From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7FBA9F53D69 for ; Mon, 16 Mar 2026 15:49:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CBAD96B02EA; Mon, 16 Mar 2026 11:49:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C72A56B02EC; Mon, 16 Mar 2026 11:49:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B67C86B02ED; Mon, 16 Mar 2026 11:49:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id A321B6B02EA for ; Mon, 16 Mar 2026 11:49:55 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 2C8A9C1849 for ; Mon, 16 Mar 2026 15:49:55 +0000 (UTC) X-FDA: 84552361950.02.56408FA Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf02.hostedemail.com (Postfix) with ESMTP id 3A47780005 for ; Mon, 16 Mar 2026 15:49:53 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dnNdS6JP; spf=pass (imf02.hostedemail.com: domain of vbabka@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=vbabka@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1773676193; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/zGpxTk+noseP/pytHVfCySKiUhW10abi1iYZzQ/sPI=; b=bh/TIqJfCmZ8UGSqACYB5QH//9WvSmcF99WiNYS8K4+xVCJAlXGV+J3oLfzvjoIj7n1qpv rdGdXcKBjXqAx7X1uqxVwvNFvpA+OdEypiZQy3ki2r84H7lpRe5lDmUey2SG6zg368gicG PPn9KanSGxLAocSIjz6xNizrKjq6Bvk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773676193; a=rsa-sha256; cv=none; b=nnuHYC5lFAGsKFoId9iJ4WLb5QJ2xc9ImrlnlCTeMfF0WT47Parf2qj6otedKbvjjCTz2Z PJpDYhe99EaW1VjR2ZYdP152Wm/5cyZio7TTEt1LSYb+upOiYUBZ4lVcEvOIbpgtxN+qCU Wg38R+szCAy0jvqtK67/nciYjpD+mds= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=dnNdS6JP; spf=pass (imf02.hostedemail.com: domain of vbabka@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=vbabka@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 06A3C40479; Mon, 16 Mar 2026 15:49:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7C85C19421; Mon, 16 Mar 2026 15:49:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773676191; bh=yjd8NtgZHV8vh5dTR2BKFX8AF+cyPjyTRX8mDhKOXNk=; h=Date:From:Subject:To:References:In-Reply-To:From; b=dnNdS6JPE6qD2jCA3kQJjIdRQTEImwtT4IQd5np/fj4QggzDeGkshtI8ChdkVfnNm qJoSB1cAsevGgmwZHC+UNpQ6/Zqv55lzoc+Vn9HSZ1o3n2pBIUMfgfhu5eTKasUwOv nnOVYNmuGNN4BVuJTYa+xoO20R5sGn2/SyZHXFVgXXoIbBlAv9yC/6G7IrRl1A9Jqq Lm3/6jmPUQQEel7kT+F3tS9PEYNIvb8KbN+EjeRT7BwnzwD3EvL2r+HFdpZ5pLSrKi JFLMV99cXmWqvB2RWYEFMPfEn4S3qZVL1zq6wyoF7YV1ETfMFVTNF5TzyhXSCY2Bu8 ajuv4mXvA4vwA== Message-ID: Date: Mon, 16 Mar 2026 16:49:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Vlastimil Babka Subject: Re: [PATCH v2 2/3] vmalloc: Optimize vfree Content-Language: en-US To: Muhammad Usama Anjum , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Uladzislau Rezki , Nick Terrell , David Sterba , "Vishal Moola (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Ryan.Roberts@arm.com, david.hildenbrand@arm.com References: <20260316113209.945853-1-usama.anjum@arm.com> <20260316113209.945853-3-usama.anjum@arm.com> In-Reply-To: <20260316113209.945853-3-usama.anjum@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: qyo9i7bhoezyustwxe3z8cttapdfjiiy X-Rspamd-Queue-Id: 3A47780005 X-Rspamd-Server: rspam03 X-HE-Tag: 1773676192-835256 X-HE-Meta: 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 IdeAHFK9 rfcSIUl+KoOFDhBWPFbuAz4HxOB5XpYzH9WgWlpER0RINj+opjNtI2NDXqU7RvV1bZ9MZ5LGtjwJKYLD4NyWgJphEUyOan1OttJOCWfXT/kI0mfkaePcl6wkbEv6UYf5AoYqV50EcDvG81AXj70fbmXD5Y0ON0sCYAgS/FZFCIjzUGT2i/2zxP8PomWQfMmc75e8y46IypGbXnricRM14uISXAZVNVzvg2iRwLQH4E6ytQ1GdxQoE3esduQPn9LaYG1bIm3hPNv86wXQVK+GGumy/CQ3G+yaImyO0t04ZczMyQKQ+RrE9Au94PLlp+tJxrMYLAjuqihgnF47z1So+UPU3QtWhrso7iM2YkiSZ4JzY5ttCLDAdIQ3qzw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/16/26 