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Commit 6fb8f7ac authored by Andrea Reale's avatar Andrea Reale Committed by Sudarshan Rajagopalan
Browse files

arm64: Add "remove" probe driver for memory hot-remove 



Allows to remove sections of memory that have been previously offlined
from userspace.

This is symmetric to the "memory probe" interface, as described in
Documentation/memory-hotplug.txt. It can be used to manually notify the
OS that one memory section has been removed.

Please, remind that a memory section can only be removed after it has
been logically off-lined; trying to remove a section which has not been
previously off-lined is not supported and will have undefined (but most
likely very bad) behaviour.

To offline a section one can:

To use the remove interface to remove the section:

where 0xYYYYYY is the physical address of the memory section to remove.

Change-Id: I1ab2fafe17b2697a5c667feae25c4ac0655f394e
Signed-off-by: default avatarAndrea Reale <ar@linux.vnet.ibm.com>
Signed-off-by: default avatarMaciej Bielski <m.bielski@virtualopensystems.com>
Patch-mainline: linux-kernel @ 11 Apr 2017, 18:25
Signed-off-by: default avatarSrivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: default avatarSudarshan Rajagopalan <sudaraja@codeaurora.org>
parent 99b02db2

drivers/base/memory.c

+33 −1
Original line number Diff line number Diff line
@@ -530,7 +530,36 @@ memory_probe_store(struct device *dev, struct device_attribute *attr, 
}



static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);

#endif



#ifdef CONFIG_MEMORY_HOTREMOVE

static ssize_t

memory_remove_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t count)

{

	u64 phys_addr;

	int nid, ret;

	unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;



	ret = kstrtoull(buf, 0, &phys_addr);

	if (ret)

		return ret;



	if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))

		return -EINVAL;



	nid = memory_add_physaddr_to_nid(phys_addr);

	ret = lock_device_hotplug_sysfs();

	if (ret)

		return ret;



	remove_memory(nid, phys_addr,

			 MIN_MEMORY_BLOCK_SIZE * sections_per_block);

	unlock_device_hotplug();

	return count;

}

static DEVICE_ATTR(remove, S_IWUSR, NULL, memory_remove_store);

#endif /* CONFIG_MEMORY_HOTREMOVE */

#endif /* CONFIG_ARCH_MEMORY_PROBE */



#ifdef CONFIG_MEMORY_FAILURE

/*
@@ -790,6 +819,9 @@ bool is_memblock_offlined(struct memory_block *mem) 
static struct attribute *memory_root_attrs[] = {

#ifdef CONFIG_ARCH_MEMORY_PROBE

	&dev_attr_probe.attr,

#ifdef CONFIG_MEMORY_HOTREMOVE

	&dev_attr_remove.attr,

#endif

#endif



#ifdef CONFIG_MEMORY_FAILURE