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authorMichal Hocko <mhocko@suse.cz>2015-04-15 16:13:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-15 16:35:17 -0700
commit3b3636924dfe1e80f9bef2c0dc1207e16f3b078a (patch)
tree6492cb6d3f3e461b6b5fdc5c8943d607e5d8dfd0 /mm
parentcc5993bd7b8cff4a3e37042ee1358d1d5eafa70c (diff)
mm, memcg: sync allocation and memcg charge gfp flags for THP
memcg currently uses hardcoded GFP_TRANSHUGE gfp flags for all THP charges. THP allocations, however, might be using different flags depending on /sys/kernel/mm/transparent_hugepage/{,khugepaged/}defrag and the current allocation context. The primary difference is that defrag configured to "madvise" value will clear __GFP_WAIT flag from the core gfp mask to make the allocation lighter for all mappings which are not backed by VM_HUGEPAGE vmas. If memcg charge path ignores this fact we will get light allocation but the a potential memcg reclaim would kill the whole point of the configuration. Fix the mismatch by providing the same gfp mask used for the allocation to the charge functions. This is quite easy for all paths except for hugepaged kernel thread with !CONFIG_NUMA which is doing a pre-allocation long before the allocated page is used in collapse_huge_page via khugepaged_alloc_page. To prevent from cluttering the whole code path from khugepaged_do_scan we simply return the current flags as per khugepaged_defrag() value which might have changed since the preallocation. If somebody changed the value of the knob we would charge differently but this shouldn't happen often and it is definitely not critical because it would only lead to a reduced success rate of one-off THP promotion. [akpm@linux-foundation.org: fix weird code layout while we're there] [rientjes@google.com: clean up around alloc_hugepage_gfpmask()] Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/huge_memory.c42
1 files changed, 20 insertions, 22 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3afb5cbe1312..4914e1b29fdb 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -708,7 +708,7 @@ static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot)
static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long haddr, pmd_t *pmd,
- struct page *page)
+ struct page *page, gfp_t gfp)
{
struct mem_cgroup *memcg;
pgtable_t pgtable;
@@ -716,7 +716,7 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
VM_BUG_ON_PAGE(!PageCompound(page), page);
- if (mem_cgroup_try_charge(page, mm, GFP_TRANSHUGE, &memcg))
+ if (mem_cgroup_try_charge(page, mm, gfp, &memcg))
return VM_FAULT_OOM;
pgtable = pte_alloc_one(mm, haddr);
@@ -822,7 +822,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
}
- if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page))) {
+ if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page, gfp))) {
put_page(page);
count_vm_event(THP_FAULT_FALLBACK);
return VM_FAULT_FALLBACK;
@@ -1080,6 +1080,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long haddr;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
+ gfp_t huge_gfp; /* for allocation and charge */
ptl = pmd_lockptr(mm, pmd);
VM_BUG_ON_VMA(!vma->anon_vma, vma);
@@ -1106,10 +1107,8 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
alloc:
if (transparent_hugepage_enabled(vma) &&
!transparent_hugepage_debug_cow()) {
- gfp_t gfp;
-
- gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
- new_page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
+ huge_gfp = alloc_hugepage_gfpmask(transparent_hugepage_defrag(vma), 0);
+ new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
} else
new_page = NULL;
@@ -1130,8 +1129,7 @@ alloc:
goto out;
}
- if (unlikely(mem_cgroup_try_charge(new_page, mm,
- GFP_TRANSHUGE, &memcg))) {
+ if (unlikely(mem_cgroup_try_charge(new_page, mm, huge_gfp, &memcg))) {
put_page(new_page);
if (page) {
split_huge_page(page);
@@ -2323,19 +2321,13 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
return true;
}
-static struct page
-*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long address,
int node)
{
- gfp_t flags;
-
VM_BUG_ON_PAGE(*hpage, *hpage);
- /* Only allocate from the target node */
- flags = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
- __GFP_THISNODE;
-
/*
* Before allocating the hugepage, release the mmap_sem read lock.
* The allocation can take potentially a long time if it involves
@@ -2344,7 +2336,7 @@ static struct page
*/
up_read(&mm->mmap_sem);
- *hpage = alloc_pages_exact_node(node, flags, HPAGE_PMD_ORDER);
+ *hpage = alloc_pages_exact_node(node, gfp, HPAGE_PMD_ORDER);
if (unlikely(!*hpage)) {
count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
*hpage = ERR_PTR(-ENOMEM);
@@ -2397,13 +2389,14 @@ static bool khugepaged_prealloc_page(struct page **hpage, bool *wait)
return true;
}
-static struct page
-*khugepaged_alloc_page(struct page **hpage, struct mm_struct *mm,
+static struct page *
+khugepaged_alloc_page(struct page **hpage, gfp_t gfp, struct mm_struct *mm,
struct vm_area_struct *vma, unsigned long address,
int node)
{
up_read(&mm->mmap_sem);
VM_BUG_ON(!*hpage);
+
return *hpage;
}
#endif
@@ -2438,16 +2431,21 @@ static void collapse_huge_page(struct mm_struct *mm,
struct mem_cgroup *memcg;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
+ gfp_t gfp;
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+ /* Only allocate from the target node */
+ gfp = alloc_hugepage_gfpmask(khugepaged_defrag(), __GFP_OTHER_NODE) |
+ __GFP_THISNODE;
+
/* release the mmap_sem read lock. */
- new_page = khugepaged_alloc_page(hpage, mm, vma, address, node);
+ new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node);
if (!new_page)
return;
if (unlikely(mem_cgroup_try_charge(new_page, mm,
- GFP_TRANSHUGE, &memcg)))
+ gfp, &memcg)))
return;
/*

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