The patch titled
Subject: mm: enhence doc for extend rmap flags arguments for folio_add_new_anon_rmap
has been added to the -mm mm-unstable branch. Its filename is
mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap-fix-3.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap-fix-3.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Barry Song <v-songbaohua@xxxxxxxx>
Subject: mm: enhence doc for extend rmap flags arguments for folio_add_new_anon_rmap
Date: Sat, 22 Jun 2024 14:51:38 +1200
Link: https://lkml.kernel.org/r/20240622030256.43775-1-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: kernel test robot <lkp@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Shuai Yuan <yuanshuai@xxxxxxxx>
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>
---
mm/rmap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/rmap.c~mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap-fix-3
+++ a/mm/rmap.c
@@ -1405,7 +1405,9 @@ void folio_add_anon_rmap_pmd(struct foli
*
* 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.
*/
@@ -1417,6 +1419,7 @@ void folio_add_new_anon_rmap(struct foli
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);
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
mm-remove-the-implementation-of-swap_free-and-always-use-swap_free_nr.patch
mm-introduce-pte_move_swp_offset-helper-which-can-move-offset-bidirectionally.patch
mm-introduce-arch_do_swap_page_nr-which-allows-restore-metadata-for-nr-pages.patch
mm-swap-reuse-exclusive-folio-directly-instead-of-wp-page-faults.patch
mm-introduce-pmdpte_needs_soft_dirty_wp-helpers-for-softdirty-write-protect.patch
mm-set-pte-writable-while-pte_soft_dirty-is-true-in-do_swap_page.patch
mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap.patch
mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap-fix-2.patch
mm-extend-rmap-flags-arguments-for-folio_add_new_anon_rmap-fix-3.patch
mm-use-folio_add_new_anon_rmap-if-folio_test_anonfolio==false.patch
mm-use-folio_add_new_anon_rmap-if-folio_test_anonfolio==false-fix-2.patch
mm-remove-folio_test_anonfolio==false-path-in-__folio_add_anon_rmap.patch
tools-mm-introduce-a-tool-to-assess-swap-entry-allocation-for-thp_swapout.patch
