The quilt patch titled
Subject: mm: extend rmap flags arguments for folio_add_new_anon_rmap
has been removed from the -mm tree. Its filename was
mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Barry Song <v-songbaohua@xxxxxxxx>
Subject: mm: extend rmap flags arguments for folio_add_new_anon_rmap
Date: Tue, 18 Jun 2024 11:11:35 +1200
Patch series "mm: clarify folio_add_new_anon_rmap() and
__folio_add_anon_rmap()", v2.
This patchset is preparatory work for mTHP swapin.
folio_add_new_anon_rmap() assumes that new anon rmaps are always
exclusive. However, this assumption doesnâ??t hold true for cases like
do_swap_page(), where a new anon might be added to the swapcache and is
not necessarily exclusive.
The patchset extends the rmap flags to allow folio_add_new_anon_rmap() to
handle both exclusive and non-exclusive new anon folios. The
do_swap_page() function is updated to use this extended API with rmap
flags. Consequently, all new anon folios now consistently use
folio_add_new_anon_rmap(). The special case for !folio_test_anon() in
__folio_add_anon_rmap() can be safely removed.
In conclusion, new anon folios always use folio_add_new_anon_rmap(),
regardless of exclusivity. Old anon folios continue to use
__folio_add_anon_rmap() via folio_add_anon_rmap_pmd() and
folio_add_anon_rmap_ptes().
This patch (of 3):
In the case of a swap-in, a new anonymous folio is not necessarily
exclusive. This patch updates the rmap flags to allow a new anonymous
folio to be treated as either exclusive or non-exclusive. To maintain the
existing behavior, we always use EXCLUSIVE as the default setting.
[akpm@xxxxxxxxxxxxxxxxxxxx: cleanup and constifications per David and akpm]
[v-songbaohua@xxxxxxxx: fix missing doc for flags of folio_add_new_anon_rmap()]
Link: https://lkml.kernel.org/r/20240619210641.62542-1-21cnbao@xxxxxxxxx
[v-songbaohua@xxxxxxxx: enhance doc for extend rmap flags arguments for folio_add_new_anon_rmap]
Link: https://lkml.kernel.org/r/20240622030256.43775-1-21cnbao@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240617231137.80726-1-21cnbao@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240617231137.80726-2-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Tested-by: Shuai Yuan <yuanshuai@xxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/rmap.h | 2 +-
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 | 25 ++++++++++++++++---------
mm/swapfile.c | 2 +-
mm/userfaultfd.c | 2 +-
9 files changed, 28 insertions(+), 21 deletions(-)
--- a/include/linux/rmap.h~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/include/linux/rmap.h
@@ -244,7 +244,7 @@ void folio_add_anon_rmap_ptes(struct fol
void folio_add_anon_rmap_pmd(struct folio *, struct page *,
struct vm_area_struct *, unsigned long address, rmap_t flags);
void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
- unsigned long address);
+ unsigned long address, rmap_t flags);
void folio_add_file_rmap_ptes(struct folio *, struct page *, int nr_pages,
struct vm_area_struct *);
#define folio_add_file_rmap_pte(folio, page, vma) \
--- a/kernel/events/uprobes.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/kernel/events/uprobes.c
@@ -181,7 +181,7 @@ static int __replace_page(struct vm_area
if (new_page) {
folio_get(new_folio);
- folio_add_new_anon_rmap(new_folio, vma, addr);
+ folio_add_new_anon_rmap(new_folio, vma, addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(new_folio, vma);
} else
/* no new page, just dec_mm_counter for old_page */
--- a/mm/huge_memory.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/huge_memory.c
@@ -974,7 +974,7 @@ static vm_fault_t __do_huge_pmd_anonymou
entry = mk_huge_pmd(page, vma->vm_page_prot);
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
- folio_add_new_anon_rmap(folio, vma, haddr);
+ folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
--- a/mm/khugepaged.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/khugepaged.c
@@ -1210,7 +1210,7 @@ static int collapse_huge_page(struct mm_
spin_lock(pmd_ptl);
BUG_ON(!pmd_none(*pmd));
- folio_add_new_anon_rmap(folio, vma, address);
+ folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
pgtable_trans_huge_deposit(mm, pmd, pgtable);
set_pmd_at(mm, address, pmd, _pmd);
--- a/mm/memory.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/memory.c
@@ -930,7 +930,7 @@ copy_present_page(struct vm_area_struct
*prealloc = NULL;
copy_user_highpage(&new_folio->page, page, addr, src_vma);
__folio_mark_uptodate(new_folio);
- folio_add_new_anon_rmap(new_folio, dst_vma, addr);
+ folio_add_new_anon_rmap(new_folio, dst_vma, addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(new_folio, dst_vma);
rss[MM_ANONPAGES]++;
@@ -3402,7 +3402,7 @@ static vm_fault_t wp_page_copy(struct vm
* some TLBs while the old PTE remains in others.
