From 15bde4abab734c687c1f81704886aba3a70c268e Mon Sep 17 00:00:00 2001 From: Barry Song Date: Tue, 18 Jun 2024 11:11:35 +1200 Subject: mm: extend rmap flags arguments for folio_add_new_anon_rmap 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 doesn’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@linux-foundation.org: cleanup and constifications per David and akpm] [v-songbaohua@oppo.com: fix missing doc for flags of folio_add_new_anon_rmap()] Link: https://lkml.kernel.org/r/20240619210641.62542-1-21cnbao@gmail.com [v-songbaohua@oppo.com: enhance doc for extend rmap flags arguments for folio_add_new_anon_rmap] Link: https://lkml.kernel.org/r/20240622030256.43775-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240617231137.80726-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240617231137.80726-2-21cnbao@gmail.com Signed-off-by: Barry Song Suggested-by: David Hildenbrand Tested-by: Shuai Yuan Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Chris Li Cc: "Huang, Ying" Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Ryan Roberts Cc: Suren Baghdasaryan Cc: Yang Shi Cc: Yosry Ahmed Cc: Yu Zhao Signed-off-by: Andrew Morton --- mm/userfaultfd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/userfaultfd.c') diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 5e7f2801698a..8dedaec00486 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -216,7 +216,7 @@ int mfill_atomic_install_pte(pmd_t *dst_pmd, 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); } -- cgit v1.2.3