From 2354ad252b66695be02f4acd18e37bf6264f0464 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Fri, 11 Feb 2022 12:22:15 +0530 Subject: [PATCH] powerpc/mm: Update default hugetlb size early commit: d9c234005227 ("Do not depend on MAX_ORDER when grouping pages by mobility") introduced pageblock_order which will be used to group pages better. The kernel now groups pages based on the value of HPAGE_SHIFT. Hence HPAGE_SHIFT should be set before we call set_pageblock_order. set_pageblock_order happens early in the boot and default hugetlb page size should be initialized before that to compute the right pageblock_order value. Currently, default hugetlbe page size is set via arch_initcalls which happens late in the boot as shown via the below callstack: [c000000007383b10] [c000000001289328] hugetlbpage_init+0x2b8/0x2f8 [c000000007383bc0] [c0000000012749e4] do_one_initcall+0x14c/0x320 [c000000007383c90] [c00000000127505c] kernel_init_freeable+0x410/0x4e8 [c000000007383da0] [c000000000012664] kernel_init+0x30/0x15c [c000000007383e10] [c00000000000cf14] ret_from_kernel_thread+0x5c/0x64 and the pageblock_order initialization is done early during the boot. [c0000000018bfc80] [c0000000012ae120] set_pageblock_order+0x50/0x64 [c0000000018bfca0] [c0000000012b3d94] sparse_init+0x188/0x268 [c0000000018bfd60] [c000000001288bfc] initmem_init+0x28c/0x328 [c0000000018bfe50] [c00000000127b370] setup_arch+0x410/0x480 [c0000000018bfed0] [c00000000127401c] start_kernel+0xb8/0x934 [c0000000018bff90] [c00000000000d984] start_here_common+0x1c/0x98 delaying default hugetlb page size initialization implies the kernel will initialize pageblock_order to (MAX_ORDER - 1) which is not an optimal value for mobility grouping. IIUC we always had this issue. But it was not a problem for hash translation mode because (MAX_ORDER - 1) is the same as HUGETLB_PAGE_ORDER (8) in the case of hash (16MB). With radix, HUGETLB_PAGE_ORDER will be 5 (2M size) and hence pageblock_order should be 5 instead of 8. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220211065215.101767-1-aneesh.kumar@linux.ibm.com --- arch/powerpc/include/asm/hugetlb.h | 5 ++++- arch/powerpc/mm/book3s64/hugetlbpage.c | 2 +- arch/powerpc/mm/hugetlbpage.c | 5 +---- arch/powerpc/mm/init_64.c | 4 ++++ 4 files changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h index 962708f..6a1a1ac 100644 --- a/arch/powerpc/include/asm/hugetlb.h +++ b/arch/powerpc/include/asm/hugetlb.h @@ -15,7 +15,7 @@ extern bool hugetlb_disabled; -void __init hugetlbpage_init_default(void); +void __init hugetlbpage_init_defaultsize(void); int slice_is_hugepage_only_range(struct mm_struct *mm, unsigned long addr, unsigned long len); @@ -76,6 +76,9 @@ static inline void __init gigantic_hugetlb_cma_reserve(void) { } +static inline void __init hugetlbpage_init_defaultsize(void) +{ +} #endif /* CONFIG_HUGETLB_PAGE */ #endif /* _ASM_POWERPC_HUGETLB_H */ diff --git a/arch/powerpc/mm/book3s64/hugetlbpage.c b/arch/powerpc/mm/book3s64/hugetlbpage.c index ea8f83a..3bc0eb2 100644 --- a/arch/powerpc/mm/book3s64/hugetlbpage.c +++ b/arch/powerpc/mm/book3s64/hugetlbpage.c @@ -150,7 +150,7 @@ void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr set_huge_pte_at(vma->vm_mm, addr, ptep, pte); } -void __init hugetlbpage_init_default(void) +void __init hugetlbpage_init_defaultsize(void) { /* Set default large page size. Currently, we pick 16M or 1M * depending on what is available diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index ddead41..b642a5a 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -664,10 +664,7 @@ static int __init hugetlbpage_init(void) configured = true; } - if (configured) { - if (IS_ENABLED(CONFIG_HUGETLB_PAGE_SIZE_VARIABLE)) - hugetlbpage_init_default(); - } else + if (!configured) pr_info("Failed to initialize. Disabling HugeTLB"); return 0; diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c index 35f46bf..83c0ee9 100644 --- a/arch/powerpc/mm/init_64.c +++ b/arch/powerpc/mm/init_64.c @@ -59,6 +59,7 @@ #include #include #include +#include #include @@ -513,6 +514,9 @@ void __init mmu_early_init_devtree(void) } else hash__early_init_devtree(); + if (IS_ENABLED(CONFIG_HUGETLB_PAGE_SIZE_VARIABLE)) + hugetlbpage_init_defaultsize(); + if (!(cur_cpu_spec->mmu_features & MMU_FTR_HPTE_TABLE) && !(cur_cpu_spec->mmu_features & MMU_FTR_TYPE_RADIX)) panic("kernel does not support any MMU type offered by platform"); -- 2.7.4