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>
1 file changed