From 31bc3858ea3ebcc3157b3f5f0e624c5962f5a7a6 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 15 Mar 2016 14:56:48 -0700 Subject: memory-hotplug: add automatic onlining policy for the newly added memory Currently, all newly added memory blocks remain in 'offline' state unless someone onlines them, some linux distributions carry special udev rules like: SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online" to make this happen automatically. This is not a great solution for virtual machines where memory hotplug is being used to address high memory pressure situations as such onlining is slow and a userspace process doing this (udev) has a chance of being killed by the OOM killer as it will probably require to allocate some memory. Introduce default policy for the newly added memory blocks in /sys/devices/system/memory/auto_online_blocks file with two possible values: "offline" which preserves the current behavior and "online" which causes all newly added memory blocks to go online as soon as they're added. The default is "offline". Signed-off-by: Vitaly Kuznetsov Reviewed-by: Daniel Kiper Cc: Jonathan Corbet Cc: Greg Kroah-Hartman Cc: Daniel Kiper Cc: Dan Williams Cc: Tang Chen Cc: David Vrabel Acked-by: David Rientjes Cc: Naoya Horiguchi Cc: Xishi Qiu Cc: Mel Gorman Cc: "K. Y. Srinivasan" Cc: Igor Mammedov Cc: Kay Sievers Cc: Konrad Rzeszutek Wilk Cc: Boris Ostrovsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/base/memory.c | 34 +++++++++++++++++++++++++++++++++- drivers/xen/balloon.c | 2 +- 2 files changed, 34 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 213456c2b123..f46dba8b7092 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -251,7 +251,7 @@ memory_block_action(unsigned long phys_index, unsigned long action, int online_t return ret; } -static int memory_block_change_state(struct memory_block *mem, +int memory_block_change_state(struct memory_block *mem, unsigned long to_state, unsigned long from_state_req) { int ret = 0; @@ -438,6 +438,37 @@ print_block_size(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL); +/* + * Memory auto online policy. + */ + +static ssize_t +show_auto_online_blocks(struct device *dev, struct device_attribute *attr, + char *buf) +{ + if (memhp_auto_online) + return sprintf(buf, "online\n"); + else + return sprintf(buf, "offline\n"); +} + +static ssize_t +store_auto_online_blocks(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + if (sysfs_streq(buf, "online")) + memhp_auto_online = true; + else if (sysfs_streq(buf, "offline")) + memhp_auto_online = false; + else + return -EINVAL; + + return count; +} + +static DEVICE_ATTR(auto_online_blocks, 0644, show_auto_online_blocks, + store_auto_online_blocks); + /* * Some architectures will have custom drivers to do this, and * will not need to do it from userspace. The fake hot-add code @@ -746,6 +777,7 @@ static struct attribute *memory_root_attrs[] = { #endif &dev_attr_block_size_bytes.attr, + &dev_attr_auto_online_blocks.attr, NULL }; diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index dc4305b407bf..e6058debd01b 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -338,7 +338,7 @@ static enum bp_state reserve_additional_memory(void) } #endif - rc = add_memory_resource(nid, resource); + rc = add_memory_resource(nid, resource, false); if (rc) { pr_warn("Cannot add additional memory (%i)\n", rc); goto err; -- cgit 1.4.1