linux-kernel - Re: [PATCH v4 07/12] x86/mtrr: allocate mtrr

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Message-ID: <5990f0a0-eca2-7715-8d10-ce170686a133@suse.com>
Date:   Mon, 20 Mar 2023 16:49:27 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        "Huang, Kai" <kai.huang@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Cc:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4 07/12] x86/mtrr: allocate mtrr_value array dynamically

On 20.03.23 16:31, Dave Hansen wrote:
> On 3/20/23 06:49, Juergen Gross wrote:
>>>>
>>>> @@ -750,6 +750,7 @@ static int __init mtrr_init_finialize(void)
>>>>         * TBD: is there any system with such CPU which supports
>>>>         * suspend/resume? If no, we should remove the code.
>>>>         */
>>>> +    mtrr_value = kcalloc(num_var_ranges, sizeof(*mtrr_value),
>>>> GFP_KERNEL);
>>>
>>> Theoretically dynamic allocation can fail, although it should not
>>> happen as this
>>> happens during kernel boot and the size is small.  Maybe a WARN()?
>>
>> Fine with me.
> 
> What *actually* happens if the system is running out of memory and this
> is the _first_ failure?  Does a WARN_ON() here help someone debug what
> is going on?

Good question. Especially as we don't set __GFP_NOWARN here.


Juergen

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