[PATCH] xen/gntdev: Grant maps should not be subject to NUMA balancing

From	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Newsgroups	linux.kernel
Subject	[PATCH] xen/gntdev: Grant maps should not be subject to NUMA balancing
Date	2015-11-10 20:30 +0100
Message-ID	<qtmM9-MK-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Doing so will cause the grant to be unmapped and then, during
fault handling, the fault to be mistakenly treated as NUMA hint
fault.

In addition, even if we those maps could partcipate in NUMA
balancing it wouldn't provide any benefit since we wouldn't be
able to determine physical page's node (even if/when VNUMA is
implemented).

Marking grant maps' VMAs as VM_IO will exclude them from being
part of NUMA balancing.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 drivers/xen/gntdev.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 67b9163..bf312df 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -802,7 +802,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 
 	vma->vm_ops = &gntdev_vmops;
 
-	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
 
 	if (use_ptemod)
 		vma->vm_flags |= VM_DONTCOPY;
-- 
1.7.1

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[PATCH] xen/gntdev: Grant maps should not be subject to NUMA balancing Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-10 20:30 +0100
  Re: [PATCH] xen/gntdev: Grant maps should not be subject to NUMA  balancing Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2015-11-10 21:00 +0100

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