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Subject: Re: [PATCH 1/5] mm/resource: return real error codes from walk
 failures
To:     Bjorn Helgaas <bhelgaas@google.com>,
        Dave Hansen <dave.hansen@linux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Jiang <dave.jiang@intel.com>, zwisler@kernel.org,
        vishal.l.verma@intel.com, thomas.lendacky@amd.com,
        Andrew Morton <akpm@linux-foundation.org>, mhocko@suse.com,
        linux-nvdimm@lists.01.org, linux-mm@kvack.org,
        Huang Ying <ying.huang@intel.com>,
        Wu Fengguang <fengguang.wu@intel.com>,
        Borislav Petkov <bp@suse.de>, baiyaowei@cmss.chinamobile.com,
        Takashi Iwai <tiwai@suse.de>,
        Jerome Glisse <jglisse@redhat.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>
References: <20190124231441.37A4A305@viggo.jf.intel.com>
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From:   Dave Hansen <dave.hansen@intel.com>
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Message-ID: <4898e064-5298-6a82-83ea-23d16f3dfb3d@intel.com>
Date:   Fri, 25 Jan 2019 13:09:57 -0800
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On 1/25/19 1:02 PM, Bjorn Helgaas wrote:
>> @@ -453,7 +453,7 @@ int walk_system_ram_range(unsigned long
>>         unsigned long flags;
>>         struct resource res;
>>         unsigned long pfn, end_pfn;
>> -       int ret = -1;
>> +       int ret = -EINVAL;
> Can you either make a similar change to the powerpc version of
> walk_system_ram_range() in arch/powerpc/mm/mem.c or explain why it's
> not needed?  It *seems* like we'd want both versions of
> walk_system_ram_range() to behave similarly in this respect.

Sure.  A quick grep shows powerpc being the only other implementation.
I'll just add this hunk:

> diff -puN arch/powerpc/mm/mem.c~memory-hotplug-walk_system_ram_range-returns-neg-1 arch/powerpc/mm/mem.c
> --- a/arch/powerpc/mm/mem.c~memory-hotplug-walk_system_ram_range-returns-neg-1  2019-01-25 12:57:00.000004446 -0800
> +++ b/arch/powerpc/mm/mem.c     2019-01-25 12:58:13.215004263 -0800 
> @@ -188,7 +188,7 @@ walk_system_ram_range(unsigned long star 
>         struct memblock_region *reg; 
>         unsigned long end_pfn = start_pfn + nr_pages; 
>         unsigned long tstart, tend; 
> -       int ret = -1; 
> +       int ret = -EINVAL; 

I'll also dust off the ol' cross-compiler and make sure I didn't
fat-finger anything.