From: Michal Hocko <[email protected]> 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 <[email protected]> Signed-off-by: Michal Hocko <[email protected]> --- 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
