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b=A+trAdNZEwYhjQmBGJfZ6Vj8jtvHi8ZvdtrkS1EA5HCl3CZrzj0NNMQJ4hA/Xlo/x g83xdKCdI7meSzm/0Ceq4+qRO/SdSW1dAZGW4UBLLA5S1crR6Bwahm82LQdYEB9T4c MT3zIytjl20iBm5JJO3mgpIS+RvJcAu6nL2y0CDtbkQTcs6jfC7RqEm5TFTuUzFSBh WIBbTUmLvmi7ul1fa9xOUF6EO64uv6v+3GrDp9dcO6NgLkPFTyEZCxovNVsWhAuwry ekV9Y/Y9iAKPxpV9aTZ1n9UEJ1y24RC+dihZP7p37F3Bh/xuIPpF94AdbUqbMXpPZV SdhhXDvwSkrkg== Message-ID: <811c5456-44c9-4b90-bace-caba6cb6f972@kernel.org> Date: Thu, 26 Feb 2026 11:01:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: khugepaged: simplify scanning progress in pmd To: Vernon Yang Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, richard.weiyang@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang References: <20260226081313.53518-1-vernon2gm@gmail.com> <06ff4738-e81a-49ab-9204-74a6829d8d8b@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-Rspam-User: X-Rspamd-Queue-Id: 7869E1C0002 X-Rspamd-Server: rspam02 X-Stat-Signature: 7f3tgsme7i3px9st1bkrz3tyrhb9ft44 X-HE-Tag: 1772100069-867692 X-HE-Meta: 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 zedyyazI 11iiCIBN4JvO6yfbRvCfSrtIprpVeVBSq6PHGyE+TxehB3vQnbIQ9Esl1Jj5ObDYOMFplSL+xVD8588ARwftMKwi9METVE/OoYG+NQESEiKkNS474YIbwNTJTecy1BNs3DKOiSiXkiex/TLUpnB+fGYuT2qm6omGNZSK2r/w/9jgYaMwrgAqbRmyZClBwxy4AMG22xDsC+cWnoPgXBPzg/iMYjv9rlnb3DuQ3AqHMN3ein+kLo5RCQxsVwvHk7Nj+6pTaPDOf2oHEc+wuDhMfBjhACsA4hHav5SqFk33n991qHOaCusBEzTromi0MXSdb12aAAgO7fQ9+gvk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> >> static int khugepaged_has_work(void) >> @@ -2545,13 +2555,14 @@ static int khugepaged_wait_event(void) >> >> static void khugepaged_do_scan(struct collapse_control *cc) >> { >> - unsigned int progress = 0, pass_through_head = 0; >> - unsigned int pages = READ_ONCE(khugepaged_pages_to_scan); >> + const unsigned int progress_max = READ_ONCE(khugepaged_pages_to_scan); >> + unsigned int pass_through_head = 0; >> bool wait = true; >> enum scan_result result = SCAN_SUCCEED; >> >> lru_add_drain_all(); >> >> + cc->progress = 0; > > madvise(MADV_COLLAPSE) is missing the initialization of "cc->progress" > because "cc = kmalloc_obj(*cc)". We need to manually initialize it in > madvise_collapse(). Right, although it wouldn't matter right now, because nobody would be reading the value. It's really weird that cc is not simply completely zeroed out in madvise_collapse(). -- Cheers, David