From 5f47adf762b78cae97de58d9ff01d2d44db09467 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 6 Apr 2020 20:07:44 -0700 Subject: mm/memory_hotplug: allow to specify a default online_type For now, distributions implement advanced udev rules to essentially - Don't online any hotplugged memory (s390x) - Online all memory to ZONE_NORMAL (e.g., most virt environments like hyperv) - Online all memory to ZONE_MOVABLE in case the zone imbalance is taken care of (e.g., bare metal, special virt environments) In summary: All memory is usually onlined the same way, however, the kernel always has to ask user space to come up with the same answer. E.g., Hyper-V always waits for a memory block to get onlined before continuing, otherwise it might end up adding memory faster than onlining it, which can result in strange OOM situations. This waiting slows down adding of a bigger amount of memory. Let's allow to specify a default online_type, not just "online" and "offline". This allows distributions to configure the default online_type when booting up and be done with it. We can now specify "offline", "online", "online_movable" and "online_kernel" via - "memhp_default_state=" on the kernel cmdline - /sys/devices/system/memory/auto_online_blocks just like we are able to specify for a single memory block via /sys/devices/system/memory/memoryX/state Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Wei Yang Reviewed-by: Baoquan He Acked-by: Michal Hocko Acked-by: Pankaj Gupta Cc: Greg Kroah-Hartman Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Wei Yang Cc: Benjamin Herrenschmidt Cc: Eduardo Habkost Cc: Haiyang Zhang Cc: Igor Mammedov Cc: "K. Y. Srinivasan" Cc: Michael Ellerman Cc: Paul Mackerras Cc: Stephen Hemminger Cc: Vitaly Kuznetsov Cc: Wei Liu Cc: Yumei Huang Link: http://lkml.kernel.org/r/20200317104942.11178-9-david@redhat.com Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'mm') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 9436f7e6257a..2fb78c5ebaf3 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -74,10 +74,10 @@ int memhp_default_online_type = MMOP_ONLINE; static int __init setup_memhp_default_state(char *str) { - if (!strcmp(str, "online")) - memhp_default_online_type = MMOP_ONLINE; - else if (!strcmp(str, "offline")) - memhp_default_online_type = MMOP_OFFLINE; + const int online_type = memhp_online_type_from_str(str); + + if (online_type >= 0) + memhp_default_online_type = online_type; return 1; } -- cgit v1.2.3