From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Xu Subject: Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared memory types Date: Mon, 30 May 2022 14:29:31 -0400 Message-ID: References: <20220527193936.30678-1-peterx@redhat.com> <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935379; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=HbBF2ajaufZl9/WUtxyDJxCGJ9BcRQz/emu2qDiECh2i5UBkeWh6TtnQT3PjvYY6l7es4L 3G/Q11/CJkMBZz1hC5mVhwu/tKZIJ5EMd75pJNM4heYAIld/c/yvBrPTjjfZZIlZEMTa+c wzKHAMoIoP3+DAvw0soTcPl5tm37JoM= In-Reply-To: Content-Disposition: inline List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Heiko Carstens Cc: Christian Borntraeger , 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 On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu 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 4AD12C433F5 for ; Mon, 30 May 2022 18:29:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242748AbiE3S3o (ORCPT ); Mon, 30 May 2022 14:29:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242755AbiE3S3m (ORCPT ); Mon, 30 May 2022 14:29:42 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 208A36212E for ; Mon, 30 May 2022 11:29:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935378; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=MWCMyyjKq+nRsU1/E2gQwxH46wgLGr/ocdisVFG0vLsWPtOiumnskJ2064A5WnrOgrTAZJ 2gtTHxcY1TmLno+4FOSlws0frcW0tkSZ2i9Y3zUw043tBhAPIixFMz3pBN4P9KZ/7bnoN7 MMNOZpVOn2ePwNiCaXI2tfxkHSc9+EI= Received: from mail-il1-f198.google.com (mail-il1-f198.google.com [209.85.166.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-247-d5GjGejgOyy93imet6VTGQ-1; Mon, 30 May 2022 14:29:37 -0400 X-MC-Unique: d5GjGejgOyy93imet6VTGQ-1 Received: by mail-il1-f198.google.com with SMTP id b13-20020a92670d000000b002d1a5d6b795so8766763ilc.16 for ; Mon, 30 May 2022 11:29:37 -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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=C+p7i8NI+q/8+ZAjDDD5Quj4Py8cXJSKlxmRKy4yJ9iXKy/2CChiZ9N+hl4L/HdY8o viEdJuZtm5vhHi1/JSsA4Yf6SE1M3KQixV9ki0u7Ee2pHOefr2z6WkVdgM5DDDnERkKU Xmh7coN00gJhLZEqIC9/twBlWN5CS4rJoN0iTUBtrQ5vdrE8PoUL3C8cZbwfcV8hQ+bQ ieoLXgAMh411t5HuNOSdadiuZWeVkR7YFDO5PCMcZccgZ5liE/aLWyTkPaf3WRBjKSck o53H1VyS9C7PXRX4OQcEXV4Magj9iQccyRGk3E+eL9qBhQ1hOQhA3hUVIBpmnKPwM1j4 WTLQ== X-Gm-Message-State: AOAM532Mxm/FOuNaZVn49NA3H+0Q+Iekig9KOHSOB/8G/JF0ic8rWksL m68Xl/J9HJ5KwfleLN1MmOzZFbYiIoFHuwF1ldkH45Hi6H0lnEfAoYVII96/obTKBQK6qlF9PxV SnAeUymQvFK3HNeff4Co+vg== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171857iln.207.1653935377083; Mon, 30 May 2022 11:29:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy3wrc9ZuPCRdn+Dbnr8a7+sDY/SXALiOk3qZ3Cm9Rs8SSVa+bj9UHR0EABkWjwoIvWxsPXBw== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171841iln.207.1653935376794; Mon, 30 May 2022 11:29:36 -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 cn9-20020a0566383a0900b003313b7a5731sm183095jab.178.2022.05.30.11.29.