From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 24 Oct 2018 13:57:50 +0200 (CEST) Received: from mail-pf1-x443.google.com ([IPv6:2607:f8b0:4864:20::443]:41517 "EHLO mail-pf1-x443.google.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23990947AbeJXL5oKoRY- (ORCPT ); Wed, 24 Oct 2018 13:57:44 +0200 Received: by mail-pf1-x443.google.com with SMTP id a19-v6so2292400pfo.8 for ; Wed, 24 Oct 2018 04:57:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=r4S1JZtjtEoZRmv1cmbD7oqQ5fBxxZJ0gckdgeOcI14=; b=rxvOMkoPR1fl+wChK1gmiyTy80jYizuSzzLNsN1UW/nn68lcvDelAzg7q5xRULAFwF 88m9+eaacj9fu1oQRgbn9o9rL5OobsROYLsUPy8Jgnz+ao671RDA5Lk1ggZYlGqX9SbG 9RUUixIOumM9W9fFeC11ng0GECm2HV0kpOJEacCyBhFOab2Q3i4VFHF0QbnxQWZzkmCY Lire1m9l7AF9VgUbUKgofuhPxpehLdKNOXRb6mUKntibxqs2pslottwNtAIjzUINJV13 bV4f1WLD9yCA7Iyr+h+lgaNFbMHR6/U4tmHoxnhQ/7prUqBNDcYtn35v7xWxzF+rGnLI 1zrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=r4S1JZtjtEoZRmv1cmbD7oqQ5fBxxZJ0gckdgeOcI14=; b=QBbqTVNoRLbxdLnlgM6OhcSYhYtnpTsa804zCBagSPMKZeyco2L2Dqx6liVXpuZOnf wZl6cmbygqFwlUWREV4D510Sm6NlfJeVmSsalOwsJ6SbGiHiLO8f3g+YmAKA1FFblUmX Uhzd1umXUpbJNJYdwXkWqKLdP6Wud/RDMmb1ZoGrwqqpwHG/qdZGGYcE1DTMCcH6+jQe vqpZ7HfXJT2C5mQRjQtIxr2BPlLnGgBWZ+cvR35vHCHIhmY8OjGLdfSt2FSVGtibQRnV 846TY4Jf0sbY9kGrh7DTp3Vuf2NAAjfdFbTaLMIV0CE1EV9RE3VgNIw0n76oq3oZ2zJI NJ9Q== X-Gm-Message-State: AGRZ1gK5QR69azDtlssOIjUJhEvW9qqAecn6rU4/PlTqCdd9ZJKMdaUs M2pr7NCLRsK5MyrCmfJhssM= X-Google-Smtp-Source: AJdET5fJWm/yEunoAdHkJCNfHZyAKT69zWrP0KZ/06Nf8Zmi/6rvBn7LEzBt+uDaB55Nx51vc0n+3g== X-Received: by 2002:a62:6383:: with SMTP id x125-v6mr2334785pfb.13.1540382257876; Wed, 24 Oct 2018 04:57:37 -0700 (PDT) Received: from localhost (14-202-194-140.static.tpgi.com.au. [14.202.194.140]) by smtp.gmail.com with ESMTPSA id t5-v6sm3677450pfm.26.2018.10.24.04.57.35 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 24 Oct 2018 04:57:36 -0700 (PDT) Date: Wed, 24 Oct 2018 22:57:33 +1100 From: Balbir Singh To: "Kirill A. Shutemov" Cc: "Joel Fernandes (Google)" , linux-kernel@vger.kernel.org, kernel-team@android.com, minchan@kernel.org, pantin@google.com, hughd@google.com, lokeshgidra@google.com, dancol@google.com, mhocko@kernel.org, akpm@linux-foundation.org, Andrey Ryabinin , Andy Lutomirski , anton.ivanov@kot-begemot.co.uk, Borislav Petkov , Catalin Marinas , Chris Zankel , Dave Hansen , "David S. Miller" , elfring@users.sourceforge.net, Fenghua Yu , Geert Uytterhoeven , Guan Xuetao , Helge Deller , Ingo Molnar , "James E.J. Bottomley" , Jeff Dike , Jonas Bonn , Julia Lawall , kasan-dev@googlegroups.com, kvmarm@lists.cs.columbia.edu, Ley Foon Tan , linux-alpha@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@linux-mips.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, Max Filippov , nios2-dev@lists.rocketboards.org, Peter Zijlstra , Richard Weinberger , Rich Felker , Sam Creasey , sparclinux@vger.kernel.org, Stafford Horne , Stefan Kristiansson , Thomas Gleixner , Tony Luck , Will Deacon , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Yoshinori Sato Subject: Re: [PATCH 2/4] mm: speed up mremap by 500x on large regions (v2) Message-ID: <20181024115733.GN8537@350D> References: <20181013013200.206928-1-joel@joelfernandes.org> <20181013013200.206928-3-joel@joelfernandes.org> <20181024101255.it4lptrjogalxbey@kshutemo-mobl1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181024101255.it4lptrjogalxbey@kshutemo-mobl1> User-Agent: Mutt/1.9.4 (2018-02-28) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 66918 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: bsingharora@gmail.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Wed, Oct 24, 2018 at 01:12:56PM +0300, Kirill A. Shutemov wrote: > On Fri, Oct 12, 2018 at 06:31:58PM -0700, Joel Fernandes (Google) wrote: > > diff --git a/mm/mremap.c b/mm/mremap.c > > index 9e68a02a52b1..2fd163cff406 100644 > > --- a/mm/mremap.c > > +++ b/mm/mremap.c > > @@ -191,6 +191,54 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, > > drop_rmap_locks(vma); > > } > > > > +static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr, > > + unsigned long new_addr, unsigned long old_end, > > + pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush) > > +{ > > + spinlock_t *old_ptl, *new_ptl; > > + struct mm_struct *mm = vma->vm_mm; > > + > > + if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK) > > + || old_end - old_addr < PMD_SIZE) > > + return false; > > + > > + /* > > + * The destination pmd shouldn't be established, free_pgtables() > > + * should have release it. > > + */ > > + if (WARN_ON(!pmd_none(*new_pmd))) > > + return false; > > + > > + /* > > + * We don't have to worry about the ordering of src and dst > > + * ptlocks because exclusive mmap_sem prevents deadlock. > > + */ > > + old_ptl = pmd_lock(vma->vm_mm, old_pmd); > > + if (old_ptl) { > > How can it ever be false? > > > + pmd_t pmd; > > + > > + new_ptl = pmd_lockptr(mm, new_pmd); Looks like this is largely inspired by move_huge_pmd(), I guess a lot of the code applies, why not just reuse as much as possible? The same comments w.r.t mmap_sem helping protect against lock order issues applies as well. > > + if (new_ptl != old_ptl) > > + spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); > > + > > + /* Clear the pmd */ > > + pmd = *old_pmd; > > + pmd_clear(old_pmd); > > + > > + VM_BUG_ON(!pmd_none(*new_pmd)); > > + > > + /* Set the new pmd */ > > + set_pmd_at(mm, new_addr, new_pmd, pmd); > > + if (new_ptl != old_ptl) > > + spin_unlock(new_ptl); > > + spin_unlock(old_ptl); > > + > > + *need_flush = true; > > + return true; > > + } > > + return false; > > +} > > + > -- > Kirill A. Shutemov >