Fortunately, the last user (KSM) is gone, so let's just remove this
rather special code from generic GUP handling -- especially because KSM
never required the PMD handling as KSM only deals with individual base
pages.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/mm.h | 1 -
mm/gup.c | 55 +++++-----------------------------------------
2 files changed, 5 insertions(+), 51 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e56dd8f7eae1..4c176e308ead 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2942,7 +2942,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
* and return without waiting upon it */
#define FOLL_NOFAULT 0x80 /* do not fault in pages */
#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
-#define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */
#define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */
#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
#define FOLL_ANON 0x8000 /* don't do file mappings */
diff --git a/mm/gup.c b/mm/gup.c
index ce00a4c40da8..37195c549f68 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -537,30 +537,13 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
(FOLL_PIN | FOLL_GET)))
return ERR_PTR(-EINVAL);
-retry:
if (unlikely(pmd_bad(*pmd)))
return no_page_table(vma, flags);
ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
pte = *ptep;
- 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))
- 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 retry;
- }
+ if (!pte_present(pte))
+ goto no_page;
if (pte_protnone(pte) && !gup_can_follow_protnone(flags))
goto no_page;
@@ -682,28 +665,8 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
return page;
return no_page_table(vma, flags);
}
-retry:
- if (!pmd_present(pmdval)) {
- /*
- * Should never reach here, if thp migration is not supported;
- * Otherwise, it must be a thp migration entry.
- */
- VM_BUG_ON(!thp_migration_supported() ||
- !is_pmd_migration_entry(pmdval));
-
- if (likely(!(flags & FOLL_MIGRATION)))
- return no_page_table(vma, flags);
-
- pmd_migration_entry_wait(mm, pmd);
- pmdval = READ_ONCE(*pmd);
- /*
- * MADV_DONTNEED may convert the pmd to null because
- * mmap_lock is held in read mode
- */
- if (pmd_none(pmdval))
- return no_page_table(vma, flags);
- goto retry;
- }
+ if (!pmd_present(pmdval))
+ return no_page_table(vma, flags);
if (pmd_devmap(pmdval)) {
ptl = pmd_lock(mm, pmd);
page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
@@ -717,18 +680,10 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma,
if (pmd_protnone(pmdval) && !gup_can_follow_protnone(flags))
return no_page_table(vma, flags);
-retry_locked:
ptl = pmd_lock(mm, pmd);
- if (unlikely(pmd_none(*pmd))) {
- spin_unlock(ptl);
- return no_page_table(vma, flags);
- }
if (unlikely(!pmd_present(*pmd))) {
spin_unlock(ptl);
- if (likely(!(flags & FOLL_MIGRATION)))
- return no_page_table(vma, flags);
- pmd_migration_entry_wait(mm, pmd);
- goto retry_locked;
+ return no_page_table(vma, flags);
}
if (unlikely(!pmd_trans_huge(*pmd))) {
spin_unlock(ptl);
--
2.37.3
