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> Subject: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Date: Mon, 4 Sep 2017 10:21:48 +0200 [thread overview] Message-ID: <20170904082148.23131-3-mhocko@kernel.org> (raw) In-Reply-To: <20170904082148.23131-1-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. 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
WARNING: multiple messages have this Message-ID (diff)
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> Subject: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Date: Mon, 4 Sep 2017 10:21:48 +0200 [thread overview] Message-ID: <20170904082148.23131-3-mhocko@kernel.org> (raw) In-Reply-To: <20170904082148.23131-1-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. 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-09-04 8:22 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-09-04 8:21 [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko 2017-09-04 8:21 ` Michal Hocko 2017-09-04 8:21 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko 2017-09-04 8:21 ` Michal Hocko 2017-09-05 6:29 ` Anshuman Khandual 2017-09-05 6:29 ` Anshuman Khandual 2017-09-05 7:13 ` Michal Hocko 2017-09-05 7:13 ` Michal Hocko 2017-09-08 17:26 ` Vlastimil Babka 2017-09-08 17:26 ` Vlastimil Babka 2017-09-11 8:17 ` Michal Hocko 2017-09-11 8:17 ` Michal Hocko 2017-09-13 11:41 ` Vlastimil Babka 2017-09-13 11:41 ` Vlastimil Babka 2017-09-13 12:10 ` Michal Hocko 2017-09-13 12:10 ` Michal Hocko 2017-09-13 12:14 ` Michal Hocko 2017-09-13 12:14 ` Michal Hocko 2017-09-13 12:19 ` Vlastimil Babka 2017-09-13 12:19 ` Vlastimil Babka 2017-09-13 12:32 ` Michal Hocko 2017-09-13 12:32 ` Michal Hocko 2017-09-04 8:21 ` Michal Hocko [this message] 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 8:58 ` Xishi Qiu 2017-09-04 9:01 ` Michal Hocko 2017-09-04 9:01 ` Michal Hocko 2017-09-04 9:05 ` Xishi Qiu 2017-09-04 9:05 ` Xishi Qiu 2017-09-04 9:15 ` Michal Hocko 2017-09-04 9:15 ` Michal Hocko 2017-09-05 5:46 ` Anshuman Khandual 2017-09-05 5:46 ` Anshuman Khandual 2017-09-05 7:23 ` Michal Hocko 2017-09-05 7:23 ` Michal Hocko 2017-09-05 8:54 ` Anshuman Khandual 2017-09-05 8:54 ` Anshuman Khandual 2017-09-08 17:27 ` Vlastimil Babka 2017-09-08 17:27 ` Vlastimil Babka 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 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko 2017-09-18 7:08 ` Michal Hocko
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