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b=NxQbKCg+gFl3E5wPcZrVYSzHF8bNiAVrhmlYLO7wG/CYXDHxijrKAQc3WX2YeDbx8 RF915yo98iZ2nG+JKEtJY4HNIHHDGxMcvYM8GrikGndsY00A8uk0GsDzR92Q5phGHm X1gS5kdwQW2+O2eRjqtMRuOw34zaJAQszMTskM1FjO78iCtutgnPbijhr8ID2rS4Ob aRfD6A89SCAHUxE9RKGob9d1DXgaG+K2dey/SzGjpXgovKtNBuRkrHUB359+h2CWqH MJbXN485NcJKbAF6HD9vO3yWCiOXixFKZrVeKVFKSxL8TKbT0lv7qUjVSoHaRSMImu zQbnUjy+ThWow== Message-ID: Date: Mon, 17 Aug 2026 18:19:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] mm: khugepaged: fix swap entry value to folio_pfn() To: "Lorenzo Stoakes (ARM)" , Vernon Yang Cc: akpm@linux-foundation.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, zokeefe@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vernon Yang , stable@vger.kernel.org References: <20260815051924.194810-1-vernon2gm@gmail.com> <20260815051924.194810-2-vernon2gm@gmail.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 X-Stat-Signature: xttc8ns1n95oh8xk46w94pobj71dyftt X-Rspamd-Queue-Id: E27201C000C X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1786983562-21458 X-HE-Meta: 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 MGROPdz/ 3JMIa4aBnDASFcxghYX1i3ps5Su35d6JazQJRF5iPm51R0CQq2l03/K3dSFW+1r7oTsLx1mDIOhrYeTZnG1ewXmMXBQp+RqJG0rRFSzkERIeoFICqgACBeXnFAmDcpdYkxVqra9Ptb72T4iDZ5C22BkxPvz15B0g49aVbZgmb4QVrKwOdupqGGa/Vxf3vKc4oZLiAN2QWsZSZXVc0M0/xMTQCTRFuKORniIjpiDCyk+V7qLvEUT+9kNvaxJ5floHDsfIneraa482uAxbhvdnCI/ss/lSwoWcjQ9f23mAa+xuNYUkUmp+EhZ8IE1STF3DY6zfCjeUkES66PTc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > I mean maybe better to just reduce this to something like: > > /* folio is NULL unless exited early. */ > trace_mm_khugepaged_scan_file(mm, > (!folio || xa_is_value(folio)) ? -1 : folio_pfn(folio), > file, present, swap, result); > > As the least invasive way of fixing the trace + limiting the contageon? I raised that using a folio after dropping relevant refs+locks is in general an anti-pattern (IOW wrong if folios can just get split afterwards and are suddenly no longer folios). I'd like us to avoid that where possible (and suspect Willy will thank us later ;) ) Isn't there some minimal way to just calculate the pfn once we obtain a folio? I was assuming that there should be an easier way to do that. -- Cheers, David