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From: Michal Hocko <mhocko@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory
Date: Mon, 18 Sep 2017 09:08:34 +0200
Message-ID: <20170918070834.13083-3-mhocko@kernel.org> (raw)
In-Reply-To: <20170918070834.13083-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

We have a hardcoded 120s timeout after which the memory offline fails
basically since the hot remove has been introduced. This is essentially
a policy implemented in the kernel. Moreover there is no way to adjust
the timeout and so we are sometimes facing memory offline failures if
the system is under a heavy memory pressure or very intensive CPU
workload on large machines.

It is not very clear what purpose the timeout actually serves. The
offline operation is interruptible by a signal so if userspace wants
some timeout based termination this can be done trivially by sending a
signal.

If there is a strong usecase to do this from the kernel then we should
do it properly and have a it tunable from the userspace with the timeout
disabled by default along with the explanation who uses it and for what
purporse.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c9dcbe6d2ac6..b8a85c11360e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1593,9 +1593,9 @@ static void node_states_clear_node(int node, struct memory_notify *arg)
 }
 
 static int __ref __offline_pages(unsigned long start_pfn,
-		  unsigned long end_pfn, unsigned long timeout)
+		  unsigned long end_pfn)
 {
-	unsigned long pfn, nr_pages, expire;
+	unsigned long pfn, nr_pages;
 	long offlined_pages;
 	int ret, node;
 	unsigned long flags;
@@ -1633,12 +1633,8 @@ static int __ref __offline_pages(unsigned long start_pfn,
 		goto failed_removal;
 
 	pfn = start_pfn;
-	expire = jiffies + timeout;
 repeat:
 	/* start memory hot removal */
-	ret = -EBUSY;
-	if (time_after(jiffies, expire))
-		goto failed_removal;
 	ret = -EINTR;
 	if (signal_pending(current))
 		goto failed_removal;
@@ -1711,7 +1707,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
 /* Must be protected by mem_hotplug_begin() or a device_lock */
 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
-	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
+	return __offline_pages(start_pfn, start_pfn + nr_pages);
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
-- 
2.14.1

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  parent reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-18  7:08 [PATCH v2 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-18  7:08 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-10-10 12:05   ` Michael Ellerman
2017-10-10 12:27     ` Michal Hocko
2017-10-11  2:37       ` Michael Ellerman
2017-10-11  5:19         ` Michael Ellerman
2017-10-11 14:05           ` Anshuman Khandual
2017-10-11 14:16             ` Michal Hocko
2017-10-11  6:51         ` Michal Hocko
2017-10-11  8:04           ` Vlastimil Babka
2017-10-11  8:13             ` Michal Hocko
2017-10-11 11:17               ` Vlastimil Babka
2017-10-11 11:24                 ` Michal Hocko
2017-10-13 11:42             ` Michael Ellerman
2017-10-13 11:58               ` Michal Hocko
2017-10-13 12:00                 ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michal Hocko
2017-10-13 12:00                   ` [PATCH 2/2] mm, page_alloc: fail has_unmovable_pages when seeing reserved pages Michal Hocko
2017-10-13 12:04                     ` Vlastimil Babka
2017-10-13 12:07                       ` Michal Hocko
2017-10-17 13:03                         ` Vlastimil Babka
2017-10-17 11:41                   ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michael Ellerman
2017-10-17 12:03                     ` Michal Hocko
2017-10-17 13:02                   ` Vlastimil Babka
2017-10-19  2:51                   ` Joonsoo Kim
2017-10-19  7:15                     ` Michal Hocko
2017-10-19  7:33                       ` Joonsoo Kim
2017-10-19  8:20                         ` Michal Hocko
2017-10-19 12:21                           ` Michal Hocko
2017-10-20  2:13                             ` Joonsoo Kim
2017-10-20  5:59                               ` Michal Hocko
2017-10-20  6:50                                 ` Joonsoo Kim
2017-10-20  7:02                                   ` Michal Hocko
2017-10-23  5:23                                     ` Joonsoo Kim
2017-10-23  8:10                                       ` Michal Hocko
2017-10-24  4:44                                         ` Joonsoo Kim
2017-10-24  7:44                                           ` Michal Hocko
2017-10-24  8:12                                           ` Vlastimil Babka
2017-10-24 12:25                                             ` Michal Hocko
2017-10-26  2:47                                             ` Joonsoo Kim
2017-10-26  7:41                                               ` Michal Hocko
2017-10-20  7:22                               ` Xishi Qiu
2017-10-20  8:17                                 ` Michal Hocko
2017-10-23  5:26                                   ` Joonsoo Kim
2017-10-26 13:04                             ` Vlastimil Babka
2017-10-26 13:59                             ` Michal Hocko
2017-09-18  7:08 ` Michal Hocko [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-09-04  8:21 [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-04  8:21 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko
2017-09-04  8:58   ` Xishi Qiu
2017-09-04  9:01     ` Michal Hocko
2017-09-04  9:05       ` Xishi Qiu
2017-09-04  9:15         ` Michal Hocko
2017-09-05  5:46           ` Anshuman Khandual
2017-09-05  7:23             ` Michal Hocko
2017-09-05  8:54               ` Anshuman Khandual
2017-09-08 17:27   ` Vlastimil Babka

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