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Mon, 13 Apr 2026 15:39:58 -0700 (PDT) Sender: Minchan Kim From: Minchan Kim To: akpm@linux-foundation.org Cc: david@kernel.org, mhocko@suse.com, brauner@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, surenb@google.com, timmurray@google.com, Minchan Kim Subject: [RFC 2/3] mm: process_mrelease: skip LRU movement for exclusive file folios Date: Mon, 13 Apr 2026 15:39:47 -0700 Message-ID: <20260413223948.556351-3-minchan@kernel.org> X-Mailer: git-send-email 2.54.0.rc0.605.g598a273b03-goog In-Reply-To: <20260413223948.556351-1-minchan@kernel.org> References: <20260413223948.556351-1-minchan@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit For the process_mrelease reclaim, skip LRU handling for exclusive file-backed folios since they will be freed soon so pointless to move around in the LRU. This avoids costly LRU movement which accounts for a significant portion of the time during unmap_page_range. - 91.31% 0.00% mmap_exit_test [kernel.kallsyms] [.] exit_mm exit_mm __mmput exit_mmap unmap_vmas - unmap_page_range - 55.75% folio_mark_accessed + 48.79% __folio_batch_add_and_move 4.23% workingset_activation + 12.94% folio_remove_rmap_ptes + 9.86% page_table_check_clear + 3.34% tlb_flush_mmu 1.06% __page_table_check_pte_clear Signed-off-by: Minchan Kim --- mm/memory.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 2f815a34d924..25e17893c919 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1640,6 +1640,8 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, bool delay_rmap = false; if (!folio_test_anon(folio)) { + bool skip_mark_accessed; + ptent = get_and_clear_full_ptes(mm, addr, pte, nr, tlb->fullmm); if (pte_dirty(ptent)) { folio_mark_dirty(folio); @@ -1648,7 +1650,16 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, *force_flush = true; } } - if (pte_young(ptent) && likely(vma_has_recency(vma))) + + /* + * For the process_mrelease reclaim, skip LRU handling for exclusive + * file-backed folios since they will be freed soon so pointless + * to move around in the LRU. + */ + skip_mark_accessed = mm_flags_test(MMF_UNSTABLE, mm) && + folio_mapcount(folio) < 2; + if (likely(!skip_mark_accessed) && pte_young(ptent) && + likely(vma_has_recency(vma))) folio_mark_accessed(folio); rss[mm_counter(folio)] -= nr; } else { -- 2.54.0.rc0.605.g598a273b03-goog