[PATCH v4 08/17] mm/rmap: drop "compound" parameter from page_add_new_anon_rmap()

David Hildenbrand
2022-04-28T08:38:47Z

New anonymous pages are always mapped natively: only THP/khugepaged code
maps a new compound anonymous page and passes "true". Otherwise, we're
just dealing with simple, non-compound pages.

Let's give the interface clearer semantics and document these. Remove
the PageTransCompound() sanity check from page_add_new_anon_rmap().

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/rmap.h | 3 ++-
kernel/events/uprobes.c | 2 +-
mm/huge_memory.c | 2 +-
mm/khugepaged.c | 2 +-
mm/memory.c | 10 +++++-----
mm/migrate_device.c | 2 +-
mm/rmap.c | 11 ++++++-----
mm/swapfile.c | 2 +-
mm/userfaultfd.c | 2 +-
9 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index f47bc937c383..9c120e1b1bc7 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -185,11 +185,12 @@ void page_move_anon_rmap(struct page *, struct vm_area_struct *);
void page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long address, rmap_t flags);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
- unsigned long address, bool compound);
+ unsigned long address);
void page_add_file_rmap(struct page *, struct vm_area_struct *,
bool compound);
void page_remove_rmap(struct page *, struct vm_area_struct *,
bool compound);
+
void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long address, rmap_t flags);
void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 6418083901d4..4ef5385815d3 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -180,7 +180,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,

if (new_page) {
get_page(new_page);
- page_add_new_anon_rmap(new_page, vma, addr, false);
+ page_add_new_anon_rmap(new_page, vma, addr);
lru_cache_add_inactive_or_unevictable(new_page, vma);
} else
/* no new page, just dec_mm_counter for old_page */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6232b6817fab..c0365280b481 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -647,7 +647,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,

entry = mk_huge_pmd(page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
- page_add_new_anon_rmap(page, vma, haddr, true);
+ page_add_new_anon_rmap(page, vma, haddr);
lru_cache_add_inactive_or_unevictable(page, vma);
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a4e5eaf3eb01..9bb32fb7ec74 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1183,7 +1183,7 @@ static void collapse_huge_page(struct mm_struct *mm,

spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
- page_add_new_anon_rmap(new_page, vma, address, true);
+ page_add_new_anon_rmap(new_page, vma, address);
lru_cache_add_inactive_or_unevictable(new_page, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, address, pmd, _pmd);
diff --git a/mm/memory.c b/mm/memory.c
index f46504191571..22e732c266dd 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -893,7 +893,7 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
*prealloc = NULL;
copy_user_highpage(new_page, page, addr, src_vma);
__SetPageUptodate(new_page);
- page_add_new_anon_rmap(new_page, dst_vma, addr, false);
+ page_add_new_anon_rmap(new_page, dst_vma, addr);
lru_cache_add_inactive_or_unevictable(new_page, dst_vma);
rss[mm_counter(new_page)]++;

@@ -3058,7 +3058,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
* some TLBs while the old PTE remains in others.
*/
ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
- page_add_new_anon_rmap(new_page, vma, vmf->address, false);
+ page_add_new_anon_rmap(new_page, vma, vmf->address);
lru_cache_add_inactive_or_unevictable(new_page, vma);
/*
* We call the notify macro here because, when using secondary
@@ -3698,7 +3698,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)

/* ksm created a completely new copy */
if (unlikely(page != swapcache && swapcache)) {
- page_add_new_anon_rmap(page, vma, vmf->address, false);
+ page_add_new_anon_rmap(page, vma, vmf->address);
lru_cache_add_inactive_or_unevictable(page, vma);
} else {
page_add_anon_rmap(page, vma, vmf->address, rmap_flags);
@@ -3848,7 +3848,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
}

inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
- page_add_new_anon_rmap(page, vma, vmf->address, false);
+ page_add_new_anon_rmap(page, vma, vmf->address);
lru_cache_add_inactive_or_unevictable(page, vma);
setpte:
set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
@@ -4035,7 +4035,7 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
/* copy-on-write page */
if (write && !(vma->vm_flags & VM_SHARED)) {
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
- page_add_new_anon_rmap(page, vma, addr, false);
+ page_add_new_anon_rmap(page, vma, addr);
lru_cache_add_inactive_or_unevictable(page, vma);
} else {
inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 70c7dc05bbfc..fb6d7d5499f5 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -610,7 +610,7 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
goto unlock_abort;

inc_mm_counter(mm, MM_ANONPAGES);
- page_add_new_anon_rmap(page, vma, addr, false);
+ page_add_new_anon_rmap(page, vma, addr);
if (!is_zone_device_page(page))
lru_cache_add_inactive_or_unevictable(page, vma);
get_page(page);
diff --git a/mm/rmap.c b/mm/rmap.c
index 065501642401..d98011ad05ca 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1182,19 +1182,22 @@ void page_add_anon_rmap(struct page *page,
}

/**
- * page_add_new_anon_rmap - add pte mapping to a new anonymous page
+ * page_add_new_anon_rmap - add mapping to a new anonymous page
* @page: the page to add the mapping to
* @vma: the vm area in which the mapping is added
* @address: the user virtual address mapped
- * @compound: charge the page as compound or small page
+ *
+ * If it's a compound page, it is accounted as a compound page. As the page
+ * is new, it's assume to get mapped exclusively by a single process.
*
* Same as page_add_anon_rmap but must only be called on *new* pages.
* This means the inc-and-test can be bypassed.
* Page does not have to be locked.
*/
void page_add_new_anon_rmap(struct page *page,
- struct vm_area_struct *vma, unsigned long address, bool compound)
+ struct vm_area_struct *vma, unsigned long address)
{
+ const bool compound = PageCompound(page);
int nr = compound ? thp_nr_pages(page) : 1;

VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
@@ -1207,8 +1210,6 @@ void page_add_new_anon_rmap(struct page *page,

__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
} else {
- /* Anon THP always mapped first with PMD */
- VM_BUG_ON_PAGE(PageTransCompound(page), page);
/* increment count (starts at -1) */
atomic_set(&page->_mapcount, 0);
}
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1ba525a2179d..0ad7ed7ded21 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1802,7 +1802,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
if (page == swapcache) {
page_add_anon_rmap(page, vma, addr, RMAP_NONE);
} else { /* ksm created a completely new copy */
- page_add_new_anon_rmap(page, vma, addr, false);
+ page_add_new_anon_rmap(page, vma, addr);
lru_cache_add_inactive_or_unevictable(page, vma);
}
set_pte_at(vma->vm_mm, addr, pte,
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index e9bb6db002aa..dae25d985d15 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -104,7 +104,7 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
lru_cache_add(page);
page_add_file_rmap(page, dst_vma, false);
} else {
- page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
+ page_add_new_anon_rmap(page, dst_vma, dst_addr);
lru_cache_add_inactive_or_unevictable(page, dst_vma);
}

--
2.35.1