rcjny68qSLZUQ+CWsJBDnhKihdq85hky9QJaJKWBdlvhdbLgI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724100060; c=relaxed/simple; bh=J9DYvjOTNMlPj8lUuRSwuumR69rHflgqAun/m3FrUfs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SYQyoSX415ItF4taKdh5He9GqBb4wAcJRC7lUoITG/eecz0nNdgUY7HqfQgB0uc5VLucOfGiOk+OIOWHIw7a0k/QRhNjd+KobVCkIyIyLT9xDMtjwGdF/ovgbKyfX7aq0juTH1z1w+dHq2o5+sbNPq54Mu1RYpcbp+i2kkZFt5o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=YJUfES/u; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YJUfES/u" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=LR6gvp9HK2PILfTwueGWU5zqNdGWBxGU2nJl4V1AU5w=; b=YJUfES/uXnOPWqvoLRT4IA16LY E2sDhQrmGnA+ej3QJ7G8AwZLUKpmn7Oy8XmfWGc2RAO20izOrDIe8PTnnEO1+q5XLiF7Hjh7IvFRk VQR6yYcvzSVent7qK2wDkUPn7M7LRUSn0rDUx6xTM9EP8BFooJaXqfPT/QmrLF894OKm+uvYasrj4 OAbRHEX/VcOmDRuW9JBmjXEMPsueiTvBwQddu1bJYNOvAQR/RudrviNHypci/dXjY/PS9OFvdspDN EuYKGy4xtRANSUtr0T2kxuhFzRz0fS47Fp9+50O6Y4ilw8rWchVLgMJSn7XPCiGq0NCNcfBaf/Clv q2rhdYkA==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg9B4-000000079lt-26nJ; Mon, 19 Aug 2024 20:40:34 +0000 Date: Mon, 19 Aug 2024 21:40:34 +0100 From: Matthew Wilcox To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, corbet@lwn.net, arnd@arndb.de, mcgrof@kernel.org, rppt@kernel.org, paulmck@kernel.org, thuth@redhat.com, tglx@linutronix.de, bp@alien8.de, xiongwei.song@windriver.com, ardb@kernel.org, david@redhat.com, vbabka@suse.cz, mhocko@suse.com, hannes@cmpxchg.org, roman.gushchin@linux.dev, dave@stgolabs.net, liam.howlett@oracle.com, pasha.tatashin@soleen.com, souravpanda@google.com, keescook@chromium.org, dennis@kernel.org, jhubbard@nvidia.com, yuzhao@google.com, vvvvvv@google.com, rostedt@goodmis.org, iamjoonsoo.kim@lge.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 5/5] alloc_tag: config to store page allocation tag refs in page flags Message-ID: References: <20240819151512.2363698-1-surenb@google.com> <20240819151512.2363698-6-surenb@google.com> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Aug 19, 2024 at 01:39:16PM -0700, Suren Baghdasaryan wrote: > On Mon, Aug 19, 2024 at 12:34 PM Matthew Wilcox wrote: > > So if ALLOC_TAG_REF_WIDTH is big enough, it's going to force last_cpupid > > into struct page. > > Thanks for taking a look! > Yes, but how is this field different from say KASAN_TAG_WIDTH which > can also force last_cpupid out of page flags? Because KASAN isn't for production use? > > That will misalign struct page and disable HVO -- with no warning! > > mminit_verify_pageflags_layout already has a mminit_dprintk() to > indicate this condition. Is that not enough? Fair.