mm: remove CONFIG_DISCONTIGMEM

There are no architectures that support DISCONTIGMEM left.

Remove the configuration option and the dead code it was guarding in the
generic memory management code.

Link: https://lkml.kernel.org/r/20210608091316.3622-6-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index 7637fb4..a2c8ed6 100644 (file)
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -6,47 +6,18 @@
 
 #ifndef __ASSEMBLY__
 
+/*
+ * supports 3 memory models.
+ */
 #if defined(CONFIG_FLATMEM)
 
 #ifndef ARCH_PFN_OFFSET
 #define ARCH_PFN_OFFSET                (0UL)
 #endif
 
-#elif defined(CONFIG_DISCONTIGMEM)
-
-#ifndef arch_pfn_to_nid
-#define arch_pfn_to_nid(pfn)   pfn_to_nid(pfn)
-#endif
-
-#ifndef arch_local_page_offset
-#define arch_local_page_offset(pfn, nid)       \
-       ((pfn) - NODE_DATA(nid)->node_start_pfn)
-#endif
-
-#endif /* CONFIG_DISCONTIGMEM */
-
-/*
- * supports 3 memory models.
- */
-#if defined(CONFIG_FLATMEM)
-
 #define __pfn_to_page(pfn)     (mem_map + ((pfn) - ARCH_PFN_OFFSET))
 #define __page_to_pfn(page)    ((unsigned long)((page) - mem_map) + \
                                 ARCH_PFN_OFFSET)
-#elif defined(CONFIG_DISCONTIGMEM)
-
-#define __pfn_to_page(pfn)                     \
-({     unsigned long __pfn = (pfn);            \
-       unsigned long __nid = arch_pfn_to_nid(__pfn);  \
-       NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
-})
-
-#define __page_to_pfn(pg)                                              \
-({     const struct page *__pg = (pg);                                 \
-       struct pglist_data *__pgdat = NODE_DATA(page_to_nid(__pg));     \
-       (unsigned long)(__pg - __pgdat->node_mem_map) +                 \
-        __pgdat->node_start_pfn;                                       \
-})
 
 #elif defined(CONFIG_SPARSEMEM_VMEMMAP)
 
@@ -70,7 +41,7 @@
        struct mem_section *__sec = __pfn_to_section(__pfn);    \
        __section_mem_map_addr(__sec) + __pfn;          \
 })
-#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
+#endif /* CONFIG_FLATMEM/SPARSEMEM */
 
 /*
  * Convert a physical address to a Page Frame Number and back

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3e62e8e..6f98295 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -749,10 +749,12 @@ struct zonelist {
        struct zoneref _zonerefs[MAX_ZONES_PER_ZONELIST + 1];
 };
 
-#ifndef CONFIG_DISCONTIGMEM
-/* The array of struct pages - for discontigmem use pgdat->lmem_map */
+/*
+ * The array of struct pages for flatmem.
+ * It must be declared for SPARSEMEM as well because there are configurations
+ * that rely on that.
+ */
 extern struct page *mem_map;
-#endif
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 struct deferred_split {

diff --git a/mm/Kconfig b/mm/Kconfig
index 02d44e3..218b96c 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -19,7 +19,7 @@ choice
 
 config FLATMEM_MANUAL
        bool "Flat Memory"
-       depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
+       depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
        help
          This option is best suited for non-NUMA systems with
          flat address space. The FLATMEM is the most efficient
@@ -32,21 +32,6 @@ config FLATMEM_MANUAL
 
          If unsure, choose this option (Flat Memory) over any other.
 
-config DISCONTIGMEM_MANUAL
-       bool "Discontiguous Memory"
-       depends on ARCH_DISCONTIGMEM_ENABLE
-       help
-         This option provides enhanced support for discontiguous
-         memory systems, over FLATMEM.  These systems have holes
-         in their physical address spaces, and this option provides
-         more efficient handling of these holes.
-
-         Although "Discontiguous Memory" is still used by several
-         architectures, it is considered deprecated in favor of
-         "Sparse Memory".
-
-         If unsure, choose "Sparse Memory" over this option.
-
 config SPARSEMEM_MANUAL
        bool "Sparse Memory"
        depends on ARCH_SPARSEMEM_ENABLE
@@ -62,17 +47,13 @@ config SPARSEMEM_MANUAL
 
 endchoice
 
-config DISCONTIGMEM
-       def_bool y
-       depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
-
 config SPARSEMEM
        def_bool y
        depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 
 config FLATMEM
        def_bool y
-       depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
+       depends on !SPARSEMEM || FLATMEM_MANUAL
 
 config FLAT_NODE_MEM_MAP
        def_bool y
@@ -85,7 +66,7 @@ config FLAT_NODE_MEM_MAP
 #
 config NEED_MULTIPLE_NODES
        def_bool y
-       depends on DISCONTIGMEM || NUMA
+       depends on NUMA
 
 #
 # SPARSEMEM_EXTREME (which is the default) does some bootmem

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 58f7a32..8926f3f 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -349,20 +349,7 @@ compound_page_dtor * const compound_page_dtors[NR_COMPOUND_DTORS] = {
 
 int min_free_kbytes = 1024;
 int user_min_free_kbytes = -1;
-#ifdef CONFIG_DISCONTIGMEM
-/*
- * DiscontigMem defines memory ranges as separate pg_data_t even if the ranges
- * are not on separate NUMA nodes. Functionally this works but with
- * watermark_boost_factor, it can reclaim prematurely as the ranges can be
- * quite small. By default, do not boost watermarks on discontigmem as in
- * many cases very high-order allocations like THP are likely to be
- * unsupported and the premature reclaim offsets the advantage of long-term
- * fragmentation avoidance.
- */
-int watermark_boost_factor __read_mostly;
-#else
 int watermark_boost_factor __read_mostly = 15000;
-#endif
 int watermark_scale_factor = 10;
 
 static unsigned long nr_kernel_pages __initdata;