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 145571FC110 for ; Wed, 11 Mar 2026 16:46:32 +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=1773247593; cv=none; b=pXCEtb0ptdKxT/4hhptqlQ9Mydqxliizk+/a6qW2BFmGNts0ANnnXXfyUTQG6Opw0l4q06lfUQ9762o43CDsnk137Ed4K60IvK+4pJ0WIF3crAdpRI8jFnEZojFIWIhGL8fv+sUdwX+f9n2DIVUutIHpoPCa/tB+dKGds/9LeAs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773247593; c=relaxed/simple; bh=2E82letygI+4/uceOMbFsW+duYW+YCpibIx/qSenY4U=; h=Date:To:From:Subject:Message-Id; b=eleDyWqESjSN4HzaiE9fj7N1WzSbth1fd8RXNdAecSgLr7s06DnKioRET93NLODv+z9CXu+LjAT5nlcT7UHFszRJcb8eDc76tQJmHH8Amsj0KMzDxCG9N21rgklK//L4wOYxc6NFeVMKi7Ep8s5os1UliO7xE+j/Zonfp+dxCCA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=bVNUp3Kg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="bVNUp3Kg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B4FFC4CEF7; Wed, 11 Mar 2026 16:46:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773247592; bh=2E82letygI+4/uceOMbFsW+duYW+YCpibIx/qSenY4U=; h=Date:To:From:Subject:From; b=bVNUp3KgMz+4BwyK0mwXlXNkai4SVCTGvtNdX3y1y7uAIUSIucM6App0YoQ55K5U/ tKPekwPjW0gkoAOJTmUvC7hn2vobVE6pkg0FLnUP6oLCtn786rzzjS0ZfPAiaunA6P DrM23VYvxhEnUXAjjxTgXiTnteUD8IM+/svT9PYc= Date: Wed, 11 Mar 2026 09:46:31 -0700 To: mm-commits@vger.kernel.org,skhawaja@google.com,rppt@kernel.org,pratyush@kernel.org,pasha.tatashin@soleen.com,mclapinski@google.com,graf@amazon.com,epetron@amazon.de,akpm@linux-foundation.org From: Andrew Morton Subject: + kho-make-preserved-pages-compatible-with-deferred-struct-page-init.patch added to mm-unstable branch Message-Id: <20260311164632.9B4FFC4CEF7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: kho: make preserved pages compatible with deferred struct page init has been added to the -mm mm-unstable branch. Its filename is kho-make-preserved-pages-compatible-with-deferred-struct-page-init.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kho-make-preserved-pages-compatible-with-deferred-struct-page-init.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Evangelos Petrongonas Subject: kho: make preserved pages compatible with deferred struct page init Date: Wed, 11 Mar 2026 13:55:39 +0100 When CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, struct page initialization is deferred to parallel kthreads that run later in the boot process. During KHO restoration, kho_preserved_memory_reserve() writes metadata for each preserved memory region. However, if the struct page has not been initialized, this write targets uninitialized memory, potentially leading to errors like: BUG: unable to handle page fault for address: ... Fix this by introducing kho_get_preserved_page(), which ensures all struct pages in a preserved region are initialized by calling init_deferred_page() which is a no-op when the struct page is already initialized. Link: https://lkml.kernel.org/r/20260311125539.4123672-3-mclapinski@google.com Signed-off-by: Evangelos Petrongonas Co-developed-by: Michal Clapinski Signed-off-by: Michal Clapinski Reviewed-by: Pratyush Yadav (Google) Reviewed-by: Pasha Tatashin Reviewed-by: Mike Rapoport (Microsoft) Cc: Alexander Graf Cc: Samiullah Khawaja Signed-off-by: Andrew Morton --- kernel/liveupdate/Kconfig | 2 -- kernel/liveupdate/kexec_handover.c | 27 ++++++++++++++++++++++++++- 2 files changed, 26 insertions(+), 3 deletions(-) --- a/kernel/liveupdate/Kconfig~kho-make-preserved-pages-compatible-with-deferred-struct-page-init +++ a/kernel/liveupdate/Kconfig @@ -1,12 +1,10 @@ # SPDX-License-Identifier: GPL-2.0-only menu "Live Update and Kexec HandOver" - depends on !DEFERRED_STRUCT_PAGE_INIT config KEXEC_HANDOVER bool "kexec handover" depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE - depends on !DEFERRED_STRUCT_PAGE_INIT select MEMBLOCK_KHO_SCRATCH select KEXEC_FILE select LIBFDT --- a/kernel/liveupdate/kexec_handover.c~kho-make-preserved-pages-compatible-with-deferred-struct-page-init +++ a/kernel/liveupdate/kexec_handover.c @@ -470,6 +470,31 @@ struct page *kho_restore_pages(phys_addr } EXPORT_SYMBOL_GPL(kho_restore_pages); +/* + * With CONFIG_DEFERRED_STRUCT_PAGE_INIT, struct pages in higher memory regions + * may not be initialized yet at the time KHO deserializes preserved memory. + * KHO uses the struct page to store metadata and a later initialization would + * overwrite it. + * Ensure all the struct pages in the preservation are + * initialized. kho_preserved_memory_reserve() marks the reservation as noinit + * to make sure they don't get re-initialized later. + */ +static struct page *__init kho_get_preserved_page(phys_addr_t phys, + unsigned int order) +{ + unsigned long pfn = PHYS_PFN(phys); + int nid; + + if (!IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT)) + return pfn_to_page(pfn); + + nid = early_pfn_to_nid(pfn); + for (unsigned long i = 0; i < (1UL << order); i++) + init_deferred_page(pfn + i, nid); + + return pfn_to_page(pfn); +} + static int __init kho_preserved_memory_reserve(phys_addr_t phys, unsigned int order) { @@ -478,7 +503,7 @@ static int __init kho_preserved_memory_r u64 sz; sz = 1 << (order + PAGE_SHIFT); - page = phys_to_page(phys); + page = kho_get_preserved_page(phys, order); /* Reserve the memory preserved in KHO in memblock */ memblock_reserve(phys, sz); _ Patches currently in -mm which might be from epetron@amazon.de are kho-make-preserved-pages-compatible-with-deferred-struct-page-init.patch