From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2606D44E03B for ; Tue, 28 Jul 2026 14:37:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785249454; cv=none; b=DPSHrEINYviu85P7a/dpZjeB5/UjPIGI8VGtsgdCfO2jKjCq2g/igyjDBRDsAsEOOBABQRSpaXRjw3oxFdeabNbn7In723FWNgKknXHrXWkPnwBGX8tXxqH7apCBQ7UwSeqhZWLN7tGicGmnKC5izPv4sK9FX5dtmxDmmmDyBXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785249454; c=relaxed/simple; bh=OLbqxPsgmr9A4bqs940p5LYiyOD+x5+jV9TnPDVJwn0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ed3a58MsCXVFMawjKLtwFdpkHMXdvROGHtdRNpsHj7wf7kgelOgskyyBm6vvDEWdWS+yx6livzaxFnQD9z9d5e5o9nZ0bF94tmnIg1XZHPlNV9cCSMEKR92iwMlILViFO7VNZGLAV14xq1n6E3YOquvc5Fnn8LaAJudHaPW/BYU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nc26FOHP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nc26FOHP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CAA61F000E9; Tue, 28 Jul 2026 14:37:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785249450; bh=ZDkk7PDtexhsBzVT9GWHhsxn7eilb1XwsTmiTnabsNY=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=nc26FOHPHYa9+8isLzyk0zxQfzaTb0OA2pPhKpbyYczQVTRy6FuWreWujR95MzVdg 8V5iMwIzJWE8pVxklYHkEBbw9SMYalKGI8aWBEmO/813/x/QKcOZVsf4OKFcMviYu6 F7BHRI2q+YBxtJsLz7B6DfQqqYINP84nYofCR1Y4mPeRUb4MatyytBNFpT8K28Ishv OFcq8cMmk5AHLuJag0dHBnurSCJ0ACBEYb6XJACN3TB2nSwVJvVvabEMSgOPe4dU0n HZsS3IgfHeKSx4blTi7u63QzixOnTAxG9B2N2TNrRS67Fu/3ZIsLCN8hszAm3my6x4 2QFGKWdOJKihQ== From: Pratyush Yadav To: Mike Rapoport Cc: Pratyush Yadav , Pasha Tatashin , Alexander Graf , Muchun Song , Oscar Salvador , David Hildenbrand , Andrew Morton , Jason Miu , Jork Loeser , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 00/21] kho: make boot time huge page allocation work nicely with KHO In-Reply-To: (Mike Rapoport's message of "Tue, 28 Jul 2026 16:35:41 +0300") References: <20260725172133.4018491-1-pratyush@kernel.org> Date: Tue, 28 Jul 2026 16:37:26 +0200 Message-ID: <2vxzecgn89jt.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Tue, Jul 28 2026, Mike Rapoport wrote: > On Sat, Jul 25, 2026 at 07:21:00PM +0200, Pratyush Yadav wrote: >> From: "Pratyush Yadav (Google)" >> >> Hi, >> >> Gigantic huge page allocation is somewhat broken currently with KHO. >> >> First, they break scratch size accounting. Since they are allocated >> using the memblock alloc APIs, they count towards RSRV_KERN, and this >> scratch size when using scratch_scale. This means if huge pages take a >> large enough chunk of system memory scratch size will blow up and fail >> to allocate. >> >> Second, scratch can not contain preserved memory, and if hugepages are >> allocated from scratch, they will fail to be preserved with the upcoming >> hugetlb preservation series [0]. >> >> Fix this by introducing the concept of extended scratch areas. They are >> areas that the kernel discovers on boot by walking the radix tree and >> finding free memory ranges. See patch 10 for more details. >> >> Muchun Song (1): >> mm/mm_init: simplify deferred_free_pages() migratetype init >> >> Pratyush Yadav (Google) (20): >> kho: generalize radix tree APIs >> kho: make radix max key width more obvious >> kho: disallow wide keys in radix tree >> kho: return virtual address of mem_map from kho_get_mem_map() >> kho: store incoming radix tree in kho_in >> kho: move all memory retrieval logic to kho_mem_retrieve() >> kho: add a struct for radix callbacks >> kho: add callback for table pages >> kho: add data argument to radix walk callback >> kho: allow early-boot usage of the KHO radix tree >> kho: allow destroying KHO radix tree >> kho: add kho_radix_init_tree() >> kho: expose kho_scratch_overlap() to kexec_handover.h >> kho: initialize kho_scratch pointer earlier in boot >> kho: initialize preserved memory map radix tree earlier >> mm/mm_init: don't rely on memblock to get KHO scratch migratetype >> kho: extend scratch >> memblock: make HugeTLB bootmem allocation work with KHO >> memblock: add memblock_reserved_hugetlb_size() >> kho: exclude hugetlb memory from scratch size calculation > > I added it to the liveupdate tree. Thanks! > > Please take a look at Sashiko comments, we might need v5 if it has valid > (not pre-existing) points. I took a quick look and the only valid points I can see are the ones on patch 19/21 "memblock: make HugeTLB bootmem allocation work with KHO". All others are pre-existing problems. Is it okay if I send a single follow up patch to fix 19/21? Or would you prefer a full respin? Also, general thing, but I should go and fix all the pre-existing problems too at some point. I sent a fix for a really simple one already, but Sashiko has found other problems too... -- Regards, Pratyush Yadav