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Date: Thu, 29 Feb 2024 11:42:23 +0200
From: Mike Rapoport <rppt@kernel.org>
To: Yaxiong Tian <13327272236@163.com>
Cc: David Hildenbrand <david@redhat.com>, rafael@kernel.org, pavel@ucw.cz,
	len.brown@intel.com, keescook@chromium.org, tony.luck@intel.com,
	gpiccoli@igalia.com, akpm@linux-foundation.org, ardb@kernel.org,
	wangkefeng.wang@huawei.com, catalin.marinas@arm.com,
	will@kernel.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
	Yaxiong Tian <tianyaxiong@kylinos.cn>,
	xiongxin <xiongxin@kylinos.cn>
Subject: Re: [PATCH] PM: hibernate: Fix level3 translation fault in
 swsusp_save()
Message-ID: <ZeBRfxQ8WTEVzpfL@kernel.org>
References: <20240226034225.48689-1-13327272236@163.com>
 <8d70939f-ca14-4167-9647-b8f44ddcbb98@redhat.com>
 <ZdxWcG2XCqBum3_R@kernel.org>
 <3399d2af-3d42-4ac1-9b74-8475bec25f7f@163.com>
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In-Reply-To: <3399d2af-3d42-4ac1-9b74-8475bec25f7f@163.com>

On Tue, Feb 27, 2024 at 03:51:25PM +0800, Yaxiong Tian wrote:
> 
> 在 2024/2/26 17:14, Mike Rapoport 写道:
> > On Mon, Feb 26, 2024 at 09:37:06AM +0100, David Hildenbrand wrote:
> > > On 26.02.24 04:42, Yaxiong Tian wrote:
> > > > From: Yaxiong Tian <tianyaxiong@kylinos.cn>
> > > > 
> > > > On ARM64 machines using UEFI, if the linear map is not set (can_set_direct_map()
> > > > return false), swsusp_save() will fail due to can't finding the map table
> > > > under the nomap memory.such as:
> > can_set_direct_map() has nothing to do with presence or absence of the
> > linear map.
> > 
> > Do you mean that kernel_page_present() presumes that a page is present when
> > can_set_direct_map() returns false even for NOMAP ranges?
> Yes， in swsusp_save()->copy_data_pages()->page_is_saveable(),
> kernel_page_present() presumes that a page is present when
> can_set_direct_map()
> returns false even for NOMAP ranges.So NOMAP pages will saved in after,and
> then
> cause level3 translation fault in this pages.

So this should be the description of the problem in the changelog rather
than saying "if the linear map is not set (can_set_direct_map() return
false)"

> > > > QEMU ARM64 using UEFI also has the problem by setting can_set_direct_map()
> > > > return false.
> >
> > Huh?
> > Why would you do that?
> >
> I discovered this problem when upgrading from 5.4 to 6.6 using the 5.4
> configuration.
> So I using latest linux-next code,find the problem still exist.To rule out
> the effects
> of a particular machine，I also use qemu to check it.

I believe this can be reproduced if you boot with rodata=off and then
a better description would be something like

	This issue can be reproduced in QEMU when booting with rodata=off

-- 
Sincerely yours,
Mike.