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
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