mm/memory_hotplug: make add_memory() take the device_hotplug_lock

[ Upstream commit 8df1d0e4a265f25dc1e7e7624ccdbcb4a6630c89 ]

add_memory() currently does not take the device_hotplug_lock, however
is aleady called under the lock from
	arch/powerpc/platforms/pseries/hotplug-memory.c
	drivers/acpi/acpi_memhotplug.c
to synchronize against CPU hot-remove and similar.

In general, we should hold the device_hotplug_lock when adding memory to
synchronize against online/offline request (e.g.  from user space) - which
already resulted in lock inversions due to device_lock() and
mem_hotplug_lock - see 30467e0b3be ("mm, hotplug: fix concurrent memory
hot-add deadlock").  add_memory()/add_memory_resource() will create memory
block devices, so this really feels like the right thing to do.

Holding the device_hotplug_lock makes sure that a memory block device
can really only be accessed (e.g. via .online/.state) from user space,
once the memory has been fully added to the system.

The lock is not held yet in
	drivers/xen/balloon.c
	arch/powerpc/platforms/powernv/memtrace.c
	drivers/s390/char/sclp_cmd.c
	drivers/hv/hv_balloon.c
So, let's either use the locked variants or take the lock.

Don't export add_memory_resource(), as it once was exported to be used by
XEN, which is never built as a module.  If somebody requires it, we also
have to export a locked variant (as device_hotplug_lock is never
exported).

Link: http://lkml.kernel.org/r/20180925091457.28651-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mathieu Malaterre <malat@debian.org>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index c0a0947f43bbb71cdc8f5c09e4255659c9149679..656bbbd731d03b7eddb7cb75285c0238661a7c5e 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -616,7 +616,7 @@ static int dlpar_add_lmb(struct of_drconf_cell *lmb)
        nid = memory_add_physaddr_to_nid(lmb->base_addr);
 
        /* Add the memory */
-       rc = add_memory(nid, lmb->base_addr, block_sz);
+       rc = __add_memory(nid, lmb->base_addr, block_sz);
        if (rc) {
                dlpar_remove_device_tree_lmb(lmb);
                dlpar_release_drc(lmb->drc_index);

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 6b0d3ef7309cb710a63b38848ad35b770fed3c1a..2ccfbb61ca89987d67d68da320251ba291a6982b 100644 (file)
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -228,7 +228,7 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
                if (node < 0)
                        node = memory_add_physaddr_to_nid(info->start_addr);
 
-               result = add_memory(node, info->start_addr, info->length);
+               result = __add_memory(node, info->start_addr, info->length);
 
                /*
                 * If the memory block has been used by the kernel, add_memory()

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index c5cdd190b7816ce446d6d7b06235c5f995c4c3f2..9f96f1b43c15fee32258b84d67a21312096bb675 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -500,15 +500,20 @@ memory_probe_store(struct device *dev, struct device_attribute *attr,
        if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
                return -EINVAL;
 
+       ret = lock_device_hotplug_sysfs();
+       if (ret)
+               goto out;
+
        nid = memory_add_physaddr_to_nid(phys_addr);
-       ret = add_memory(nid, phys_addr,
-                        MIN_MEMORY_BLOCK_SIZE * sections_per_block);
+       ret = __add_memory(nid, phys_addr,
+                          MIN_MEMORY_BLOCK_SIZE * sections_per_block);
 
        if (ret)
                goto out;
 
        ret = count;
 out:
+       unlock_device_hotplug();
        return ret;
 }
 

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 6af117af978041d9ec2438df5829f6f4e9012993..731cf54f75c6585b40d28b8d398187a00ced2d2c 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -358,7 +358,10 @@ static enum bp_state reserve_additional_memory(void)
         * callers drop the mutex before trying again.
         */
        mutex_unlock(&balloon_mutex);
+       /* add_memory_resource() requires the device_hotplug lock */
+       lock_device_hotplug();
        rc = add_memory_resource(nid, resource, memhp_auto_online);
+       unlock_device_hotplug();
        mutex_lock(&balloon_mutex);
 
        if (rc) {

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 134a2f69c21abf7921181af0adff033bb459edc5..9469eef300952cb0956a2d9f6a6dbe2816d5fe7b 100644 (file)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -272,6 +272,7 @@ static inline void remove_memory(int nid, u64 start, u64 size) {}
 
 extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
                void *arg, int (*func)(struct memory_block *, void *));
+extern int __add_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
 extern int add_memory_resource(int nid, struct resource *resource, bool online);
 extern int zone_for_memory(int nid, u64 start, u64 size, int zone_default,

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b4c8d7b9ab820f61cf5d5c6080119cb90d2c9d94..449999657c0bb3bb370dbe7070b481d60ccd8a1f 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1340,7 +1340,12 @@ static int online_memory_block(struct memory_block *mem, void *arg)
        return memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 }
 
-/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
+/*
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations (triggered e.g. by sysfs).
+ *
+ * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
+ */
 int __ref add_memory_resource(int nid, struct resource *res, bool online)
 {
        u64 start, size;
@@ -1418,9 +1423,9 @@ out:
        mem_hotplug_done();
        return ret;
 }
-EXPORT_SYMBOL_GPL(add_memory_resource);
 
-int __ref add_memory(int nid, u64 start, u64 size)
+/* requires device_hotplug_lock, see add_memory_resource() */
+int __ref __add_memory(int nid, u64 start, u64 size)
 {
        struct resource *res;
        int ret;
@@ -1434,6 +1439,17 @@ int __ref add_memory(int nid, u64 start, u64 size)
                release_memory_resource(res);
        return ret;
 }
+
+int add_memory(int nid, u64 start, u64 size)
+{
+       int rc;
+
+       lock_device_hotplug();
+       rc = __add_memory(nid, start, size);
+       unlock_device_hotplug();
+
+       return rc;
+}
 EXPORT_SYMBOL_GPL(add_memory);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE