The patch titled
Subject: mm/memory-hotplug: add sysfs hot-remove trigger
has been added to the -mm tree. Its filename is
mm-memory-hotplug-add-sysfs-hot-remove-trigger.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory-hotplug-add-sysfs-hot-remove-trigger.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory-hotplug-add-sysfs-hot-remove-trigger.patch
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------------------------------------------------------
From: Robin Murphy <robin.murphy@xxxxxxx>
Subject: mm/memory-hotplug: add sysfs hot-remove trigger
ARCH_MEMORY_PROBE is a useful thing for testing and debugging hotplug, but
being able to exercise the (arguably trickier) hot-remove path would be
even more useful. Extend the feature to allow removal of offline sections
to be triggered manually to aid development.
Since process dictates the new sysfs entry be documented, let's also
document the existing probe entry to match - better 13-and-a-half years
late than never, as they say...
Link: http://lkml.kernel.org/r/49ef5e6c12f5ede189419d4dcced5dc04957c34d.1549906631.git.robin.murphy@xxxxxxx
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-devices-memory | 25 ++++++++
drivers/base/memory.c | 42 ++++++++++++++-
2 files changed, 66 insertions(+), 1 deletion(-)
--- a/Documentation/ABI/testing/sysfs-devices-memory~mm-memory-hotplug-add-sysfs-hot-remove-trigger
+++ a/Documentation/ABI/testing/sysfs-devices-memory
@@ -91,3 +91,28 @@ Description:
memory section directory. For example, the following symbolic
link is created for memory section 9 on node0.
/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
+
+What: /sys/devices/system/memory/probe
+Date: October 2005
+Contact: Linux Memory Management list <linux-mm@xxxxxxxxx>
+Description:
+ The file /sys/devices/system/memory/probe is write-only, and
+ when written will simulate a physical hot-add of a memory
+ section at the given address. For example, assuming a section
+ of unused memory exists at physical address 0x80000000, it can
+ be introduced to the kernel with the following command:
+ # echo 0x80000000 > /sys/devices/system/memory/probe
+Users: Memory hotplug testing and development
+
+What: /sys/devices/system/memory/memoryX/remove
+Date: February 2019
+Contact: Linux Memory Management list <linux-mm@xxxxxxxxx>
+Description:
+ The file /sys/devices/system/memory/memoryX/remove is
+ write-only, and when written with a boolean 'true' value will
+ simulate a physical hot-remove of that memory section. For
+ example, assuming a 1GB section size, the section added by the
+ above "probe" example could be removed again with the following
+ command:
+ # echo 1 > /sys/devices/system/memory/memory2/remove
+Users: Memory hotplug testing and development
--- a/drivers/base/memory.c~mm-memory-hotplug-add-sysfs-hot-remove-trigger
+++ a/drivers/base/memory.c
@@ -521,7 +521,44 @@ out:
}
static DEVICE_ATTR_WO(probe);
-#endif
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct memory_block *mem = to_memory_block(dev);
+ unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
+ bool remove;
+ int ret;
+
+ ret = kstrtobool(buf, &remove);
+ if (ret)
+ return ret;
+ if (!remove)
+ return count;
+
+ if (!is_memblock_offlined(mem))
+ return -EBUSY;
+
+ ret = lock_device_hotplug_sysfs();
+ if (ret)
+ return ret;
+
+ if (device_remove_file_self(dev, attr)) {
+ __remove_memory(pfn_to_nid(start_pfn), PFN_PHYS(start_pfn),
+ MIN_MEMORY_BLOCK_SIZE * sections_per_block);
+ ret = count;
+ } else {
+ ret = -EBUSY;
+ }
+
+ unlock_device_hotplug();
+ return ret;
+}
+
+static DEVICE_ATTR_WO(remove);
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_ARCH_MEMORY_PROBE */
#ifdef CONFIG_MEMORY_FAILURE
/*
@@ -615,6 +652,9 @@ static struct attribute *memory_memblk_a
&dev_attr_removable.attr,
#ifdef CONFIG_MEMORY_HOTREMOVE
&dev_attr_valid_zones.attr,
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+ &dev_attr_remove.attr,
+#endif
#endif
NULL
};
_
Patches currently in -mm which might be from robin.murphy@xxxxxxx are
mm-memory-hotplug-add-sysfs-hot-remove-trigger.patch
