From: David Hildenbrand david@redhat.com
[ 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 --- .../platforms/pseries/hotplug-memory.c | 2 +- drivers/acpi/acpi_memhotplug.c | 2 +- drivers/base/memory.c | 9 ++++++-- drivers/xen/balloon.c | 3 +++ include/linux/memory_hotplug.h | 1 + mm/memory_hotplug.c | 22 ++++++++++++++++--- 6 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c index 1d48ab424bd9..c197ea8dde01 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -784,7 +784,7 @@ 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); return rc; diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c index 6b0d3ef7309c..2ccfbb61ca89 100644 --- 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 1d60b58a8c19..9a9aebb4bd19 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -517,15 +517,20 @@ 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 065f0b607373..6e39a0c10f93 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -401,7 +401,10 @@ 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 58e110aee7ab..d36a02935391 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -316,6 +316,7 @@ 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 arch_add_memory(int nid, u64 start, u64 size, bool want_memblock); diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index d4b5f29906b9..dc60f2f27389 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1109,7 +1109,12 @@ static int online_memory_block(struct memory_block *mem, void *arg) return device_online(&mem->dev); }
-/* 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; @@ -1202,9 +1207,9 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online) 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; @@ -1218,6 +1223,17 @@ 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