From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A399834FF7B for ; Tue, 16 Dec 2025 15:19:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765898374; cv=none; b=UEiKVpnkLH21Y+3wJSM0o4PH+zLYk6igBW55amDoZzA6Lx4Q8pIH2Dj/26usSiTjCJw8T7nyzDJi4CUwh0EeGgW+oh0GL7PpeQaRuY0zT8KCqWqnGyXYnaTICQmjHxUoPJysl3omoCj3aqn95imow5Gd8igM+qHHlc14eGEZins= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765898374; c=relaxed/simple; bh=1C3O1RJhSl5a7OnhBSz/2GvP934zpCWD3sNtHJ+8dxY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=vGfUgYkmreh44Hpj+ByYsDS6ZZQLYMuVfJpno5WFr35PddznBOahL7ch4eE/tp8U/maKre0OEXRtyGqQLueZzqkV1tPbPjdi93x4ne2JHJ80XjUfsxLeCtMLOHsqbIF6hrFxw3fPT29pKIw+lCfwgNeFf+UhM/CxYRwaFdDBQSY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nBLlXIJz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nBLlXIJz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB4CFC4CEF1; Tue, 16 Dec 2025 15:19:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765898374; bh=1C3O1RJhSl5a7OnhBSz/2GvP934zpCWD3sNtHJ+8dxY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nBLlXIJzdfgq1Dnn+DyMW+MquYwEJofXKI4D2doa79u6kD0MRYJb6l1wAT6BKDb4s XkpwiiFiqbKfGMVfvT8HoBcPne3ZtUfGcQMHgNMjZOdEox5BZGDjUu6NLw/q73HkDN KIcn8FPQaV0jrEW+3EZd6+NHCZ/C7oJrgbMiniwrgh/D+B2YyTkzf9rkuWnnrw5zNV oExQ+29v47kcWhJnY1/nU0WUAgIKX8vBNRqiM1O/2Zuj8ibSW0Yxgw1vrdCldKRTfW 8MoQF0Q/RYYNs23aF991zxpDZQRIciTAlIu5nMZBXmqE3+uw9puCKIyTokUzycVfJk GwSD2QuKfRARA== Date: Tue, 16 Dec 2025 17:19:26 +0200 From: Mike Rapoport To: Pasha Tatashin Cc: Evangelos Petrongonas , Pratyush Yadav , Alexander Graf , Andrew Morton , Jason Miu , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, nh-open-source@amazon.com Subject: Re: [PATCH] kho: add support for deferred struct page init Message-ID: References: <20251216084913.86342-1-epetron@amazon.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Dec 16, 2025 at 10:05:27AM -0500, Pasha Tatashin wrote: > > > +static struct page *__init kho_get_preserved_page(phys_addr_t phys, > > > + unsigned int order) > > > +{ > > > + unsigned long pfn = PHYS_PFN(phys); > > > + int nid = early_pfn_to_nid(pfn); > > > + > > > + for (int i = 0; i < (1 << order); i++) > > > + init_deferred_page(pfn + i, nid); > > > > This will skip pages below node->first_deferred_pfn, we need to use > > __init_page_from_nid() here. > > Mike, but those struct pages should be initialized early anyway. If > they are not yet initialized we have a problem, as they are going to > be re-initialized later. Can say I understand your point. Which pages should be initialized earlt? And which pages will be reinitialized? > > > + > > > + return pfn_to_page(pfn); > > > +} > > > + > > > static void __init deserialize_bitmap(unsigned int order, > > > struct khoser_mem_bitmap_ptr *elm) > > > { > > > @@ -449,7 +466,7 @@ static void __init deserialize_bitmap(unsigned int order, > > > int sz = 1 << (order + PAGE_SHIFT); > > > phys_addr_t phys = > > > elm->phys_start + (bit << (order + PAGE_SHIFT)); > > > - struct page *page = phys_to_page(phys); > > > + struct page *page = kho_get_preserved_page(phys, order); > > > > I think it's better to initialize deferred struct pages later in > > kho_restore_page. deserialize_bitmap() runs before SMP and it already does > > The KHO memory should still be accessible early in boot, right? The memory is accessible. And we anyway should not use struct page for preserved memory before kho_restore_{folio,pages}. > > heavy lifting of memblock_reserve()s. Delaying struct page initialization > > until restore makes it at least run in parallel with other initialization > > tasks. > > > > I started to work on this just before plumbers and I have something > > untested here: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=kho/deferred-page/v0.1 > > > > > union kho_page_info info; > > > > > > memblock_reserve(phys, sz); > > > -- -- Sincerely yours, Mike.