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![Joel Granados](/assets/img/avatar_default.png)
This commit comes at the tail end of a greater effort to remove the empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Remove sentinel from all files under mm/ that register a sysctl table. Link: https://lkml.kernel.org/r/20240328-jag-sysctl_remset_misc-v1-1-47c1463b3af2@samsung.com Signed-off-by: Joel Granados <j.granados@samsung.com> Reviewed-by: Muchun Song <muchun.song@linux.dev> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
699 lines
21 KiB
C
699 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* HugeTLB Vmemmap Optimization (HVO)
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*
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* Copyright (c) 2020, ByteDance. All rights reserved.
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*
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* Author: Muchun Song <songmuchun@bytedance.com>
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*
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* See Documentation/mm/vmemmap_dedup.rst
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*/
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#define pr_fmt(fmt) "HugeTLB: " fmt
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#include <linux/pgtable.h>
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#include <linux/moduleparam.h>
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#include <linux/bootmem_info.h>
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#include <linux/mmdebug.h>
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#include <linux/pagewalk.h>
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#include <asm/pgalloc.h>
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#include <asm/tlbflush.h>
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#include "hugetlb_vmemmap.h"
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/**
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* struct vmemmap_remap_walk - walk vmemmap page table
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*
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* @remap_pte: called for each lowest-level entry (PTE).
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* @nr_walked: the number of walked pte.
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* @reuse_page: the page which is reused for the tail vmemmap pages.
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* @reuse_addr: the virtual address of the @reuse_page page.
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* @vmemmap_pages: the list head of the vmemmap pages that can be freed
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* or is mapped from.
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* @flags: used to modify behavior in vmemmap page table walking
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* operations.
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*/
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struct vmemmap_remap_walk {
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void (*remap_pte)(pte_t *pte, unsigned long addr,
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struct vmemmap_remap_walk *walk);
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unsigned long nr_walked;
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struct page *reuse_page;
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unsigned long reuse_addr;
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struct list_head *vmemmap_pages;
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/* Skip the TLB flush when we split the PMD */
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#define VMEMMAP_SPLIT_NO_TLB_FLUSH BIT(0)
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/* Skip the TLB flush when we remap the PTE */
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#define VMEMMAP_REMAP_NO_TLB_FLUSH BIT(1)
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unsigned long flags;
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};
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static int vmemmap_split_pmd(pmd_t *pmd, struct page *head, unsigned long start,
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struct vmemmap_remap_walk *walk)
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{
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pmd_t __pmd;
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int i;
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unsigned long addr = start;
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pte_t *pgtable;
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pgtable = pte_alloc_one_kernel(&init_mm);
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if (!pgtable)
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return -ENOMEM;
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pmd_populate_kernel(&init_mm, &__pmd, pgtable);
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for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
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pte_t entry, *pte;
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pgprot_t pgprot = PAGE_KERNEL;
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entry = mk_pte(head + i, pgprot);
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pte = pte_offset_kernel(&__pmd, addr);
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set_pte_at(&init_mm, addr, pte, entry);
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}
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spin_lock(&init_mm.page_table_lock);
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if (likely(pmd_leaf(*pmd))) {
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/*
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* Higher order allocations from buddy allocator must be able to
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* be treated as indepdenent small pages (as they can be freed
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* individually).
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*/
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if (!PageReserved(head))
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split_page(head, get_order(PMD_SIZE));
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/* Make pte visible before pmd. See comment in pmd_install(). */
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smp_wmb();
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pmd_populate_kernel(&init_mm, pmd, pgtable);
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if (!(walk->flags & VMEMMAP_SPLIT_NO_TLB_FLUSH))
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flush_tlb_kernel_range(start, start + PMD_SIZE);
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} else {
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pte_free_kernel(&init_mm, pgtable);
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}
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spin_unlock(&init_mm.page_table_lock);
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return 0;
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}
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static int vmemmap_pmd_entry(pmd_t *pmd, unsigned long addr,
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unsigned long next, struct mm_walk *walk)
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{
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int ret = 0;
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struct page *head;
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struct vmemmap_remap_walk *vmemmap_walk = walk->private;
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/* Only splitting, not remapping the vmemmap pages. */
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if (!vmemmap_walk->remap_pte)
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walk->action = ACTION_CONTINUE;
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spin_lock(&init_mm.page_table_lock);
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head = pmd_leaf(*pmd) ? pmd_page(*pmd) : NULL;
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/*
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* Due to HugeTLB alignment requirements and the vmemmap
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* pages being at the start of the hotplugged memory
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* region in memory_hotplug.memmap_on_memory case. Checking
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* the vmemmap page associated with the first vmemmap page
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* if it is self-hosted is sufficient.
