Using static tracepoints, data of functions is recorded.
It is good to automatize debugging without doing a lot
of changes in the source code.
This patch adds tracepoint for khugepaged_scan_pmd,
collapse_huge_page and __collapse_huge_page_isolate.
Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
---
Changes in v2:
- Nothing changed
Changes in v3:
- Print page address instead of vm_start (Vlastimil Babka)
- Define constants to specify exact tracepoint result (Vlastimil Babka)
include/linux/mm.h | 18 ++++++
include/trace/events/huge_memory.h | 100 ++++++++++++++++++++++++++++++++
mm/huge_memory.c | 114 +++++++++++++++++++++++++++----------
3 files changed, 203 insertions(+), 29 deletions(-)
create mode 100644 include/trace/events/huge_memory.h
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7f47178..bf341c0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -21,6 +21,24 @@
#include <linux/resource.h>
#include <linux/page_ext.h>
+#define MM_PMD_NULL 0
+#define MM_EXCEED_NONE_PTE 3
+#define MM_PTE_NON_PRESENT 4
+#define MM_PAGE_NULL 5
+#define MM_SCAN_ABORT 6
+#define MM_PAGE_COUNT 7
+#define MM_PAGE_LRU 8
+#define MM_ANY_PROCESS 0
+#define MM_VMA_NULL 2
+#define MM_VMA_CHECK 3
+#define MM_ADDRESS_RANGE 4
+#define MM_PAGE_LOCK 2
+#define MM_SWAP_CACHE_PAGE 6
+#define MM_ISOLATE_LRU_PAGE 7
+#define MM_ALLOC_HUGE_PAGE_FAIL 6
+#define MM_CGROUP_CHARGE_FAIL 7
+#define MM_COLLAPSE_ISOLATE_FAIL 5
+
struct mempolicy;
struct anon_vma;
struct anon_vma_chain;
diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
new file mode 100644
index 0000000..cbc56fc
--- /dev/null
+++ b/include/trace/events/huge_memory.h
@@ -0,0 +1,100 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM huge_memory
+
+#if !defined(__HUGE_MEMORY_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __HUGE_MEMORY_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(mm_khugepaged_scan_pmd,
+
+ TP_PROTO(struct mm_struct *mm, struct page *page, bool writable,
+ bool referenced, int none_or_zero, int ret),
+
+ TP_ARGS(mm, page, writable, referenced, none_or_zero, ret),
+
+ TP_STRUCT__entry(
+ __field(struct mm_struct *, mm)
+ __field(struct page *, page)
+ __field(bool, writable)
+ __field(bool, referenced)
+ __field(int, none_or_zero)
+ __field(int, ret)
+ ),
+
+ TP_fast_assign(
+ __entry->mm = mm;
+ __entry->page = page;
+ __entry->writable = writable;
+ __entry->referenced = referenced;
+ __entry->none_or_zero = none_or_zero;
+ __entry->ret = ret;
+ ),
+
+ TP_printk("mm=%p, page=%p, writable=%d, referenced=%d, none_or_zero=%d, ret=%d",
+ __entry->mm,
+ __entry->page,
+ __entry->writable,
+ __entry->referenced,
+ __entry->none_or_zero,
+ __entry->ret)
+);
+
+TRACE_EVENT(mm_collapse_huge_page,
+
+ TP_PROTO(struct mm_struct *mm, int isolated, int ret),
+
+ TP_ARGS(mm, isolated, ret),
+
+ TP_STRUCT__entry(
+ __field(struct mm_struct *, mm)
+ __field(int, isolated)
+ __field(int, ret)
+ ),
+
+ TP_fast_assign(
+ __entry->mm = mm;
+ __entry->isolated = isolated;
+ __entry->ret = ret;
+ ),
+
+ TP_printk("mm=%p, isolated=%d, ret=%d",
+ __entry->mm,
+ __entry->isolated,
+ __entry->ret)
+);
+
+TRACE_EVENT(mm_collapse_huge_page_isolate,
+
+ TP_PROTO(struct page *page, int none_or_zero,
+ bool referenced, bool writable, int ret),
+
+ TP_ARGS(page, none_or_zero, referenced, writable, ret),
+
+ TP_STRUCT__entry(
+ __field(struct page *, page)
+ __field(int, none_or_zero)
+ __field(bool, referenced)
+ __field(bool, writable)
+ __field(int, ret)
+ ),
+
+ TP_fast_assign(
+ __entry->page = page;
+ __entry->none_or_zero = none_or_zero;
+ __entry->referenced = referenced;
+ __entry->writable = writable;
+ __entry->ret = ret;
+ ),
+
+ TP_printk("page=%p, none_or_zero=%d, referenced=%d, writable=%d, ret=%d",
+ __entry->page,
+ __entry->none_or_zero,
