The patch titled
Subject: mm, memory_hotplug: remove timeout from __offline_memory
has been added to the -mm tree. Its filename is
mm-memory_hotplug-remove-timeout-from-__offline_memory.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory_hotplug-remove-timeout-from-__offline_memory.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory_hotplug-remove-timeout-from-__offline_memory.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, memory_hotplug: remove timeout from __offline_memory
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.
Link: http://lkml.kernel.org/r/20170918070834.13083-3-mhocko@xxxxxxxxxx
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <yasu.isimatu@xxxxxxxxx>
Cc: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Cc: Igor Mammedov <imammedo@xxxxxxxxxx>
Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff -puN mm/memory_hotplug.c~mm-memory_hotplug-remove-timeout-from-__offline_memory mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~mm-memory_hotplug-remove-timeout-from-__offline_memory
+++ a/mm/memory_hotplug.c
@@ -1594,9 +1594,9 @@ static void node_states_clear_node(int n
}
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;
@@ -1634,12 +1634,8 @@ static int __ref __offline_pages(unsigne
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;
@@ -1712,7 +1708,7 @@ failed_removal:
/* 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 */
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
mm-oom_reaper-skip-mm-structs-with-mmu-notifiers.patch
mm-memcg-remove-hotplug-locking-from-try_charge.patch
mm-memory_hotplug-add-scheduling-point-to-__add_pages.patch
mm-page_alloc-add-scheduling-point-to-memmap_init_zone.patch
memremap-add-scheduling-point-to-devm_memremap_pages.patch
mm-memory_hotplug-do-not-back-off-draining-pcp-free-pages-from-kworker-context.patch
mm-memory_hotplug-do-not-fail-offlining-too-early.patch
mm-memory_hotplug-remove-timeout-from-__offline_memory.patch
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