From: Michal Hocko <mhocko@kernel.org>
To: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
n-horiguchi@ah.jp.nec.com, mike.kravetz@Oracle.com,
aneesh.kumar@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com,
punit.agrawal@arm.com, arnd@arndb.de, gerald.schaefer@de.ibm.com,
aarcange@redhat.com, oleg@redhat.com,
penguin-kernel@I-love.SAKURA.ne.jp, mingo@kernel.org,
kirill.shutemov@linux.intel.com, vdavydov.dev@gmail.com,
willy@infradead.org
Subject: Re: [RFC PATCH 1/1] mm/hugetlb mm/oom_kill: Add support for reclaiming hugepages on OOM events.
Date: Fri, 28 Jul 2017 08:46:02 +0200 [thread overview]
Message-ID: <20170728064602.GC2274@dhcp22.suse.cz> (raw)
In-Reply-To: <20170727180236.6175-2-Liam.Howlett@Oracle.com>
On Thu 27-07-17 14:02:36, Liam R. Howlett wrote:
> When a system runs out of memory it may be desirable to reclaim
> unreserved hugepages. This situation arises when a correctly configured
> system has a memory failure and takes corrective action of rebooting and
> removing the memory from the memory pool results in a system failing to
> boot. With this change, the out of memory handler is able to reclaim
> any pages that are free and not reserved.
I am sorry but I have to Nack this. You are breaking the basic contract
of hugetlb user API. Administrator configures the pool to suit a
workload. It is a deliberate and privileged action. We allow to
overcommit that pool should there be a immediate need for more hugetlb
pages and we do remove those when they are freed. If we don't then this
should be fixed.
Other than that hugetlb pages are not reclaimable by design and users
do rely on that. Otherwise they could consider using THP instead.
If somebody configures the initial pool too high it is a configuration
bug. Just think about it, we do not want to reset lowmem reserves
configured by admin just because we are hitting the oom killer and yes
insanely large lowmem reserves might lead to early OOM as well.
Nacked-by: Michal Hocko <mhocko@suse.com>
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-07-28 6:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-27 18:02 [RFC PATCH 0/1] oom support for reclaiming of hugepages Liam R. Howlett
2017-07-27 18:02 ` [RFC PATCH 1/1] mm/hugetlb mm/oom_kill: Add support for reclaiming hugepages on OOM events Liam R. Howlett
2017-07-28 6:46 ` Michal Hocko [this message]
2017-07-28 11:33 ` Kirill A. Shutemov
2017-07-28 12:23 ` Michal Hocko
2017-07-28 12:44 ` Michal Hocko
2017-07-29 1:56 ` Liam R. Howlett
2017-07-31 9:10 ` Michal Hocko
2017-07-31 13:56 ` Liam R. Howlett
2017-07-31 14:08 ` Michal Hocko
2017-07-31 14:37 ` Matthew Wilcox
2017-07-31 14:49 ` Michal Hocko
2017-08-01 1:25 ` Liam R. Howlett
2017-08-01 8:28 ` Michal Hocko
2017-08-01 1:11 ` Liam R. Howlett
2017-08-01 8:29 ` Michal Hocko
2017-08-01 14:41 ` Liam R. Howlett
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