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

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Message-ID: <c33ab0c1-6b73-2489-efab-972c8d7fa80b@oracle.com>
Date:   Tue, 29 Mar 2022 10:43:09 -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 3/28/22 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.

-- 
Mike Kravetz

> 
> Some other tests for current linux-master:
> 
> cmdline:
> hugepagesz=1G hugepages=1 hugepagesz=1G hugepages=2
> dmesg:
> HugeTLB: hugepagesz=1G specified twice, ignoring
> Unknown kernel command line parameters " hugepagesz=1G hugepages=2"
> 
> cmdline:
> hugepagesz=1Y hugepages=1
> dmesg:
> HugeTLB: unsupported hugepagesz=1Y
> HugeTLB: hugepages=1 does not follow a valid hugepagesz, ignoring
> Unknown kernel command line parameters "hugepagesz=1Y hugepages=1"
> 
> -- 
> Peng Liu
> .