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 3F0FA332628 for ; Tue, 17 Mar 2026 17:46:42 +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=1773769602; cv=none; b=qf6L+LMQ+Vy/YCaSlhjIwqFIPxNhO7zpULaR/tc0W1x6NGprBs+DlBgydEE1Gz/rGVxQjC1PCNpYCZYx3qh+7d3V0zr2YLaQuGxSArY3LEARRscupwI7TSEp7y3CMkUHIlUpATr19Cb3eWX2+S6Sl64betRGxbErn1yXf83hnZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773769602; c=relaxed/simple; bh=hP3BWdEqXFzuDqIZhpvhnQIqE0kOztlu3bEx68E/oII=; h=Date:To:From:Subject:Message-Id; b=Zwx4FJikZKWoFfcbDiwdgl2EF5C03CBkyi9L9v4hNvJCrXAScZOjSwJ9ksffS1Etf8FyMyfPAm1i9wknbk6rvfQ5D5gB6gicDdwUPZlkIe+TVt5vaAua5SP6zerCGU8s/pQEdLWOCls8BC5fYQmUNc9Bzb4A0mjkZ1dNR6p6m5g= 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=DI/4n9LO; 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="DI/4n9LO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B9C2C4CEF7; Tue, 17 Mar 2026 17:46:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773769602; bh=hP3BWdEqXFzuDqIZhpvhnQIqE0kOztlu3bEx68E/oII=; h=Date:To:From:Subject:From; b=DI/4n9LOkbqjbQaR3xee67N4m2amFzGdl0gOeCbjS/OLsiAjyqwT6qv3C0SGpD/rN y70/ZIB6Qs+zJiiAxTFlal1B4yavm4tXFnRFW7RFFZ1GGTMezHGxTGcfYsmrb5dLon jMJFxNS/oH+fvtvJaoShw3bvxqLnmlfZmEcDyHX0= Date: Tue, 17 Mar 2026 10:46:41 -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-new branch Message-Id: <20260317174642.0B9C2C4CEF7@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-new 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-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next 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: Tue, 17 Mar 2026 15:15:34 +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/20260317141534.815634-4-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 @@ -471,6 +471,31 @@ 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) { @@ -479,7 +504,7 @@ 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