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b=CzqjY0GpYRBoRH5wfJ7qOPgfofiRN3ukCODjKqJ9Otaoj5ox0eR5hogOK9BhTiIdC HaiICmEpGcxK5rPTcirhIp7HnQ0Vowjb+FmsAJGJRZzQwuDqULh31j3ENf5VTj4xmv dqT1UOqBkgSWTAWbgKE2VvrXBGE7d1H8LIWeIHhcynIPPNFlpON3BdTstI3U+abwlb NOeju95h6yOj8SnR4ot4yLZC9vii4975H7Wk9sjdr75PeqEiG25fp732DOlR5TQduu 4W+yiV9Mhq5WWjCn/dZCJWutSSeMyV814jn5Dms4tAT3nVD8MKm6DNUMw9s0FOdaiJ DfCY9fH/rgJfQ== Date: Tue, 17 Mar 2026 13:04:15 +0200 From: Mike Rapoport To: Pratyush Yadav Cc: Alexander Graf , Pasha Tatashin , Andrew Morton , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kho: drop restriction on maximum page order Message-ID: References: <20260309123410.382308-1-pratyush@kernel.org> <20260309123410.382308-2-pratyush@kernel.org> <2vxzo6kmddl8.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxzo6kmddl8.fsf@kernel.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3C58F14000A X-Stat-Signature: 7t3oscwobfe7xzkzi3od5ph6uyqzkes9 X-Rspam-User: X-HE-Tag: 1773745462-611524 X-HE-Meta: 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 nTJxV5Nh c8UsjsbrZALyXU/RUTQrmod/A24xexYwwzggDqp7TZTtS0K3yw2FQQeWAQ0GqdKM+clrXx9gylO/+aUVqGT6rG/qnPhO+0asbTvsW/g1U9DCxSOxPsofWPlJI5hzI6JChrOXYj4AMMDIHtW+PM91l+GJlVctcjzoUSJzhQ0vIOF++V6ll0+OMk4Czyvc+zy6WACG9IxK2lWlCdYubQZXUFO9K5u/CeU8AVleEIV75nR/Dp1TLfyxiuVN0K1kEO6DYHWCwh5M9hW0t1T9idFVlvbuSnWzJO8LiKqkiylFK69uSvHbBuoyIDPNTtg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 17, 2026 at 09:12:19AM +0000, Pratyush Yadav wrote: > On Tue, Mar 10 2026, Mike Rapoport wrote: > > > On Mon, Mar 09, 2026 at 12:34:07PM +0000, Pratyush Yadav wrote: > >> KHO currently restricts the maximum order of a restored page to the > >> maximum order supported by the buddy allocator. While this works fine > >> for much of the data passed across kexec, it is possible to have pages > >> larger than MAX_PAGE_ORDER. > >> > >> For one, it is possible to get a larger order when using > >> kho_preserve_pages() if the number of pages is large enough, since it > >> tries to combine multiple aligned 0-order preservations into one higher > >> order preservation. > >> > >> For another, upcoming support for hugepages can have gigantic hugepages > >> being preserved over KHO. > >> > >> There is no real reason for this limit. The KHO preservation machinery > >> can handle any page order. Remove this artificial restriction on max > >> page order. > >> > >> Signed-off-by: Pratyush Yadav > >> Signed-off-by: Pratyush Yadav (Google) > > > > One SOB should be enough ;-) > > Hmm, I figured the unemployed me (who originally wrote the patch) and > the employed-by-google me (who is doing this new version) would count as > two separate entities and there should be a S-o-b for both. Maybe than something like: Signed-off-by: Pratyush Yadav (Hobbyist) Signed-off-by: Pratyush Yadav (Google) ;-) > Anyway, I am fine with dropping either one of the two. > > > > > Reviewed-by: Mike Rapoport (Microsoft) > > Thanks! > > [...] > > -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.