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authorJason J. Herne <jjherne@linux.vnet.ibm.com>2015-11-20 15:57:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-20 16:17:32 -0800
commit1a763615688b891246c5b0a932d7a95fea4c1a68 (patch)
treeff7dac4e67a0d7121b156b6e06544b5c94469f53
parent7511c3ede752e6dd67df20779b4e11effe102637 (diff)
downloadop-kernel-dev-1a763615688b891246c5b0a932d7a95fea4c1a68.zip
op-kernel-dev-1a763615688b891246c5b0a932d7a95fea4c1a68.tar.gz
mm: loosen MADV_NOHUGEPAGE to enable Qemu postcopy on s390
MADV_NOHUGEPAGE processing is too restrictive. kvm already disables hugepage but hugepage_madvise() takes the error path when we ask to turn on the MADV_NOHUGEPAGE bit and the bit is already on. This causes Qemu's new postcopy migration feature to fail on s390 because its first action is to madvise the guest address space as NOHUGEPAGE. This patch modifies the code so that the operation succeeds without error now. For consistency reasons do the same for MADV_HUGEPAGE. Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/huge_memory.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c29ddeb..62fe06b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2009,7 +2009,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
/*
* Be somewhat over-protective like KSM for now!
*/
- if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
+ if (*vm_flags & VM_NO_THP)
return -EINVAL;
*vm_flags &= ~VM_NOHUGEPAGE;
*vm_flags |= VM_HUGEPAGE;
@@ -2025,7 +2025,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
/*
* Be somewhat over-protective like KSM for now!
*/
- if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
+ if (*vm_flags & VM_NO_THP)
return -EINVAL;
*vm_flags &= ~VM_HUGEPAGE;
*vm_flags |= VM_NOHUGEPAGE;
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