From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 9D4C96B0343 for ; Fri, 24 Mar 2017 07:23:12 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id n11so19782302pfg.7 for ; Fri, 24 Mar 2017 04:23:12 -0700 (PDT) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id j63si1741140pfg.107.2017.03.24.04.23.11 for ; Fri, 24 Mar 2017 04:23:11 -0700 (PDT) From: Punit Agrawal Subject: Re: [RFC PATCH 0/2] Add hstate parameter to huge_pte_offset() References: <20170323125823.429-1-punit.agrawal@arm.com> <20170324103709.253qw6pyjaq5wrgb@node.shutemov.name> Date: Fri, 24 Mar 2017 11:23:08 +0000 In-Reply-To: <20170324103709.253qw6pyjaq5wrgb@node.shutemov.name> (Kirill A. Shutemov's message of "Fri, 24 Mar 2017 13:37:09 +0300") Message-ID: <87efxmhqar.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Mike Kravetz , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Andrew Morton , "Kirill A. Shutemov" , Tyler Baicar "Kirill A. Shutemov" writes: > On Thu, Mar 23, 2017 at 01:55:27PM -0700, Mike Kravetz wrote: >> On 03/23/2017 05:58 AM, Punit Agrawal wrote: >> > On architectures that support hugepages composed of contiguous pte as >> > well as block entries at the same level in the page table, >> > huge_pte_offset() is not able to determine the right offset to return >> > when it encounters a swap entry (which is used to mark poisoned as >> > well as migrated pages in the page table). >> > >> > huge_pte_offset() needs to know the size of the hugepage at the >> > requested address to determine the offset to return - the current >> > entry or the first entry of a set of contiguous hugepages. This came >> > up while enabling support for memory failure handling on arm64[0]. >> > >> > Patch 1 adds a hstate parameter to huge_pte_offset() to provide >> > additional information about the target address. It also updates the >> > signatures (and usage) of huge_pte_offset() for architectures that >> > override the generic implementation. This patch has been compile >> > tested on ia64 and x86. >> >> I haven't looked at the performance implications of making huge_pte_offset >> just a little slower. But, I think you can get hstate from the parameters >> passed today. >> >> vma = find_vma(mm, addr); >> h = hstate_vma(vma); > > It's better to avoid find_vma() in fast(?) path if possible. So passing it > down is probably better. Also most call sites of huge_pte_offset() already have the hstate (or the vma) readily available. So adding overhead feels unnecessary. I agree that merging the patch will need some co-ordination but lets at the least give it a shot. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org