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Sun, 19 Jul 2026 20:19:32 -0700 (PDT) Received: from localhost.localdomain ([221.227.131.254]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cb517aada63sm3827465a12.3.2026.07.19.20.19.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jul 2026 20:19:32 -0700 (PDT) From: Vernon Yang To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, jannh@google.com, baohua@kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vernon Yang Subject: [RFC PATCH] mm: madvise: use per_vma lock for MADV_COLD/PAGEOUT Date: Mon, 20 Jul 2026 11:19:01 +0800 Message-ID: <20260720031901.1724737-1-vernon2gm@gmail.com> X-Mailer: git-send-email 2.53.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 09239140009 X-Stat-Signature: tbu55zteupo5u3abj1nama95ynzpqoqe X-HE-Tag: 1784517573-702579 X-HE-Meta: U2FsdGVkX18J/b+/L6mBQShvT/7yHH3d+GEJ7VHB64sz/68evg7IoHqMiS8od81OuwWgZJlq/g6PmF7yGt39oUpjls/KTO0SISpmbaUT4tzQTiT99tuMu20dfUY71zs2/thzdF7TkNSQtcK5dDA9Nnlnpo8a8lNp2dwGbFdN3zy2TBoe3QAhWogCIMFIApqjtBCQzxK7I45H1gchPNzg6rrzpnqBhwyxTr0tEQXsBgg8NOCLy+QIFf0dXN01JaeR7sxfOSSt4h1kuuDbVevxqfUcenxng88I46ozVmHuMNDdHJh4YFzAUIHJ6xrf65bSA0w6YCOTnv0eIvtJBjBtpfUowQrzm3hLhTEybIVrYKP/7o90/zwJcVPtmwi+xiTxADTdsQP/O9DhS1Vp2neQ09JkSANAUjcrUUmBNx4BhfIUiv9HZIQZFdjeuoVTcAC89bqfdr4QYY3boYLx7Xc7sqWiBTf9gWGJEUBD4txeePETryuvLvhWLVHzTTsSdxaIUr7dfUk9VDlzdlTOg3ntVYIGxDzFfDhEmybWOrzp/DWAwEl3wVtbXwZK5E5XCsFl1q9tUXZNEIQpqaJ+e8PJpoUQDXfYGw6/MUcqB14Eo8txIN1WLVlxxTZ7uh5va0tYdXH5ckfaVilNCjE2R2OCIknTlJlTaXfGvwBetbp42Cr+LETHZ1DHadEdo1Q0hrfUTzl4y3CeMycd3r+w/JnCBQqZlE0mKfq0icUovX/icnkiMgqhY2t75IpBbzHcvGLRItPysskLeU0DiVFno2JJ6m1pM3rCWmgAKX3izeVOUzLv9zGZVTFWyFrDv5scedgT5tvgYUGu1eDLWn2l6WTSEHzAQSRltUvzPf+jGoBGiL71kcsw7R4nN8F19gHYwDoblD7cti+gXxOGNBtijqm/MEICBmc2KcUEA93j2JsGUE0bECqqwCEZCMdXLSyrVIU5Bxkc8+4gNQARQPV+k0W Ot5UcdRL vgbqCCfKGgZVbzq7DEF7e+VPmcJ5X3/TiEXStHeiYgNAP3XRODAFuedQvTEA5OgytrpER9WYvHXpgXdfj+G+jOoauVIUkyDYZW9/h0I7vnm3gDHaH4Wa+xtf+Nov6ycd27PjLCxyKscNhVQUpgFFz9q7rSwWPxPwlkxeUHjw11YF10Wq+xKqzCs2l1L9PGACNcUNrG+H0r0azTEa8CUYw/jSsGMAw53mYevlkkGXlOtcP+57k3fkiwxlS8S47MiHPGS4G24aZ1EUsvQSzxpq6dp4YdWMF8PBDP9sUykSxYwvz7FHE1AZ5EPXmONBp/xo+HEgsKDjrZTuoVDCyLDoBEn+fzy3nLj+hXVDXcfFTecH1TQeGMWipL+VGtcNdESleZdpwnUtBC1KIPUScmKO+n1e/iFbyWSRH3nZbFCEjgp6lqMFY+ZcMrDMEYcG1Z9Md403CVEu8/PBcS1OEYredU+6WeepeshfGXOV+xRC+XOrJezwU0RNfKpTQWQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Vernon Yang MADV_COLD and MADV_PAGEOUT hold the mmap_lock read lock while walking the target range. When a concurrent mmap_lock write lock is held, MADV_COLD/PAGEOUT must wait and execute serially, even for unrelated VMAs. MADV_FREE/DONTNEED have already achieved this goal using the per_vma read lock. With only simple modifications, MADV_COLD/PAGEOUT can also use the per_vma read lock to replace the mmap_lock read lock. Start 16 threads running mmap/unmap on separate VMAs, and benchmark the time taken by 10,000 madvise(MADV_COLD/PAGEOUT) calls on another VMA[1]. before after MADV_COLD 8.09 s 0.07 s MADV_PAGEOUT 11.68 s 0.40 s [1] https://github.com/vernon2gh/app_and_module/blob/main/madvise/app.c Signed-off-by: Vernon Yang --- mm/madvise.c | 52 ++++++++++++++++++++++++++++------------------------ 1 file changed, 28 insertions(+), 24 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index cd9bb077072c..795a8a6fb237 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -566,10 +566,19 