| Message ID | 20180918114822.21926-3-david@redhat.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | mm: online/offline_pages called w.o. mem_hotplug_lock | expand |
On Tue, Sep 18, 2018 at 1:48 PM David Hildenbrand <david@redhat.com> wrote: > > 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). > > 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: Andrew Morton <akpm@linux-foundation.org> > 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: Oscar Salvador <osalvador@suse.de> > Cc: Mathieu Malaterre <malat@debian.org> > Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> > Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com> > Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > .../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 b3f54466e25f..2e6f41dc103a 100644 > --- a/arch/powerpc/platforms/pseries/hotplug-memory.c > +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c > @@ -702,7 +702,7 @@ static int dlpar_add_lmb(struct drmem_lmb *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 811148415993..8fe0960ea572 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 817320c7c4c1..40cac122ec73 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -519,15 +519,20 @@ 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 e12bb256036f..6bab019a82b1 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -395,7 +395,10 @@ 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 1f096852f479..ffd9cd10fcf3 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -324,6 +324,7 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {} > extern void __ref free_area_init_core_hotplug(int nid); > 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, > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index b8b1bd970322..ef5444145c88 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1111,7 +1111,12 @@ 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; > @@ -1180,9 +1185,9 @@ 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; > @@ -1196,6 +1201,17 @@ 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 > -- Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c index b3f54466e25f..2e6f41dc103a 100644 --- a/arch/powerpc/platforms/pseries/hotplug-memory.c +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c @@ -702,7 +702,7 @@ static int dlpar_add_lmb(struct drmem_lmb *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 811148415993..8fe0960ea572 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 817320c7c4c1..40cac122ec73 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -519,15 +519,20 @@ 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 e12bb256036f..6bab019a82b1 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -395,7 +395,10 @@ 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 1f096852f479..ffd9cd10fcf3 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -324,6 +324,7 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {} extern void __ref free_area_init_core_hotplug(int nid); 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, diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index b8b1bd970322..ef5444145c88 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1111,7 +1111,12 @@ 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; @@ -1180,9 +1185,9 @@ 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; @@ -1196,6 +1201,17 @@ 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
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). 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: Andrew Morton <akpm@linux-foundation.org> 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: Oscar Salvador <osalvador@suse.de> Cc: Mathieu Malaterre <malat@debian.org> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com> Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- .../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(-)