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*
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* [ hotplugged memory ]
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* [ section ][...][ section ]
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* [ vmemmap ][ usable memory ]
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* ^ | ^ |
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* +--+ | |
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* +------------------------+
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*/
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if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) && unlikely(!vmemmap_walk->nr_walked)) {
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struct page *page = head ? head + pte_index(addr) :
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pte_page(ptep_get(pte_offset_kernel(pmd, addr)));
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if (PageVmemmapSelfHosted(page))
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ret = -ENOTSUPP;
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}
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spin_unlock(&init_mm.page_table_lock);
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if (!head || ret)
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return ret;
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return vmemmap_split_pmd(pmd, head, addr & PMD_MASK, vmemmap_walk);
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}
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static int vmemmap_pte_entry(pte_t *pte, unsigned long addr,
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unsigned long next, struct mm_walk *walk)
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{
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struct vmemmap_remap_walk *vmemmap_walk = walk->private;
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/*
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* The reuse_page is found 'first' in page table walking before
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* starting remapping.
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*/
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if (!vmemmap_walk->reuse_page)
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vmemmap_walk->reuse_page = pte_page(ptep_get(pte));
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else
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vmemmap_walk->remap_pte(pte, addr, vmemmap_walk);
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vmemmap_walk->nr_walked++;
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return 0;
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}
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static const struct mm_walk_ops vmemmap_remap_ops = {
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.pmd_entry = vmemmap_pmd_entry,
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.pte_entry = vmemmap_pte_entry,
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};
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static int vmemmap_remap_range(unsigned long start, unsigned long end,
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struct vmemmap_remap_walk *walk)
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{
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int ret;
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VM_BUG_ON(!PAGE_ALIGNED(start | end));
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mmap_read_lock(&init_mm);
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ret = walk_page_range_novma(&init_mm, start, end, &vmemmap_remap_ops,
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NULL, walk);
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mmap_read_unlock(&init_mm);
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if (ret)
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return ret;
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if (walk->remap_pte && !(walk->flags & VMEMMAP_REMAP_NO_TLB_FLUSH))
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flush_tlb_kernel_range(start, end);
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return 0;
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}
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/*
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* Free a vmemmap page. A vmemmap page can be allocated from the memblock
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* allocator or buddy allocator. If the PG_reserved flag is set, it means
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* that it allocated from the memblock allocator, just free it via the
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* free_bootmem_page(). Otherwise, use __free_page().
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*/
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static inline void free_vmemmap_page(struct page *page)
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{
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if (PageReserved(page))
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free_bootmem_page(page);
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else
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__free_page(page);
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}
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/* Free a list of the vmemmap pages */
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static void free_vmemmap_page_list(struct list_head *list)
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{
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struct page *page, *next;
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list_for_each_entry_safe(page, next, list, lru)
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free_vmemmap_page(page);
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}
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static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
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struct vmemmap_remap_walk *walk)
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{
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/*
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* Remap the tail pages as read-only to catch illegal write operation
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* to the tail pages.
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*/
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pgprot_t pgprot = PAGE_KERNEL_RO;
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struct page *page = pte_page(ptep_get(pte));
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pte_t entry;
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/* Remapping the head page requires r/w */
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if (unlikely(addr == walk->reuse_addr)) {
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pgprot = PAGE_KERNEL;
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list_del(&walk->reuse_page->lru);
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/*
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* Makes sure that preceding stores to the page contents from
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* vmemmap_remap_free() become visible before the set_pte_at()
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* write.
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*/
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smp_wmb();
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}
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entry = mk_pte(walk->reuse_page, pgprot);
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list_add(&page->lru, walk->vmemmap_pages);
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set_pte_at(&init_mm, addr, pte, entry);
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}
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/*
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* How many struct page structs need to be reset. When we reuse the head
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* struct page, the special metadata (e.g. page->flags or page->mapping)
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* cannot copy to the tail struct page structs. The invalid value will be
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* checked in the free_tail_page_prepare(). In order to avoid the message
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* of "corrupted mapping in tail page". We need to reset at least 3 (one
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* head struct page struct and two tail struct page structs) struct page
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* structs.
