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b=WgZEtF18f1MnI0Xd+bo2kF+iWwLij9SaxuFHznIM8SypLV1RU6RW2p0NLy81G9ZB0 Q3AZao7w7PbbsTMlMSMUakc8vIk5NW9snO6/QZV+/wKXX0Z/kdItHWoocB6ygmU8nl jDbiF02hKKG0DryqLCdEH5fvy1xgwaKxi+PmLcaHoaMzvajDZYrSIg1F97aBrwJjqL ayAO1TBN0JjCXmY2S0DyTa6+JwY/eYrmXbwDPEYd85U5uRgPPipuV6eig+3Zj6/iY2 +I3fa5U8uVBEcvniTqtDI7j1BCQdlPqCw0VKUsO2BfeQGhKmP7ucf8gqi2Pjr25HcI 53BnIOUKnFiqg== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, youngjun.park@lge.com, jp.kobryn@linux.dev, usama.arif@linux.dev, shakeel.butt@linux.dev, "Barry Song (Xiaomi)" Subject: [RFC PATCH 2/3] mm: drop stale folio_ref_count()==1 check in do_swap_page reuse logic Date: Thu, 11 Jun 2026 18:51:23 +0800 Message-Id: <20260611105124.98668-3-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260611105124.98668-1-baohua@kernel.org> References: <20260611105124.98668-1-baohua@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: 3akmc1iq4txgepfao98p9cducn7w4ryg X-Rspamd-Queue-Id: D7D7A40004 X-HE-Tag: 1781175103-635278 X-HE-Meta: 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 SR5K7XMc ErcBqG9Muxlp8TfbGqwVyggZ1pZ+6DRtSPxJt50QhwLwYvbWLWhlqKFBJC8QMAbnSu+dknjDWuunCP+3DL+MVupDgcCJprmNpmbVI6Q0Y8ebIM/y0XSe805aKqMvDDqFLO6o8erZvfQnVE9Sc4uavJzPOiNnUOFciDRZqDc1svC6TlEdmYmy8HLaHW039fGxSL+CnpFjJsna/4RjYLaeKJNk/OZrAU7JtMRS5Qh+X3popfV/a+hss/iXpygdysDzaav48vLs2fNRyK3WUYXih9qayETjHkK9s77QWFvK8I8AqYLBGimev2Lfh6Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The "we just allocated them without exposing them to the swapcache" case no longer exists, as Kairui has routed synchronous I/O through the swapcache as well in his series "unify swapin use swap cache and cleanup flags"[1]. As a result, folio_ref_count() should never be 1 in this path, since at least two references are held (base ref plus swapcache). Remove the folio_ref_count()==1 check and update the comment accordingly. [1] https://lore.kernel.org/all/20251220-swap-table-p2-v5-0-8862a265a033@tencent.com/ Signed-off-by: Barry Song (Xiaomi) --- mm/memory.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 487a34377a7b..ce8ef27e7a54 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5049,12 +5049,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) /* * Same logic as in do_wp_page(); however, optimize for pages that are - * certainly not shared either because we just allocated them without - * exposing them to the swapcache or because the swap entry indicates - * exclusivity. + * certainly not because the swap entry indicates exclusivity. */ - if (!folio_test_ksm(folio) && - (exclusive || folio_ref_count(folio) == 1)) { + if (!folio_test_ksm(folio) && exclusive) { if ((vma->vm_flags & VM_WRITE) && !userfaultfd_pte_wp(vma, pte) && !pte_needs_soft_dirty_wp(vma, pte)) { pte = pte_mkwrite(pte, vma); -- 2.39.3 (Apple Git-146)