diff options
| -rw-r--r-- | include/linux/mm.h | 1 | ||||
| -rw-r--r-- | mm/ksm.c | 2 | ||||
| -rw-r--r-- | mm/memory.c | 20 |
3 files changed, 20 insertions, 3 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 6124f1db50fe..e7c3f9a0111a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1651,6 +1651,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma, #define FOLL_SPLIT 0x80 /* don't return transhuge pages, split them */ #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */ #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ +#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); @@ -364,7 +364,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr) do { cond_resched(); - page = follow_page(vma, addr, FOLL_GET); + page = follow_page(vma, addr, FOLL_GET | FOLL_MIGRATION); if (IS_ERR_OR_NULL(page)) break; if (PageKsm(page)) diff --git a/mm/memory.c b/mm/memory.c index 5d2ef1217d0c..ec8ba011fa7d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1548,8 +1548,24 @@ split_fallthrough: ptep = pte_offset_map_lock(mm, pmd, address, &ptl); pte = *ptep; - if (!pte_present(pte)) - goto no_page; + if (!pte_present(pte)) { + swp_entry_t entry; + /* + * KSM's break_ksm() relies upon recognizing a ksm page + * even while it is being migrated, so for that case we + * need migration_entry_wait(). + */ + if (likely(!(flags & FOLL_MIGRATION))) + goto no_page; + if (pte_none(pte) || pte_file(pte)) + goto no_page; + entry = pte_to_swp_entry(pte); + if (!is_migration_entry(entry)) + goto no_page; + pte_unmap_unlock(ptep, ptl); + migration_entry_wait(mm, pmd, address); + goto split_fallthrough; + } if ((flags & FOLL_NUMA) && pte_numa(pte)) goto no_page; if ((flags & FOLL_WRITE) && !pte_write(pte)) |