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 <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220211065215.101767-1-aneesh.kumar@linux.ibm.com

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 962708fa1017823e9be09e8fd7a7917625272298..6a1a1ac5743b8a2ff7a5ea6f8cf63f883b268f21 100644 (file)
--- 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 ea8f83afb0ae2650799c96e47849d6744a64401a..3bc0eb21b2a005538a7493cf8ebc7c34a6332801 100644 (file)
--- 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 ddead41e21943d3acd0b9f55cc6de81a806e8647..b642a5a8668fb9233f6d5ced228537d0bbfcdd3e 100644 (file)
--- 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 35f46bf5428198c369cfb8047806f505a63e4252..83c0ee9fbf05bc9ac7f72da02499065a61877cdf 100644 (file)
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -59,6 +59,7 @@
 #include <asm/sections.h>
 #include <asm/iommu.h>
 #include <asm/vdso.h>
+#include <asm/hugetlb.h>
 
 #include <mm/mmu_decl.h>
 
@@ -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");