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b=L9ltC+2PmAsjD6RD3FhjaLQ88mtFPqKCZ5e5wnXlbMD0IE9ci1RMSYc2iX7AMzX2x FjYVkT+gjdl/yDn4ixlebZZ+2qW2aDJguNj3A/VBCQP9agUS4lHl8yk0KWw9VvMIXO J7vr5Wg3QsfH7xzwVn0AgUtwCcaD/g2GsqkxKns3rKpMmSp2LxSdLI2Z4E9rk+133W JG7fXKrDdeY4Z1Ksm/FRtx1S1+r14I/wUqQVqO6Ge7JvNdImtPHqNsEPwMm2rZUfJv uOkHS/OYVXSHVS3P/53PHq+FigYnABJvBNjGBfIb924tCSOAW91pKd6lCAKkX/1ygE hJ3HQ35zk27RA== From: Pratyush Yadav To: Mike Rapoport Cc: Pratyush Yadav , 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 In-Reply-To: (Mike Rapoport's message of "Tue, 17 Mar 2026 13:04:15 +0200") References: <20260309123410.382308-1-pratyush@kernel.org> <20260309123410.382308-2-pratyush@kernel.org> <2vxzo6kmddl8.fsf@kernel.org> Date: Fri, 20 Mar 2026 10:24:08 +0000 Message-ID: <2vxzy0jmajef.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 585B1100005 X-Stat-Signature: qzn7tyc3hbgkx5uo85bippyxrmu168q6 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1774002253-747331 X-HE-Meta: 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 kQ6xgfho jVgT21MYBNI9/TohcpOz0hEgOg8bT9vcm9BdBBP7bh5kkPurw0H43jIYWcKKKp6F2JEJNaDxfQk/AYCm5DpGANCoKt9E7+flNPYC9vxcvHE8uEN1xLYr14fF4tcFB8ZR4H8yLQAch3WnOhY6gV8sPlhMYiY58OmpulNLBmiila72uAAOC00aLhG/gxQq2J1FOlG7BoJ/1iUAlNc9ShtMx2saJbMu0nKnvGlxV 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, Mike Rapoport wrote: > 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) > > ;-) > Yeah, that works too :-) I'll use that when I redo some of the HugeTLB patches too -- Regards, Pratyush Yadav