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 11:29:36 -0700 (PDT) Date: Mon, 30 May 2022 14:29:31 -0400 From: Peter Xu To: Heiko Carstens Cc: Christian Borntraeger , 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: Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Xu Date: Mon, 30 May 2022 18:29:31 +0000 Subject: Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared memory types Message-Id: List-Id: References: <20220527193936.30678-1-peterx@redhat.com> <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Heiko Carstens Cc: Christian Borntraeger , 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 On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 625B2C433F5 for ; Mon, 30 May 2022 18:29:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5c63FcTPDguGJ2H844myCGtYOwjPt3y2gra7bkhlyz8=; b=DeiUl4oIkp8csY RaQWhFRdiU4bY4iXj5QvsbaockCc+nwik2BxE4HjeftgpynmZ8/Dgv+8QZMxSJYV6UbJ28k33iO5Y oO9zPNrGxB/6Fcd8pW1e+Ejl1rY+Wgw1jizbPxNeQlCePCilg4WYOdxyOWBx8CqAX7A0lt7i0FHEo AjwvibkPt5PwSA4Ak8/s5sgDpRKXnnVuMlBmYRHCs7lAIH/RFcK60lnbs4lSM6m/asf+U5Vvz9KHx Lw6pLy+fI5fOwDXc16B/V7lNKS5ptLg7XQQg1kfHJg0E7nFzIzRW1hxeBrxm5rtjO8YFbIaYvuOK1 DFLd/GEKitmfYy15Z0uQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvk9A-007rHz-Bv; Mon, 30 May 2022 18:29:44 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvk96-007rFO-FD for linux-riscv@lists.infradead.org; Mon, 30 May 2022 18:29:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935378; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=MWCMyyjKq+nRsU1/E2gQwxH46wgLGr/ocdisVFG0vLsWPtOiumnskJ2064A5WnrOgrTAZJ 2gtTHxcY1TmLno+4FOSlws0frcW0tkSZ2i9Y3zUw043tBhAPIixFMz3pBN4P9KZ/7bnoN7 MMNOZpVOn2ePwNiCaXI2tfxkHSc9+EI= 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-ijJtm6A0P4KnDqXof7VRjA-1; Mon, 30 May 2022 14:29:37 -0400 X-MC-Unique: ijJtm6A0P4KnDqXof7VRjA-1 Received: by mail-il1-f197.google.com with SMTP id r9-20020a92cd89000000b002d16798b3cfso8753437ilb.22 for ; Mon, 30 May 2022 11:29:37 -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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=cKUHatRgr44zw3XqOBF2syvuVWvQWCi46JgKVbGFjK2AYaPdx7hzIIunH9RWdc7Izw 8URnwJxn4Uqoylivp3s9soXTirp6kWW4YMEe20WfbAPlhQP4u7uaTri04rkgFYGMSQHc sW8Y5BkKVAQE9WQ03TkcY/tWmB+DvbhF1/2zGzIT4vrITUlrWZpdEycuD8SI1AlwXVUW BGcDG62pV9sMWeMvNISw8ym2oAm5UlApdERUTqfxuh1cD7Sy/B4Opsd/AtLvMn9cusKd i9a003Sw+dlaPN7fZxZSTgltC3hgPP/jeNY+QerQpr+ic262MCwPDcoldvZ3mY4CSaR/ bdEg== X-Gm-Message-State: AOAM530TpUw/mVSp8rzn7GEcVwiUiTrZPKMQR+PDsFCgSFF4C/PY5lAv CJn4+/AH2vj1L4mVVn7yNOp5gtp394iQUQIfg7iRk4IZAzz2ES6kBoKtcF6ERw0aTQAvyjWdi6U WSLybcm44v1N2FQvJ4/R6BBVAQvdk X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171907iln.207.1653935377088; Mon, 30 May 2022 11:29:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy3wrc9ZuPCRdn+Dbnr8a7+sDY/SXALiOk3qZ3Cm9Rs8SSVa+bj9UHR0EABkWjwoIvWxsPXBw== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171841iln.207.1653935376794; Mon, 30 May 2022 11:29:36 -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 cn9-20020a0566383a0900b003313b7a5731sm183095jab.178.2022.05.30.11.29.