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 283B01E9B36; Tue, 11 Mar 2025 05:27:44 +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=1741670865; cv=none; b=X6kHiJVNCkMETPquYj/huoBxdI1KdxXqqtxC1PFWOz+2EtDYg8I++jwEir3vNThzfiu5M3DAMjLjmJjm81jgj2gW+fET2Ga4Kqay4y5NkH6zDfrFPLznYpaPJq7V8QA2CISSqSKW9uKX21ILkVnGEQUd1lCqEI4fZBq/vkXvFcA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741670865; c=relaxed/simple; bh=6FrJToULI5AieC/xcPkMqRkdPc73MU/g7qUb/+Gf2LU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TPdHR+VcMpP0/xLzNbTVaQP1+BMnPpVWa2+eCjR+/LLomqNS3d6Fo5o5JGHqHN5Ow6rbVeH+pCXvr+izPnMRJZPlnc3X08+kdkk+K6RTagmH0Qyx5VmZHRGS5zpok4LHXrwCFCys8QWmBKJyCKT0IpLBVoCj8m69+Kr0pnIYe9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GAHpdUKS; 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="GAHpdUKS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACB76C4CEEC; Tue, 11 Mar 2025 05:27:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741670864; bh=6FrJToULI5AieC/xcPkMqRkdPc73MU/g7qUb/+Gf2LU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GAHpdUKSmv1QM82YGoNX6ldSWprWPtoQeq7oZVYRSenmRL5V3mQA0Z/8J1J7rkbXY DCZ1PolWSm96XtMjC6zHeV/4BIYLkdQBd+2LSkhUUHx/NvSeQhtKi3xVRFBvvahBI6 Fgecu8QW9SZnOgCJFzyGzUd8oW5EhoPWaTHjItebVqj/yACpIkHUi3606UEwiKBAbx 3YfDwolecrwr/CHlFMVtqpXQ8QtwdePj5lo049ABQgMlHqkjpQCaCVHGRbh/9KJaaJ GKa8u7BRKr01NRTAB8Jp1oImuXWXsRmL8WzrwbdwZpVY+aPZzBz/SBsDbDXNSbRoaJ K0Cd6UgpZbrJA== Date: Tue, 11 Mar 2025 07:27:23 +0200 From: Mike Rapoport To: Wei Yang Cc: linux-kernel@vger.kernel.org, Alexander Graf , Andrew Morton , Andy Lutomirski , Anthony Yznaga , Arnd Bergmann , Ashish Kalra , Benjamin Herrenschmidt , Borislav Petkov , Catalin Marinas , Dave Hansen , David Woodhouse , Eric Biederman , Ingo Molnar , James Gowans , Jonathan Corbet , Krzysztof Kozlowski , Mark Rutland , Paolo Bonzini , Pasha Tatashin , "H. Peter Anvin" , Peter Zijlstra , Pratyush Yadav , Rob Herring , Rob Herring , Saravana Kannan , Stanislav Kinsburskii , Steven Rostedt , Thomas Gleixner , Tom Lendacky , Usama Arif , Will Deacon , devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH v4 02/14] memblock: add MEMBLOCK_RSRV_KERN flag Message-ID: References: <20250206132754.2596694-1-rppt@kernel.org> <20250206132754.2596694-3-rppt@kernel.org> <20250218155004.n53fcuj2lrl5rxll@master> <20250223002229.xuk6xlp23zr72hkc@master> <20250310095124.pa7dwgqhxglqrfes@master> Precedence: bulk X-Mailing-List: devicetree@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: <20250310095124.pa7dwgqhxglqrfes@master> Hi Wei, On Mon, Mar 10, 2025 at 09:51:24AM +0000, Wei Yang wrote: > On Sun, Feb 23, 2025 at 12:22:29AM +0000, Wei Yang wrote: > >On Wed, Feb 19, 2025 at 09:24:31AM +0200, Mike Rapoport wrote: > >>Hi, > >> > >>On Tue, Feb 18, 2025 at 03:50:04PM +0000, Wei Yang wrote: > >>> On Thu, Feb 06, 2025 at 03:27:42PM +0200, Mike Rapoport wrote: > >>> >From: "Mike Rapoport (Microsoft)" > >>> > > >>> >to denote areas that were reserved for kernel use either directly with > >>> >memblock_reserve_kern() or via memblock allocations. > >>> > > >>> >Signed-off-by: Mike Rapoport (Microsoft) > >>> >--- > >>> > include/linux/memblock.h | 16 +++++++++++++++- > >>> > mm/memblock.c | 32 ++++++++++++++++++++++++-------- > >>> > 2 files changed, 39 insertions(+), 9 deletions(-) > >>> > > >>> >diff --git a/include/linux/memblock.h b/include/linux/memblock.h > >>> >index e79eb6ac516f..65e274550f5d 100644 > >>> >--- a/include/linux/memblock.h > >>> >+++ b/include/linux/memblock.h > >>> >@@ -50,6 +50,7 @@ enum memblock_flags { > >>> > MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */ > >>> > MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver */ > >>> > MEMBLOCK_RSRV_NOINIT = 0x10, /* don't initialize struct pages */ > >>> >+ MEMBLOCK_RSRV_KERN = 0x20, /* memory reserved for kernel use */ > >>> > >>> Above memblock_flags, there are comments on explaining those flags. > >>> > >>> Seems we miss it for MEMBLOCK_RSRV_KERN. > >> > >>Right, thanks! > >> > >>> > > >>> > #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP > >>> >@@ -1459,14 +1460,14 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size, > >>> > again: > >>> > found = memblock_find_in_range_node(size, align, start, end, nid, > >>> > flags); > >>> >- if (found && !memblock_reserve(found, size)) > >>> >+ if (found && !__memblock_reserve(found, size, nid, MEMBLOCK_RSRV_KERN)) > >>> > >>> Maybe we could use memblock_reserve_kern() directly. If my understanding is > >>> correct, the reserved region's nid is not used. > >> > >>We use nid of reserved regions in reserve_bootmem_region() (commit > >>61167ad5fecd ("mm: pass nid to reserve_bootmem_region()")) but KHO needs to > >>know the distribution of reserved memory among the nodes before > >>memmap_init_reserved_pages(). > >> > > > >I took another look into this commit. There maybe a very corner case in which > >will leave a reserved region with no nid set. > > > >memmap_init_reserved_pages() > > for_each_mem_region() { > > ... > > memblock_set_node(start, end, &memblock.reserved, nid); > > } > > > >We leverage the iteration here to set nid to all regions in memblock.reserved. > >But memblock_set_node() may call memblock_double_array() to expand the array, > >which may get a range before current start. So we would miss to set the > >correct nid to the new reserved region. > > > >I have tried to create a case in memblock test. This would happen when there > >are 126 memblock.reserved regions. And the last region is across the last two > >node. > > > >One way to fix this is compare type->max in memblock_set_node(). Then check > >this return value in memmap_init_reserved_pages(). If we found the size > >changes, repeat the iteration. > > > >But this is a very trivial one, not sure it worth fix. > > > > Hi, Mike > > I have done a user space test which shows we may have a chance to leave a > region with non-nid set. > > Not sure you are ok with my approach of fixing. Wouldn't it be better to check for a change in reserved.max in memmap_init_reserved_pages()? > -- > Wei Yang > Help you, Help me -- Sincerely yours, Mike.