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Subject: Re: [[PATCH]] mm: khugepaged: recalculate min_free_kbytes after
 memory hotplug as expected by khugepaged
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Song Liu <songliubraving@fb.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Allen Pais <apais@microsoft.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
References: <1599770859-14826-1-git-send-email-vijayb@linux.microsoft.com>
 <20200910220145.5j7iogqulmvg5vr6@black.fi.intel.com>
From:   Vijay Balakrishna <vijayb@linux.microsoft.com>
Message-ID: <041b4c73-42b0-5cb1-716f-0a0d466fcdf0@linux.microsoft.com>
Date:   Mon, 14 Sep 2020 22:04:11 -0700
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On 9/10/2020 3:01 PM, Kirill A. Shutemov wrote:
> On Thu, Sep 10, 2020 at 01:47:39PM -0700, Vijay Balakrishna wrote:
>> When memory is hotplug added or removed the min_free_kbytes must be
>> recalculated based on what is expected by khugepaged.  Currently
>> after hotplug, min_free_kbytes will be set to a lower default and higher
>> default set when THP enabled is lost. This leaves the system with small
>> min_free_kbytes which isn't suitable for systems especially with network
>> intensive loads.  Typical failure symptoms include HW WATCHDOG reset,
>> soft lockup hang notices, NETDEVICE WATCHDOG timeouts, and OOM process
>> kills.
>>
>> Fixes: f000565adb77 ("thp: set recommended min free kbytes")
>>
>> Signed-off-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
>> Cc: stable@vger.kernel.org
> 
> NAK. It would override min_free_kbytes set by user.

Hi Kirill,

To fix the issue you raised I just submitted
https://lore.kernel.org/lkml/1600145748-26518-1-git-send-email-vijayb@linux.microsoft.com/

Thanks,
Vijay

>