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[RFC v3 13/17] mm/spf Protect vm_policy's changes against speculative pf

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Mark the VMA touched when policy changes are applied to it so that
speculative page fault will be aborted.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
 mm/mempolicy.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1518b022927d..57ec8d0a9c95 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -444,8 +444,11 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
 	struct vm_area_struct *vma;
 
 	down_write(&mm->mmap_sem);
-	for (vma = mm->mmap; vma; vma = vma->vm_next)
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		write_seqcount_begin(&vma->vm_sequence);
 		mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
+		write_seqcount_end(&vma->vm_sequence);
+	}
 	up_write(&mm->mmap_sem);
 }
 
@@ -708,6 +711,7 @@ static int vma_replace_policy(struct vm_area_struct *vma,
 	if (IS_ERR(new))
 		return PTR_ERR(new);
 
+	write_seqcount_begin(&vma->vm_sequence);
 	if (vma->vm_ops && vma->vm_ops->set_policy) {
 		err = vma->vm_ops->set_policy(vma, new);
 		if (err)
@@ -716,10 +720,12 @@ static int vma_replace_policy(struct vm_area_struct *vma,
 
 	old = vma->vm_policy;
 	vma->vm_policy = new; /* protected by mmap_sem */
+	write_seqcount_end(&vma->vm_sequence);
 	mpol_put(old);
 
 	return 0;
  err_out:
+	write_seqcount_end(&vma->vm_sequence);
 	mpol_put(new);
 	return err;
 }
-- 
2.7.4

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[RFC v3 00/17] Speculative page faults Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 03/17] mm: Introduce pte_spinlock Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
    Re: [RFC v3 03/17] mm: Introduce pte_spinlock Matthew Wilcox <willy@infradead.org> - 2017-04-30 06:50 +0200
      Re: [RFC v3 03/17] mm: Introduce pte_spinlock Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-05-03 15:10 +0200
  [RFC v3 13/17] mm/spf Protect vm_policy's changes against speculative pf Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 04/17] mm: VMA sequence count Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 02/17] mm: Prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 12/17] mm/spf: Protect changes to vm_flags Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 14/17] x86/mm: Update the handle_speculative_fault's path Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 06/17] mm: Provide speculative fault infrastructure Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 16/17] mm: protect madvise vs speculative pf Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 09/17] mm/spf: Fix fe.sequence init in __handle_mm_fault() Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  [RFC v3 08/17] mm/spf: Try spin lock in speculative path Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200

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