mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma
The previous commit ("mm/thp: Allocate transparent hugepages on local
node") introduced alloc_hugepage_vma() to mm/mempolicy.c to perform a
special policy for THP allocations. The function has the same interface
as alloc_pages_vma(), shares a lot of boilerplate code and a long
comment.
This patch merges the hugepage special case into alloc_pages_vma. The
extra if condition should be cheap enough price to pay. We also prevent
a (however unlikely) race with parallel mems_allowed update, which could
make hugepage allocation restart only within the fallback call to
alloc_hugepage_vma() and not reconsider the special rule in
alloc_hugepage_vma().
Also by making sure mpol_cond_put(pol) is always called before actual
allocation attempt, we can use a single exit path within the function.
Also update the comment for missing node parameter and obsolete reference
to mm_sem.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8a32873..acbbf4c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1988,120 +1988,68 @@
* @order:Order of the GFP allocation.
* @vma: Pointer to VMA or NULL if not available.
* @addr: Virtual Address of the allocation. Must be inside the VMA.
+ * @node: Which node to prefer for allocation (modulo policy).
+ * @hugepage: for hugepages try only the preferred node if possible
*
* This function allocates a page from the kernel page pool and applies
* a NUMA policy associated with the VMA or the current process.
* When VMA is not NULL caller must hold down_read on the mmap_sem of the
* mm_struct of the VMA to prevent it from going away. Should be used for
- * all allocations for pages that will be mapped into
- * user space. Returns NULL when no page can be allocated.
- *
- * Should be called with the mm_sem of the vma hold.
+ * all allocations for pages that will be mapped into user space. Returns
+ * NULL when no page can be allocated.
*/
struct page *
alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
- unsigned long addr, int node)
+ unsigned long addr, int node, bool hugepage)
{
struct mempolicy *pol;
struct page *page;
unsigned int cpuset_mems_cookie;
+ struct zonelist *zl;
+ nodemask_t *nmask;
retry_cpuset:
pol = get_vma_policy(vma, addr);
cpuset_mems_cookie = read_mems_allowed_begin();
- if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
+ if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage &&
+ pol->mode != MPOL_INTERLEAVE)) {
+ /*
+ * For hugepage allocation and non-interleave policy which
+ * allows the current node, we only try to allocate from the
+ * current node and don't fall back to other nodes, as the
+ * cost of remote accesses would likely offset THP benefits.
+ *
+ * If the policy is interleave, or does not allow the current
+ * node in its nodemask, we allocate the standard way.
+ */
+ nmask = policy_nodemask(gfp, pol);
+ if (!nmask || node_isset(node, *nmask)) {
+ mpol_cond_put(pol);
+ page = alloc_pages_exact_node(node, gfp, order);
+ goto out;
+ }
+ }
+
+ if (pol->mode == MPOL_INTERLEAVE) {
unsigned nid;
nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
mpol_cond_put(pol);
page = alloc_page_interleave(gfp, order, nid);
- if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
- goto retry_cpuset;
-
- return page;
+ goto out;
}
- page = __alloc_pages_nodemask(gfp, order,
- policy_zonelist(gfp, pol, node),
- policy_nodemask(gfp, pol));
+
+ nmask = policy_nodemask(gfp, pol);
+ zl = policy_zonelist(gfp, pol, node);
mpol_cond_put(pol);
+ page = __alloc_pages_nodemask(gfp, order, zl, nmask);
+out:
if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return page;
}
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-/**
- * alloc_hugepage_vma: Allocate a hugepage for a VMA
- * @gfp:
- * %GFP_USER user allocation.
- * %GFP_KERNEL kernel allocations,
- * %GFP_HIGHMEM highmem/user allocations,
- * %GFP_FS allocation should not call back into a file system.
- * %GFP_ATOMIC don't sleep.
- *
- * @vma: Pointer to VMA or NULL if not available.
- * @addr: Virtual Address of the allocation. Must be inside the VMA.
- * @order: Order of the hugepage for gfp allocation.
- *
- * This functions allocate a huge page from the kernel page pool and applies
- * a NUMA policy associated with the VMA or the current process.
- * For policy other than %MPOL_INTERLEAVE, we make sure we allocate hugepage
- * only from the current node if the current node is part of the node mask.
- * If we can't allocate a hugepage we fail the allocation and don' try to fallback
- * to other nodes in the node mask. If the current node is not part of node mask
- * or if the NUMA policy is MPOL_INTERLEAVE we use the allocator that can
- * fallback to nodes in the policy node mask.
- *
- * When VMA is not NULL caller must hold down_read on the mmap_sem of the
- * mm_struct of the VMA to prevent it from going away. Should be used for
- * all allocations for pages that will be mapped into
- * user space. Returns NULL when no page can be allocated.
- *
- * Should be called with vma->vm_mm->mmap_sem held.
- *
- */
-struct page *alloc_hugepage_vma(gfp_t gfp, struct vm_area_struct *vma,
- unsigned long addr, int order)
-{
- struct page *page;
- nodemask_t *nmask;
- struct mempolicy *pol;
- int node = numa_node_id();
- unsigned int cpuset_mems_cookie;
-
-retry_cpuset:
- pol = get_vma_policy(vma, addr);
- cpuset_mems_cookie = read_mems_allowed_begin();
- /*
- * For interleave policy, we don't worry about
- * current node. Otherwise if current node is
- * in nodemask, try to allocate hugepage from
- * the current node. Don't fall back to other nodes
- * for THP.
- */
- if (unlikely(pol->mode == MPOL_INTERLEAVE))
- goto alloc_with_fallback;
- nmask = policy_nodemask(gfp, pol);
- if (!nmask || node_isset(node, *nmask)) {
- mpol_cond_put(pol);
- page = alloc_pages_exact_node(node, gfp, order);
- if (unlikely(!page &&
- read_mems_allowed_retry(cpuset_mems_cookie)))
- goto retry_cpuset;
- return page;
- }
-alloc_with_fallback:
- mpol_cond_put(pol);
- /*
- * if current node is not part of node mask, try
- * the allocation from any node, and we can do retry
- * in that case.
- */
- return alloc_pages_vma(gfp, order, vma, addr, node);
-}
-#endif
-
/**
* alloc_pages_current - Allocate pages.
*