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b=VBxP9NbrpfckDpEk2swimjW/OsC7MAhf/P0x5VGDHqen1jj3IVmCGvAH60i5FkDq7 z/8e0g0PYDyIhwe8jw4BtvcMQQF41Sc2vdXH15miWTlGng97Au3n0SjTQPDyF5rXDY Fb673rEDbIlq4KuqgbkAmTzpXFhHWohHQo7rh9SRL1LalbacniFG80OBSAKFURo87P Qtp0Tmr8RONXDwZb28MGk2fnylWa6YegUIgJcR/OM8Cf+FKniCIwMqJcl8vazUgvSO jLYbtf+BElr8zN4yYgbooVA2TXFMoxZVJMpdWEUV5Wi6+ZYN5kIA7M9Oa9HqXUjyth 8J/yQbK9oPFXg== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: baoquan.he@linux.dev, chrisl@kernel.org, david@kernel.org, jp.kobryn@linux.dev, kasong@tencent.com, liam@infradead.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, nphamcs@gmail.com, rppt@kernel.org, shakeel.butt@linux.dev, shikemeng@huaweicloud.com, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, youngjun.park@lge.com, "Barry Song (Xiaomi)" , Kairui Song Subject: [PATCH v2 4/4] mm: try to free swapcache for non-LRU folios Date: Wed, 24 Jun 2026 07:16:35 +0800 Message-Id: <20260623231635.43086-5-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260623231635.43086-1-baohua@kernel.org> References: <20260623231635.43086-1-baohua@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1E05940007 X-Stat-Signature: micbfqrbwwxzf3ckbnuorqmnq1bdaxxq X-HE-Tag: 1782256620-744192 X-HE-Meta: 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 ftXn3pMW 1PMRAUkKBCSSPb/c/71BMfxPTKMmVk9+W7ZIesB+snEqlgxH/YfKcS1P6FPduypq68TznjmgExLAPJS1kJTpzOT8nEAoKB/41Htwmm2Z+2uhLXH/j8EbXA8Jz5mTLP8eOileWv2DIwPZYaiqceE/voiTAP1n0/faq7ENd/NKS8GGvQbcdXwUNI3zeBjPY94x9qzBVhEK+bEa3D9V6+scpT73K9Nw/vqfDTA2jRacx3KwTAg8F0BlezOI7EDda381+gXnl Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Originally, we unconditionally called lru_add_drain() for write swap-in page faults. This might drop the reference held by the per-CPU LRU cache if the folio happened to reside there. However, there was no guarantee that the folio was actually cached on the current CPU. Now that lru_add_drain() has been removed, we have lost one opportunity to drop a reference held by the LRU cache. We could instead incorporate that possibility into the condition evaluated by should_try_to_free_swap(). Suggested-by: Kairui Song Signed-off-by: Barry Song (Xiaomi) --- mm/memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 2983a6baf474..14577c67c61a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5087,8 +5087,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) * Remove the swap entry and conditionally try to free up the swapcache. * Do it after mapping, so raced page faults will likely see the folio * in swap cache and wait on the folio lock. + * Assume non-LRU folios may be queued in the LRU cache, which contributes + * an additional reference to the folio. */ - if (should_try_to_free_swap(si, folio, vma, nr_pages, vmf->flags)) + if (should_try_to_free_swap(si, folio, vma, nr_pages + + !folio_test_lru(folio), vmf->flags)) folio_free_swap(folio); folio_unlock(folio); -- 2.39.3 (Apple Git-146)