diff options
Diffstat (limited to 'mm/khugepaged.c')
| -rw-r--r-- | mm/khugepaged.c | 54 |
1 files changed, 38 insertions, 16 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index acf66c5dc9bd..349b4782d9f4 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -53,6 +53,9 @@ enum scan_result { #define CREATE_TRACE_POINTS #include <trace/events/huge_memory.h> +static struct task_struct *khugepaged_thread __read_mostly; +static DEFINE_MUTEX(khugepaged_mutex); + /* default scan 8*512 pte (or vmas) every 30 second */ static unsigned int khugepaged_pages_to_scan __read_mostly; static unsigned int khugepaged_pages_collapsed; @@ -394,7 +397,7 @@ static void insert_to_mm_slots_hash(struct mm_struct *mm, static inline int khugepaged_test_exit(struct mm_struct *mm) { - return atomic_read(&mm->mm_users) == 0; + return atomic_read(&mm->mm_users) == 0 || !mmget_still_valid(mm); } int __khugepaged_enter(struct mm_struct *mm) @@ -407,7 +410,7 @@ int __khugepaged_enter(struct mm_struct *mm) return -ENOMEM; /* __khugepaged_exit() must not run from under us */ - VM_BUG_ON_MM(khugepaged_test_exit(mm), mm); + VM_BUG_ON_MM(atomic_read(&mm->mm_users) == 0, mm); if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) { free_mm_slot(mm_slot); return 0; @@ -801,6 +804,18 @@ static struct page *khugepaged_alloc_hugepage(bool *wait) static bool khugepaged_prealloc_page(struct page **hpage, bool *wait) { + /* + * If the hpage allocated earlier was briefly exposed in page cache + * before collapse_file() failed, it is possible that racing lookups + * have not yet completed, and would then be unpleasantly surprised by + * finding the hpage reused for the same mapping at a different offset. + * Just release the previous allocation if there is any danger of that. + */ + if (*hpage && page_count(*hpage) > 1) { + put_page(*hpage); + *hpage = NULL; + } + if (!*hpage) *hpage = khugepaged_alloc_hugepage(wait); @@ -1006,9 +1021,6 @@ static void collapse_huge_page(struct mm_struct *mm, * handled by the anon_vma lock + PG_lock. */ down_write(&mm->mmap_sem); - result = SCAN_ANY_PROCESS; - if (!mmget_still_valid(mm)) - goto out; result = hugepage_vma_revalidate(mm, address, &vma); if (result) goto out; @@ -1252,6 +1264,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot) static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) { struct vm_area_struct *vma; + struct mm_struct *mm; unsigned long addr; pmd_t *pmd, _pmd; @@ -1265,7 +1278,8 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) continue; if (vma->vm_end < addr + HPAGE_PMD_SIZE) continue; - pmd = mm_find_pmd(vma->vm_mm, addr); + mm = vma->vm_mm; + pmd = mm_find_pmd(mm, addr); if (!pmd) continue; /* @@ -1274,14 +1288,16 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) * re-fault. Not ideal, but it's more important to not disturb * the system too much. */ - if (down_write_trylock(&vma->vm_mm->mmap_sem)) { - spinlock_t *ptl = pmd_lock(vma->vm_mm, pmd); - /* assume page table is clear */ - _pmd = pmdp_collapse_flush(vma, addr, pmd); - spin_unlock(ptl); - up_write(&vma->vm_mm->mmap_sem); - atomic_long_dec(&vma->vm_mm->nr_ptes); - pte_free(vma->vm_mm, pmd_pgtable(_pmd)); + if (down_write_trylock(&mm->mmap_sem)) { + if (!khugepaged_test_exit(mm)) { + spinlock_t *ptl = pmd_lock(mm, pmd); + /* assume page table is clear */ + _pmd = pmdp_collapse_flush(vma, addr, pmd); + spin_unlock(ptl); + atomic_long_dec(&mm->nr_ptes); + pte_free(mm, pmd_pgtable(_pmd)); + } + up_write(&mm->mmap_sem); } } i_mmap_unlock_write(mapping); @@ -1936,8 +1952,6 @@ static void set_recommended_min_free_kbytes(void) int start_stop_khugepaged(void) { - static struct task_struct *khugepaged_thread __read_mostly; - static DEFINE_MUTEX(khugepaged_mutex); int err = 0; mutex_lock(&khugepaged_mutex); @@ -1964,3 +1978,11 @@ fail: mutex_unlock(&khugepaged_mutex); return err; } + +void khugepaged_min_free_kbytes_update(void) +{ + mutex_lock(&khugepaged_mutex); + if (khugepaged_enabled() && khugepaged_thread) + set_recommended_min_free_kbytes(); + mutex_unlock(&khugepaged_mutex); +} |