From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3D4AF3A961F for ; Tue, 10 Mar 2026 07:30:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773127850; cv=none; b=W9NhJTj2wXjREizGFWbraPeBlJgQCf5E/U4pV1LXfPuEa0v/TunTATaAXhIcEs3mR3FF1EQLzdFm0HhiRwMWTd50G7a4Ve0o1nn9BrxX+EIq7oqnF7BWPmS1U7URkW2GS4F08rMCiWEYs1cv4st4vmcbnrbd8Ae5EMMgupcGxJQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773127850; c=relaxed/simple; bh=tZhotkbPU/s4tjG5Ltgz1x5VFnlO8/7vNQBWyevwfeo=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=ASFHptbK6RL3HjZWVRy6kv0vpu5Z3YkZRljlBxRjv+VID+hXsFOI9nkqzpL1zBAYjU6sGXnB0A8btxSy5Q8igGDLWdBEwvrIUrqOe4HqKPJGUDvrlRdmRf1qunD0Sj/b6m4LRQSnpHQiAeHKXskNK1sOMyXWbDxk57SDwh3o6MM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0968C152B; Tue, 10 Mar 2026 00:30:40 -0700 (PDT) Received: from a080796.blr.arm.com (a080796.arm.com [10.164.21.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5A5A43F73B; Tue, 10 Mar 2026 00:30:37 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, david@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com Cc: weixugc@google.com, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, youngjun.park@lge.com, ziy@nvidia.com, kas@kernel.org, willy@infradead.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, Dev Jain Subject: [PATCH 0/9] mm/rmap: Optimize anonymous large folio unmapping Date: Tue, 10 Mar 2026 13:00:04 +0530 Message-Id: <20260310073013.4069309-1-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Speed up unmapping of anonymous large folios by clearing the ptes, and setting swap ptes, in one go. The following benchmark (stolen from Barry at [1]) is used to measure the time taken to swapout 256M worth of memory backed by 64K large folios: #define _GNU_SOURCE #include #include #include #include #include #include #include #define SIZE_MB 256 #define SIZE_BYTES (SIZE_MB * 1024 * 1024) int main() { void *addr = mmap(NULL, SIZE_BYTES, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (addr == MAP_FAILED) { perror("mmap failed"); return 1; } memset(addr, 0, SIZE_BYTES); struct timespec start, end; clock_gettime(CLOCK_MONOTONIC, &start); if (madvise(addr, SIZE_BYTES, MADV_PAGEOUT) != 0) { perror("madvise(MADV_PAGEOUT) failed"); munmap(addr, SIZE_BYTES); return 1; } clock_gettime(CLOCK_MONOTONIC, &end); long duration_ns = (end.tv_sec - start.tv_sec) * 1e9 + (end.tv_nsec - start.tv_nsec); printf("madvise(MADV_PAGEOUT) took %ld ns (%.3f ms)\n", duration_ns, duration_ns / 1e6); munmap(addr, SIZE_BYTES); return 0; } On arm64, only showing one of the middle values in the distribution: without patch: madvise(MADV_PAGEOUT) took 52192959 ns (52.193 ms) with patch: madvise(MADV_PAGEOUT) took 26676625 ns (26.677 ms) [1] https://lore.kernel.org/all/20250513084620.58231-1-21cnbao@gmail.com/ --- Based on mm-unstable bb420884e9e0. mm-selftests pass. Dev Jain (9): mm/rmap: make nr_pages signed in try_to_unmap_one mm/rmap: initialize nr_pages to 1 at loop start in try_to_unmap_one mm/rmap: refactor lazyfree unmap commit path to commit_ttu_lazyfree_folio() mm/memory: Batch set uffd-wp markers during zapping mm/rmap: batch unmap folios belonging to uffd-wp VMAs mm/swapfile: Make folio_dup_swap batchable mm/swapfile: Make folio_put_swap batchable mm/rmap: introduce folio_try_share_anon_rmap_ptes mm/rmap: enable batch unmapping of anonymous folios include/linux/mm_inline.h | 37 +++-- include/linux/page-flags.h | 11 ++ include/linux/rmap.h | 38 ++++- mm/internal.h | 26 ++++ mm/memory.c | 26 +--- mm/mprotect.c | 17 --- mm/rmap.c | 274 ++++++++++++++++++++++++------------- mm/shmem.c | 8 +- mm/swap.h | 10 +- mm/swapfile.c | 25 ++-- 10 files changed, 298 insertions(+), 174 deletions(-) -- 2.34.1