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*/
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#define NR_RESET_STRUCT_PAGE 3
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static inline void reset_struct_pages(struct page *start)
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{
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struct page *from = start + NR_RESET_STRUCT_PAGE;
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BUILD_BUG_ON(NR_RESET_STRUCT_PAGE * 2 > PAGE_SIZE / sizeof(struct page));
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memcpy(start, from, sizeof(*from) * NR_RESET_STRUCT_PAGE);
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}
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static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
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struct vmemmap_remap_walk *walk)
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{
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pgprot_t pgprot = PAGE_KERNEL;
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struct page *page;
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void *to;
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BUG_ON(pte_page(ptep_get(pte)) != walk->reuse_page);
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page = list_first_entry(walk->vmemmap_pages, struct page, lru);
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list_del(&page->lru);
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to = page_to_virt(page);
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copy_page(to, (void *)walk->reuse_addr);
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reset_struct_pages(to);
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/*
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* Makes sure that preceding stores to the page contents become visible
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* before the set_pte_at() write.
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*/
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smp_wmb();
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set_pte_at(&init_mm, addr, pte, mk_pte(page, pgprot));
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}
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/**
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* vmemmap_remap_split - split the vmemmap virtual address range [@start, @end)
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* backing PMDs of the directmap into PTEs
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* @start: start address of the vmemmap virtual address range that we want
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* to remap.
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* @end: end address of the vmemmap virtual address range that we want to
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* remap.
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* @reuse: reuse address.
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*
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* Return: %0 on success, negative error code otherwise.
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*/
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static int vmemmap_remap_split(unsigned long start, unsigned long end,
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unsigned long reuse)
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{
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struct vmemmap_remap_walk walk = {
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.remap_pte = NULL,
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.flags = VMEMMAP_SPLIT_NO_TLB_FLUSH,
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};
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/* See the comment in the vmemmap_remap_free(). */
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BUG_ON(start - reuse != PAGE_SIZE);
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return vmemmap_remap_range(reuse, end, &walk);
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}
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/**
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* vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end)
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* to the page which @reuse is mapped to, then free vmemmap
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* which the range are mapped to.
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* @start: start address of the vmemmap virtual address range that we want
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* to remap.
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* @end: end address of the vmemmap virtual address range that we want to
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* remap.
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* @reuse: reuse address.
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* @vmemmap_pages: list to deposit vmemmap pages to be freed. It is callers
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* responsibility to free pages.
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* @flags: modifications to vmemmap_remap_walk flags
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*
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* Return: %0 on success, negative error code otherwise.
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*/
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static int vmemmap_remap_free(unsigned long start, unsigned long end,
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unsigned long reuse,
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struct list_head *vmemmap_pages,
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unsigned long flags)
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{
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int ret;
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struct vmemmap_remap_walk walk = {
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.remap_pte = vmemmap_remap_pte,
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.reuse_addr = reuse,
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.vmemmap_pages = vmemmap_pages,
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.flags = flags,
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};
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int nid = page_to_nid((struct page *)reuse);
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gfp_t gfp_mask = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
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/*
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* Allocate a new head vmemmap page to avoid breaking a contiguous
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* block of struct page memory when freeing it back to page allocator
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* in free_vmemmap_page_list(). This will allow the likely contiguous
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* struct page backing memory to be kept contiguous and allowing for
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* more allocations of hugepages. Fallback to the currently
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* mapped head page in case should it fail to allocate.
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*/
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walk.reuse_page = alloc_pages_node(nid, gfp_mask, 0);
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if (walk.reuse_page) {
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copy_page(page_to_virt(walk.reuse_page),
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(void *)walk.reuse_addr);
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list_add(&walk.reuse_page->lru, vmemmap_pages);
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}
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/*
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* In order to make remapping routine most efficient for the huge pages,
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* the routine of vmemmap page table walking has the following rules
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* (see more details from the vmemmap_pte_range()):
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*
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* - The range [@start, @end) and the range [@reuse, @reuse + PAGE_SIZE)
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* should be continuous.
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* - The @reuse address is part of the range [@reuse, @end) that we are
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* walking which is passed to vmemmap_remap_range().
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* - The @reuse address is the first in the complete range.
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*
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* So we need to make sure that @start and @reuse meet the above rules.