+ __entry->referenced,
+ __entry->writable,
+ __entry->ret)
+);
+
+#endif /* __HUGE_MEMORY_H */
+#include <trace/define_trace.h>
+
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9671f51..595edd9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -29,6 +29,9 @@
#include <asm/pgalloc.h>
#include "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/huge_memory.h>
+
/*
* By default transparent hugepage support is disabled in order that avoid
* to risk increase the memory footprint of applications without a guaranteed
@@ -2190,25 +2193,32 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
unsigned long address,
pte_t *pte)
{
- struct page *page;
+ struct page *page = NULL;
pte_t *_pte;
- int none_or_zero = 0;
+ int none_or_zero = 0, ret = 0;
bool referenced = false, writable = false;
for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
_pte++, address += PAGE_SIZE) {
pte_t pteval = *_pte;
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none)
+ ++none_or_zero <= khugepaged_max_ptes_none) {
continue;
- else
+ } else {
+ ret = MM_EXCEED_NONE_PTE;
goto out;
+ }
}
- if (!pte_present(pteval))
+ if (!pte_present(pteval)) {
+ ret = MM_PTE_NON_PRESENT;
goto out;
+ }
+
page = vm_normal_page(vma, address, pteval);
- if (unlikely(!page))
+ if (unlikely(!page)) {
+ ret = MM_PAGE_NULL;
goto out;
+ }
VM_BUG_ON_PAGE(PageCompound(page), page);
VM_BUG_ON_PAGE(!PageAnon(page), page);
@@ -2220,8 +2230,10 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
* is needed to serialize against split_huge_page
* when invoked from the VM.
*/
- if (!trylock_page(page))
+ if (!trylock_page(page)) {
+ ret = MM_PAGE_LOCK;
goto out;
+ }
/*
* cannot use mapcount: can't collapse if there's a gup pin.
@@ -2230,6 +2242,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
*/
if (page_count(page) != 1 + !!PageSwapCache(page)) {
unlock_page(page);
+ ret = MM_PAGE_COUNT;
goto out;
}
if (pte_write(pteval)) {
@@ -2237,6 +2250,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
} else {
if (PageSwapCache(page) && !reuse_swap_page(page)) {
unlock_page(page);
+ ret = MM_SWAP_CACHE_PAGE;
goto out;
}
/*
@@ -2251,6 +2265,7 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
*/
if (isolate_lru_page(page)) {
unlock_page(page);
+ ret = MM_ISOLATE_LRU_PAGE;
goto out;
}
/* 0 stands for page_is_file_cache(page) == false */
@@ -2263,11 +2278,16 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
- if (likely(referenced && writable))
+ if (likely(referenced && writable)) {
+ trace_mm_collapse_huge_page_isolate(page, none_or_zero,
+ referenced, writable, ret);
return 1;
+ }
out:
release_pte_pages(pte, _pte);
- return 0;
+ trace_mm_collapse_huge_page_isolate(page, none_or_zero,
+ referenced, writable, ret);
+ return ret;
}
static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
@@ -2501,7 +2521,7 @@ static void collapse_huge_page(struct mm_struct *mm,
pgtable_t pgtable;
struct page *new_page;
spinlock_t *pmd_ptl, *pte_ptl;
- int isolated;
+ int isolated = 0, ret = 1;
unsigned long hstart, hend;
struct mem_cgroup *memcg;
unsigned long mmun_start; /* For mmu_notifiers */
@@ -2516,12 +2536,18 @@ static void collapse_huge_page(struct mm_struct *mm,
/* release the mmap_sem read lock. */
new_page = khugepaged_alloc_page(hpage, gfp, mm, vma, address, node);
- if (!new_page)
+ if (!new_page) {
+ ret = MM_ALLOC_HUGE_PAGE_FAIL;
+ trace_mm_collapse_huge_page(mm, isolated, ret);
return;
+ }
if (unlikely(mem_cgroup_try_charge(new_page, mm,
- gfp, &memcg)))
+ gfp, &memcg))) {
+ ret = MM_CGROUP_CHARGE_FAIL;
+ trace_mm_collapse_huge_page(mm, isolated, ret);
return;
+ }
/*
* Prevent all access to pagetables with the exception of
@@ -2529,21 +2555,31 @@ static void collapse_huge_page(struct mm_struct *mm,
* handled by the anon_vma lock + PG_lock.