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 11:29:36 -0700 (PDT) Date: Mon, 30 May 2022 14:29:31 -0400 From: Peter Xu To: Heiko Carstens Cc: Christian Borntraeger , 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 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220530_112940_694016_0389941F X-CRM114-Status: GOOD ( 24.41 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B47BEC433EF for ; Mon, 30 May 2022 18:29:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=/922Bts53gN54IXn0VL1z6TAb9gxgc1ppKRimF+Oku0=; b=LwfztG4y+RWDMz owXgwTyUYV9FnV1Ms9HRr3EFAcKKjezRY7pRu619azpY25xcj0V9oLom389YmdHzJk3nNkFFXednx 6ItjCl41hxvxUHlzyPV/CZHIx0xMXcLOlw/jEu7pZeC2GBTCd5/gTpajDwnHga6POsjVbTIx6BpqJ b1p6r0yiDmkhj2Wj+cwv4LfmH9/NmXU52fiaGXtbJFo+QTx4vmQa1RaIANCkv6QIeLihem4RXD4RH TiKMqrHbyN0xQW3u/a33pSwLEf/4JFx2mseO6213aqEOKlUeLwL2NfeHX4i3b5b3ek8KOEi+v9GvM FEKE2wcWKIbTtiCjIY0Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvk9D-007rJX-JB; Mon, 30 May 2022 18:29:47 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nvk96-007rFP-FE for linux-snps-arc@lists.infradead.org; Mon, 30 May 2022 18:29:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935378; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=MWCMyyjKq+nRsU1/E2gQwxH46wgLGr/ocdisVFG0vLsWPtOiumnskJ2064A5WnrOgrTAZJ 2gtTHxcY1TmLno+4FOSlws0frcW0tkSZ2i9Y3zUw043tBhAPIixFMz3pBN4P9KZ/7bnoN7 MMNOZpVOn2ePwNiCaXI2tfxkHSc9+EI= Received: from mail-il1-f199.google.com (mail-il1-f199.google.com [209.85.166.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-616-ueTSRWasOb-LL5C-IN1CaA-1; Mon, 30 May 2022 14:29:37 -0400 X-MC-Unique: ueTSRWasOb-LL5C-IN1CaA-1 Received: by mail-il1-f199.google.com with SMTP id i16-20020a056e021d1000b002d3bbe39232so74956ila.20 for ; Mon, 30 May 2022 11:29:37 -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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=WdzBlwpKMALcFMzzXuIu8/1cp5b271VvoPP5BewFy+W/sgslFt2zJrFc+smnjaKut4 xHuC1bZI2QIZ4MH9cEGhs1JR18FqCjVWBVQb8WpeDtRgAmzVXGatw/YMStmN53ZqIU6i lk1KGQnjSolC9TvbuUZPI8yKxrZ7IpNjHubvkPEtIHIMf2TLzoy+XweUYcxn1T6aAbN2 lfpWBvu7rN2DQ1raJohN24ajckpLU2z+rGpgH3fQuEKf5u87/wuXfi2lUkxnUH2tUaPY UPq/wv+LtO0BXnFa84fs1Me9mEvevWvh3gLTprxOMTsviYwClncRVb+QIk+5/FI2AMEX kbvw== X-Gm-Message-State: AOAM532yY3ZK8hLpRliSqaPH/ZeM8gxCvNjxEQXeT1VSYuQYsuFwqsLw b6ujHakUhyGTPvp/m0cc7MTNidn2hbVFq4M6FX9kpy+mu4aefPfVB24hZocXHpNPHyPbxYCtqP4 K+bdpfSJbINl8sTeEbsN1rgdQStUHENSJ X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171867iln.207.1653935377084; Mon, 30 May 2022 11:29:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy3wrc9ZuPCRdn+Dbnr8a7+sDY/SXALiOk3qZ3Cm9Rs8SSVa+bj9UHR0EABkWjwoIvWxsPXBw== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171841iln.207.1653935376794; Mon, 30 May 2022 11:29:36 -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 cn9-20020a0566383a0900b003313b7a5731sm183095jab.178.2022.05.30.11.29.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 11:29:36 -0700 (PDT) Date: Mon, 30 May 2022 14:29:31 -0400 From: Peter Xu To: Heiko Carstens Cc: Christian Borntraeger , 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 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220530_112940_714562_30EBC35E X-CRM114-Status: GOOD ( 24.41 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc 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 mail.librecores.org (lists.librecores.org [88.198.125.70]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED96DC433FE for ; Mon, 30 May 2022 18:29:42 +0000 (UTC) Received: from [172.31.1.100] (localhost.localdomain [127.0.0.1]) by