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*/
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BUG_ON(start - reuse != PAGE_SIZE);
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ret = vmemmap_remap_range(reuse, end, &walk);
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if (ret && walk.nr_walked) {
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end = reuse + walk.nr_walked * PAGE_SIZE;
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/*
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* vmemmap_pages contains pages from the previous
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* vmemmap_remap_range call which failed. These
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* are pages which were removed from the vmemmap.
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* They will be restored in the following call.
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*/
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walk = (struct vmemmap_remap_walk) {
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.remap_pte = vmemmap_restore_pte,
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.reuse_addr = reuse,
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.vmemmap_pages = vmemmap_pages,
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.flags = 0,
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};
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vmemmap_remap_range(reuse, end, &walk);
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}
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return ret;
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}
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static int alloc_vmemmap_page_list(unsigned long start, unsigned long end,
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struct list_head *list)
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{
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gfp_t gfp_mask = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
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unsigned long nr_pages = (end - start) >> PAGE_SHIFT;
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int nid = page_to_nid((struct page *)start);
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struct page *page, *next;
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while (nr_pages--) {
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page = alloc_pages_node(nid, gfp_mask, 0);
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if (!page)
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goto out;
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list_add(&page->lru, list);
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}
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return 0;
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out:
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list_for_each_entry_safe(page, next, list, lru)
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__free_page(page);
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return -ENOMEM;
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}
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/**
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* vmemmap_remap_alloc - remap the vmemmap virtual address range [@start, end)
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* to the page which is from the @vmemmap_pages
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* respectively.
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* @start: start address of the vmemmap virtual address range that we want
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* to remap.
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* @end: end address of the vmemmap virtual address range that we want to
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* remap.
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* @reuse: reuse address.
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* @flags: modifications to vmemmap_remap_walk flags
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*
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* Return: %0 on success, negative error code otherwise.
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*/
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static int vmemmap_remap_alloc(unsigned long start, unsigned long end,
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unsigned long reuse, unsigned long flags)
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{
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LIST_HEAD(vmemmap_pages);
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struct vmemmap_remap_walk walk = {
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.remap_pte = vmemmap_restore_pte,
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.reuse_addr = reuse,
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.vmemmap_pages = &vmemmap_pages,
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.flags = flags,
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};
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/* See the comment in the vmemmap_remap_free(). */
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BUG_ON(start - reuse != PAGE_SIZE);
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if (alloc_vmemmap_page_list(start, end, &vmemmap_pages))
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return -ENOMEM;
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return vmemmap_remap_range(reuse, end, &walk);
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}
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DEFINE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
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EXPORT_SYMBOL(hugetlb_optimize_vmemmap_key);
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static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON);
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core_param(hugetlb_free_vmemmap, vmemmap_optimize_enabled, bool, 0);
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static int __hugetlb_vmemmap_restore_folio(const struct hstate *h,
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struct folio *folio, unsigned long flags)
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{
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int ret;
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unsigned long vmemmap_start = (unsigned long)&folio->page, vmemmap_end;
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unsigned long vmemmap_reuse;
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VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
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if (!folio_test_hugetlb_vmemmap_optimized(folio))
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return 0;
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vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h);
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vmemmap_reuse = vmemmap_start;
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vmemmap_start += HUGETLB_VMEMMAP_RESERVE_SIZE;
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/*
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* The pages which the vmemmap virtual address range [@vmemmap_start,
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* @vmemmap_end) are mapped to are freed to the buddy allocator, and
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* the range is mapped to the page which @vmemmap_reuse is mapped to.
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* When a HugeTLB page is freed to the buddy allocator, previously
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* discarded vmemmap pages must be allocated and remapping.
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*/
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ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, vmemmap_reuse, flags);
|
|
if (!ret) {
|
|
folio_clear_hugetlb_vmemmap_optimized(folio);
|
|
static_branch_dec(&hugetlb_optimize_vmemmap_key);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* hugetlb_vmemmap_restore_folio - restore previously optimized (by
|
|
* hugetlb_vmemmap_optimize_folio()) vmemmap pages which
|
|
* will be reallocated and remapped.
|
|
* @h: struct hstate.
|
|
* @folio: the folio whose vmemmap pages will be restored.
|
|
*
|
|
* Return: %0 if @folio's vmemmap pages have been reallocated and remapped,
|
|
* negative error code otherwise.
