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b30fe6c7ce
The problem is that we check nr_ptes/nr_pmds in exit_mmap() which happens *before* pgd_free(). And if an arch does pte/pmd allocation in pgd_alloc() and frees them in pgd_free() we see offset in counters by the time of the checks. We tried to workaround this by offsetting expected counter value according to FIRST_USER_ADDRESS for both nr_pte and nr_pmd in exit_mmap(). But it doesn't work in some cases: 1. ARM with LPAE enabled also has non-zero USER_PGTABLES_CEILING, but upper addresses occupied with huge pmd entries, so the trick with offsetting expected counter value will get really ugly: we will have to apply it nr_pmds, but not nr_ptes. 2. Metag has non-zero FIRST_USER_ADDRESS, but doesn't do allocation pte/pmd page tables allocation in pgd_alloc(), just setup a pgd entry which is allocated at boot and shared accross all processes. The proposal is to move the check to check_mm() which happens *after* pgd_free() and do proper accounting during pgd_alloc() and pgd_free() which would bring counters to zero if nothing leaked. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Tyler Baker <tyler.baker@linaro.org> Tested-by: Tyler Baker <tyler.baker@linaro.org> Tested-by: Nishanth Menon <nm@ti.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: James Hogan <james.hogan@imgtec.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
106 lines
2.2 KiB
C
106 lines
2.2 KiB
C
/*
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* linux/arch/unicore32/mm/pgd.c
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*
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* Code specific to PKUnity SoC and UniCore ISA
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*
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* Copyright (C) 2001-2010 GUAN Xue-tao
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/mm.h>
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#include <linux/gfp.h>
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#include <linux/highmem.h>
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#include <asm/pgalloc.h>
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#include <asm/page.h>
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#include <asm/tlbflush.h>
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#include "mm.h"
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#define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
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/*
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* need to get a 4k page for level 1
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*/
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pgd_t *get_pgd_slow(struct mm_struct *mm)
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{
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pgd_t *new_pgd, *init_pgd;
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pmd_t *new_pmd, *init_pmd;
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pte_t *new_pte, *init_pte;
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new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 0);
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if (!new_pgd)
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goto no_pgd;
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memset(new_pgd, 0, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
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/*
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* Copy over the kernel and IO PGD entries
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*/
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init_pgd = pgd_offset_k(0);
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memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
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(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
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clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
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if (!vectors_high()) {
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/*
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* On UniCore, first page must always be allocated since it
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* contains the machine vectors.
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*/
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new_pmd = pmd_alloc(mm, (pud_t *)new_pgd, 0);
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if (!new_pmd)
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goto no_pmd;
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new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
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if (!new_pte)
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goto no_pte;
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init_pmd = pmd_offset((pud_t *)init_pgd, 0);
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init_pte = pte_offset_map(init_pmd, 0);
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set_pte(new_pte, *init_pte);
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pte_unmap(init_pte);
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pte_unmap(new_pte);
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}
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return new_pgd;
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no_pte:
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pmd_free(mm, new_pmd);
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mm_dec_nr_pmds(mm);
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no_pmd:
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free_pages((unsigned long)new_pgd, 0);
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no_pgd:
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return NULL;
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}
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void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
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{
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pmd_t *pmd;
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pgtable_t pte;
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if (!pgd)
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return;
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/* pgd is always present and good */
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pmd = pmd_off(pgd, 0);
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if (pmd_none(*pmd))
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goto free;
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if (pmd_bad(*pmd)) {
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pmd_ERROR(*pmd);
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pmd_clear(pmd);
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goto free;
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}
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pte = pmd_pgtable(*pmd);
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pmd_clear(pmd);
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pte_free(mm, pte);
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atomic_long_dec(&mm->nr_ptes);
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pmd_free(mm, pmd);
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mm_dec_nr_pmds(mm);
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free:
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free_pages((unsigned long) pgd, 0);
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}
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