From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753815Ab3KUMre (ORCPT ); Thu, 21 Nov 2013 07:47:34 -0500 Received: from mga11.intel.com ([192.55.52.93]:26147 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751225Ab3KUMrd (ORCPT ); Thu, 21 Nov 2013 07:47:33 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,744,1378882800"; d="scan'208";a="437269831" From: "Kirill A. Shutemov" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH] x86, mm: do not leak page->ptl for pmd page tables Date: Thu, 21 Nov 2013 14:46:47 +0200 Message-Id: <1385038007-29666-1-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 1.8.4.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Reported-and-Tested-by: Andrey Vagin --- Documentation/vm/split_page_table_lock | 6 +++--- 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 a7cccb6d7fec..7be5809754cf 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 -- 1.8.4.3