Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751840Ab3FSEgs (ORCPT ); Wed, 19 Jun 2013 00:36:48 -0400 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:42370 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750802Ab3FSEgr (ORCPT ); Wed, 19 Jun 2013 00:36:47 -0400 X-AuditID: 9c93016f-b7b6cae000007078-97-51c1355dd614 Date: Wed, 19 Jun 2013 13:36:50 +0900 From: Minchan Kim To: John Stultz Cc: LKML , Andrew Morton , Android Kernel Team , Robert Love , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Dmitry Adamushko , Dave Chinner , Neil Brown , Andrea Righi , Andrea Arcangeli , "Aneesh Kumar K.V" , Mike Hommey , Taras Glek , Dhaval Giani , Jan Kara , KOSAKI Motohiro , Michel Lespinasse , "linux-mm@kvack.org" Subject: Re: [PATCH 8/8] vrange: Send SIGBUS when user try to access purged page Message-ID: <20130619043650.GB10961@bbox> References: <1371010971-15647-1-git-send-email-john.stultz@linaro.org> <1371010971-15647-9-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1371010971-15647-9-git-send-email-john.stultz@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8581 Lines: 260 On Tue, Jun 11, 2013 at 09:22:51PM -0700, John Stultz wrote: > From: Minchan Kim > > By vrange(2) semantic, user should see SIGBUG if he try to access > purged page without vrange(...VRANGE_NOVOLATILE). > > This patch implements it. > > XXX: I reused PSE bit for quick prototype without enough considering > so need time to see what's empty bit and I am surely missing > many places to handle vrange pte bit. I should investigate all of > pte handling places, especially pte_none case. > > Cc: Andrew Morton > Cc: Android Kernel Team > Cc: Robert Love > Cc: Mel Gorman > Cc: Hugh Dickins > Cc: Dave Hansen > Cc: Rik van Riel > Cc: Dmitry Adamushko > Cc: Dave Chinner > Cc: Neil Brown > Cc: Andrea Righi > Cc: Andrea Arcangeli > Cc: Aneesh Kumar K.V > Cc: Mike Hommey > Cc: Taras Glek > Cc: Dhaval Giani > Cc: Jan Kara > Cc: KOSAKI Motohiro > Cc: Michel Lespinasse > Cc: Minchan Kim > Cc: linux-mm@kvack.org > > Signed-off-by: Minchan Kim > [jstultz: Extended to work with file pages] > Signed-off-by: John Stultz > --- > arch/x86/include/asm/pgtable_types.h | 2 ++ > include/asm-generic/pgtable.h | 11 +++++++++++ > include/linux/vrange.h | 2 ++ > mm/memory.c | 23 +++++++++++++++++++++-- > mm/vrange.c | 35 ++++++++++++++++++++++++++++++++++- > 5 files changed, 70 insertions(+), 3 deletions(-) > This patch fixes the problem Dhaval reported. >From e789359cf2ac706e1ebc925f14eb2d7187cd2267 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 11 Jun 2013 21:22:51 -0700 Subject: [PATCH 2/2] vrange: Send SIGBUS when user try to access purged page By vrange(2) semantic, user should see SIGBUG if he try to access purged page without vrange(...VRANGE_NOVOLATILE). This patch implements it. XXX: I reused PSE bit for quick prototype without enough considering so need time to see what's empty bit and I am surely missing many places to handle vrange pte bit. I should investigate all of pte handling places, especially pte_none case. Cc: Andrew Morton Cc: Android Kernel Team Cc: Robert Love Cc: Mel Gorman Cc: Hugh Dickins Cc: Dave Hansen Cc: Rik van Riel Cc: Dmitry Adamushko Cc: Dave Chinner Cc: Neil Brown Cc: Andrea Righi Cc: Andrea Arcangeli Cc: Aneesh Kumar K.V Cc: Mike Hommey Cc: Taras Glek Cc: Dhaval Giani Cc: Jan Kara Cc: KOSAKI Motohiro Cc: Michel Lespinasse Cc: Minchan Kim Cc: linux-mm@kvack.org Signed-off-by: Minchan Kim [jstultz: Extended to work with file pages] Signed-off-by: John Stultz --- arch/x86/include/asm/pgtable_types.h | 2 ++ include/asm-generic/pgtable.h | 11 +++++++++++ include/linux/vrange.h | 2 ++ mm/memory.c | 23 +++++++++++++++++++++-- mm/vrange.c | 31 +++++++++++++++++++++++++++++++ 5 files changed, 67 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index e642300..d7ea6a0 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -64,6 +64,8 @@ #define _PAGE_FILE (_AT(pteval_t, 1) << _PAGE_BIT_FILE) #define _PAGE_PROTNONE (_AT(pteval_t, 1) << _PAGE_BIT_PROTNONE) +#define _PAGE_VRANGE _PAGE_BIT_PSE + /* * _PAGE_NUMA indicates that this page will trigger a numa hinting * minor page fault to gather numa placement statistics (see diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index a59ff51..91e8f6f 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -479,6 +479,17 @@ static inline unsigned long my_zero_pfn(unsigned long addr) #ifdef CONFIG_MMU +static inline pte_t pte_mkvrange(pte_t pte) +{ + pte = pte_set_flags(pte, _PAGE_VRANGE); + return pte_clear_flags(pte, _PAGE_PRESENT); +} + +static inline int pte_vrange(pte_t pte) +{ + return ((pte_flags(pte) | _PAGE_PRESENT) == _PAGE_VRANGE); +} + #ifndef CONFIG_TRANSPARENT_HUGEPAGE static inline int pmd_trans_huge(pmd_t pmd) { diff --git a/include/linux/vrange.h b/include/linux/vrange.h index cbb609a..75754d1 100644 --- a/include/linux/vrange.h +++ b/include/linux/vrange.h @@ -41,6 +41,8 @@ int discard_vpage(struct page *page); bool vrange_address(struct mm_struct *mm, unsigned long start, unsigned long end); +extern bool is_purged_vrange(struct mm_struct *mm, unsigned long address); + #else static inline void vrange_init(void) {}; diff --git a/mm/memory.c b/mm/memory.c index 61a262b..cc5c70b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -59,6 +59,7 @@ #include #include #include +#include #include #include @@ -832,7 +833,7 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, /* pte contains position in swap or file, so copy. */ if (unlikely(!pte_present(pte))) { - if (!pte_file(pte)) { + if (!pte_file(pte) && !pte_vrange(pte)) { swp_entry_t entry = pte_to_swp_entry(pte); if (swap_duplicate(entry) < 0) @@ -1172,7 +1173,7 @@ again: if (pte_file(ptent)) { if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) print_bad_pte(vma, addr, ptent, NULL); - } else { + } else if (!pte_vrange(ptent)) { swp_entry_t entry = pte_to_swp_entry(ptent); if (!non_swap_entry(entry)) @@ -3707,9 +3708,27 @@ int handle_pte_fault(struct mm_struct *mm, return do_linear_fault(mm, vma, address, pte, pmd, flags, entry); } +anon: return do_anonymous_page(mm, vma, address, pte, pmd, flags); } + + if (unlikely(pte_vrange(entry))) { + if (!is_purged_vrange(mm, address)) { + /* zap pte */ + ptl = pte_lockptr(mm, pmd); + spin_lock(ptl); + if (unlikely(!pte_same(*pte, entry))) + goto unlock; + flush_cache_page(vma, address, pte_pfn(*pte)); + ptep_clear_flush(vma, address, pte); + pte_unmap_unlock(pte, ptl); + goto anon; + } + + return VM_FAULT_SIGBUS; + } + if (pte_file(entry)) return do_nonlinear_fault(mm, vma, address, pte, pmd, flags, entry); diff --git a/mm/vrange.c b/mm/vrange.c index d57cb38..9cafb01 100644 --- a/mm/vrange.c +++ b/mm/vrange.c @@ -521,6 +521,7 @@ int try_to_discard_one(struct vrange_root *vroot, struct page *page, BUG_ON(1); } + set_pte_at(mm, addr, pte, pte_mkvrange(*pte)); pte_unmap_unlock(pte, ptl); mmu_notifier_invalidate_page(mm, addr); ret = 1; @@ -696,3 +697,33 @@ int discard_vpage(struct page *page) return 0; } +bool is_purged_vrange(struct mm_struct *mm, unsigned long address) +{ + struct vrange_root *vroot; + struct interval_tree_node *node; + struct vrange *range; + unsigned long vstart_idx; + struct vm_area_struct *vma; + bool ret = false; + + vma = find_vma(mm, address); + if (vma->vm_file && (vma->vm_flags & VM_SHARED)) { + vroot = &vma->vm_file->f_mapping->vroot; + vstart_idx = vma->vm_pgoff + address - vma->vm_start; + } else { + vroot = &mm->vroot; + vstart_idx = address; + } + + vrange_lock(vroot); + node = interval_tree_iter_first(&vroot->v_rb, vstart_idx, + vstart_idx + PAGE_SIZE - 1); + if (node) { + range = container_of(node, struct vrange, node); + if (range->purged) + ret = true; + } + vrange_unlock(vroot); + return ret; +} + -- 1.7.9.5 -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/