From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 40B33CCD193 for ; Mon, 20 Oct 2025 08:05:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 76B178E000E; Mon, 20 Oct 2025 04:05:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 71B948E0007; Mon, 20 Oct 2025 04:05:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 631718E000E; Mon, 20 Oct 2025 04:05:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 4EAEA8E0007 for ; Mon, 20 Oct 2025 04:05:57 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id D6EBF5B2BF for ; Mon, 20 Oct 2025 08:05:56 +0000 (UTC) X-FDA: 84017759112.06.E941CD1 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf23.hostedemail.com (Postfix) with ESMTP id 4C555140009 for ; Mon, 20 Oct 2025 08:05:55 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=RorPQ5ol; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1760947555; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HQz87CQCR7nEfb2O028+GBtmwHCB0SHAP1SZSbYDhlc=; b=Q7j7ka1uWec/Rb2ps4P+iUxFs2VmqoLVh8bWNPvsAhPaQMiXkE/UGgNEdvChiIp3DAv3x5 VZJwrblFbllpTcf+M8mRjXqLcJcYyOtD0VqcOVr6814S3yBIwK9JGgaq1+AdG+yMAJ5JQN HQzqXMr5gqQdE1BkY01xVbOi9b9vXdA= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=RorPQ5ol; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1760947555; a=rsa-sha256; cv=none; b=TocxuSebrOq1IDJgFOs+n4uKrt8lczFYIryFQqpSRitgizyFft6ITFi3fq2TD0nbW5qT7G ZDsF6sn4cXFHtDq0yTno2NwLKppKpXiiGtB0Uzo8WZe/IvAuIDYLc290D3AScS4iLcW9lj Lym5zGY6gj1w5d10LXfOPkUGfWkSEmk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 8F4A260555; Mon, 20 Oct 2025 08:05:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9AC4C4CEF9; Mon, 20 Oct 2025 08:05:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760947554; bh=rXda7spHoPBZ+btkYMydEsdxIcZXVOZHXuPQfGL5NOo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RorPQ5olAs/Pyghkzn3Qc8h10zq3G79fwC1hL8SfRWZb9JgJbZWZsx3QyuBAuZhwQ C1pNEdrWswDJ/U1+Ggy6ILEYWd99LIk6R1hdOqrP4sXWYKO9i7qz2dJyUEr1B3lrhf UYJRcNABMc67F7U0tQR/iMO1gUOg4Tci/IGLfMczunIcDga+dIX/gDtgb8+UHrsmsD pkSGFCN7LagnLRbPFB3utcBqN8bA0jptZQSAm9+VdUZx75mWv4I4/dUaPyhrVkPv3w etGxXmQyQ35MZu+MQQAby00aklXEEhMx9yUpIY7rVOE/JEFD3jw9azZUII1W2dJCY+ 1aZYlWJKxnePg== Date: Mon, 20 Oct 2025 11:05:44 +0300 From: Mike Rapoport To: Pasha Tatashin Cc: akpm@linux-foundation.org, brauner@kernel.org, corbet@lwn.net, graf@amazon.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, masahiroy@kernel.org, ojeda@kernel.org, pratyush@kernel.org, rdunlap@infradead.org, tj@kernel.org, jasonmiu@google.com, dmatlack@google.com, skhawaja@google.com Subject: Re: [PATCH v6 10/10] liveupdate: kho: allocate metadata directly from the buddy allocator Message-ID: References: <20251018171756.1724191-1-pasha.tatashin@soleen.com> <20251018171756.1724191-11-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251018171756.1724191-11-pasha.tatashin@soleen.com> X-Stat-Signature: iiktux87fdbtjtzyrsguhb6rdjt8n41u X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4C555140009 X-HE-Tag: 1760947555-304666 X-HE-Meta: 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 Xm/dCTjJ ZGFYW0p+IxWIhuL+vYOo/cjbvapFQNJY0E1PqPXoFFqYDukYRVY3DUt5zExxZ879sdLdtM7VdCESKAJq/oxFdrhLXKMvsjrk3gyyaYE2x/bxzBkxxCimd82aB5cvdEAvNt5xatYvgmZUhyx2K4sGRpC4OWUXmh0/lW1pp81AfNJ7MlxQkYRZX+w8H5ETKcxGsSgax1wsw8Ptwvphq+6vSf8YYrr3FJAHZNxYw4DmsafBa4KIxI9baRQ/W93Q2CxvN4CMDimPqecx1AgHyb1tV1Y+q+GIY1Ii0Glllq7XRgBM9dvM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Oct 18, 2025 at 01:17:56PM -0400, Pasha Tatashin wrote: > KHO allocates metadata for its preserved memory map using the slab > allocator via kzalloc(). This metadata is temporary and is used by the > next kernel during early boot to find preserved memory. > > A problem arises when KFENCE is enabled. kzalloc() calls can be > randomly intercepted by kfence_alloc(), which services the allocation > from a dedicated KFENCE memory pool. This pool is allocated early in > boot via memblock. > > When booting via KHO, the memblock allocator is restricted to a "scratch > area", forcing the KFENCE pool to be allocated within it. This creates a > conflict, as the scratch area is expected to be ephemeral and > overwriteable by a subsequent kexec. If KHO metadata is placed in this > KFENCE pool, it leads to memory corruption when the next kernel is > loaded. > > To fix this, modify KHO to allocate its metadata directly from the buddy > allocator instead of slab. > > Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") > Signed-off-by: Pasha Tatashin > Reviewed-by: Pratyush Yadav > --- > kernel/liveupdate/kexec_handover.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c > index 7c8e89a6b953..92662739a3a2 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -132,6 +132,8 @@ static struct kho_out kho_out = { > .finalized = false, > }; > > +DEFINE_FREE(kho_free_page, void *, free_page((unsigned long)_T)) > + Just drop kho_ prefix and stick it into include/linux/gfp.h: DEFINE_FREE(free_page, void *, if (_T) free_page((unsigned long)_T)) > static void *xa_load_or_alloc(struct xarray *xa, unsigned long index) > { > void *res = xa_load(xa, index); > @@ -139,7 +141,7 @@ static void *xa_load_or_alloc(struct xarray *xa, unsigned long index) > if (res) > return res; > > - void *elm __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL); > + void *elm __free(kho_free_page) = (void *)get_zeroed_page(GFP_KERNEL); > > if (!elm) > return ERR_PTR(-ENOMEM); > @@ -352,9 +354,9 @@ static_assert(sizeof(struct khoser_mem_chunk) == PAGE_SIZE); > static struct khoser_mem_chunk *new_chunk(struct khoser_mem_chunk *cur_chunk, > unsigned long order) > { > - struct khoser_mem_chunk *chunk __free(kfree) = NULL; > + struct khoser_mem_chunk *chunk __free(kho_free_page) = NULL; > > - chunk = kzalloc(PAGE_SIZE, GFP_KERNEL); > + chunk = (void *)get_zeroed_page(GFP_KERNEL); > if (!chunk) > return ERR_PTR(-ENOMEM); > > -- > 2.51.0.915.g61a8936c21-goog > -- Sincerely yours, Mike.