From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1CF44FD707B for ; Tue, 17 Mar 2026 11:04:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=feNhlZakbRYDJtWwge52jbrFTlGD2WIO1+iPdyuWmss=; b=iXu5jVvfBU0IkNZJbJ2746lqbU uOB96AUQZbAwDB4rZdQOjorpn5wtP6t0weLTMYAUh+tgvvz8pkENV/sFKSia7IdqiyjGLvazBGw6Y AKMxOmbBjdx+5JVvpvwBdO/vr+D9PYYeVGakt20golnI9SMlpWd47H+Y/Th3Q88+DVmmdzlax57Ig k9uM3u+8nEpD1tXxaYAdLL8twO+TyFsJ5JUdct/eR0cxE0rKy0ha2yswTUEYViBhBpXpgBn9zVet7 mdmYvv57DFGuuWIDwDXjM0lvDLqXVKorK8c6BBX3L7Vs5VRwprZtnhjJg7+Jkn6XFyDdhfsXwU8Q6 Ym83xxDg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2SDp-000000065MY-2joI; Tue, 17 Mar 2026 11:04:25 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1w2SDm-000000065MA-26Ym for kexec@lists.infradead.org; Tue, 17 Mar 2026 11:04:23 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 2CCD64170C; Tue, 17 Mar 2026 11:04:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6C76C4CEF7; Tue, 17 Mar 2026 11:04:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773745461; bh=FzN+JR6wTdlWoYca/iDWtBJ00teqmkhdZDjQECTdE30=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; 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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260317_040422_561418_4A7FDC55 X-CRM114-Status: GOOD ( 18.76 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org 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.