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authorDan Williams <dan.j.williams@intel.com>2015-08-09 15:29:06 -0400
committerDan Williams <dan.j.williams@intel.com>2015-08-27 19:40:58 -0400
commit033fbae988fcb67e5077203512181890848b8e90 (patch)
treed0b9e418ab4f1df15435c098edf5ad687b426b3f /mm/memory_hotplug.c
parent012dcef3f058385268630c0003e9b7f8dcafbeb4 (diff)
downloadop-kernel-dev-033fbae988fcb67e5077203512181890848b8e90.zip
op-kernel-dev-033fbae988fcb67e5077203512181890848b8e90.tar.gz
mm: ZONE_DEVICE for "device memory"
While pmem is usable as a block device or via DAX mappings to userspace there are several usage scenarios that can not target pmem due to its lack of struct page coverage. In preparation for "hot plugging" pmem into the vmemmap add ZONE_DEVICE as a new zone to tag these pages separately from the ones that are subject to standard page allocations. Importantly "device memory" can be removed at will by userspace unbinding the driver of the device. Having a separate zone prevents allocation and otherwise marks these pages that are distinct from typical uniform memory. Device memory has different lifetime and performance characteristics than RAM. However, since we have run out of ZONES_SHIFT bits this functionality currently depends on sacrificing ZONE_DMA. Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Jerome Glisse <j.glisse@gmail.com> [hch: various simplifications in the arch interface] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'mm/memory_hotplug.c')
-rw-r--r--mm/memory_hotplug.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 26fbba7..24e4c76 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -770,7 +770,10 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
start = phys_start_pfn << PAGE_SHIFT;
size = nr_pages * PAGE_SIZE;
- ret = release_mem_region_adjustable(&iomem_resource, start, size);
+
+ /* in the ZONE_DEVICE case device driver owns the memory region */
+ if (!is_dev_zone(zone))
+ ret = release_mem_region_adjustable(&iomem_resource, start, size);
if (ret) {
resource_size_t endres = start + size - 1;
@@ -1207,8 +1210,13 @@ static int should_add_memory_movable(int nid, u64 start, u64 size)
return 0;
}
-int zone_for_memory(int nid, u64 start, u64 size, int zone_default)
+int zone_for_memory(int nid, u64 start, u64 size, int zone_default,
+ bool for_device)
{
+#ifdef CONFIG_ZONE_DEVICE
+ if (for_device)
+ return ZONE_DEVICE;
+#endif
if (should_add_memory_movable(nid, start, size))
return ZONE_MOVABLE;
@@ -1249,7 +1257,7 @@ int __ref add_memory(int nid, u64 start, u64 size)
}
/* call arch's memory hotadd */
- ret = arch_add_memory(nid, start, size);
+ ret = arch_add_memory(nid, start, size, false);
if (ret < 0)
goto error;
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