*/
down_write(&mm->mmap_sem);
- if (unlikely(khugepaged_test_exit(mm)))
+ if (unlikely(khugepaged_test_exit(mm))) {
+ ret = MM_ANY_PROCESS;
goto out;
+ }
vma = find_vma(mm, address);
- if (!vma)
+ if (!vma) {
+ ret = MM_VMA_NULL;
goto out;
+ }
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
- if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+ if (address < hstart || address + HPAGE_PMD_SIZE > hend) {
+ ret = MM_ADDRESS_RANGE;
goto out;
- if (!hugepage_vma_check(vma))
+ }
+ if (!hugepage_vma_check(vma)) {
+ ret = MM_VMA_CHECK;
goto out;
+ }
pmd = mm_find_pmd(mm, address);
- if (!pmd)
+ if (!pmd) {
+ ret = MM_PMD_NULL;
goto out;
+ }
anon_vma_lock_write(vma->anon_vma);
@@ -2568,7 +2604,7 @@ static void collapse_huge_page(struct mm_struct *mm,
isolated = __collapse_huge_page_isolate(vma, address, pte);
spin_unlock(pte_ptl);
- if (unlikely(!isolated)) {
+ if (unlikely(isolated != 1)) {
pte_unmap(pte);
spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
@@ -2580,6 +2616,7 @@ static void collapse_huge_page(struct mm_struct *mm,
pmd_populate(mm, pmd, pmd_pgtable(_pmd));
spin_unlock(pmd_ptl);
anon_vma_unlock_write(vma->anon_vma);
+ ret = MM_COLLAPSE_ISOLATE_FAIL;
goto out;
}
@@ -2619,6 +2656,7 @@ static void collapse_huge_page(struct mm_struct *mm,
khugepaged_pages_collapsed++;
out_up_write:
up_write(&mm->mmap_sem);
+ trace_mm_collapse_huge_page(mm, isolated, ret);
return;
out:
@@ -2634,7 +2672,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
pmd_t *pmd;
pte_t *pte, *_pte;
int ret = 0, none_or_zero = 0;
- struct page *page;
+ struct page *page = NULL;
unsigned long _address;
spinlock_t *ptl;
int node = NUMA_NO_NODE;
@@ -2643,8 +2681,10 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
pmd = mm_find_pmd(mm, address);
- if (!pmd)
+ if (!pmd) {
+ ret = MM_PMD_NULL;
goto out;
+ }
memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
@@ -2653,19 +2693,26 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
pte_t pteval = *_pte;
if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
if (!userfaultfd_armed(vma) &&
- ++none_or_zero <= khugepaged_max_ptes_none)
+ ++none_or_zero <= khugepaged_max_ptes_none) {
continue;
- else
+ } else {
+ ret = MM_EXCEED_NONE_PTE;
goto out_unmap;
+ }
}
- if (!pte_present(pteval))
+ if (!pte_present(pteval)) {
+ ret = MM_PTE_NON_PRESENT;
goto out_unmap;
+ }
if (pte_write(pteval))
writable = true;
page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page))
+ if (unlikely(!page)) {
+ ret = MM_PAGE_NULL;
goto out_unmap;
+ }
+
/*
* Record which node the original page is from and save this
* information to khugepaged_node_load[].
@@ -2673,33 +2720,42 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
* hit record.
*/
node = page_to_nid(page);
- if (khugepaged_scan_abort(node))
+ if (khugepaged_scan_abort(node)) {
+ ret = MM_SCAN_ABORT;
goto out_unmap;
+ }
khugepaged_node_load[node]++;
VM_BUG_ON_PAGE(PageCompound(page), page);
- if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
+ if (!PageLRU(page) || PageLocked(page) || !PageAnon(page)) {
+ ret = MM_PAGE_LRU;
goto out_unmap;
+ }
/*
* cannot use mapcount: can't collapse if there's a gup pin.
* The page must only be referenced by the scanned process
* and page swap cache.
*/
- if (page_count(page) != 1 + !!PageSwapCache(page))
+ if (page_count(page) != 1 + !!PageSwapCache(page)) {
+ ret = MM_PAGE_COUNT;
goto out_unmap;
+ }
if (pte_young(pteval) || PageReferenced(page) ||
mmu_notifier_test_young(vma->vm_mm, address))
referenced = true;
}
+ /* only 1 for scan succeed case */
if (referenced && writable)
ret = 1;
out_unmap:
pte_unmap_unlock(pte, ptl);
- if (ret) {
+ if (ret == 1) {
node = khugepaged_find_target_node();
/* collapse_huge_page will return with the mmap_sem released */
collapse_huge_page(mm, address, hpage, vma, node);
}
out:
+ trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
+ none_or_zero, ret);
return ret;
}
@@ -2795,7 +2851,7 @@ skip:
/* move to next address */
khugepaged_scan.address += HPAGE_PMD_SIZE;
progress += HPAGE_PMD_NR;
- if (ret)
+ if (ret == 1)
/* we released mmap_sem so break loop */
goto breakouterloop_mmap_sem;
if (progress >= pages)
--
1.9.1
--
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