|
|
*/
|
|
int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio)
|
|
{
|
|
return __hugetlb_vmemmap_restore_folio(h, folio, 0);
|
|
}
|
|
|
|
/**
|
|
* hugetlb_vmemmap_restore_folios - restore vmemmap for every folio on the list.
|
|
* @h: hstate.
|
|
* @folio_list: list of folios.
|
|
* @non_hvo_folios: Output list of folios for which vmemmap exists.
|
|
*
|
|
* Return: number of folios for which vmemmap was restored, or an error code
|
|
* if an error was encountered restoring vmemmap for a folio.
|
|
* Folios that have vmemmap are moved to the non_hvo_folios
|
|
* list. Processing of entries stops when the first error is
|
|
* encountered. The folio that experienced the error and all
|
|
* non-processed folios will remain on folio_list.
|
|
*/
|
|
long hugetlb_vmemmap_restore_folios(const struct hstate *h,
|
|
struct list_head *folio_list,
|
|
struct list_head *non_hvo_folios)
|
|
{
|
|
struct folio *folio, *t_folio;
|
|
long restored = 0;
|
|
long ret = 0;
|
|
|
|
list_for_each_entry_safe(folio, t_folio, folio_list, lru) {
|
|
if (folio_test_hugetlb_vmemmap_optimized(folio)) {
|
|
ret = __hugetlb_vmemmap_restore_folio(h, folio,
|
|
VMEMMAP_REMAP_NO_TLB_FLUSH);
|
|
if (ret)
|
|
break;
|
|
restored++;
|
|
}
|
|
|
|
/* Add non-optimized folios to output list */
|
|
list_move(&folio->lru, non_hvo_folios);
|
|
}
|
|
|
|
if (restored)
|
|
flush_tlb_all();
|
|
if (!ret)
|
|
ret = restored;
|
|
return ret;
|
|
}
|
|
|
|
/* Return true iff a HugeTLB whose vmemmap should and can be optimized. */
|
|
static bool vmemmap_should_optimize_folio(const struct hstate *h, struct folio *folio)
|
|
{
|
|
if (folio_test_hugetlb_vmemmap_optimized(folio))
|
|
return false;
|
|
|
|
if (!READ_ONCE(vmemmap_optimize_enabled))
|
|
return false;
|
|
|
|
if (!hugetlb_vmemmap_optimizable(h))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
|
|
struct folio *folio,
|
|
struct list_head *vmemmap_pages,
|
|
unsigned long flags)
|
|
{
|
|
int ret = 0;
|
|
unsigned long vmemmap_start = (unsigned long)&folio->page, vmemmap_end;
|
|
unsigned long vmemmap_reuse;
|
|
|
|
VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);
|
|
if (!vmemmap_should_optimize_folio(h, folio))
|
|
return ret;
|
|
|
|
static_branch_inc(&hugetlb_optimize_vmemmap_key);
|
|
/*
|
|
* Very Subtle
|
|
* If VMEMMAP_REMAP_NO_TLB_FLUSH is set, TLB flushing is not performed
|
|
* immediately after remapping. As a result, subsequent accesses
|
|
* and modifications to struct pages associated with the hugetlb
|
|
* page could be to the OLD struct pages. Set the vmemmap optimized
|
|
* flag here so that it is copied to the new head page. This keeps
|
|
* the old and new struct pages in sync.
|
|
* If there is an error during optimization, we will immediately FLUSH
|
|
* the TLB and clear the flag below.
|
|
*/
|
|
folio_set_hugetlb_vmemmap_optimized(folio);
|
|
|
|
vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h);
|
|
vmemmap_reuse = vmemmap_start;
|
|
vmemmap_start += HUGETLB_VMEMMAP_RESERVE_SIZE;
|
|
|
|
/*
|
|
* Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end)
|
|
* to the page which @vmemmap_reuse is mapped to. Add pages previously
|
|
* mapping the range to vmemmap_pages list so that they can be freed by
|
|
* the caller.
|
|
*/
|
|
ret = vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse,
|
|
vmemmap_pages, flags);
|
|
if (ret) {
|
|
static_branch_dec(&hugetlb_optimize_vmemmap_key);
|
|
folio_clear_hugetlb_vmemmap_optimized(folio);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* hugetlb_vmemmap_optimize_folio - optimize @folio's vmemmap pages.
|
|
* @h: struct hstate.
|
|
* @folio: the folio whose vmemmap pages will be optimized.
