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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="c/ne9JZ6"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5BF35606D801 for ; Tue, 3 Nov 2026 16:55:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=c/ne9JZ6 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFBB31F000C1; Tue, 3 Nov 2026 16:55:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793724938; bh=8YfZexZ1JYycRhSHeLVRER/xerbsZZLglZfGs4x8Tlc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=c/ne9JZ6JImyHkQVNBrOmaYf+pq+Dc1L6hkV9Qvgb32JqmLL0tRIDfheyHQhKFhs3 xyHUpt33FhRGfUfyCa41jUM7K2bxIyoRC5v4Nj59XUeHVV+Stx+rJp8mdULx9o8kvw a1ejku2NyW6yatQu+Z4RkgSC5cDLvCJogCYZG+93FViEbPrajbY5yn6GVgkBlHWBoq 2WU0Uiv0j9MJM1AHQFEeY7H2wmGjLn/K5CnazWecRhrDSus5D9Ao/7inwU5qIXD+Ys dSrrchgTP6ND/xS7zRF/gshnxLsm5zcmWVKybEWmcJ1vKUKvQn+kUnmQO0cvWk/5vU lCEgEzWsUgWaA== Message-ID: <1affac11-da98-40b3-8cc2-6e8374b5ab69@kernel.org> Date: Tue, 3 Nov 2026 17:55:31 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 8/8] mm/gup: batch contiguous same-folio PTEs into one refcount grab To: Rik van Riel , linux-kernel@vger.kernel.org, Yeoreum Yun Cc: Andrew Morton , Jason Gunthorpe , John Hubbard , Peter Xu , Suren Baghdasaryan , Yuan-Hao Hsu , Christoph Hellwig , linux-mm@kvack.org References: <20261102193026.3860700-1-riel@surriel.com> <20261102193026.3860700-9-riel@surriel.com> <9d1572bd5e868d3c9d953aa5fae81967cc81ba55.camel@surriel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/3/26 17:42, Rik van Riel wrote: > On Tue, 2026-11-03 at 09:35 +0100, David Hildenbrand (Arm) wrote: >> On 11/2/26 20:30, Rik van Riel wrote: >>> >>> +/* >>> + * Return how many PTEs map consecutive pages of the same folio >>> and can be >>> + * committed as one run. Always at least 1. >>> + * >>> + * The write-fault and unshare checks in gup_lookup_pte() are per >>> PTE, but a >>> + * writable run needs no repeat: a writable anon page is >>> exclusive. A read-only >>> + * run under FOLL_WRITE or FOLL_PIN does need the per-page check, >>> so it stays >>> + * one page at a time. >> >> That's a clear indication that this needs more work. >> >> I'll try to get to it soon and see how it could be done in a cleaner >> way, likely >> it should be based on top of the gup-fast series where we will have >> helpers to >> check for required unsharing of multiple PTEs. > > I'm all for sharing the same helpers. > > How would you like to sequence things? > > Do you prefer to merge both series separately, > and then get a follow-up series that merges > the helper functions? > > Would you like Yeoreum Yun and me to combine > the series, merge the helper functions beforehand, > and then send you one larger, combined series? > > I have spent enough time in gup.c that I would > be happy to get rid of some more of that code. My plan is to get the small series for gup-fast ready, stage that, and then build on top of it. By then I should have been able to dig through most of your series. The cleanups can stay part of this series. -- Cheers, David