]> git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - include/linux/page-flags-layout.h
Merge tag 'gfs2-4.7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2...
[mirror_ubuntu-zesty-kernel.git] / include / linux / page-flags-layout.h
1 #ifndef PAGE_FLAGS_LAYOUT_H
2 #define PAGE_FLAGS_LAYOUT_H
3
4 #include <linux/numa.h>
5 #include <generated/bounds.h>
6
7 /*
8 * When a memory allocation must conform to specific limitations (such
9 * as being suitable for DMA) the caller will pass in hints to the
10 * allocator in the gfp_mask, in the zone modifier bits. These bits
11 * are used to select a priority ordered list of memory zones which
12 * match the requested limits. See gfp_zone() in include/linux/gfp.h
13 */
14 #if MAX_NR_ZONES < 2
15 #define ZONES_SHIFT 0
16 #elif MAX_NR_ZONES <= 2
17 #define ZONES_SHIFT 1
18 #elif MAX_NR_ZONES <= 4
19 #define ZONES_SHIFT 2
20 #elif MAX_NR_ZONES <= 8
21 #define ZONES_SHIFT 3
22 #else
23 #error ZONES_SHIFT -- too many zones configured adjust calculation
24 #endif
25
26 #ifdef CONFIG_SPARSEMEM
27 #include <asm/sparsemem.h>
28
29 /* SECTION_SHIFT #bits space required to store a section # */
30 #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
31
32 #endif /* CONFIG_SPARSEMEM */
33
34 /*
35 * page->flags layout:
36 *
37 * There are five possibilities for how page->flags get laid out. The first
38 * pair is for the normal case without sparsemem. The second pair is for
39 * sparsemem when there is plenty of space for node and section information.
40 * The last is when there is insufficient space in page->flags and a separate
41 * lookup is necessary.
42 *
43 * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS |
44 * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS |
45 * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS |
46 * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS |
47 * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS |
48 */
49 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
50 #define SECTIONS_WIDTH SECTIONS_SHIFT
51 #else
52 #define SECTIONS_WIDTH 0
53 #endif
54
55 #define ZONES_WIDTH ZONES_SHIFT
56
57 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
58 #define NODES_WIDTH NODES_SHIFT
59 #else
60 #ifdef CONFIG_SPARSEMEM_VMEMMAP
61 #error "Vmemmap: No space for nodes field in page flags"
62 #endif
63 #define NODES_WIDTH 0
64 #endif
65
66 #ifdef CONFIG_NUMA_BALANCING
67 #define LAST__PID_SHIFT 8
68 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1)
69
70 #define LAST__CPU_SHIFT NR_CPUS_BITS
71 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1)
72
73 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT)
74 #else
75 #define LAST_CPUPID_SHIFT 0
76 #endif
77
78 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
79 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
80 #else
81 #define LAST_CPUPID_WIDTH 0
82 #endif
83
84 /*
85 * We are going to use the flags for the page to node mapping if its in
86 * there. This includes the case where there is no node, so it is implicit.
87 */
88 #if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
89 #define NODE_NOT_IN_PAGE_FLAGS
90 #endif
91
92 #if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
93 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS
94 #endif
95
96 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */