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authorDavid Hildenbrand <david@redhat.com>2020-10-16 06:08:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-16 21:11:18 +0300
commit9ca6551ee24368a4d2b09566ea4d10fe87860379 (patch)
tree20c9b1243ffac81a6d13a6a919f0f2ad8da74f8f /mm
parentb6117199787c60539105d2de0d010146e8396fc3 (diff)
downloadlinux-9ca6551ee24368a4d2b09566ea4d10fe87860379.tar.xz
mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System RAM resources
Some add_memory*() users add memory in small, contiguous memory blocks. Examples include virtio-mem, hyper-v balloon, and the XEN balloon. This can quickly result in a lot of memory resources, whereby the actual resource boundaries are not of interest (e.g., it might be relevant for DIMMs, exposed via /proc/iomem to user space). We really want to merge added resources in this scenario where possible. Let's provide a flag (MEMHP_MERGE_RESOURCE) to specify that a resource either created within add_memory*() or passed via add_memory_resource() shall be marked mergeable and merged with applicable siblings. To implement that, we need a kernel/resource interface to mark selected System RAM resources mergeable (IORESOURCE_SYSRAM_MERGEABLE) and trigger merging. Note: We really want to merge after the whole operation succeeded, not directly when adding a resource to the resource tree (it would break add_memory_resource() and require splitting resources again when the operation failed - e.g., due to -ENOMEM). Signed-off-by: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kees Cook <keescook@chromium.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Wei Liu <wei.liu@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Roger Pau Monné <roger.pau@citrix.com> Cc: Julien Grall <julien@xen.org> Cc: Baoquan He <bhe@redhat.com> Cc: Wei Yang <richardw.yang@linux.intel.com> Cc: Anton Blanchard <anton@ozlabs.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Leonardo Bras <leobras.c@gmail.com> Cc: Libor Pechacek <lpechacek@suse.cz> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: "Oliver O'Halloran" <oohall@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Link: https://lkml.kernel.org/r/20200911103459.10306-6-david@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory_hotplug.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dba71bc34daa..dc7d82ece6cb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1103,6 +1103,13 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
/* device_online() will take the lock when calling online_pages() */
mem_hotplug_done();
+ /*
+ * In case we're allowed to merge the resource, flag it and trigger
+ * merging now that adding succeeded.
+ */
+ if (mhp_flags & MEMHP_MERGE_RESOURCE)
+ merge_system_ram_resource(res);
+
/* online pages if requested */
if (memhp_default_online_type != MMOP_OFFLINE)
walk_memory_blocks(start, size, NULL, online_memory_block);