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mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma

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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>
This commit is contained in:
Vlastimil Babka 2015-02-11 15:27:15 -08:00 committed by Linus Torvalds
parent 077fcf116c
commit be97a41b29
2 changed files with 39 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/linux/gfp.h
View File

@ -334,22 +334,22 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
}
extern struct page *alloc_pages_vma(gfp_t gfp_mask, int order,
struct vm_area_struct *vma, unsigned long addr,
int node);
extern struct page *alloc_hugepage_vma(gfp_t gfp, struct vm_area_struct *vma,
unsigned long addr, int order);
int node, bool hugepage);
#define alloc_hugepage_vma(gfp_mask, vma, addr, order) \
alloc_pages_vma(gfp_mask, order, vma, addr, numa_node_id(), true)
#else
#define alloc_pages(gfp_mask, order) \
alloc_pages_node(numa_node_id(), gfp_mask, order)
#define alloc_pages_vma(gfp_mask, order, vma, addr, node) \
#define alloc_pages_vma(gfp_mask, order, vma, addr, node, false)\
alloc_pages(gfp_mask, order)
#define alloc_hugepage_vma(gfp_mask, vma, addr, order) \
alloc_pages(gfp_mask, order)
#endif
#define alloc_page(gfp_mask) alloc_pages(gfp_mask, 0)
#define alloc_page_vma(gfp_mask, vma, addr) \
alloc_pages_vma(gfp_mask, 0, vma, addr, numa_node_id())
alloc_pages_vma(gfp_mask, 0, vma, addr, numa_node_id(), false)
#define alloc_page_vma_node(gfp_mask, vma, addr, node) \
alloc_pages_vma(gfp_mask, 0, vma, addr, node)
alloc_pages_vma(gfp_mask, 0, vma, addr, node, false)
extern struct page *alloc_kmem_pages(gfp_t gfp_mask, unsigned int order);
extern struct page *alloc_kmem_pages_node(int nid, gfp_t gfp_mask,

118
mm/mempolicy.c
View File

@ -1988,120 +1988,68 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
* @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.
*