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 519502309BA; Thu, 21 Nov 2024 02:01:12 +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=1732154474; cv=none; b=QJ7kJbMT9W8nuHNs6wup4zmAB6qMWXqBjEcUFkyWviOmj/UAG+vjn5YBc4UZdXv477LKcmbRzjKJyfPJ9QECpUucWnFYOnquaWIY87f6wp+Q0WIMnHx0wFM9Zws/4jZRQ9eVAIvYB4dQPr1O2h90am5TrqTP/i1ghPVES/AZBX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732154474; c=relaxed/simple; bh=bxamo9rYmX+GVPA2lopJxh4MsaXA2RWPPtWjqDZaDI8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=S4ViZyZGV+B5U5wM1fnk2WBCN3SEZt41LH6xpFIij3zYuNZT8GUBEhaVBvOnNMj+VV1lUSTbel88L1HKb9UzKbVR2LdnK5VathJcKuqNw0dCGl8IgTiZQ8j3sZmXM4/TCwndaMvpxf//rycMXAasbtVlJkrtluQUrs/jOV1AKyc= 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=OdR3j38l; 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="OdR3j38l" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bxamo9rYmX+GVPA2lopJxh4MsaXA2RWPPtWjqDZaDI8=; b=OdR3j38lGwZkou1FB3obQlS4MS eEoAMeVrw/5QMUla6nQVPRCXq+E+6Ndfx+2bqIfcuzjRpAWSFCloyPSOZbRzkfaboMCOrt7kQShy3 gfgyKMhtMnBWOZMuYyLmprVUM/LJq3+g1kdXZQQE+O+t+U2Qg/2vyrRsiYYDva/g9Khf2NhhVEdHG KTFutIw+54d8Ust3b1tjP8rdGo8Him2r1Q9X+iX2OxTfQGUBX6CAt5fqtB1gjc3E0BwDS5fEtK+NW PiYfEYiiuCtWLYmy2Bd0cs4k/oKPkKXhwqmpmP3n0UV0RS0YgTfgvv003ny0mioPpBijcu/6iqmc5 r/zifiiA==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tDwUw-00000005rF4-1u0R; Thu, 21 Nov 2024 02:00:46 +0000 Date: Thu, 21 Nov 2024 02:00:46 +0000 From: Matthew Wilcox To: Shakeel Butt Cc: Suren Baghdasaryan , akpm@linux-foundation.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, minchan@google.com, jannh@google.com, souravpanda@google.com, pasha.tatashin@soleen.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v4 0/5] move per-vma lock into vm_area_struct Message-ID: References: <20241120000826.335387-1-surenb@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 20, 2024 at 02:10:44PM -0800, Shakeel Butt wrote: > If 'struct vm_area_struct' is prone to performance issues due to > cacheline misalignments then we should do something about the > __randomize_layout tag for it. I imagine we can identify the fields > which might be performance critical to be on same cacheline or different > cacheline due to false sharing then we can divide the fields into > different cacheline groups and fields can be __randomize_layout within > the group. WDYT? Pretty sure the people who think security is more important than performance are the only ones who randomize structs.