mail.librecores.org (Postfix) with ESMTP id 893ED240FC; Mon, 30 May 2022 20:29:41 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mail.librecores.org (Postfix) with ESMTP id ED18E23E0C for ; Mon, 30 May 2022 20:29:39 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935379; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=HbBF2ajaufZl9/WUtxyDJxCGJ9BcRQz/emu2qDiECh2i5UBkeWh6TtnQT3PjvYY6l7es4L 3G/Q11/CJkMBZz1hC5mVhwu/tKZIJ5EMd75pJNM4heYAIld/c/yvBrPTjjfZZIlZEMTa+c wzKHAMoIoP3+DAvw0soTcPl5tm37JoM= Received: from mail-il1-f198.google.com (mail-il1-f198.google.com [209.85.166.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-365-_ssiL9j8PAOVHdlBl1BMtg-1; Mon, 30 May 2022 14:29:37 -0400 X-MC-Unique: _ssiL9j8PAOVHdlBl1BMtg-1 Received: by mail-il1-f198.google.com with SMTP id c1-20020a928e01000000b002d1b20aa761so8770534ild.6 for ; Mon, 30 May 2022 11:29:37 -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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=OkDxRtQfBGdL8J0PyMKhxNLzZZpJwiNL5+EEG6Y/1Xb5vZeHHWbm56JSxE+LLWGXfL WA7+blh3msDIg/XVjO0zd8VriSAwBiQhlgGFF+LlHFEFfCWh1XRPnRCoXawMX20LsLhK uwC4gnlyCpgSnQLGglPW9vJOs4/sgf6DpuICvY6L9Qo88qWaF7JrKKgPs2UyIaCvtO+e o9gaErtjfdFp2ln6zXeUKjVR5i0uY4belVVlkqhEKr6ZyNESU8QrqqKqn3cjYp2oHo7T 2t0Lf+LbKhnAMMeR7kp2n5J7vFr6N4psK1+cf8iROf87ft+StAJSZVip4fJt++ny3Kav VJyQ== X-Gm-Message-State: AOAM533Ke5yfnt71yxsveevukLWvvA3abRsHixSgX4oc6Pav7uDvrnGC KWBoYErRQLvEdQkLn5JHPY+agG6GIYumWTFOP0/JF79ClYp0hgmRTN0ylkq6tI1r4cbcvdwigWB JxrdGb+CKyYMGsYZzJVSXrpm0xQ== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171917iln.207.1653935377091; Mon, 30 May 2022 11:29:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy3wrc9ZuPCRdn+Dbnr8a7+sDY/SXALiOk3qZ3Cm9Rs8SSVa+bj9UHR0EABkWjwoIvWxsPXBw== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171841iln.207.1653935376794; Mon, 30 May 2022 11:29:36 -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 cn9-20020a0566383a0900b003313b7a5731sm183095jab.178.2022.05.30.11.29.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 11:29:36 -0700 (PDT) Date: Mon, 30 May 2022 14:29:31 -0400 From: Peter Xu To: Heiko Carstens 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 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-BeenThere: openrisc@lists.librecores.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Discussion around the OpenRISC processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rich Felker , linux-ia64@vger.kernel.org, David Hildenbrand , Peter Zijlstra , Benjamin Herrenschmidt , Dave Hansen , x86@kernel.org, linux-mips@vger.kernel.org, "James E . J . Bottomley" , linux-mm@kvack.org, Guo Ren , "H . Peter Anvin" , sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, Alexander Gordeev , Will Deacon , Thomas Gleixner , Paul Mackerras , Anton Ivanov , Jonas Bonn , linux-s390@vger.kernel.org, Janosch Frank , Yoshinori Sato , linux-sh@vger.kernel.org, Michael Ellerman , Helge Deller , Alistair Popple , Hugh Dickins , Russell King , linux-csky@vger.kernel.org, Ingo Molnar , Andrea Arcangeli , linux-arm-kernel@lists.infradead.org, Vineet Gupta , Matt Turner , linux-snps-arc@lists.infradead.org, Catalin Marinas , linux-xtensa@linux-xtensa.org, Albert