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e12e4044ae
In case a fork or a clone system fails in copy_process and the error handling does the mmput() at the bad_fork_cleanup_mm label, the following warning messages will appear on the console: BUG: non-zero pgtables_bytes on freeing mm: 16384 The reason for that is the tricks we play with mm_inc_nr_puds() and mm_inc_nr_pmds() in init_new_context(). A normal 64-bit process has 3 levels of page table, the p4d level and the pud level are folded. On process termination the free_pud_range() function in mm/memory.c will subtract 16KB from pgtable_bytes with a mm_dec_nr_puds() call, but there actually is not really a pud table. One issue with this is the fact that pgtable_bytes is usually off by a few kilobytes, but the more severe problem is that for a failed fork or clone the free_pgtables() function is not called. In this case there is no mm_dec_nr_puds() or mm_dec_nr_pmds() that go together with the mm_inc_nr_puds() and mm_inc_nr_pmds in init_new_context(). The pgtable_bytes will be off by 16384 or 32768 bytes and we get the BUG message. The message itself is purely cosmetic, but annoying. To fix this override the mm_pmd_folded, mm_pud_folded and mm_p4d_folded function to check for the true size of the address space. Reported-by: Li Wang <liwang@redhat.com> Tested-by: Li Wang <liwang@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
157 lines
4.3 KiB
C
157 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* S390 version
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* Copyright IBM Corp. 1999, 2000
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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/string.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#define CRST_ALLOC_ORDER 2
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unsigned long *crst_table_alloc(struct mm_struct *);
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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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struct page *page_table_alloc_pgste(struct mm_struct *mm);
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void page_table_free(struct mm_struct *, unsigned long *);
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void page_table_free_rcu(struct mmu_gather *, unsigned long *, unsigned long);
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void page_table_free_pgste(struct page *page);
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extern int page_table_allocate_pgste;
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static inline void crst_table_init(unsigned long *crst, unsigned long entry)
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{
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memset64((u64 *)crst, entry, _CRST_ENTRIES);
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}
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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_pmd_folded(mm))
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return _SEGMENT_ENTRY_EMPTY;
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if (mm_pud_folded(mm))
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return _REGION3_ENTRY_EMPTY;
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if (mm_p4d_folded(mm))
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return _REGION2_ENTRY_EMPTY;
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return _REGION1_ENTRY_EMPTY;
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}
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int crst_table_upgrade(struct mm_struct *mm, unsigned long limit);
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void crst_table_downgrade(struct mm_struct *);
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static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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unsigned long *table = crst_table_alloc(mm);
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if (table)
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crst_table_init(table, _REGION2_ENTRY_EMPTY);
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return (p4d_t *) table;
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}
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#define p4d_free(mm, p4d) crst_table_free(mm, (unsigned long *) p4d)
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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);
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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);
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if (!table)
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return NULL;
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crst_table_init(table, _SEGMENT_ENTRY_EMPTY);
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if (!pgtable_pmd_page_ctor(virt_to_page(table))) {
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crst_table_free(mm, table);
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return NULL;
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}
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return (pmd_t *) table;
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}
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static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
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{
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pgtable_pmd_page_dtor(virt_to_page(pmd));
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crst_table_free(mm, (unsigned long *) pmd);
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}
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static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d)
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{
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pgd_val(*pgd) = _REGION1_ENTRY | __pa(p4d);
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}
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static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4d, pud_t *pud)
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{
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p4d_val(*p4d) = _REGION2_ENTRY | __pa(pud);
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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_val(*pud) = _REGION3_ENTRY | __pa(pmd);
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}
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static inline pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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unsigned long *table = crst_table_alloc(mm);
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if (!table)
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return NULL;
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if (mm->context.asce_limit == _REGION3_SIZE) {
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/* Forking a compat process with 2 page table levels */
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if (!pgtable_pmd_page_ctor(virt_to_page(table))) {
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crst_table_free(mm, table);
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return NULL;
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}
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}
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return (pgd_t *) table;
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}
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static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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if (mm->context.asce_limit == _REGION3_SIZE)
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pgtable_pmd_page_dtor(virt_to_page(pgd));
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crst_table_free(mm, (unsigned long *) pgd);
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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_val(*pmd) = _SEGMENT_ENTRY + __pa(pte);
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}
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#define pmd_populate_kernel(mm, pmd, pte) pmd_populate(mm, pmd, pte)
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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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extern void rcu_table_freelist_finish(void);
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void vmem_map_init(void);
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void *vmem_crst_alloc(unsigned long val);
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pte_t *vmem_pte_alloc(void);
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unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages);
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void base_asce_free(unsigned long asce);
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#endif /* _S390_PGALLOC_H */
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