Subject: + x86-mm-do-not-leak-page-ptl-for-pmd-page-tables.patch added to -mm tree
To: kirill.shutemov@xxxxxxxxxxxxxxx,avagin@xxxxxxxxxx,mingo@xxxxxxxxxx,peterz@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 20 Nov 2013 14:47:05 -0800
The patch titled
Subject: x86, mm: do not leak page->ptl for pmd page tables
has been added to the -mm tree. Its filename is
x86-mm-do-not-leak-page-ptl-for-pmd-page-tables.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-mm-do-not-leak-page-ptl-for-pmd-page-tables.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-mm-do-not-leak-page-ptl-for-pmd-page-tables.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxxx>
Reported-by: Andrey Vagin <avagin@xxxxxxxxxx>
Tested-by: Andrey Vagin <avagin@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/split_page_table_lock | 6 +++---
arch/x86/mm/pgtable.c | 4 +++-
2 files changed, 6 insertions(+), 4 deletions(-)
diff -puN Documentation/vm/split_page_table_lock~x86-mm-do-not-leak-page-ptl-for-pmd-page-tables Documentation/vm/split_page_table_lock
--- a/Documentation/vm/split_page_table_lock~x86-mm-do-not-leak-page-ptl-for-pmd-page-tables
+++ a/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 -puN arch/x86/mm/pgtable.c~x86-mm-do-not-leak-page-ptl-for-pmd-page-tables arch/x86/mm/pgtable.c
--- a/arch/x86/mm/pgtable.c~x86-mm-do-not-leak-page-ptl-for-pmd-page-tables
+++ a/arch/x86/mm/pgtable.c
@@ -61,6 +61,7 @@ void ___pte_free_tlb(struct mmu_gather *
#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 *
#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
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
origin.patch
x86-mm-do-not-leak-page-ptl-for-pmd-page-tables.patch
x86-mm-get-aslr-work-for-hugetlb-mappings.patch
linux-next.patch
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