*/
ptep_clear_flush(vma, vmf->address, vmf->pte);
- folio_add_new_anon_rmap(new_folio, vma, vmf->address);
+ folio_add_new_anon_rmap(new_folio, vma, vmf->address, RMAP_EXCLUSIVE);
folio_add_lru_vma(new_folio, vma);
BUG_ON(unshare && pte_write(entry));
set_pte_at(mm, vmf->address, vmf->pte, entry);
@@ -4339,7 +4339,7 @@ check_folio:
/* ksm created a completely new copy */
if (unlikely(folio != swapcache && swapcache)) {
- folio_add_new_anon_rmap(folio, vma, address);
+ folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
} else {
folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
@@ -4594,7 +4594,7 @@ static vm_fault_t do_anonymous_page(stru
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC);
#endif
- folio_add_new_anon_rmap(folio, vma, addr);
+ folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
setpte:
if (vmf_orig_pte_uffd_wp(vmf))
@@ -4792,7 +4792,7 @@ void set_pte_range(struct vm_fault *vmf,
/* copy-on-write page */
if (write && !(vma->vm_flags & VM_SHARED)) {
VM_BUG_ON_FOLIO(nr != 1, folio);
- folio_add_new_anon_rmap(folio, vma, addr);
+ folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
} else {
folio_add_file_rmap_ptes(folio, page, nr, vma);
--- a/mm/migrate_device.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/migrate_device.c
@@ -658,7 +658,7 @@ static void migrate_vma_insert_page(stru
goto unlock_abort;
inc_mm_counter(mm, MM_ANONPAGES);
- folio_add_new_anon_rmap(folio, vma, addr);
+ folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
if (!folio_is_zone_device(folio))
folio_add_lru_vma(folio, vma);
folio_get(folio);
--- a/mm/rmap.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/rmap.c
@@ -1401,30 +1401,35 @@ void folio_add_anon_rmap_pmd(struct foli
* @folio: The folio to add the mapping to.
* @vma: the vm area in which the mapping is added
* @address: the user virtual address mapped
+ * @flags: The rmap flags
*
* Like folio_add_anon_rmap_*() but must only be called on *new* folios.
* This means the inc-and-test can be bypassed.
- * The folio does not have to be locked.
+ * The folio doesn't necessarily need to be locked while it's exclusive
+ * unless two threads map it concurrently. However, the folio must be
+ * locked if it's shared.
*
- * If the folio is pmd-mappable, it is accounted as a THP. As the folio
- * is new, it's assumed to be mapped exclusively by a single process.
+ * If the folio is pmd-mappable, it is accounted as a THP.
*/
void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
- unsigned long address)
+ unsigned long address, rmap_t flags)
{
- int nr = folio_nr_pages(folio);
+ const int nr = folio_nr_pages(folio);
+ const bool exclusive = flags & RMAP_EXCLUSIVE;
int nr_pmdmapped = 0;
VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
+ VM_WARN_ON_FOLIO(!exclusive && !folio_test_locked(folio), folio);
VM_BUG_ON_VMA(address < vma->vm_start ||
address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
__folio_set_swapbacked(folio);
- __folio_set_anon(folio, vma, address, true);
+ __folio_set_anon(folio, vma, address, exclusive);
if (likely(!folio_test_large(folio))) {
/* increment count (starts at -1) */
atomic_set(&folio->_mapcount, 0);
- SetPageAnonExclusive(&folio->page);
+ if (exclusive)
+ SetPageAnonExclusive(&folio->page);
} else if (!folio_test_pmd_mappable(folio)) {
int i;
@@ -1433,7 +1438,8 @@ void folio_add_new_anon_rmap(struct foli
/* increment count (starts at -1) */
atomic_set(&page->_mapcount, 0);
- SetPageAnonExclusive(page);
+ if (exclusive)
+ SetPageAnonExclusive(page);
}
/* increment count (starts at -1) */
@@ -1445,7 +1451,8 @@ void folio_add_new_anon_rmap(struct foli
/* increment count (starts at -1) */
atomic_set(&folio->_large_mapcount, 0);
atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);
- SetPageAnonExclusive(&folio->page);
+ if (exclusive)
+ SetPageAnonExclusive(&folio->page);
nr_pmdmapped = nr;
}
--- a/mm/swapfile.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/swapfile.c
@@ -1911,7 +1911,7 @@ static int unuse_pte(struct vm_area_stru
folio_add_anon_rmap_pte(folio, page, vma, addr, rmap_flags);
} else { /* ksm created a completely new copy */
- folio_add_new_anon_rmap(folio, vma, addr);
+ folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, vma);
}
new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
--- a/mm/userfaultfd.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap
+++ a/mm/userfaultfd.c
@@ -216,7 +216,7 @@ int mfill_atomic_install_pte(pmd_t *dst_
folio_add_lru(folio);
folio_add_file_rmap_pte(folio, page, dst_vma);
} else {
- folio_add_new_anon_rmap(folio, dst_vma, dst_addr);
+ folio_add_new_anon_rmap(folio, dst_vma, dst_addr, RMAP_EXCLUSIVE);
folio_add_lru_vma(folio, dst_vma);
}
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
tools-mm-introduce-a-tool-to-assess-swap-entry-allocation-for-thp_swapout.patch
