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Subject: Re: [RFC][PATCH 05/10] x86/mm: do not auto-massage page protections
To:     Nadav Amit <namit@vmware.com>
References: <20180222203651.B776810C@viggo.jf.intel.com>
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From:   Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <754bf1d5-759b-0162-98ae-1800f075b8eb@linux.intel.com>
Date:   Thu, 22 Feb 2018 13:52:47 -0800
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On 02/22/2018 01:46 PM, Nadav Amit wrote:
>>
>> +static inline pgprotval_t check_pgprot(pgprot_t pgprot)
>> +{
>> +	pgprotval_t massaged_val = massage_pgprot(pgprot);
>> +
>> +	WARN_ONCE(pgprot_val(pgprot) != massaged_val,
>> +		  "attempted to set unsupported pgprot: %016lx "
>> +		  "bits: %016lx supported: %016lx\n",
>> +		  pgprot_val(pgprot),
>> +		  pgprot_val(pgprot) ^ massaged_val,
>> +		  __supported_pte_mask);
> Perhaps use VM_WARN_ONCE instead to avoid any overhead on production
> systems?

Sounds sane enough.  I'll change it.