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Subject[RFC 5/8] mm: Add new flag VM_CDM for coherent device memory
Date
VMAs containing coherent device memory should be marked with VM_CDM. These
VMAs need to be identified in various core kernel paths and this new flag
will help in this regard.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
include/linux/mm.h | 5 +++++
mm/mempolicy.c | 43 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 48 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3a19185..acee4d1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -182,6 +182,11 @@ extern unsigned int kobjsize(const void *objp);
#define VM_ACCOUNT 0x00100000 /* Is a VM accounted object */
#define VM_NORESERVE 0x00200000 /* should the VM suppress accounting */
#define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */
+
+#ifdef CONFIG_COHERENT_DEVICE
+#define VM_CDM 0x00800000 /* Contains coherent device memory */
+#endif
+
#define VM_ARCH_1 0x01000000 /* Architecture-specific flag */
#define VM_ARCH_2 0x02000000
#define VM_DONTDUMP 0x04000000 /* Do not include in the core dump */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index cb1ba01..b983cea 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -174,6 +174,47 @@ static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
nodes_onto(*ret, tmp, *rel);
}

+#ifdef CONFIG_COHERENT_DEVICE
+static bool nodemask_contains_cdm(nodemask_t *nodes)
+{
+ int weight, nid, i;
+ nodemask_t mask;
+
+
+ if (!nodes)
+ return false;
+
+ mask = *nodes;
+ weight = nodes_weight(mask);
+ nid = first_node(mask);
+ for (i = 0; i < weight; i++) {
+ if (isolated_cdm_node(nid))
+ return true;
+ nid = next_node(nid, mask);
+ }
+ return false;
+}
+
+static void update_coherent_vma_flag(nodemask_t *nmask,
+ struct page *page, struct vm_area_struct *vma)
+{
+ if (!page)
+ return;
+
+ if (nodemask_contains_cdm(nmask)) {
+ if (!(vma->vm_flags & VM_CDM)) {
+ if (isolated_cdm_node(page_to_nid(page)))
+ vma->vm_flags |= VM_CDM;
+ }
+ }
+}
+#else
+static void update_coherent_vma_flag(nodemask_t *nmask,
+ struct page *page, struct vm_area_struct *vma)
+{
+}
+#endif
+
static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
{
if (nodes_empty(*nodes))
@@ -2045,6 +2086,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
zl = policy_zonelist(gfp, pol, node);
mpol_cond_put(pol);
page = __alloc_pages_nodemask(gfp, order, zl, nmask);
+ update_coherent_vma_flag(nmask, page, vma);
+
out:
if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
--
2.1.0
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