Re: [PATCH v2 4/4] mm, arch: add generic implementation of pfn_valid() for FLATMEM

From: Mike Rapoport <rppt@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>, Brian Cain <bcain@quicinc.com>,
	"David S. Miller" <davem@davemloft.net>,
	Dinh Nguyen <dinguyen@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Greg Ungerer <gerg@linux-m68k.org>, Guo Ren <guoren@kernel.org>,
	Helge Deller <deller@gmx.de>, Huacai Chen <chenhuacai@kernel.org>,
	Matt Turner <mattst88@gmail.com>,
	Max Filippov <jcmvbkbc@gmail.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Michal Simek <monstr@monstr.eu>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Rich Felker <dalias@libc.org>,
	Richard Weinberger <richard@nod.at>,
	Russell King <linux@armlinux.org.uk>,
	Stafford Horne <shorne@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Vineet Gupta <vgupta@kernel.org>, WANG Xuerui <kernel@xen0n.name>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
	linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
	linux-mips@vger.kernel.org, linux-mm@kvack.org,
	linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
	linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev,
	openrisc@lists.librecores.org, sparclinux@vger.kernel.org,
	x86@kernel.org, Huacai Chen <chenhuacai@loongson.cn>
Subject: Re: [PATCH v2 4/4] mm, arch: add generic implementation of pfn_valid() for FLATMEM
Date: Mon, 13 Feb 2023 09:54:17 +0200	[thread overview]
Message-ID: <Y+nsqV6u/PqNlwDS@kernel.org> (raw)
In-Reply-To: <15a2c023-fdfa-9543-ac36-a846e5f8a000@roeck-us.net>

Andrew, 

On Sun, Feb 12, 2023 at 10:37:15PM -0800, Guenter Roeck wrote:
> On 2/12/23 17:26, Mike Rapoport wrote:
> > On Sun, Feb 12, 2023 at 08:13:20AM -0800, Guenter Roeck wrote:
> > > On Sun, Jan 29, 2023 at 02:42:35PM +0200, Mike Rapoport wrote:
> > > > From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> > > > 
> > > > Every architecture that supports FLATMEM memory model defines its own
> > > > version of pfn_valid() that essentially compares a pfn to max_mapnr.
> > > > 
> > > > Use mips/powerpc version implemented as static inline as a generic
> > > > implementation of pfn_valid() and drop its per-architecture definitions.
> > > > 
> > > 
> > > With this patch in the tree, sh4 and sh4eb qemu emulations no longer boot.
> > > Reverting this patch fixes the problem.
> > 
> > This should be a better fix than a revert:
> > 
> > diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
> > index 506784702430..bf1b54055316 100644
> > --- a/arch/sh/mm/init.c
> > +++ b/arch/sh/mm/init.c
> > @@ -301,6 +301,7 @@ void __init paging_init(void)
> >   	 */
> >   	max_low_pfn = max_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
> >   	min_low_pfn = __MEMORY_START >> PAGE_SHIFT;
> > +	set_max_mapnr(max_low_pfn - min_low_pfn);
> >   	nodes_clear(node_online_map);
> 
> Confirmed, this fixes the problem for me.

What is your preference for this and m68k fix? Fixups on top of mm-stable
or v3 of the entire series? 

> Thanks,
> Guenter

-- 
Sincerely yours,
Mike.