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, return 0; } -static const struct mm_walk_ops cold_walk_ops = { - .pmd_entry = madvise_cold_or_pageout_pte_range, - .walk_lock = PGWALK_RDLOCK, -}; +static inline enum page_walk_lock get_walk_lock(enum madvise_lock_mode mode) +{ + switch (mode) { + case MADVISE_VMA_READ_LOCK: + return PGWALK_VMA_RDLOCK_VERIFY; + case MADVISE_MMAP_READ_LOCK: + return PGWALK_RDLOCK; + default: + /* Other modes don't require fixing up the walk_lock */ + WARN_ON_ONCE(1); + return PGWALK_RDLOCK; + } +} static void madvise_cold_page_range(struct mmu_gather *tlb, struct madvise_behavior *madv_behavior) @@ -577,13 +586,17 @@ static void madvise_cold_page_range(struct mmu_gather *tlb, { struct vm_area_struct *vma = madv_behavior->vma; struct madvise_behavior_range *range = &madv_behavior->range; + struct mm_walk_ops walk_ops = { + .pmd_entry = madvise_cold_or_pageout_pte_range, + }; struct madvise_walk_private walk_private = { .pageout = false, .tlb = tlb, }; + walk_ops.walk_lock = get_walk_lock(madv_behavior->lock_mode); tlb_start_vma(tlb, vma); - walk_page_range_vma(vma, range->start, range->end, &cold_walk_ops, + walk_page_range_vma(vma, range->start, range->end, &walk_ops, &walk_private); tlb_end_vma(tlb, vma); } @@ -611,15 +624,20 @@ static long madvise_cold(struct madvise_behavior *madv_behavior) static void madvise_pageout_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, - struct madvise_behavior_range *range) + struct madvise_behavior *madv_behavior) { + struct madvise_behavior_range *range = &madv_behavior->range; + struct mm_walk_ops walk_ops = { + .pmd_entry = madvise_cold_or_pageout_pte_range, + }; struct madvise_walk_private walk_private = { .pageout = true, .tlb = tlb, }; + walk_ops.walk_lock = get_walk_lock(madv_behavior->lock_mode); tlb_start_vma(tlb, vma); - walk_page_range_vma(vma, range->start, range->end, &cold_walk_ops, + walk_page_range_vma(vma, range->start, range->end, &walk_ops, &walk_private); tlb_end_vma(tlb, vma); } @@ -644,7 +662,7 @@ static long madvise_pageout(struct madvise_behavior *madv_behavior) lru_add_drain(); tlb_gather_mmu(&tlb, madv_behavior->mm); - madvise_pageout_page_range(&tlb, vma, &madv_behavior->range); + madvise_pageout_page_range(&tlb, vma, madv_behavior); tlb_finish_mmu(&tlb); return 0; @@ -783,20 +801,6 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, return 0; } -static inline enum page_walk_lock get_walk_lock(enum madvise_lock_mode mode) -{ - switch (mode) { - case MADVISE_VMA_READ_LOCK: - return PGWALK_VMA_RDLOCK_VERIFY; - case MADVISE_MMAP_READ_LOCK: - return PGWALK_RDLOCK; - default: - /* Other modes don't require fixing up the walk_lock */ - WARN_ON_ONCE(1); - return PGWALK_RDLOCK; - } -} - static int madvise_free_single_vma(struct madvise_behavior *madv_behavior) { struct mm_struct *mm = madv_behavior->mm; @@ -1748,8 +1752,6 @@ static enum madvise_lock_mode get_lock_mode(struct madvise_behavior *madv_behavi switch (madv_behavior->behavior) { case MADV_REMOVE: case MADV_WILLNEED: - case MADV_COLD: - case MADV_PAGEOUT: case MADV_POPULATE_READ: case MADV_POPULATE_WRITE: case MADV_COLLAPSE: @@ -1759,6 +1761,8 @@ static enum madvise_lock_mode get_lock_mode(struct madvise_behavior *madv_behavi case MADV_DONTNEED: case MADV_DONTNEED_LOCKED: case MADV_FREE: + case MADV_COLD: + case MADV_PAGEOUT: return MADVISE_VMA_READ_LOCK; default: return MADVISE_MMAP_WRITE_LOCK; -- 2.53.0