From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
To: paulmck@linux.vnet.ibm.com, peterz@infradead.org,
akpm@linux-foundation.org, kirill@shutemov.name,
ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net,
jack@suse.cz, Matthew Wilcox <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com,
npiggin@gmail.com, bsingharora@gmail.com,
Tim Chen <tim.c.chen@linux.intel.com>
Subject: [RFC v5 01/11] mm: Dont assume page-table invariance during faults
Date: Fri, 16 Jun 2017 19:52:25 +0200 [thread overview]
Message-ID: <1497635555-25679-2-git-send-email-ldufour@linux.vnet.ibm.com> (raw)
In-Reply-To: <1497635555-25679-1-git-send-email-ldufour@linux.vnet.ibm.com>
From: Peter Zijlstra <peterz@infradead.org>
One of the side effects of speculating on faults (without holding
mmap_sem) is that we can race with free_pgtables() and therefore we
cannot assume the page-tables will stick around.
Remove the relyance on the pte pointer.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
mm/memory.c | 27 ---------------------------
1 file changed, 27 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 2e65df1831d9..fd952f05e016 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2102,30 +2102,6 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
}
EXPORT_SYMBOL_GPL(apply_to_page_range);
-/*
- * handle_pte_fault chooses page fault handler according to an entry which was
- * read non-atomically. Before making any commitment, on those architectures
- * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
- * parts, do_swap_page must check under lock before unmapping the pte and
- * proceeding (but do_wp_page is only called after already making such a check;
- * and do_anonymous_page can safely check later on).
- */
-static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
- pte_t *page_table, pte_t orig_pte)
-{
- int same = 1;
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
- if (sizeof(pte_t) > sizeof(unsigned long)) {
- spinlock_t *ptl = pte_lockptr(mm, pmd);
- spin_lock(ptl);
- same = pte_same(*page_table, orig_pte);
- spin_unlock(ptl);
- }
-#endif
- pte_unmap(page_table);
- return same;
-}
-
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
{
debug_dma_assert_idle(src);
@@ -2682,9 +2658,6 @@ int do_swap_page(struct vm_fault *vmf)
int exclusive = 0;
int ret = 0;
- if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
- goto out;
-
entry = pte_to_swp_entry(vmf->orig_pte);
if (unlikely(non_swap_entry(entry))) {
if (is_migration_entry(entry)) {
--
2.7.4
--
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next prev parent reply other threads:[~2017-06-16 17:52 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-16 17:52 [RFC v5 00/11] Speculative page faults Laurent Dufour
2017-06-16 17:52 ` Laurent Dufour [this message]
2017-07-07 7:07 ` [RFC v5 01/11] mm: Dont assume page-table invariance during faults Balbir Singh
2017-07-10 17:48 ` Laurent Dufour
2017-07-11 4:26 ` Balbir Singh
2017-08-08 10:04 ` Anshuman Khandual
2017-08-08 9:45 ` Anshuman Khandual
2017-08-08 12:11 ` Laurent Dufour
2017-06-16 17:52 ` [RFC v5 02/11] mm: Prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2017-08-08 10:24 ` Anshuman Khandual
2017-08-08 10:42 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 03/11] mm: Introduce pte_spinlock " Laurent Dufour
2017-08-08 10:35 ` Anshuman Khandual
2017-08-08 12:16 ` Laurent Dufour
2017-06-16 17:52 ` [RFC v5 04/11] mm: VMA sequence count Laurent Dufour
2017-08-08 10:59 ` Anshuman Khandual
2017-08-08 11:04 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 05/11] mm: fix lock dependency against mapping->i_mmap_rwsem Laurent Dufour
2017-08-08 11:17 ` Anshuman Khandual
2017-08-08 12:20 ` Laurent Dufour
2017-08-08 12:49 ` Jan Kara
2017-08-08 13:08 ` Laurent Dufour
2017-08-08 13:15 ` Peter Zijlstra
2017-08-08 13:34 ` Laurent Dufour
2017-06-16 17:52 ` [RFC v5 06/11] mm: Protect VMA modifications using VMA sequence count Laurent Dufour
2017-06-16 17:52 ` [RFC v5 07/11] mm: RCU free VMAs Laurent Dufour
2017-06-16 17:52 ` [RFC v5 08/11] mm: Provide speculative fault infrastructure Laurent Dufour
2017-06-16 17:52 ` [RFC v5 09/11] mm: Try spin lock in speculative path Laurent Dufour
2017-07-05 18:50 ` Peter Zijlstra
2017-07-06 13:46 ` Laurent Dufour
2017-07-06 14:48 ` Peter Zijlstra
2017-07-06 15:29 ` Laurent Dufour
2017-07-06 16:13 ` Peter Zijlstra
2017-06-16 17:52 ` [RFC v5 10/11] x86/mm: Add speculative pagefault handling Laurent Dufour
2017-06-16 17:52 ` [RFC v5 11/11] powerpc/mm: Add speculative page fault Laurent Dufour
2017-07-03 17:32 ` [RFC v5 00/11] Speculative page faults Laurent Dufour
2017-07-07 1:54 ` Balbir Singh
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