From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1C083793B6 for ; Mon, 9 Feb 2026 14:07:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770646070; cv=none; b=f2XHEsjzSGmRYI1fFJOsiDCo9So8mnMETR5y3asqKTscJTLQOxspWH/t0kNszfu3Y3VhdpBAkgSWapTA/hXTLHLp0tQNrLYUNa6yNi6Y7VPAMH+K/sZD4NvccXG/hy/mPkHVQOqPxW90JuEHQ1TrdbtT13f4g78hdl6PgTkFqwc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770646070; c=relaxed/simple; bh=h5E2ztR8Fy8XpGZdPUZIfo61rpw9EbiuxKBoS8pk6Zc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JIpSbb9rMhJTk5xN0edfkrk+WAV6qOz0Ds9qxnf/sMiFWmGoS8qHk6cWQNIT2wc/ruYXX+l0rGT2BujTpWR3ewTUKx4RvT7ttsTZ9323vuxafIJERIeYKwz4JW4cqQcEB1y2ZjZrF2BoOKToMGkb5Ui9YX2wkdBQHuFAqiLaa2E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=xMrHHPeb; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="xMrHHPeb" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1770646066; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=xtnCI5sMjOjZdukKqKEgSsDbixroOMT6jGSMxfo0RNQ=; b=xMrHHPebhvoDQXtBpXZCQ1PusufVUV0AiO6W3ddUMZRuc987/sPaBbSOMTR+pMSEyF/aNfAYad6sh8fT9BRHhXmud6jU0Qk03Ec8XveeraxE/Tm0/c3BDxrsjEA4JNlHkYsrcWFJlAOz/6SHL/viRr4kwJedM1ylj6rJGvL9/EM= Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Wyt-ZaP_1770646064 cluster:ay36) by smtp.aliyun-inc.com; Mon, 09 Feb 2026 22:07:45 +0800 From: Baolin Wang To: akpm@linux-foundation.org, david@kernel.org, catalin.marinas@arm.com, will@kernel.org Cc: lorenzo.stoakes@oracle.com, ryan.roberts@arm.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, willy@infradead.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 5/5] mm: rmap: support batched unmapping for file large folios Date: Mon, 9 Feb 2026 22:07:28 +0800 Message-ID: X-Mailer: git-send-email 2.47.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Similar to folio_referenced_one(), we can apply batched unmapping for file large folios to optimize the performance of file folios reclamation. Barry previously implemented batched unmapping for lazyfree anonymous large folios[1] and did not further optimize anonymous large folios or file-backed large folios at that stage. As for file-backed large folios, the batched unmapping support is relatively straightforward, as we only need to clear the consecutive (present) PTE entries for file-backed large folios. Note that it's not ready to support batched unmapping for uffd case, so let's still fallback to per-page unmapping for the uffd case. Performance testing: Allocate 10G clean file-backed folios by mmap() in a memory cgroup, and try to reclaim 8G file-backed folios via the memory.reclaim interface. I can observe 75% performance improvement on my Arm64 32-core server (and 50%+ improvement on my X86 machine) with this patch. W/o patch: real 0m1.018s user 0m0.000s sys 0m1.018s W/ patch: real 0m0.249s user 0m0.000s sys 0m0.249s [1] https://lore.kernel.org/all/20250214093015.51024-4-21cnbao@gmail.com/T/#u Reviewed-by: Ryan Roberts Acked-by: Barry Song Reviewed-by: Harry Yoo Signed-off-by: Baolin Wang --- mm/rmap.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 8807f8a7df28..43cb9ac6f523 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1945,12 +1945,16 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio, end_addr = pmd_addr_end(addr, vma->vm_end); max_nr = (end_addr - addr) >> PAGE_SHIFT; - /* We only support lazyfree batching for now ... */ - if (!folio_test_anon(folio) || folio_test_swapbacked(folio)) + /* We only support lazyfree or file folios batching for now ... */ + if (folio_test_anon(folio) && folio_test_swapbacked(folio)) return 1; + if (pte_unused(pte)) return 1; + if (userfaultfd_wp(vma)) + return 1; + return folio_pte_batch(folio, pvmw->pte, pte, max_nr); } @@ -2313,7 +2317,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, * * See Documentation/mm/mmu_notifier.rst */ - dec_mm_counter(mm, mm_counter_file(folio)); + add_mm_counter(mm, mm_counter_file(folio), -nr_pages); } discard: if (unlikely(folio_test_hugetlb(folio))) { -- 2.47.3