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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11F53C4332F for ; Mon, 30 May 2022 15:59:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239703AbiE3P7p (ORCPT ); Mon, 30 May 2022 11:59:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240957AbiE3P7g (ORCPT ); Mon, 30 May 2022 11:59:36 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7135C33894 for ; Mon, 30 May 2022 08:53:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653925982; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=bDYue/Afd3VGZHzU7tYF7qy5xBeBUpqe85rLuoAiRcE=; b=AkXHNJKvAQRHb5OqI+OhXnw4AlFTHU7SQ25I25r8DrkTB9nwXx2U3S7uy3yWEhfxPKMgZ0 MCHoCCU4ElbTk7DKNd2mXmRpWE6tOdwsDRWpn7scMraYzymGuve2EYFM1vMWpJYkKpJQS0 OjtcJUf23O2R/uhMV8v3cei4In0oe2Y= Received: from mail-il1-f197.google.com (mail-il1-f197.google.com [209.85.166.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-616-rHMqKuLoNvmODNjkT5hcPg-1; Mon, 30 May 2022 11:53:01 -0400 X-MC-Unique: rHMqKuLoNvmODNjkT5hcPg-1 Received: by mail-il1-f197.google.com with SMTP id m9-20020a056e021c2900b002d13627892eso8554296ilh.20 for ; Mon, 30 May 2022 08:53:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=bDYue/Afd3VGZHzU7tYF7qy5xBeBUpqe85rLuoAiRcE=; b=0CTP6iv0J4QeiUOZdw7ooYTuicGE1e1+BrPHuNi8h0XsEjwyemzhx4SGlKXSBMJhWO 3VO2SEQ7XFk15eWHOkvDwLefqBdEdM51+dVwqOSGFK7pKOP/09Va+JyvbOPQyNwDaeff MNI/1I0LrefN+c/4CIrw10AYTK1C8A1lAyrX8s8f9wHlEYQvMgRZsK+X9r40zWG4HBtH cZ9fuSyqkg00+Tm+gMbxuQnAEGBWdKYwGoeFTQL+zrSDArRWYWTf2TXNVeVXu3BXzD9m L1y6Eys5KF6E9HGaRlcK8xO6bnOCvDJkbR4N0aQ2tWXcZizOJqvhHltqJgOA/SA3Ls+Q +2OQ== X-Gm-Message-State: AOAM533j97ddh0quNiTurMC84Ug0oGf4EAmLiNoYA8LU9Bek29BBjqST 9dOoxrVPGLvsOjCIH3wPfNfaXHsZ70qOc8cEzPHilZysRZf1obbTuBEkZAlqsRY3+P/Pyntexd8 kowvl0kBoavVchRgU6MB4Sw== X-Received: by 2002:a5d:9cc8:0:b0:663:2899:4b8 with SMTP id w8-20020a5d9cc8000000b00663289904b8mr16857382iow.192.1653925980595; Mon, 30 May 2022 08:53:00 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyKQIoyyqGc41UCjMUnObS0GZ5Lh8IPSVLY8KDGIOa5YRMfMwdzANPXLWIG/1E7oUnwvcvO1w== X-Received: by 2002:a5d:9cc8:0:b0:663:2899:4b8 with SMTP id w8-20020a5d9cc8000000b00663289904b8mr16857337iow.192.1653925980357; Mon, 30 May 2022 08:53:00 -0700 (PDT) Received: from xz-m1.local (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id 66-20020a021d45000000b0032e75bfe344sm2781109jaj.171.2022.05.30.08.52.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 08:52:59 -0700 (PDT) Date: Mon, 30 May 2022 11:52:54 -0400 From: Peter Xu To: Christian Borntraeger Cc: Heiko Carstens , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Will Deacon , Matt Turner , linux-s390@vger.kernel.org, Andrew Morton , Brian Cain , Borislav Petkov , linux-alpha@vger.kernel.org, Alistair Popple , Jonas Bonn , linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, Michael Ellerman , Stefan Kristiansson , linux-snps-arc@lists.infradead.org, Vineet Gupta , Vasily Gorbik , Vlastimil Babka , Ivan Kokshaysky , Rich Felker , sparclinux@vger.kernel.org, Russell King , David Hildenbrand , Benjamin Herrenschmidt , Nicholas Piggin , "James E . J . Bottomley" , linux-xtensa@linux-xtensa.org, linux-sh@vger.kernel.org, Paul Walmsley , linux-m68k@lists.linux-m68k.org, linuxppc-dev@lists.ozlabs.org, Richard Henderson , Guo Ren , linux-parisc@vger.kernel.org, Andrea Arcangeli , Helge Deller , Al Viro , Albert Ou , linux-um@lists.infradead.org, "H . Peter Anvin" , Janosch Frank , Sven Schnelle , Anton Ivanov , openrisc@lists.librecores.org, Thomas Bogendoerfer , linux-hexagon@vger.kernel.org, Andy Lutomirski , Stafford Horne , linux-csky@vger.kernel.org, Thomas Gleixner , linux-mips@vger.kernel.org, Paul Mackerras , Alexander Gordeev , Dinh Nguyen , Palmer Dabbelt , "David S . Miller" , Johannes Weiner , Hugh Dickins , Ingo Molnar , Peter Zijlstra , linux-riscv@lists.infradead.org, Max Filippov , Catalin Marinas , Geert Uytterhoeven , Johannes Berg , Chris Zankel , Michal Simek , x86@kernel.org, Yoshinori Sato , Dave Hansen , Richard Weinberger , Ingo Molnar Subject: Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared memory types Message-ID: References: <20220527193936.30678-1-peterx@redhat.com> <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > Am 29.05.22 um 22:33 schrieb Heiko Carstens: > [...] > > > > Guess the patch below on top of your patch is what we want. > > Just for clarification: if gmap is not NULL then the process is a kvm > > process. So, depending on the workload, this optimization makes sense. > > > > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c > > index 4608cc962ecf..e1d40ca341b7 100644 > > --- a/arch/s390/mm/fault.c > > +++ b/arch/s390/mm/fault.c > > @@ -436,12 +436,11 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) > > /* The fault is fully completed (including releasing mmap lock) */ > > if (fault & VM_FAULT_COMPLETED) { > > - /* > > - * Gmap will need the mmap lock again, so retake it. TODO: > > - * only conditionally take the lock when CONFIG_PGSTE set. > > - */ > > - mmap_read_lock(mm); > > - goto out_gmap; > > + if (gmap) { > > + mmap_read_lock(mm); > > + goto out_gmap; > > + } > > + goto out; > > Yes, that makes sense. With that > > Acked-by: Christian Borntraeger Looks sane, thanks Heiko, Christian. I'll cook another one. -- Peter Xu