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Date: Mon, 22 Apr 2024 12:18:46 +0300
From: Mike Rapoport <rppt@kernel.org>
To: Nam Cao <namcao@linutronix.de>
Cc: kernel test robot <oliver.sang@intel.com>, oe-lkp@lists.linux.dev,
	lkp@intel.com, Linux Memory Management List <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	=?iso-8859-1?Q?Bj=F6rn_T=F6pel?= <bjorn@kernel.org>,
	Andreas Dilger <adilger@dilger.ca>, Arnd Bergmann <arnd@arndb.de>,
	Changbin Du <changbin.du@huawei.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Ingo Molnar <mingo@kernel.org>,
	Krister Johansen <kjlx@templeofstupid.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>, Tejun Heo <tj@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org
Subject: Re: [linux-next:master] [init]  b8de39bd1b:
 BUG:kernel_failed_in_early-boot_stage,last_printk:early_console_in_setup_code
Message-ID: <ZiYrdnbw5z1ajeRw@kernel.org>
References: <202404221524.4954a009-oliver.sang@intel.com>
 <20240422082942.B750cniQ@linutronix.de>
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In-Reply-To: <20240422082942.B750cniQ@linutronix.de>

On Mon, Apr 22, 2024 at 10:29:42AM +0200, Nam Cao wrote:
> On Mon, Apr 22, 2024 at 03:45:00PM +0800, kernel test robot wrote:
> > kernel test robot noticed "BUG:kernel_failed_in_early-boot_stage,last_printk:early_console_in_setup_code" on:
> > 
> > commit: b8de39bd1b76faffe7cd91e148a6d7d9bf4e38f7 ("init: fix allocated page overlapping with PTR_ERR")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> 
> I can reproduce the problem. I rebased this commit onto v6.8.7, I can still
> observe the problem.
> 
> No immediate idea what is the problem. Backtrace from gdb goes crazy:
> 
> (gdb) bt
> #0  0xffffffffb2074ded in ?? ()
> #1  0x00000000000000a1 in ?? ()
> #2  0x00000000000000a1 in ?? ()
> #3  0x000000007ffff000 in ?? ()
> #4  0x00000000543ff000 in ?? ()
> #5  0x0000000000000000 in ?? ()

The kernel config here has CONFIG_DEBUG_VIRTUAL=y, so __pa translates to
__phys_addr() in arch/x86/mm/physaddr.c and __pa(-PAGE_SIZE) triggers

		VIRTUAL_BUG_ON(y >= KERNEL_IMAGE_SIZE);

x86 has __pa_nodebug() that does not do bounds check, but it cannot be used
in generic code because no other arch except s390 define it.

For now I don't have ideas how to make this work in the general case, so
probably we should only fix riscv for now.
 
> @akpm: drop this commit until this is figured out?
> 
> Best regards,
> Nam
> 

-- 
Sincerely yours,
Mike.