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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767041561; bh=MwPgzvD78n3pW90vWtwAVJoET5+u4jzMiVKZ1kjYoMM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=UgX7+AkltaYMgD/psdVzZtaRdtN4IQkW/L62pxQLIpOZU5+2igPik9iHaYIuXbpvn lf+6ZtmgovxFo3WJ/g5L6uwhSXEko/5MDlib/U+xUEZlrqWeBeELPMqGTtB0NWebdA tlL8FScMql/gqwNNxDZXkYeoNAFrKbJsZJTsgDAEQRI0MUx67zlDWAHtTzRHv0WN+v hzH5NVYupexrRdVyfO1thgNLpV604PjbDfTz9Fcw3H+ZCPMkJKkNSeI8szZcV6vCbB uvZe6Ewy0vj89rsxgYcrgjxOKXpkOLc6mUZlDGceI9K/HvTvMyM/1gaeLqKJGSU80z d3ntCSsWSi/IQ== From: Pratyush Yadav To: Pasha Tatashin Cc: Pratyush Yadav , Andrew Morton , Alexander Graf , Mike Rapoport , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kho: simplify page initialization in kho_restore_page() In-Reply-To: (Pasha Tatashin's message of "Tue, 23 Dec 2025 12:49:39 -0500") References: <20251223104448.195589-1-pratyush@kernel.org> Date: Mon, 29 Dec 2025 21:52:37 +0100 Message-ID: <868qel9fje.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: B9E65A0013 X-Rspamd-Server: rspam03 X-Stat-Signature: sw83o5rfdccfox785djpw5ukwscu5eoy X-Rspam-User: X-HE-Tag: 1767041562-196822 X-HE-Meta: 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 15ef/8xK RHosa6aEy14DImvAaTb2w3HxPHAMfmyVSIePXH3bC3abRVXeKQmint06d15eTwe9QMPnqi3huYvK+C8/G7SiDoGBj9JaC4dukHRM/a6YyIKegVAf/3yka0BS63p9OmiP5JNKYPGKDE2himf0AS6RkszuUR+1N1fdOTHoyLf/onGa+Zl7J1F5I35Wwe2wBq2bbO7HyM+Qz/MFA8HtD/eHu+ppathkjsNqZpHsG4P6QThoBjSeX0XrieWd7G639c5PX1MQYa9doqzWUdtwaQAvvYGV9QrBWzvgBr9TG 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 Tue, Dec 23 2025, Pasha Tatashin wrote: > On Tue, Dec 23, 2025 at 5:45=E2=80=AFAM Pratyush Yadav wrote: >> >> When restoring a page (from kho_restore_pages()) or folio (from >> kho_restore_folio()), KHO must initialize the struct page. The >> initialization differs slightly depending on if a folio is requested or >> a set of 0-order pages is requested. >> >> Conceptually, it is quite simple to understand. When restoring 0-order >> pages, each page gets a refcount of 1 and that's it. When restoring a >> folio, head page gets a refcount of 1 and tail pages get 0. >> >> kho_restore_page() tries to combine the two separate initialization flow >> into one piece of code. While it works fine, it is more complicated to >> read than it needs to be. Make the code simpler by splitting the two >> initalization paths into two separate functions. This improves >> readability by clearly showing how each type must be initialized. >> >> Signed-off-by: Pratyush Yadav >> --- >> >> Notes: >> This patch is a follow up from >> https://lore.kernel.org/linux-mm/86ms42mj44.fsf@kernel.org/ >> >> kernel/liveupdate/kexec_handover.c | 41 ++++++++++++++++++++---------- >> 1 file changed, 27 insertions(+), 14 deletions(-) >> >> diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexe= c_handover.c >> index 2d9ce33c63dc..304c26fd5ee6 100644 >> --- a/kernel/liveupdate/kexec_handover.c >> +++ b/kernel/liveupdate/kexec_handover.c >> @@ -219,11 +219,33 @@ static int __kho_preserve_order(struct kho_mem_tra= ck *track, unsigned long pfn, >> return 0; >> } >> >> +/* For physically contiguous 0-order pages. */ >> +static void kho_init_pages(struct page *page, unsigned int nr_pages) > > Here and in other places below, it is better for nr_pages to be > unsigned long. This is consistent with other places in mm, where we > have gradually moved on from int/unsigned int to unsigned long for > npages (see gup.c for example). Otherwise, LGTM. Thanks. Will do. [...] --=20 Regards, Pratyush Yadav