linux-kernel - Re: [PATCH RFC 2/2] mm, hugetlb: do not rely on overcommit limit during migration

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Message-ID: <20171129112322.ix3b4byfx2a3aktd@dhcp22.suse.cz>
Date:   Wed, 29 Nov 2017 12:23:22 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     linux-mm@...ck.org
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC 2/2] mm, hugetlb: do not rely on overcommit limit
 during migration

On Wed 29-11-17 10:22:34, Michal Hocko wrote:
> What about this on top. I haven't tested this yet though.

OK, it seem to work:
root@...t1:~# echo 1 > /proc/sys/vm/nr_hugepages
root@...t1:~# echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_overcommit_hugepages

root@...t1:~# grep . /sys/devices/system/node/node*/hugepages/hugepages-2048kB/*
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:1
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0

# mmap 2 huge pages

root@...t1:~# grep . /sys/devices/system/node/node*/hugepages/hugepages-2048kB/*
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:2
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:1

root@...t1:~# migratepages $(pidof map_hugetlb) 1 0

/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:2
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:1
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0

and exit the mmap

root@...t1:~# grep . /sys/devices/system/node/node*/hugepages/hugepages-2048kB/*
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:1
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0
-- 
Michal Hocko
SUSE Labs