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authorYang Shi <yang.shi@linaro.org>2016-05-26 15:16:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-26 15:35:44 -0700
commit957949243bac5dc25e2a651f17059f54f184913e (patch)
treee8848b501570ca042a5a2a88b5a318c655260da6
parent50755bc1c305340660bbfa65fdae3ed113d8fe0e (diff)
downloadlinux-957949243bac5dc25e2a651f17059f54f184913e.tar.bz2
mm: make CONFIG_DEFERRED_STRUCT_PAGE_INIT depends on !FLATMEM explicitly
Per the suggestion from Michal Hocko [1], DEFERRED_STRUCT_PAGE_INIT requires some ordering wrt other initialization operations, e.g. page_ext_init has to happen after the whole memmap is initialized properly. For SPARSEMEM this requires to wait for page_alloc_init_late. Other memory models (e.g. flatmem) might have different initialization layouts (page_ext_init_flatmem). Currently DEFERRED_STRUCT_PAGE_INIT depends on MEMORY_HOTPLUG which in turn depends on SPARSEMEM || X86_64_ACPI_NUMA depends on ARCH_ENABLE_MEMORY_HOTPLUG and X86_64_ACPI_NUMA depends on NUMA which in turn disable FLATMEM memory model: config ARCH_FLATMEM_ENABLE def_bool y depends on X86_32 && !NUMA so FLATMEM is ruled out via dependency maze. Be explicit and disable FLATMEM for DEFERRED_STRUCT_PAGE_INIT so that we do not reintroduce subtle initialization bugs [1] http://lkml.kernel.org/r/20160523073157.GD2278@dhcp22.suse.cz Link: http://lkml.kernel.org/r/1464027356-32282-1-git-send-email-yang.shi@linaro.org Signed-off-by: Yang Shi <yang.shi@linaro.org> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 2664c118b5d2..22fa8189e4fc 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -649,6 +649,7 @@ config DEFERRED_STRUCT_PAGE_INIT
default n
depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
depends on MEMORY_HOTPLUG
+ depends on !FLATMEM
help
Ordinarily all struct pages are initialised during early boot in a
single thread. On very large machines this can take a considerable