Re: [PATCH v1 5/5] mm/memory_hotplug: allow to specify a default online_type
From: Wei Yang <hidden>
Date: 2020-03-11 14:26:38
Also in:
linux-hyperv, linux-mm, lkml
On Wed, Mar 11, 2020 at 01:30:26PM +0100, David Hildenbrand wrote:
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 userspace to come up with the same answer. E.g., HyperV always waits for a memory block to get onlined before continuing, otherwise it might end up adding memory faster than hotplugging it, which can result in strange OOM situations. 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/systemn/memory/auto_online_blocks just like we are able to specify for a single memory block via /sys/devices/systemn/memory/memoryX/state Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Baoquan He <bhe@redhat.com> Cc: Wei Yang <redacted> Signed-off-by: David Hildenbrand <redacted>
Ok, I got the reason to leave the change on string compare here. Reviewed-by: Wei Yang <redacted>
quoted hunk ↗ jump to hunk
--- drivers/base/memory.c | 11 +++++------ include/linux/memory_hotplug.h | 2 ++ mm/memory_hotplug.c | 8 ++++---- 3 files changed, 11 insertions(+), 10 deletions(-)diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 8d3e16dab69f..2b09b68b9f78 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c@@ -35,7 +35,7 @@ static const char *const online_type_to_str[] = {[MMOP_ONLINE_MOVABLE] = "online_movable", }; -static int memhp_online_type_from_str(const char *str) +int memhp_online_type_from_str(const char *str) { int i;@@ -394,13 +394,12 @@ static ssize_t auto_online_blocks_store(struct device *dev,struct device_attribute *attr, const char *buf, size_t count) { - if (sysfs_streq(buf, "online")) - memhp_default_online_type = MMOP_ONLINE; - else if (sysfs_streq(buf, "offline")) - memhp_default_online_type = MMOP_OFFLINE; - else + const int online_type = memhp_online_type_from_str(buf); + + if (online_type < 0) return -EINVAL; + memhp_default_online_type = online_type; return count; }diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index c6e090b34c4b..ef55115320fb 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h@@ -117,6 +117,8 @@ extern int arch_add_memory(int nid, u64 start, u64 size,struct mhp_restrictions *restrictions); extern u64 max_mem_size; +extern int memhp_online_type_from_str(const char *str); + /* Default online_type (MMOP_*) when new memory blocks are added. */ extern int memhp_default_online_type; /* If movable_node boot option specified */diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 01443c70aa27..4a96273eafa7 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c@@ -75,10 +75,10 @@ EXPORT_SYMBOL_GPL(memhp_default_online_type);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; } -- 2.24.1
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