[PATCH v2 2/3] arm64: mm: don't call page table ctors for init_mm
From: Yu Zhao <hidden>
Date: 2019-02-18 23:13:36
Also in:
linux-arch, linux-mm, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
init_mm doesn't require page table lock to be initialized at any level. Add a separate page table allocator for it, and the new one skips page table ctors. The ctors allocate memory when ALLOC_SPLIT_PTLOCKS is set. Not calling them avoids memory leak in case we call pte_free_kernel() on init_mm. Signed-off-by: Yu Zhao <redacted> --- arch/arm64/mm/mmu.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index fa7351877af3..e8bf8a6300e8 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c@@ -370,6 +370,16 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys, } while (pgdp++, addr = next, addr != end); } +static phys_addr_t pgd_kernel_pgtable_alloc(int shift) +{ + void *ptr = (void *)__get_free_page(PGALLOC_GFP); + BUG_ON(!ptr); + + /* Ensure the zeroed page is visible to the page table walker */ + dsb(ishst); + return __pa(ptr); +} + static phys_addr_t pgd_pgtable_alloc(int shift) { void *ptr = (void *)__get_free_page(PGALLOC_GFP);
@@ -591,7 +601,7 @@ static int __init map_entry_trampoline(void) /* Map only the text into the trampoline page table */ memset(tramp_pg_dir, 0, PGD_SIZE); __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, - prot, pgd_pgtable_alloc, 0); + prot, pgd_kernel_pgtable_alloc, 0); /* Map both the text and data into the kernel page table */ __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot);
@@ -1067,7 +1077,8 @@ int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap, flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), - size, PAGE_KERNEL, pgd_pgtable_alloc, flags); + size, PAGE_KERNEL, pgd_kernel_pgtable_alloc, + flags); return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, altmap, want_memblock);
--
2.21.0.rc0.258.g878e2cd30e-goog
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