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 6D33E30F956 for ; Thu, 27 Nov 2025 05:05:48 +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=1764219950; cv=none; b=AyNM7D4etBF7RhS6/ghRgqnvFe/2GDfpZKJ6hqAl3Bdxrf4qio1qTodz7AZq5XmXlNK2gA7nh0nNMAgNdZXkASQeYl6H1b/GvWC4bAvoZui9JGEOI8dlhzHU4vGWvoeEeQcPuhkVYhKqUg6qmFH6vHPq//1BNh3N7F4CM8x8C8c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764219950; c=relaxed/simple; bh=Nl9RwO91yTa5covY+c2/N9Gq4s0OvI/oEAchPUaaHrI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Jpd0DMLCllNfoBiNpqy2C14hSspOycX3yxdayH44r3w+/NGhzfvB6KC33cGQI4mFOreffGXDpWtw9oLs+G+UHKO6atvZCSth+QLJYfuV9/WCGV62unqc/Z6sQYLQKNMsgG/gwPRBmWCRl7sj0ZFT8659iRYsRuksW3JjrAkOMvA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H4jAdZwu; 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="H4jAdZwu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A0DEC4CEF8; Thu, 27 Nov 2025 05:05:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764219947; bh=Nl9RwO91yTa5covY+c2/N9Gq4s0OvI/oEAchPUaaHrI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H4jAdZwu3Sd4OjszEkHlJtz4SnzwWGXrgyaOCalfAVVClCU29XQXAC0JKogFFq9sq zfgHOpWN+oVfBr555kCBzeAzfAliqANmAe++un6WB8Y+mQrKzT4hnA6Qa70HJJfMeK HRqfMJRPLFbLVti/I2v4I3InHPGzVtf5Nk4mlbdxVdU4vBr+VA+q+U233XhVyKEcvy 4pPBwgFCPs8W3b3DDj1JrtQXgL4RIZDYN2/MohtkNtNmhQSjjqNEdgRWJDAjyaCCxn 3d3gNFgh07WSRkNajVcF4mcWMFN0cgepD2nu7HJzgcVbgkp5heeYUNsq1PtZm+pO7c VSh9U+RbFsZbA== Date: Thu, 27 Nov 2025 07:05:40 +0200 From: Mike Rapoport To: Usama Arif Cc: Andrew Morton , changyuanl@google.com, graf@amazon.com, leitao@debian.org, thevlad@meta.com, pratyush@kernel.org, dave.hansen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] mm/memblock: only mark/clear KHO scratch memory when needed Message-ID: References: <20251126072051.546700-1-usamaarif642@gmail.com> 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: <20251126072051.546700-1-usamaarif642@gmail.com> On Wed, Nov 26, 2025 at 07:20:51AM +0000, Usama Arif wrote: > The scratch memory for kexec handover is used to bootstrap the > kexec'ed kernel. It is only needed when CONFIG_MEMBLOCK_KHO_SCRATCH > is enabled (selected by KHO) and if it is a KHO boot. Add checks > to prevent marking a KHO scratch region unless needed. > > kexec_handover.h is now unconditionally included for is_kho_boot. > > Fixes: a2daf83e10378 ("x86/e820: temporarily enable KHO scratch for memory below 1M") > Reported-by: Vlad Poenaru > Signed-off-by: Usama Arif > --- > mm/memblock.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index e23e16618e9b3..5c85d575bb61c 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -20,8 +20,8 @@ > > #ifdef CONFIG_KEXEC_HANDOVER > #include > -#include > #endif /* CONFIG_KEXEC_HANDOVER */ > +#include > > #include > #include > @@ -1126,8 +1126,11 @@ int __init_memblock memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t > */ > __init int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size) > { > - return memblock_setclr_flag(&memblock.memory, base, size, 1, > - MEMBLOCK_KHO_SCRATCH); > + if (IS_ENABLED(CONFIG_MEMBLOCK_KHO_SCRATCH) && is_kho_boot()) > + return memblock_setclr_flag(&memblock.memory, base, size, 1, > + MEMBLOCK_KHO_SCRATCH); > + else else is not needed. > + return 0; > } > > /** > @@ -1140,8 +1143,11 @@ __init int memblock_mark_kho_scratch(phys_addr_t base, phys_addr_t size) > */ > __init int memblock_clear_kho_scratch(phys_addr_t base, phys_addr_t size) > { > - return memblock_setclr_flag(&memblock.memory, base, size, 0, > - MEMBLOCK_KHO_SCRATCH); > + if (IS_ENABLED(CONFIG_MEMBLOCK_KHO_SCRATCH) && is_kho_boot()) > + return memblock_setclr_flag(&memblock.memory, base, size, 0, > + MEMBLOCK_KHO_SCRATCH); > + else Ditto. > + return 0; > } > > static bool should_skip_region(struct memblock_type *type, > -- > 2.47.3 > -- Sincerely yours, Mike.