On 11/21/2017, 08:24 AM, Michal Hocko wrote: > On Thu 16-11-17 20:46:01, Pavel Tatashin wrote: >> There is no need to have ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT, >> as all the page initialization code is in common code. >> >> Also, there is no need to depend on MEMORY_HOTPLUG, as initialization code >> does not really use hotplug memory functionality. So, we can remove this >> requirement as well. >> >> This patch allows to use deferred struct page initialization on all >> platforms with memblock allocator. >> >> Tested on x86, arm64, and sparc. Also, verified that code compiles on >> PPC with CONFIG_MEMORY_HOTPLUG disabled. > > There is slight risk that we will encounter corner cases on some > architectures with weird memory layout/topology Which x86_32-pae seems to be. Many bad page state errors are emitted during boot when this patch is applied: BUG: Bad page state in process swapper pfn:3c01c page:f566c3f0 count:0 mapcount:1 mapping:00000000 index:0x0 flags: 0x0() raw: 00000000 00000000 00000000 00000000 00000000 00000100 00000200 00000000 raw: 00000000 page dumped because: nonzero mapcount Modules linked in: CPU: 0 PID: 0 Comm: swapper Tainted: G B 4.17.1-4.gdf028bb-pae #1 openSUSE Tumbleweed (unreleased) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0x7d/0xbd bad_page.cold.111+0x90/0xc7 free_pages_check_bad+0x52/0x70 free_pcppages_bulk+0x37d/0x570 free_unref_page_commit+0x9a/0xc0 free_unref_page+0x6a/0xa0 __free_pages+0x17/0x30 free_highmem_page+0x1e/0x50 add_highpages_with_active_regions+0xd6/0x113 set_highmem_pages_init+0x67/0x7d mem_init+0x23/0x1d9 start_kernel+0x1c2/0x437 i386_start_kernel+0x98/0x9c startup_32_smp+0x164/0x168 free_pages_check_bad expects mapcount == -1, but it is 1 with this patch. Reverting the patch makes the BUGs go away -- the config diff is then: @@ -617,7 +617,7 @@ # CONFIG_PGTABLE_MAPPING is not set # CONFIG_ZSMALLOC_STAT is not set CONFIG_GENERIC_EARLY_IOREMAP=y -CONFIG_DEFERRED_STRUCT_PAGE_INIT=y +CONFIG_ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT=y # CONFIG_IDLE_PAGE_TRACKING is not set CONFIG_FRAME_VECTOR=y # CONFIG_PERCPU_STATS is not set >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -148,7 +148,6 @@ config PPC >> select ARCH_MIGHT_HAVE_PC_PARPORT >> select ARCH_MIGHT_HAVE_PC_SERIO >> select ARCH_SUPPORTS_ATOMIC_RMW >> - select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT >> select ARCH_USE_BUILTIN_BSWAP >> select ARCH_USE_CMPXCHG_LOCKREF if PPC64 >> select ARCH_WANT_IPC_PARSE_VERSION >> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig >> index 863a62a6de3c..525c2e3df6f5 100644 >> --- a/arch/s390/Kconfig >> +++ b/arch/s390/Kconfig >> @@ -108,7 +108,6 @@ config S390 >> select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE >> select ARCH_SAVE_PAGE_KEYS if HIBERNATION >> select ARCH_SUPPORTS_ATOMIC_RMW >> - select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT >> select ARCH_SUPPORTS_NUMA_BALANCING >> select ARCH_USE_BUILTIN_BSWAP >> select ARCH_USE_CMPXCHG_LOCKREF >> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >> index df3276d6bfe3..00a5446de394 100644 >> --- a/arch/x86/Kconfig >> +++ b/arch/x86/Kconfig >> @@ -69,7 +69,6 @@ config X86 >> select ARCH_MIGHT_HAVE_PC_PARPORT >> select ARCH_MIGHT_HAVE_PC_SERIO >> select ARCH_SUPPORTS_ATOMIC_RMW >> - select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT >> select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 >> select ARCH_USE_BUILTIN_BSWAP >> select ARCH_USE_QUEUED_RWLOCKS >> diff --git a/mm/Kconfig b/mm/Kconfig >> index 9c4bdddd80c2..c6bd0309ce7a 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -639,15 +639,10 @@ config MAX_STACK_SIZE_MB >> >> A sane initial value is 80 MB. >> >> -# For architectures that support deferred memory initialisation >> -config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT >> - bool >> - >> config DEFERRED_STRUCT_PAGE_INIT >> bool "Defer initialisation of struct pages to kthreads" >> default n >> - depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT >> - depends on NO_BOOTMEM && MEMORY_HOTPLUG >> + depends on NO_BOOTMEM >> depends on !FLATMEM >> help >> Ordinarily all struct pages are initialised during early boot in a thanks, -- js suse labs
