diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2013-11-21 14:32:09 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-21 16:42:28 -0800 |
| commit | c283610e44ec4ccc412dde8b71cf297ed9515f2f (patch) | |
| tree | dd3c83db8dabefbeb3733cd428cced7c62602beb | |
| parent | 3a72660b07d86d60457ca32080b1ce8c2b628ee2 (diff) | |
| download | linux-c283610e44ec4ccc412dde8b71cf297ed9515f2f.tar.bz2 | |
x86, mm: do not leak page->ptl for pmd page tables
There are two code paths how page with pmd page table can be freed:
pmd_free() and pmd_free_tlb().
I've missed the second one and didn't add page table destructor call
there. It leads to leak of page->ptl for pmd page tables, if
dynamically allocated page->ptl is in use.
The patch adds the missed destructor and modifies documentation
accordingly.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Andrey Vagin <avagin@openvz.org>
Tested-by: Andrey Vagin <avagin@openvz.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | Documentation/vm/split_page_table_lock | 6 | ||||
| -rw-r--r-- | arch/x86/mm/pgtable.c | 4 |
2 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/vm/split_page_table_lock b/Documentation/vm/split_page_table_lock index 7521d367f21d..6dea4fd5c961 100644 --- a/Documentation/vm/split_page_table_lock +++ b/Documentation/vm/split_page_table_lock @@ -63,9 +63,9 @@ levels. PMD split lock enabling requires pgtable_pmd_page_ctor() call on PMD table allocation and pgtable_pmd_page_dtor() on freeing. -Allocation usually happens in pmd_alloc_one(), freeing in pmd_free(), but -make sure you cover all PMD table allocation / freeing paths: i.e X86_PAE -preallocate few PMDs on pgd_alloc(). +Allocation usually happens in pmd_alloc_one(), freeing in pmd_free() and +pmd_free_tlb(), but make sure you cover all PMD table allocation / freeing +paths: i.e X86_PAE preallocate few PMDs on pgd_alloc(). With everything in place you can set CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK. diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 36aa999b2631..c96314abd144 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -61,6 +61,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte) #if PAGETABLE_LEVELS > 2 void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) { + struct page *page = virt_to_page(pmd); paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT); /* * NOTE! For PAE, any changes to the top page-directory-pointer-table @@ -69,7 +70,8 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd) #ifdef CONFIG_X86_PAE tlb->need_flush_all = 1; #endif - tlb_remove_page(tlb, virt_to_page(pmd)); + pgtable_pmd_page_dtor(page); + tlb_remove_page(tlb, page); } #if PAGETABLE_LEVELS > 3 |