Re: [PATCH] PM: hibernate: Fix level3 translation fault in swsusp_save()

[Mike Rapoport <rppt@kernel.org>]

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.