The patch titled Subject: mm: fix false-positive warning on exit due mm_nr_pmds(mm) has been removed from the -mm tree. Its filename was mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Subject: mm: fix false-positive warning on exit due mm_nr_pmds(mm) 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@xxxxxxxxxxxxxxx> Reported-by: Tyler Baker <tyler.baker@xxxxxxxxxx> Tested-by: Tyler Baker <tyler.baker@xxxxxxxxxx> Tested-by: Nishanth Menon <nm@xxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxxx> Cc: James Hogan <james.hogan@xxxxxxxxxx> Cc: Guan Xuetao <gxt@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm/mm/pgd.c | 4 ++++ arch/unicore32/mm/pgd.c | 3 +++ kernel/fork.c | 8 ++++++++ mm/mmap.c | 5 ----- 4 files changed, 15 insertions(+), 5 deletions(-) diff -puN arch/arm/mm/pgd.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm arch/arm/mm/pgd.c --- a/arch/arm/mm/pgd.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm +++ a/arch/arm/mm/pgd.c @@ -97,6 +97,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm) no_pte: pmd_free(mm, new_pmd); + mm_dec_nr_pmds(mm); no_pmd: pud_free(mm, new_pud); no_pud: @@ -130,9 +131,11 @@ void pgd_free(struct mm_struct *mm, pgd_ pte = pmd_pgtable(*pmd); pmd_clear(pmd); pte_free(mm, pte); + atomic_long_dec(&mm->nr_ptes); no_pmd: pud_clear(pud); pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); no_pud: pgd_clear(pgd); pud_free(mm, pud); @@ -152,6 +155,7 @@ no_pgd: pmd = pmd_offset(pud, 0); pud_clear(pud); pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); pgd_clear(pgd); pud_free(mm, pud); } diff -puN arch/unicore32/mm/pgd.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm arch/unicore32/mm/pgd.c --- a/arch/unicore32/mm/pgd.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm +++ a/arch/unicore32/mm/pgd.c @@ -69,6 +69,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm no_pte: pmd_free(mm, new_pmd); + mm_dec_nr_pmds(mm); no_pmd: free_pages((unsigned long)new_pgd, 0); no_pgd: @@ -96,7 +97,9 @@ void free_pgd_slow(struct mm_struct *mm, pte = pmd_pgtable(*pmd); pmd_clear(pmd); pte_free(mm, pte); + atomic_long_dec(&mm->nr_ptes); pmd_free(mm, pmd); + mm_dec_nr_pmds(mm); free: free_pages((unsigned long) pgd, 0); } diff -puN kernel/fork.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm kernel/fork.c --- a/kernel/fork.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm +++ a/kernel/fork.c @@ -606,6 +606,14 @@ static void check_mm(struct mm_struct *m printk(KERN_ALERT "BUG: Bad rss-counter state " "mm:%p idx:%d val:%ld\n", mm, i, x); } + + if (atomic_long_read(&mm->nr_ptes)) + pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n", + atomic_long_read(&mm->nr_ptes)); + if (mm_nr_pmds(mm)) + pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n", + mm_nr_pmds(mm)); + #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS VM_BUG_ON_MM(mm->pmd_huge_pte, mm); #endif diff -puN mm/mmap.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm mm/mmap.c --- a/mm/mmap.c~mm-fix-false-positive-warning-on-exit-due-mm_nr_pmdsmm +++ a/mm/mmap.c @@ -2851,11 +2851,6 @@ void exit_mmap(struct mm_struct *mm) vma = remove_vma(vma); } vm_unacct_memory(nr_accounted); - - WARN_ON(atomic_long_read(&mm->nr_ptes) > - round_up(FIRST_USER_ADDRESS, PMD_SIZE) >> PMD_SHIFT); - WARN_ON(mm_nr_pmds(mm) > - round_up(FIRST_USER_ADDRESS, PUD_SIZE) >> PUD_SHIFT); } /* Insert vm structure into process list sorted by address _ Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are origin.patch mm-numa-do-not-dereference-pmd-outside-of-the-lock-during-numa-hinting-fault.patch mm-add-p-protnone-helpers-for-use-by-numa-balancing.patch mm-convert-p_numa-users-to-p_protnone_numa.patch ppc64-add-paranoid-warnings-for-unexpected-dsisr_protfault.patch mm-convert-p_mknonnuma-and-remaining-page-table-manipulations.patch mm-remove-remaining-references-to-numa-hinting-bits-and-helpers.patch mm-numa-do-not-trap-faults-on-the-huge-zero-page.patch x86-mm-restore-original-pte_special-check.patch mm-numa-add-paranoid-check-around-pte_protnone_numa.patch mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch mm-do-not-use-mm-nr_pmds-on-mmu-configurations.patch mm-fix-xip-fault-vs-truncate-race.patch mm-fix-xip-fault-vs-truncate-race-fix.patch mm-allow-page-fault-handlers-to-perform-the-cow.patch mm-allow-page-fault-handlers-to-perform-the-cow-fix.patch vfsext2-introduce-is_daxinode.patch daxext2-replace-xip-read-and-write-with-dax-i-o.patch daxext2-replace-ext2_clear_xip_target-with-dax_clear_blocks.patch daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler.patch daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler-fix.patch daxext2-replace-xip_truncate_page-with-dax_truncate_page.patch dax-replace-xip-documentation-with-dax-documentation.patch vfs-remove-get_xip_mem.patch ext2-remove-ext2_xip_verify_sb.patch ext2-remove-ext2_use_xip.patch ext2-remove-xipc-and-xiph.patch vfsext2-remove-config_ext2_fs_xip-and-rename-config_fs_xip-to-config_fs_dax.patch ext2-remove-ext2_aops_xip.patch ext2-get-rid-of-most-mentions-of-xip-in-ext2.patch dax-add-dax_zero_page_range.patch dax-add-dax_zero_page_range-fix.patch ext4-add-dax-functionality.patch brd-rename-xip-to-dax.patch powerpc-drop-_page_file-and-pte_file-related-helpers.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html