Re: [PATCH 1/2] m68k: nommu: register start of the memory with memblock

[Mike Rapoport]

Hi Greg,

On Mon, Jun 29, 2020 at 11:10:16AM +1000, Greg Ungerer wrote:
> Hi Mike,
> 
> On 17/6/20 10:33 pm, Greg Ungerer wrote:
> > Hi Mike,
> > 
> > On 17/6/20 4:53 pm, Mike Rapoport wrote:
> > > From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> > > 
> > > The m68k nommu setup code didn't register the beginning of the physical
> > > memory with memblock because it was anyway occupied by the kernel. However,
> > > commit fa3354e4ea39 ("mm: free_area_init: use maximal zone PFNs rather than
> > > zone sizes") changed zones initialization to use memblock.memory to detect
> > > the zone extents and this caused inconsistency between zone PFNs and the
> > > actual PFNs:
> > > 
> > > BUG: Bad page state in process swapper  pfn:20165
> > > page:41fe0ca0 refcount:0 mapcount:1 mapping:00000000 index:0x0 flags: 0x0()
> > > raw: 00000000 00000100 00000122 00000000 00000000 00000000 00000000 00000000
> > > page dumped because: nonzero mapcount
> > > CPU: 0 PID: 1 Comm: swapper Not tainted 5.8.0-rc1-00001-g3a38f8a60c65-dirty #1
> > > Stack from 404c9ebc:
> > >          404c9ebc 4029ab28 4029ab28 40088470 41fe0ca0 40299e21 40299df1 404ba2a4
> > >          00020165 00000000 41fd2c10 402c7ba0 41fd2c04 40088504 41fe0ca0 40299e21
> > >          00000000 40088a12 41fe0ca0 41fe0ca4 0000020a 00000000 00000001 402ca000
> > >          00000000 41fe0ca0 41fd2c10 41fd2c10 00000000 00000000 402b2388 00000001
> > >          400a0934 40091056 404c9f44 404c9f44 40088db4 402c7ba0 00000001 41fd2c04
> > >          41fe0ca0 41fd2000 41fe0ca0 40089e02 4026ecf4 40089e4e 41fe0ca0 ffffffff
> > > Call Trace:
> > >          [<40088470>] 0x40088470
> > >   [<40088504>] 0x40088504
> > >   [<40088a12>] 0x40088a12
> > >   [<402ca000>] 0x402ca000
> > >   [<400a0934>] 0x400a0934
> > > 
> > > Adjust the memory registration with memblock to include the beginning of
> > > the physical memory and make sure that the area occupied by the kernel is
> > > marked as reserved.
> > > 
> > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> > 
> > Acked-by: Greg Ungerer <gerg@xxxxxxxxxxxxxx>
> 
> What path do you anticipate this taking into mainline?
> I see it is still broken in 5.8-rc3.

I thought it will go through m68k tree.

> Regards
> Greg
> 
> 
> 
> > > ---
> > >   arch/m68k/kernel/setup_no.c | 3 ++-
> > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/m68k/kernel/setup_no.c b/arch/m68k/kernel/setup_no.c
> > > index e779b19e0193..f66f4b1d062e 100644
> > > --- a/arch/m68k/kernel/setup_no.c
> > > +++ b/arch/m68k/kernel/setup_no.c
> > > @@ -138,7 +138,8 @@ void __init setup_arch(char **cmdline_p)
> > >       pr_debug("MEMORY -> ROMFS=0x%p-0x%06lx MEM=0x%06lx-0x%06lx\n ",
> > >            __bss_stop, memory_start, memory_start, memory_end);
> > > -    memblock_add(memory_start, memory_end - memory_start);
> > > +    memblock_add(_rambase, memory_end - _rambase);
> > > +    memblock_reserve(_rambase, memory_start - _rambase);
> > >       /* Keep a copy of command line */
> > >       *cmdline_p = &command_line[0];
> > > 

-- 
Sincerely yours,
Mike.