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21d9ee3eda
This patch removes the NUMA PTE bits and associated helpers. As a
side-effect it increases the maximum possible swap space on x86-64.
One potential source of problems is races between the marking of PTEs
PROT_NONE, NUMA hinting faults and migration. It must be guaranteed that
a PTE being protected is not faulted in parallel, seen as a pte_none and
corrupting memory. The base case is safe but transhuge has problems in
the past due to an different migration mechanism and a dependance on page
lock to serialise migrations and warrants a closer look.
task_work hinting update parallel fault
------------------------ --------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
pmd_none
do_huge_pmd_anonymous_page
read? pmd_lock blocks until hinting complete, fail !pmd_none test
write? __do_huge_pmd_anonymous_page acquires pmd_lock, checks pmd_none
pmd_modify
set_pmd_at
task_work hinting update parallel migration
------------------------ ------------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
do_huge_pmd_numa_page
migrate_misplaced_transhuge_page
pmd_lock waits for updates to complete, recheck pmd_same
pmd_modify
set_pmd_at
Both of those are safe and the case where a transhuge page is inserted
during a protection update is unchanged. The case where two processes try
migrating at the same time is unchanged by this series so should still be
ok. I could not find a case where we are accidentally depending on the
PTE not being cleared and flushed. If one is missed, it'll manifest as
corruption problems that start triggering shortly after this series is
merged and only happen when NUMA balancing is enabled.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
184 lines
4.5 KiB
C
184 lines
4.5 KiB
C
#ifndef _ASM_X86_PGTABLE_64_H
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#define _ASM_X86_PGTABLE_64_H
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#include <linux/const.h>
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#include <asm/pgtable_64_types.h>
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#ifndef __ASSEMBLY__
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/*
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* This file contains the functions and defines necessary to modify and use
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* the x86-64 page table tree.
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*/
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#include <asm/processor.h>
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#include <linux/bitops.h>
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#include <linux/threads.h>
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extern pud_t level3_kernel_pgt[512];
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extern pud_t level3_ident_pgt[512];
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extern pmd_t level2_kernel_pgt[512];
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extern pmd_t level2_fixmap_pgt[512];
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extern pmd_t level2_ident_pgt[512];
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extern pte_t level1_fixmap_pgt[512];
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extern pgd_t init_level4_pgt[];
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#define swapper_pg_dir init_level4_pgt
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extern void paging_init(void);
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#define pte_ERROR(e) \
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pr_err("%s:%d: bad pte %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pte_val(e))
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#define pmd_ERROR(e) \
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pr_err("%s:%d: bad pmd %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pmd_val(e))
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#define pud_ERROR(e) \
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pr_err("%s:%d: bad pud %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pud_val(e))
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#define pgd_ERROR(e) \
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pr_err("%s:%d: bad pgd %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pgd_val(e))
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struct mm_struct;
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void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte);
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static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep)
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{
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*ptep = native_make_pte(0);
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}
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static inline void native_set_pte(pte_t *ptep, pte_t pte)
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{
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*ptep = pte;
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}
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static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
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{
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native_set_pte(ptep, pte);
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}
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static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
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{
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*pmdp = pmd;
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}
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static inline void native_pmd_clear(pmd_t *pmd)
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{
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native_set_pmd(pmd, native_make_pmd(0));
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}
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static inline pte_t native_ptep_get_and_clear(pte_t *xp)
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{
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#ifdef CONFIG_SMP
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return native_make_pte(xchg(&xp->pte, 0));
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#else
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/* native_local_ptep_get_and_clear,
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but duplicated because of cyclic dependency */
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pte_t ret = *xp;
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native_pte_clear(NULL, 0, xp);
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return ret;
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#endif
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}
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static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
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{
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#ifdef CONFIG_SMP
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return native_make_pmd(xchg(&xp->pmd, 0));
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#else
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/* native_local_pmdp_get_and_clear,
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but duplicated because of cyclic dependency */
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pmd_t ret = *xp;
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native_pmd_clear(xp);
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return ret;
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#endif
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}
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static inline void native_set_pud(pud_t *pudp, pud_t pud)
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{
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*pudp = pud;
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}
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static inline void native_pud_clear(pud_t *pud)
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{
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native_set_pud(pud, native_make_pud(0));
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}
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static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
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{
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*pgdp = pgd;
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}
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static inline void native_pgd_clear(pgd_t *pgd)
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{
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native_set_pgd(pgd, native_make_pgd(0));
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}
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extern void sync_global_pgds(unsigned long start, unsigned long end,
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int removed);
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/*
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* Conversion functions: convert a page and protection to a page entry,
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* and a page entry and page directory to the page they refer to.
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*/
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/*
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* Level 4 access.
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*/
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static inline int pgd_large(pgd_t pgd) { return 0; }
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#define mk_kernel_pgd(address) __pgd((address) | _KERNPG_TABLE)
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/* PUD - Level3 access */
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/* PMD - Level 2 access */
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/* PTE - Level 1 access. */
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/* x86-64 always has all page tables mapped. */
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#define pte_offset_map(dir, address) pte_offset_kernel((dir), (address))
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#define pte_unmap(pte) ((void)(pte))/* NOP */
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/* Encode and de-code a swap entry */
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#define SWP_TYPE_BITS 5
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#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
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#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
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#define __swp_type(x) (((x).val >> (_PAGE_BIT_PRESENT + 1)) \
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& ((1U << SWP_TYPE_BITS) - 1))
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#define __swp_offset(x) ((x).val >> SWP_OFFSET_SHIFT)
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#define __swp_entry(type, offset) ((swp_entry_t) { \
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((type) << (_PAGE_BIT_PRESENT + 1)) \
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| ((offset) << SWP_OFFSET_SHIFT) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) })
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#define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val })
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extern int kern_addr_valid(unsigned long addr);
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extern void cleanup_highmap(void);
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#define HAVE_ARCH_UNMAPPED_AREA
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#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
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#define pgtable_cache_init() do { } while (0)
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#define check_pgt_cache() do { } while (0)
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#define PAGE_AGP PAGE_KERNEL_NOCACHE
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#define HAVE_PAGE_AGP 1
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/* fs/proc/kcore.c */
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#define kc_vaddr_to_offset(v) ((v) & __VIRTUAL_MASK)
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#define kc_offset_to_vaddr(o) ((o) | ~__VIRTUAL_MASK)
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#define __HAVE_ARCH_PTE_SAME
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#define vmemmap ((struct page *)VMEMMAP_START)
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extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
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extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PGTABLE_64_H */
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