From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH] mm/pgtable: Drop pgtable_t variable from pte_fn_t functions Date: Fri, 3 May 2019 06:27:33 -0700 Message-ID: <20190503132733.GA5201@bombadil.infradead.org> References: <1556803126-26596-1-git-send-email-anshuman.khandual@arm.com> <20190502134623.GA18948@bombadil.infradead.org> <20190502161457.1c9dbd94@mschwideX1> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190502161457.1c9dbd94@mschwideX1> Sender: linux-kernel-owner@vger.kernel.org To: Martin Schwidefsky Cc: Anshuman Khandual , akpm@linux-foundation.org, linux-mm@kvack.org, Ard Biesheuvel , Russell King , Catalin Marinas , Will Deacon , Thomas Gleixner , Ingo Molnar , Michal Hocko , Logan Gunthorpe , "Kirill A. Shutemov" , Dan Williams , jglisse@redhat.com, Mike Rapoport , x86@kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Thu, May 02, 2019 at 04:14:57PM +0200, Martin Schwidefsky wrote: > On Thu, 2 May 2019 06:46:23 -0700 > Matthew Wilcox wrote: > > > On Thu, May 02, 2019 at 06:48:46PM +0530, Anshuman Khandual wrote: > > > Drop the pgtable_t variable from all implementation for pte_fn_t as none of > > > them use it. apply_to_pte_range() should stop computing it as well. Should > > > help us save some cycles. > > > > You didn't add Martin Schwidefsky for some reason. He introduced > > it originally for s390 for sub-page page tables back in 2008 (commit > > 2f569afd9c). I think he should confirm that he no longer needs it. > > With its 2K pte tables s390 can not deal with a (struct page *) as a reference > to a page table. But if there are no user of the apply_to_page_range() API > left which actually make use of the token argument we can safely drop it. Interestingly, I don't think there ever was a user which used that argument. Looking at your 2f56 patch, you only converted one function (presumably there was only one caller of apply_to_page_range() at the time), and it didn't u se any of the arguments. Xen was the initial user, and the two other functions they added also didn't use that argument. Looking at a quick sample of users added since, none of them appear to have ever used that argument. So removing it seems best. Acked-by: Matthew Wilcox