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Subject[RFC v3 16/17] mm: protect madvise vs speculative pf
Date
This is an attempt to protect madvise's effect against the speculative
page fault handler.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
mm/madvise.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 0e3828eae9f8..f91b64564571 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -132,8 +132,9 @@ static long madvise_behavior(struct vm_area_struct *vma,
/*
* vm_flags is protected by the mmap_sem held in write mode.
*/
+ write_seqcount_begin(&vma->vm_sequence);
vma->vm_flags = new_flags;
-
+ write_seqcount_end(&vma->vm_sequence);
out:
if (error == -ENOMEM)
error = -EAGAIN;
@@ -403,9 +404,11 @@ static void madvise_free_page_range(struct mmu_gather *tlb,
.private = tlb,
};

+ write_seqcount_begin(&vma->vm_sequence);
tlb_start_vma(tlb, vma);
walk_page_range(addr, end, &free_walk);
tlb_end_vma(tlb, vma);
+ write_seqcount_end(&vma->vm_sequence);
}

static int madvise_free_single_vma(struct vm_area_struct *vma,
--
2.7.4
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