Ou , Vasily Gorbik , Chris Zankel , Johannes Weiner , linux-um@lists.infradead.org, Nicholas Piggin , Richard Weinberger , linux-m68k@lists.linux-m68k.org, openrisc@lists.librecores.org, Borislav Petkov , Al Viro , Andy Lutomirski , Paul Walmsley , Ingo Molnar , Vlastimil Babka , Richard Henderson , Brian Cain , Michal Simek , Christian Borntraeger , linux-parisc@vger.kernel.org, Max Filippov , linux-kernel@vger.kernel.org, Johannes Berg , Dinh Nguyen , linux-riscv@lists.infradead.org, Palmer Dabbelt , Sven Schnelle , linux-alpha@vger.kernel.org, Ivan Kokshaysky , Andrew Morton , Thomas Bogendoerfer , linuxppc-dev@lists.ozlabs.org, "David S . Miller" Errors-To: openrisc-bounces@lists.librecores.org Sender: "OpenRISC" On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 21458C433F5 for ; Mon, 30 May 2022 22:30:30 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LBqqS4Zy1z2ymf for ; Tue, 31 May 2022 08:30:28 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=evP/CaZS; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=evP/CaZS; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.133.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=peterx@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=evP/CaZS; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=evP/CaZS; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4LBkTm3b9Kz2xh0 for ; Tue, 31 May 2022 04:29:45 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935382; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=evP/CaZSx5h3qClziv1mdzlf1RuwfeCv9z0Pc1DZ9iggYkq7cgRkTLffnWFdW2p4v64ZEL aJGJzv+LxylwnATRnTBC88Wi27sj9+6yu6BSRZcgicozvw3QYT7yE4TLDL8kE2q7qM9QYi Rf+7Ys7gPQ319wEmdRBNXEWx9OcI77I= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653935382; 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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=evP/CaZSx5h3qClziv1mdzlf1RuwfeCv9z0Pc1DZ9iggYkq7cgRkTLffnWFdW2p4v64ZEL aJGJzv+LxylwnATRnTBC88Wi27sj9+6yu6BSRZcgicozvw3QYT7yE4TLDL8kE2q7qM9QYi Rf+7Ys7gPQ319wEmdRBNXEWx9OcI77I= Received: from mail-il1-f200.google.com (mail-il1-f200.google.com [209.85.166.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-326-yQxoEMOSMta465rsfe2gzA-1; Mon, 30 May 2022 14:29:37 -0400 X-MC-Unique: yQxoEMOSMta465rsfe2gzA-1 Received: by mail-il1-f200.google.com with SMTP id c1-20020a928e01000000b002d1b20aa761so8770537ild.6 for ; Mon, 30 May 2022 11:29:37 -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=+ALrzFnb0YEuDamJlOSrZjOy/DY+2J0hn9MNRn5A9C4=; b=izct+NSlEX0pb+n/LIKeVpHRzGQ3OLABQsv6Ndt3k1dCk7j+KF77VkfTBgNmclkwaF 4H1EQfHywMPR4y0jzXZ5otGy4PhmlV3RFVzdncYIXtX5KHYcYzO0CmC3r7RnoTFoopCv AMDLvV/gQEkmI+gyfybF8rf3pPEp0CqlvlCViJ/Jb+KWxDNw0qgkpP8VNUKO9LMfxD2c ydhw6dHk9sfK5D0y8EO6CRVQXhSnZ3je+Br8i0+W4zs0NET4tG/h84AVfRvxk7GENXFC ApOeqFHXAIy3wyY8A8UJ69BeueypfzWWdmR+6s2ij/OKt2Ulo7ZM9lm/CoOPk4nB+sh5 U84Q== X-Gm-Message-State: AOAM531lwjarDsTF8uVoJXZ5eiEq7DQiD1Wx30loufq2AcZvFxuGt4Fz GGm4NozxULTveMy+V+O32llWdF1NcEauR1WYRZrsuuuXhp6lUY0Anvb2etix/lXT8S9vfE3gCA0 1k6HSgOlKlM2F8yFbxzqOblqpgQ== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171889iln.207.1653935377089; Mon, 30 May 2022 11:29:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy3wrc9ZuPCRdn+Dbnr8a7+sDY/SXALiOk3qZ3Cm9Rs8SSVa+bj9UHR0EABkWjwoIvWxsPXBw== X-Received: by 2002:a92:d785:0:b0:2d1:7ce6:b834 with SMTP id d5-20020a92d785000000b002d17ce6b834mr25171841iln.207.1653935376794; Mon, 30 May 2022 11:29:36 -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 cn9-20020a0566383a0900b003313b7a5731sm183095jab.178.2022.05.30.11.29.