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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23DA1C433FE for ; Mon, 30 May 2022 15:53:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B17F76B0071; Mon, 30 May 2022 11:53:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ACB616B0072; Mon, 30 May 2022 11:53:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 93F446B0073; Mon, 30 May 2022 11:53:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 853B46B0071 for ; Mon, 30 May 2022 11:53:03 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 5BC0E60BDA for ; Mon, 30 May 2022 15:53:03 +0000 (UTC) X-FDA: 79522853046.01.757DC2D Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf20.hostedemail.com (Postfix) with ESMTP id 7438F1C004F for ; Mon, 30 May 2022 15:52:45 +0000 (UTC) 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-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-219-ZCIfoI5yOG2vH3mDBTzQiw-1; Mon, 30 May 2022 11:53:01 -0400 X-MC-Unique: ZCIfoI5yOG2vH3mDBTzQiw-1 Received: by mail-il1-f198.google.com with SMTP id m9-20020a056e021c2900b002d13627892eso8554294ilh.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=qwMt4OsxQwmY0VbLf0HyLN92NrUDgxIpHMFD27LU348u5SfNOuN8PsO4Rjqe9Ck8cJ dxp0JY8H2IURkw9lkZPfVTOuDrdNm83IEbnSvwVy+Qu0EmTh5I3vkm6It0rRZwPc7rLo SAjsfquRldebWwkXV7wTc/S/L2zxO6Rqb+27fqlTRngucBXzwx3u/pyliHFHsY4IgY3G je0UX0ZlBuzChoM/i6LtWQtJ4PkUtXzmPIGpCMuIKqmKliQ/H2tQAdCZdk/9u1awZ58S QNw4jmjW6Pfc59xLKvsRF0XWWkOhvK6I2jTLYwfWtM45XXlL/6a0AVr2SxPfW5vtxyLJ wYvw== X-Gm-Message-State: AOAM530SLA0OeSWoIUvxj+/dL8oEwdL7H1BK2jB5bKYH5ZaNp+JXtFgw X54i/ada153XwMBEUg/e4arwTCNQ5JJVERJnoqqNSFj7epPnHt1KPiLWXNBrA8vaRDnSSp5ud5i BJE3fdzhUqyQ= X-Received: by 2002:a5d:9cc8:0:b0:663:2899:4b8 with SMTP id w8-20020a5d9cc8000000b00663289904b8mr16857353iow.192.1653925980591; 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 In-Reply-To: <33fd4731-9765-d78b-bdc3-f8243c98e81f@linux.ibm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=AkXHNJKv; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf20.hostedemail.com: domain of peterx@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=peterx@redhat.com X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 7438F1C004F X-Stat-Signature: 4tbqxt3n3zgko7pogwre3n317rhn3emr X-HE-Tag: 1653925965-402128 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, 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