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authorNishanth Aravamudan <nacc@us.ibm.com>2006-09-01 00:27:53 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-01 14:39:10 -0400
commit3b98b087fc2daab67518d2baa8aef19a6ad82723 (patch)
treea7defc8fa53b2023affc072cd20c4f4734e4395d /mm/mempolicy.c
parent1678df37be8abbb381becdc40242ed915e775550 (diff)
[PATCH] fix NUMA interleaving for huge pages
Since vma->vm_pgoff is in units of smallpages, VMAs for huge pages have the lower HPAGE_SHIFT - PAGE_SHIFT bits always cleared, which results in badd offsets to the interleave functions. Take this difference from small pages into account when calculating the offset. This does add a 0-bit shift into the small-page path (via alloc_page_vma()), but I think that is negligible. Also add a BUG_ON to prevent the offset from growing due to a negative right-shift, which probably shouldn't be allowed anyways. Tested on an 8-memory node ppc64 NUMA box and got the interleaving I expected. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Andi Kleen <ak@muc.de> Acked-by: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e07e27e846a2..a9963ceddd65 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1176,7 +1176,15 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
1176 if (vma) { 1176 if (vma) {
1177 unsigned long off; 1177 unsigned long off;
1178 1178
1179 off = vma->vm_pgoff; 1179 /*
1180 * for small pages, there is no difference between
1181 * shift and PAGE_SHIFT, so the bit-shift is safe.
1182 * for huge pages, since vm_pgoff is in units of small
1183 * pages, we need to shift off the always 0 bits to get
1184 * a useful offset.
1185 */
1186 BUG_ON(shift < PAGE_SHIFT);
1187 off = vma->vm_pgoff >> (shift - PAGE_SHIFT);
1180 off += (addr - vma->vm_start) >> shift; 1188 off += (addr - vma->vm_start) >> shift;
1181 return offset_il_node(pol, vma, off); 1189 return offset_il_node(pol, vma, off);
1182 } else 1190 } else