From 033fbae988fcb67e5077203512181890848b8e90 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sun, 9 Aug 2015 15:29:06 -0400 Subject: 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 Cc: Ingo Molnar Cc: Dave Hansen Cc: Rik van Riel Cc: Mel Gorman Cc: Jerome Glisse [hch: various simplifications in the arch interface] Signed-off-by: Christoph Hellwig Signed-off-by: Dan Williams --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ef19f22b2b7d..0f19b4e18233 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -207,6 +207,9 @@ static char * const zone_names[MAX_NR_ZONES] = { "HighMem", #endif "Movable", +#ifdef CONFIG_ZONE_DEVICE + "Device", +#endif }; int min_free_kbytes = 1024; -- cgit v1.2.3