forked from luck/tmp_suning_uos_patched
50aa98bad0
Suzuki Poulose reported the following recursive locking bug on s390: Here is the stack trace : (see Appendix I for more info) [<0000000000406ed6>] _spin_lock+0x52/0x94 [<0000000000103bde>] crst_table_free+0x14e/0x1a4 [<00000000001ba684>] __pmd_alloc+0x114/0x1ec [<00000000001be8d0>] handle_mm_fault+0x2cc/0xb80 [<0000000000407d62>] do_dat_exception+0x2b6/0x3a0 [<0000000000114f8c>] sysc_return+0x0/0x8 [<00000200001642b2>] 0x200001642b2 The page_table_lock is already acquired in __pmd_alloc (mm/memory.c) and it tries to populate the pud/pgd with a new pmd allocated. If another thread populates it before we get a chance, we free the pmd using pmd_free(). On s390x, pmd_free(even pud_free ) is #defined to crst_table_free(), which acquires the page_table_lock to protect the crst_table index updates. Hence this ends up in a recursive locking of the page_table_lock. The solution suggested by Dave Hansen is to use a new spin lock in the mmu context to protect the access to the crst_list and the pgtable_list. Reported-by: Suzuki Poulose <suzuki@in.ibm.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
179 lines
4.8 KiB
C
179 lines
4.8 KiB
C
/*
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* include/asm-s390/pgalloc.h
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*
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* S390 version
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* Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Hartmut Penner (hp@de.ibm.com)
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* Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* Derived from "include/asm-i386/pgalloc.h"
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* Copyright (C) 1994 Linus Torvalds
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*/
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#ifndef _S390_PGALLOC_H
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#define _S390_PGALLOC_H
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#include <linux/threads.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#define check_pgt_cache() do {} while (0)
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unsigned long *crst_table_alloc(struct mm_struct *, int);
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void crst_table_free(struct mm_struct *, unsigned long *);
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unsigned long *page_table_alloc(struct mm_struct *);
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void page_table_free(struct mm_struct *, unsigned long *);
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void disable_noexec(struct mm_struct *, struct task_struct *);
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static inline void clear_table(unsigned long *s, unsigned long val, size_t n)
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{
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typedef struct { char _[n]; } addrtype;
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*s = val;
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n = (n / 256) - 1;
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asm volatile(
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#ifdef CONFIG_64BIT
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" mvc 8(248,%0),0(%0)\n"
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#else
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" mvc 4(252,%0),0(%0)\n"
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#endif
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"0: mvc 256(256,%0),0(%0)\n"
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" la %0,256(%0)\n"
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" brct %1,0b\n"
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: "+a" (s), "+d" (n), "=m" (*(addrtype *) s)
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: "m" (*(addrtype *) s));
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}
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static inline void crst_table_init(unsigned long *crst, unsigned long entry)
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{
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clear_table(crst, entry, sizeof(unsigned long)*2048);
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crst = get_shadow_table(crst);
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if (crst)
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clear_table(crst, entry, sizeof(unsigned long)*2048);
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}
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#ifndef __s390x__
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static inline unsigned long pgd_entry_type(struct mm_struct *mm)
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{
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return _SEGMENT_ENTRY_EMPTY;
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}
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#define pud_alloc_one(mm,address) ({ BUG(); ((pud_t *)2); })
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#define pud_free(mm, x) do { } while (0)
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#define pmd_alloc_one(mm,address) ({ BUG(); ((pmd_t *)2); })
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#define pmd_free(mm, x) do { } while (0)
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#define pgd_populate(mm, pgd, pud) BUG()
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#define pgd_populate_kernel(mm, pgd, pud) BUG()
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#define pud_populate(mm, pud, pmd) BUG()
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#define pud_populate_kernel(mm, pud, pmd) BUG()
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#else /* __s390x__ */
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static inline unsigned long pgd_entry_type(struct mm_struct *mm)
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{
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if (mm->context.asce_limit <= (1UL << 31))
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return _SEGMENT_ENTRY_EMPTY;
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if (mm->context.asce_limit <= (1UL << 42))
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return _REGION3_ENTRY_EMPTY;
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return _REGION2_ENTRY_EMPTY;
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}
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int crst_table_upgrade(struct mm_struct *, unsigned long limit);
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void crst_table_downgrade(struct mm_struct *, unsigned long limit);
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static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
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if (table)
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crst_table_init(table, _REGION3_ENTRY_EMPTY);
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return (pud_t *) table;
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}
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#define pud_free(mm, pud) crst_table_free(mm, (unsigned long *) pud)
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static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long vmaddr)
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{
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unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
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if (table)
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crst_table_init(table, _SEGMENT_ENTRY_EMPTY);
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return (pmd_t *) table;
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}
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#define pmd_free(mm, pmd) crst_table_free(mm, (unsigned long *) pmd)
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static inline void pgd_populate_kernel(struct mm_struct *mm,
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pgd_t *pgd, pud_t *pud)
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{
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pgd_val(*pgd) = _REGION2_ENTRY | __pa(pud);
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}
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static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
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{
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pgd_populate_kernel(mm, pgd, pud);
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if (mm->context.noexec) {
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pgd = get_shadow_table(pgd);
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pud = get_shadow_table(pud);
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pgd_populate_kernel(mm, pgd, pud);
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}
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}
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static inline void pud_populate_kernel(struct mm_struct *mm,
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pud_t *pud, pmd_t *pmd)
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{
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pud_val(*pud) = _REGION3_ENTRY | __pa(pmd);
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}
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static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
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{
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pud_populate_kernel(mm, pud, pmd);
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if (mm->context.noexec) {
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pud = get_shadow_table(pud);
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pmd = get_shadow_table(pmd);
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pud_populate_kernel(mm, pud, pmd);
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}
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}
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#endif /* __s390x__ */
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static inline pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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spin_lock_init(&mm->context.list_lock);
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INIT_LIST_HEAD(&mm->context.crst_list);
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INIT_LIST_HEAD(&mm->context.pgtable_list);
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return (pgd_t *) crst_table_alloc(mm, s390_noexec);
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}
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#define pgd_free(mm, pgd) crst_table_free(mm, (unsigned long *) pgd)
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static inline void pmd_populate_kernel(struct mm_struct *mm,
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pmd_t *pmd, pte_t *pte)
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{
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pmd_val(*pmd) = _SEGMENT_ENTRY + __pa(pte);
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}
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static inline void pmd_populate(struct mm_struct *mm,
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pmd_t *pmd, pgtable_t pte)
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{
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pmd_populate_kernel(mm, pmd, pte);
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if (mm->context.noexec) {
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pmd = get_shadow_table(pmd);
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pmd_populate_kernel(mm, pmd, pte + PTRS_PER_PTE);
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}
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}
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#define pmd_pgtable(pmd) \
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(pgtable_t)(pmd_val(pmd) & -sizeof(pte_t)*PTRS_PER_PTE)
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/*
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* page table entry allocation/free routines.
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*/
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#define pte_alloc_one_kernel(mm, vmaddr) ((pte_t *) page_table_alloc(mm))
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#define pte_alloc_one(mm, vmaddr) ((pte_t *) page_table_alloc(mm))
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#define pte_free_kernel(mm, pte) page_table_free(mm, (unsigned long *) pte)
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#define pte_free(mm, pte) page_table_free(mm, (unsigned long *) pte)
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#endif /* _S390_PGALLOC_H */
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