From 358e526a1648cdd773ba169da5867874ae2408e3 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 19 May 2023 21:38:06 +1000 Subject: [PATCH] powerpc/mm: Reinstate ARCH_FORCE_MAX_ORDER ranges Commit 1e8fed873e74 ("powerpc: drop ranges for definition of ARCH_FORCE_MAX_ORDER") removed the limits on the possible values for ARCH_FORCE_MAX_ORDER. However removing the ranges entirely causes some common work flows to break. For example building a defconfig (which uses 64K pages), changing the page size to 4K, and rebuilding used to work, because ARCH_FORCE_MAX_ORDER would be clamped to 12 by the ranges. With the ranges removed it creates a kernel that builds but crashes at boot: kernel BUG at mm/huge_memory.c:470! Oops: Exception in kernel mode, sig: 5 [#1] ... NIP hugepage_init+0x9c/0x278 LR do_one_initcall+0x80/0x320 Call Trace: do_one_initcall+0x80/0x320 kernel_init_freeable+0x304/0x3ac kernel_init+0x30/0x1a0 ret_from_kernel_user_thread+0x14/0x1c The reasoning for removing the ranges was that some of the values were too large. So take that into account and limit the maximums to 10 which is the default max, except for the 4K case which uses 12. Fixes: 1e8fed873e74 ("powerpc: drop ranges for definition of ARCH_FORCE_MAX_ORDER") Signed-off-by: Michael Ellerman Link: https://msgid.link/20230519113806.370635-1-mpe@ellerman.id.au --- arch/powerpc/Kconfig | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 539d1f03ff42..bff5820b7cda 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -906,11 +906,17 @@ config DATA_SHIFT config ARCH_FORCE_MAX_ORDER int "Order of maximal physically contiguous allocations" + range 7 8 if PPC64 && PPC_64K_PAGES default "8" if PPC64 && PPC_64K_PAGES + range 12 12 if PPC64 && !PPC_64K_PAGES default "12" if PPC64 && !PPC_64K_PAGES + range 8 10 if PPC32 && PPC_16K_PAGES default "8" if PPC32 && PPC_16K_PAGES + range 6 10 if PPC32 && PPC_64K_PAGES default "6" if PPC32 && PPC_64K_PAGES + range 4 10 if PPC32 && PPC_256K_PAGES default "4" if PPC32 && PPC_256K_PAGES + range 10 10 default "10" help The kernel page allocator limits the size of maximal physically