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 475ACCCF9E3 for ; Tue, 4 Nov 2025 14:32:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 72ED38E0146; Tue, 4 Nov 2025 09:32:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 705FE8E0124; Tue, 4 Nov 2025 09:32:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6439C8E0146; Tue, 4 Nov 2025 09:32:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 4FD4F8E0124 for ; Tue, 4 Nov 2025 09:32:52 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id E575A598A0 for ; Tue, 4 Nov 2025 14:32:51 +0000 (UTC) X-FDA: 84073166142.08.A6206E7 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf10.hostedemail.com (Postfix) with ESMTP id 3E112C0005 for ; Tue, 4 Nov 2025 14:32:50 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="hu/DmIlA"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1762266770; a=rsa-sha256; cv=none; b=mLgHI0vZWdeevxvrPBDOFYcUhr7WGLYRlHG4BszmL/90M3LJFIQLUKp4ec/YtgJ5LJ6cc3 FhZxK/EKmle6h8acrYoDqvjeeMchccP3nBabtLndg/tsaqlHmwdu4iEZuuY4ctqSPPkhp/ bRc2/eOMbJN7EetMfwW1G/oknxBhLPk= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b="hu/DmIlA"; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1762266770; 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=u8h3zkk6XvoyFPdG4z5IRHQ5HEXCtEyF3cXPVMqWwBU=; b=WyzFEQGnQhuEDgCUaI0SHnYCiuHzCzE0ub3ybVqOikSN2v5HW7YV5BCW41kc5LzlLSS7xv 6gxXnB9uG0yGASHrlMwAnjhBbylhpMIMDZSnNyHYuhpO/m3PjfUg12Y2xXxi9XUAV/E5hb EM9uxFBYzdLQtJnlA5Or7ObNSN7lez0= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 511E640481; Tue, 4 Nov 2025 14:32:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6212DC116B1; Tue, 4 Nov 2025 14:32:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762266769; bh=RORlDZODXaQvDU2xYSdqK34eg3g039xujjqxDT3MR80=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hu/DmIlAB5Kq9YX5KdYPEScDdxOcvtnhommT7pX+0QcphEpKxyk1bEZbEyk8V0NEk a0wrz3MWKZhMkalsjp3HtpQS1Eym66KN0kQm2gCu6/zd8BkRtQ+Cff5zRUZ+JpyOnZ hxM3eNqaBWAsZoCe6WoOlQhhLmxyWYo7WGWF64mUjG1Z0hOQRJg7xLa8RPmtRjsJst gqyR5LibszsQsOEBd3iV9M5JM2WueL0l5P4Bc7Q86iT3hTijngXJIJu5oHWXNc49YV GhBxMUrUvh7aeIABcXutqnbfg1UTsicDuZUCRD1X5Fm6R+IBQGxxVKU1xJhlrJMtDA HWUJvljcoDm3A== Date: Tue, 4 Nov 2025 16:32:42 +0200 From: Mike Rapoport To: Pratyush Yadav Cc: Andrew Morton , Baoquan He , Alexander Graf , Pasha Tatashin , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kho: warn and exit when unpreserved page wasn't preserved Message-ID: References: <20251103180235.71409-1-pratyush@kernel.org> <20251103180235.71409-3-pratyush@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251103180235.71409-3-pratyush@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3E112C0005 X-Stat-Signature: enhhknao1ef463cray45yjhfijojo33x X-HE-Tag: 1762266770-462305 X-HE-Meta: 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 RexZqjqv wWiwv1kMKjbnOgMv5woF6pljfjmzGLa4A08I8PSnfw15VaFtyM37X/gQCt/+LwF+0q8/hW+NxKutWpnkQvZCOxrvI6GJsMht/DNW/a1yHVwCl/TGxWYiFReeG6iQs1WTaDFkKPJeiL5NlXHPy86S+hZN8dE3vZWEx4NcpcoJ7QXxpsXbhoHZp1OPwmTp4O/itcW6mRTa/rMu7rL6q2w0XOiHTiSV5L9kluYi7NstXGL+8BKW5wL33xEMWsplYQ+RN8K5rHkEEKr26aiM+dd+bJPftRg== 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 Mon, Nov 03, 2025 at 07:02:32PM +0100, Pratyush Yadav wrote: > 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 Reviewed-by: Mike Rapoport (Microsoft) > --- > 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 > -- Sincerely yours, Mike.