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 May 2022 11:29:36 -0700 (PDT) Date: Mon, 30 May 2022 14:29:31 -0400 From: Peter Xu To: Heiko Carstens 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 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Mailman-Approved-At: Tue, 31 May 2022 08:25:41 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rich Felker , linux-ia64@vger.kernel.org, David Hildenbrand , Peter Zijlstra , Dave Hansen , x86@kernel.org, linux-mips@vger.kernel.org, "James E . J . Bottomley" , linux-mm@kvack.org, Guo Ren , "H . Peter Anvin" , sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, Alexander Gordeev , Will Deacon , Thomas Gleixner , Paul Mackerras , Anton Ivanov , Jonas Bonn , linux-s390@vger.kernel.org, Janosch Frank , Yoshinori Sato , linux-sh@vger.kernel.org, Helge Deller , Alistair Popple , Hugh Dickins , Russell King , linux-csky@vger.kernel.org, Ingo Molnar , Andrea Arcangeli , Geert Uytterhoeven , linux-arm-kernel@lists.infradead.org, Vineet Gupta , Matt Turner , linux-snps-arc@lists.infradead.org, Catalin Marinas , linux-xtensa@linux-xtensa.org, Albert Ou , Vasily Gorbik , Chris Zankel , Johannes Weiner , linux-um@lists.infradead.org, Nicholas Piggin , Stefan Kristiansson , Richard Weinberger , linux-m68k@lists.linux-m68k.org, openrisc@lists.librecores.org, Borislav Petkov , Al Viro , Andy Lutomirski , Paul Walmsley , Stafford Horne , Ingo Molnar , Vlastimil Babka , Richard Henderson , Brian Cain , Michal Simek , Christian Borntraeger , linux-parisc@vger.kernel.org, Max Filippov , linux-kernel@vger.kernel.org, Johannes Berg , Dinh Nguyen , linux-riscv@lists.infradead.org, Palmer Dabbelt , Sven Schnelle , linux-alpha@vger.kernel.org, Ivan Kokshaysky , Andrew Morton , Thomas Bogendoerfer , linuxppc-dev@lists.ozlabs.org, "David S . Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, May 30, 2022 at 07:03:31PM +0200, Heiko Carstens wrote: > On Mon, May 30, 2022 at 12:00:52PM -0400, Peter Xu wrote: > > On Mon, May 30, 2022 at 11:52:54AM -0400, Peter Xu wrote: > > > On Mon, May 30, 2022 at 11:35:10AM +0200, Christian Borntraeger wrote: > > > > > 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; > > > > > + } > fault = 0; <---- > > > > > + goto out; > > > > Hmm, right after I replied I found "goto out" could be problematic, since > > all s390 callers of do_exception() will assume it an error condition (side > > note: "goto out_gmap" contains one step to clear "fault" to 0). I'll > > replace this with "return 0" instead if it looks good to both of you. > > > > I'll wait for a confirmation before reposting. Thanks, > > Right, that was stupid. Thanks for double checking! > > However could you please add "fault = 0" just in front of the goto out > like above? I'd like to avoid having returns and gotos mixed. Sure thing. -- Peter Xu