|
|
*
|
|
* This function only tries to optimize @folio's vmemmap pages and does not
|
|
* guarantee that the optimization will succeed after it returns. The caller
|
|
* can use folio_test_hugetlb_vmemmap_optimized(@folio) to detect if @folio's
|
|
* vmemmap pages have been optimized.
|
|
*/
|
|
void hugetlb_vmemmap_optimize_folio(const struct hstate *h, struct folio *folio)
|
|
{
|
|
LIST_HEAD(vmemmap_pages);
|
|
|
|
__hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages, 0);
|
|
free_vmemmap_page_list(&vmemmap_pages);
|
|
}
|
|
|
|
static int hugetlb_vmemmap_split_folio(const struct hstate *h, struct folio *folio)
|
|
{
|
|
unsigned long vmemmap_start = (unsigned long)&folio->page, vmemmap_end;
|
|
unsigned long vmemmap_reuse;
|
|
|
|
if (!vmemmap_should_optimize_folio(h, folio))
|
|
return 0;
|
|
|
|
vmemmap_end = vmemmap_start + hugetlb_vmemmap_size(h);
|
|
vmemmap_reuse = vmemmap_start;
|
|
vmemmap_start += HUGETLB_VMEMMAP_RESERVE_SIZE;
|
|
|
|
/*
|
|
* Split PMDs on the vmemmap virtual address range [@vmemmap_start,
|
|
* @vmemmap_end]
|
|
*/
|
|
return vmemmap_remap_split(vmemmap_start, vmemmap_end, vmemmap_reuse);
|
|
}
|
|
|
|
void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list)
|
|
{
|
|
struct folio *folio;
|
|
LIST_HEAD(vmemmap_pages);
|
|
|
|
list_for_each_entry(folio, folio_list, lru) {
|
|
int ret = hugetlb_vmemmap_split_folio(h, folio);
|
|
|
|
/*
|
|
* Spliting the PMD requires allocating a page, thus lets fail
|
|
* early once we encounter the first OOM. No point in retrying
|
|
* as it can be dynamically done on remap with the memory
|
|
* we get back from the vmemmap deduplication.
|
|
*/
|
|
if (ret == -ENOMEM)
|
|
break;
|
|
}
|
|
|
|
flush_tlb_all();
|
|
|
|
list_for_each_entry(folio, folio_list, lru) {
|
|
int ret;
|
|
|
|
ret = __hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages,
|
|
VMEMMAP_REMAP_NO_TLB_FLUSH);
|
|
|
|
/*
|
|
* Pages to be freed may have been accumulated. If we
|
|
* encounter an ENOMEM, free what we have and try again.
|
|
* This can occur in the case that both spliting fails
|
|
* halfway and head page allocation also failed. In this
|
|
* case __hugetlb_vmemmap_optimize_folio() would free memory
|
|
* allowing more vmemmap remaps to occur.
|
|
*/
|
|
if (ret == -ENOMEM && !list_empty(&vmemmap_pages)) {
|
|
flush_tlb_all();
|
|
free_vmemmap_page_list(&vmemmap_pages);
|
|
INIT_LIST_HEAD(&vmemmap_pages);
|
|
__hugetlb_vmemmap_optimize_folio(h, folio, &vmemmap_pages,
|
|
VMEMMAP_REMAP_NO_TLB_FLUSH);
|
|
}
|
|
}
|
|
|
|
flush_tlb_all();
|
|
free_vmemmap_page_list(&vmemmap_pages);
|
|
}
|
|
|
|
static struct ctl_table hugetlb_vmemmap_sysctls[] = {
|
|
{
|
|
.procname = "hugetlb_optimize_vmemmap",
|
|
.data = &vmemmap_optimize_enabled,
|
|
.maxlen = sizeof(vmemmap_optimize_enabled),
|
|
.mode = 0644,
|
|
.proc_handler = proc_dobool,
|
|
},
|
|
};
|
|
|
|
static int __init hugetlb_vmemmap_init(void)
|
|
{
|
|
const struct hstate *h;
|
|
|
|
/* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */
|
|
BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES);
|
|
|
|
for_each_hstate(h) {
|
|
if (hugetlb_vmemmap_optimizable(h)) {
|
|
register_sysctl_init("vm", hugetlb_vmemmap_sysctls);
|
|
break;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
late_initcall(hugetlb_vmemmap_init);
|