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t=1776416154; bh=5cd38qOiEIyykacoE8rFcS3eTCpor2N3/arRUrsPyQA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=KcHQJo1nes/1+iKDfsibdtEC8iQ6iH+dBg9bfefk/Oz7MftUWgI0uTHi3HV4ziZNg XkiUCA5aWsnN5u1bM9SoH0Ers7DtWNMVMReb3ls7lwMOx9FLH9Obfr4qaw+D4rMSNc hBh/qY0HYoR2wpL5wrD/SByyGTlQ6sw+fHWvQX4fhlhvwQu0GVv/rnQocBed4sHYij DGHnme2qRlxZaOD1/EU13ucnVE+SgALZ/5Ip2UiF2d4/1gVdrtnA8WFMCxDPAi3Q+B snRRqS+FddKQdRZY7dUd+MykIX9OHRdumcnWNtB793wsppvR6dg2klBSDLIULU5BZf itvlbwdC8jcCQ== Message-ID: <82193ab8-e6f6-4664-8b4f-e30d280d8b1c@kernel.org> Date: Fri, 17 Apr 2026 10:55:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/migrate_device: Cleanup up PMD Checks and warnings To: SeongJae Park Cc: Sunny Patel , Andrew Morton , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260416235252.58831-1-sj@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: C64EA40007 X-Stat-Signature: sfgwbdguezi8kyczfpbu8orcmqgpdn36 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776416155-271571 X-HE-Meta: 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 zFrZANB6 Hjf+2XyaE245Xjme5z3FeV/QXzZWNVHxVLL1azQSC4MNfCA/vtzjq7pwnfocm/5/yJ7S79zXpkSuVkent/Mjx9/5zInIBw/GcsQoRRLKXv9RsOekioh3ps2PCcy4hfoN7VYFSIPehURM9DbpqSUyBd+me1JXx9dLPfnkKnxcFl/B3/nwST08MBbtNEkQAirvL4NolJDhxyYMrkeLBVp/YCMDeuNph0B4xCvmN5iRysySeDrSHv20M8CZlOHTWr0xek4lo1THgmA42mNPSMkDb3byKU7PbPjUXzOJTY62Gu2EA/NsuG9v28wVTyiTyqbBOyzBZA2CpJTdI3lhRTlwooeMp7xP21QyZIU3prshhmr+bQzt293Lv+kFXXoCmji4eFM5dOzAmtDBb+VlgHrzfwl2Zjw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/17/26 01:52, SeongJae Park wrote: > On Thu, 16 Apr 2026 21:44:15 +0200 "David Hildenbrand (Arm)" wrote: > >> On 4/14/26 16:13, Sunny Patel wrote: > [...] >>> @@ -865,12 +864,13 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, >>> if (userfaultfd_missing(vma)) >>> goto unlock_abort; >>> >>> - if (!pmd_none(*pmdp)) { >>> + if (pmd_present(*pmdp)) { >>> if (!is_huge_zero_pmd(*pmdp)) >>> goto unlock_abort; >>> flush = true; >>> - } else if (!pmd_none(*pmdp)) >>> + } else if (!pmd_none(*pmdp)) { >>> goto unlock_abort; >>> + } >>> >>> add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); >>> folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); >> >> is_huge_zero_pmd() checks pmd_present(), so we didn't have a bug before. >> >> We could also do: >> >> if (is_huge_zero_pmd(*pmdp)) { >> flush = true; >> } else if (!pmd_none(*pmdp)) { >> goto unlock_abort; >> } > > Then we could even further remove the braces and reduce one more line, nice! Indeed :) -- Cheers, David