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 526D931A559 for ; Mon, 3 Nov 2025 18:02:45 +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=1762192965; cv=none; b=O3R4YCEwUR3Y4+Qra2OtSzSYvvti4gw9iLKan/9A2/QYRmht8ibmBpHJByYUkQQZgnSoL4nkZJrJgu08W6tyXPmv6bKuHkVZDtbYxZLs1IU+Et2x1suToGW3y2baTfwrEGWkZmMRxciQ34khDfyW5MUQgslb/Gy0lpnEBT4WRmU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762192965; c=relaxed/simple; bh=XAwF/h8XdutL+ENyQyWob7z7axCXjW7g+SCPNNUBiyQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rqW/U/AAf+kEdV3ki8I0PRJEhq7hWvIinrXjoX4+KEE7pftfwbt7zOEkMB0d5PxuhIepwfHBwvWbghuO+I4M2bv047xrt7ozM4IXevUoj7FxB73KcaNl76JXG4jVFlqxq8kLtMWHG8v1uxg8ZrIJZCgT8D0VtQduMBfQ0BpQCDQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IogQUODJ; 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="IogQUODJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9AD2DC4AF09; Mon, 3 Nov 2025 18:02:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762192964; bh=XAwF/h8XdutL+ENyQyWob7z7axCXjW7g+SCPNNUBiyQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IogQUODJjyTWMTWVWaSKOwkSJBVW67K2O34Yde/KtslQOOC/Iz4sy8KaX6kqBr7H5 GFb0Mcw/CkdVwmgfsioszFx5cEWJnFMulKlO4IIWvyPCxOY1jfelhxhEZQ5AP4Ct20 0Vgjho6r1cDd6BAXDhjF53c2kxEy94T2XEauW2MpEwvaH7ybnXWy2ukCRmB/8Xzbk8 Q8XlwO1XtdHF4UuXTBo9/62vnf1B1SOwpRq/JctgNqhxnH4iX4n2dIk3KVMpmHVZDY fl6Itix1asg+IRwQ/C5Alq02OX92QqFS6qSZ4BEdLJGRyEcSa9MguO0nJ5vMyR8QXe Rxj/Q36Ehv0Gg== From: Pratyush Yadav To: Andrew Morton , Baoquan He , Alexander Graf , Mike Rapoport , Pasha Tatashin , Pratyush Yadav Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] kho: warn and exit when unpreserved page wasn't preserved Date: Mon, 3 Nov 2025 19:02:32 +0100 Message-ID: <20251103180235.71409-3-pratyush@kernel.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251103180235.71409-1-pratyush@kernel.org> References: <20251103180235.71409-1-pratyush@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Calling __kho_unpreserve() on a pair of (pfn, end_pfn) that wasn't preserved is a bug. Currently, if that is done, the physxa or bits can be NULL. This results in a soft lockup since a NULL physxa or bits results in redoing the loop without ever making any progress. Return when physxa or bits are not found, but WARN first to loudly indicate invalid behaviour. Fixes: fc33e4b44b271 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pratyush Yadav --- kernel/kexec_handover.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c index c2bcbb10918ce..e5fd833726226 100644 --- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -167,12 +167,12 @@ static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, const unsigned long pfn_high = pfn >> order; physxa = xa_load(&track->orders, order); - if (!physxa) - continue; + if (WARN_ON_ONCE(!physxa)) + return; bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); - if (!bits) - continue; + if (WARN_ON_ONCE(!bits)) + return; clear_bit(pfn_high % PRESERVE_BITS, bits->preserve); -- 2.47.3