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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1766051921; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HJqr5UQpT+/Rn1WsDWLivxrIk71Gu1jMuCYfXi9rDLI=; b=T0skTc9dWV+YxoPozE6pySaKWa3rK4dhCkp7uFuRMDLofMadYa4GK5Mo/XoYGsWGkCi/Yl cowOAljbRRWPZNpDRLA/T/NQuhoqsbiNkN2BnC90SjsRhfu8wb6O1ZbcIvsvYcnL//AYCj vIYzJ4pAAGDm1h6ZrlKaLFCpg556jMw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 2FE4860010; Thu, 18 Dec 2025 09:58:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F74CC4CEFB; Thu, 18 Dec 2025 09:58:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766051920; bh=OuIUjwTgczqolcJsMdctj2jhlUiyGXVpFo8wseT8OZc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MKg1sWXG6lymtLHcZEwMaPS2j7tKBYpLHl0oVGxndnymilFB+8Q0JvzVRnY7L/p4Q qEaq5FLH+eSQSNdhlhhN9L+GdNZhCMg4EHR0Bx4jNEmtVQU8+6qVSus+Gw0E5JC22B LY/f6+590Vy7obu3xEQwHiA0raJA78mbQ5j/BUuTH7TLNZ54QP3ejxCtZOA30RYkP+ U6AbsHgzMkynTq6A/yK34R7DE75Syge/kFVGlgaCYs3e/E7pJqXuDwBb7TpCb8AUQ4 9a5ESPvLHENJR7M62gCzDUFUZYcaucVaTCOqIlVIvA1glNLK91DukxEwJKb0Fuuvi7 JTq6kB3jNfgjw== Message-ID: <37c5dbc1-bd66-4124-987f-8983a06d576e@kernel.org> Date: Thu, 18 Dec 2025 10:58:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch v2] mm/huge_memory: use end_folio to terminate anonymous folio remapping To: Barry Song <21cnbao@gmail.com>, Wei Yang Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, linux-mm@kvack.org References: <20251215004836.694-1-richard.weiyang@gmail.com> <20251215084353.nmznnnmcpcqo4ldy@master> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: C8536C0003 X-Rspamd-Server: rspam10 X-Stat-Signature: tmmkfdj6h11o4pugi3y36sqdksqr97uz X-HE-Tag: 1766051921-766398 X-HE-Meta: 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 DpFBn6YC n+LIBPD9qFRr/8hHD7z6kOp/wiANf58AxHtHq0mpll1g6NhnPmZKwqe3q2NqXA54o6uxjJEO+3QSavR4S532hZcgOajZOnIYWsdcH2h2PAw8Dtsy+1G/JX8SYqX5Rjcb+MB6AenbbAOoj8R1LGPYqpAkKVukalxWZyZ0lr8AMNqinUO8XMFUVS6KPSrfoiT0kG4rayrohuf50bbjj5s3Cj2hCtmzD44ksUT6hag/QvEfBANlUZqmaB2S9Z/b3w5bxHmqaL0dSf1wKyewDvs+TRDFR5qr2YyUAwEi9AwGrpnX82haS2QHNdv6Yd5JJX2S1+IPfdCIKSr7ThCdXg8YboUiEtXSr8PrXkM3gkMtNFnNZcrcelskya6FHGmo9Dhf2pGXvmRH4DwkDPeVIPIbLLIUuVrAeOfeK3j7XuxuJh1WaKcjNB4K+V2xLSs/XMDcTZbbG 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: List-Subscribe: List-Unsubscribe: On 12/15/25 10:15, Barry Song wrote: > On Mon, Dec 15, 2025 at 4:43 PM Wei Yang wrote: >> >> On Mon, Dec 15, 2025 at 10:31:15AM +0800, Barry Song wrote: >>> On Mon, Dec 15, 2025 at 8:49 AM Wei Yang wrote: >>>> >>>> After splitting a large folio, it is necessary to remap the resulting >>>> anonymous folios. >>>> >>>> The current implementation determines the end of the remapping process >>>> by counting the number of pages that have been processed. >>>> >>>> Since the final folio in the sequence, end_folio, is already known and >>>> tracked, this commit refactors the remapping loop to leverage end_folio >>>> as the termination marker. >>>> >>>> Signed-off-by: Wei Yang >>>> Cc: Zi Yan >>>> >>>> --- >>>> v2: move folio assignment in loop >>>> --- >>>> mm/huge_memory.c | 13 ++++--------- >>>> 1 file changed, 4 insertions(+), 9 deletions(-) >>>> >>>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>>> index 40cf59301c21..fe812d9c7807 100644 >>>> --- a/mm/huge_memory.c >>>> +++ b/mm/huge_memory.c >>>> @@ -3423,20 +3423,15 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, >>>> return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); >>>> } >>>> >>>> -static void remap_page(struct folio *folio, unsigned long nr, int flags) >>>> +static void remap_page(struct folio *folio, struct folio *end_folio, int flags) >>>> { >>> >>> Do we actually see an improvement in readability or performance? >>> The existing code feels a bit more readable to me; nr is clearly >>> the number of pages :-) >>> >> >> Hi, Barry, >> >> Thanks for your review. >> >> Currently end_folio has been used in __folio_split() and >> __folio_freeze_and_split_unmapped() as a termination marker. So continue to >> use end_folio here as a termination marker looks consistent and improves >> readability to me. > > In both cases the variables are temporary, and they look fine within their > own self-documented contexts. > > Now that we’re crossing two functions in the context of remap_page(), this > doesn’t seem to be the case, though. > >> >> But yeah, this is my personal preference. If it is not the case, I am fine to >> keep as it is now. :-) > > I personally find the existing code clearer, but I’m also okay if > others like your new approach more. Me too. Well, the existing code could be cleaned up * nr -> nr_pages * remove i and subtract from nr_pages instead probably more ... :) -- Cheers David