linux-kernel - Re: [PATCH] hugetlb: Fix hugepages

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Date:   Thu, 31 Mar 2022 14:11:30 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     "liupeng (DM)" <liupeng256@...wei.com>, akpm@...ux-foundation.org,
        yaozhenguo1@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, rdunlap@...radead.org
Subject: Re: [PATCH] hugetlb: Fix hugepages_setup when deal with pernode

On 3/31/22 04:23, liupeng (DM) wrote:
> On 2022/3/30 1:43, Mike Kravetz wrote:
>> On 3/28/22 20:59, liupeng (DM) wrote:
>>> On 2022/3/29 10:46, Mike Kravetz wrote:
>>>> Yes, I agree that the change is needed and the current behavior is
>>>> unacceptable.
>>>>
>>>> One remaining question is the change from returning '0' to '1' in the case
>>>> of error.  I do understand this is to prevent the invalid parameter string
>>>> from being passed to init.  It may not be correct/right, but in every other
>>>> case where an invalid parameter in encountered in hugetlb command line
>>>> processing we return "0".  Should we perhaps change all these other places
>>>> to be consistent?  I honestly do not know what is the appropriate behavior
>>>> in these situations.
>>> Thank you for your carefulness and question.
>>>
>>> I have checked default_hugepagesz_setup and hugepages_setup will both print
>>> some information before return '0', so there is no need to print again in
>>> "Unknown kernel command line parameters".
>>>
>>> Should I send another patch to repair the rest "return 0" in hugetlb?
>> I would suggest two patches:
>>
>> 1) Fix the issue with invalid nodes specified.  However, leave the "return 0"
>>     behavior in hugepages_setup to be consistent with the rest of the code.
>>     This patch can be sent to stable with "Fixes: b5389086ad7b" tag as it
>>     addresses an existing issue.
>> 2) Clean up the places where we return 0 and it would be better to return 1.
>>     No cc stable here and just let the changes target future releases.
> I have tried to write a patch as your suggestion, but the best way I can carry it
> out is the original patch. To meet "Fix invalid nodes issue and leave thereturn
> 0 behavior", I have to add the following redundant code:
> 
>  invalid:
>         pr_warn("HugeTLB: Invalid hugepages parameter %s\n", p);
> +
> +       /* Allocate gigantic hstates for successfully parsed parameters*/
> +       if (hugetlb_max_hstate && hstate_is_gigantic(parsed_hstate))
> + hugetlb_hstate_alloc_pages(parsed_hstate);
> +       last_mhp = mhp;
> return 0;
> 

I was thinking something like the attached (untested).  It is very similar to
your original code.

-- 
Mike Kravetz
View attachment "patch" of type "text/plain" (854 bytes)