12:31, Muhammad Usama Anjum wrote: > From: Ryan Roberts > > Whenever vmalloc allocates high order pages (e.g. for a huge mapping) it > must immediately split_page() to order-0 so that it remains compatible > with users that want to access the underlying struct page. > Commit a06157804399 ("mm/vmalloc: request large order pages from buddy > allocator") recently made it much more likely for vmalloc to allocate > high order pages which are subsequently split to order-0. > > Unfortunately this had the side effect of causing performance > regressions for tight vmalloc/vfree loops (e.g. test_vmalloc.ko > benchmarks). See Closes: tag. This happens because the high order pages > must be gotten from the buddy but then because they are split to > order-0, when they are freed they are freed to the order-0 pcp. > Previously allocation was for order-0 pages so they were recycled from > the pcp. > > It would be preferable if when vmalloc allocates an (e.g.) order-3 page > that it also frees that order-3 page to the order-3 pcp, then the > regression could be removed. > > So let's do exactly that; use the new __free_contig_range() API to > batch-free contiguous ranges of pfns. This not only removes the > regression, but significantly improves performance of vfree beyond the > baseline. > > A selection of test_vmalloc benchmarks running on arm64 server class > system. mm-new is the baseline. Commit a06157804399 ("mm/vmalloc: request > large order pages from buddy allocator") was added in v6.19-rc1 where we > see regressions. Then with this change performance is much better. (>0 > is faster, <0 is slower, (R)/(I) = statistically significant > Regression/Improvement): > > +-----------------+----------------------------------------------------------+-------------------+--------------------+ > | Benchmark | Result Class | mm-new | this series | > +=================+==========================================================+===================+====================+ > | micromm/vmalloc | fix_align_alloc_test: p:1, h:0, l:500000 (usec) | 1331843.33 | (I) 67.17% | > | | fix_size_alloc_test: p:1, h:0, l:500000 (usec) | 415907.33 | -5.14% | > | | fix_size_alloc_test: p:4, h:0, l:500000 (usec) | 755448.00 | (I) 53.55% | > | | fix_size_alloc_test: p:16, h:0, l:500000 (usec) | 1591331.33 | (I) 57.26% | > | | fix_size_alloc_test: p:16, h:1, l:500000 (usec) | 1594345.67 | (I) 68.46% | > | | fix_size_alloc_test: p:64, h:0, l:100000 (usec) | 1071826.00 | (I) 79.27% | > | | fix_size_alloc_test: p:64, h:1, l:100000 (usec) | 1018385.00 | (I) 84.17% | > | | fix_size_alloc_test: p:256, h:0, l:100000 (usec) | 3970899.67 | (I) 77.01% | > | | fix_size_alloc_test: p:256, h:1, l:100000 (usec) | 3821788.67 | (I) 89.44% | > | | fix_size_alloc_test: p:512, h:0, l:100000 (usec) | 7795968.00 | (I) 82.67% | > | | fix_size_alloc_test: p:512, h:1, l:100000 (usec) | 6530169.67 | (I) 118.09% | > | | full_fit_alloc_test: p:1, h:0, l:500000 (usec) | 626808.33 | -0.98% | > | | kvfree_rcu_1_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 532145.67 | -1.68% | > | | kvfree_rcu_2_arg_vmalloc_test: p:1, h:0, l:500000 (usec) | 537032.67 | -0.96% | > | | long_busy_list_alloc_test: p:1, h:0, l:500000 (usec) | 8805069.00 | (I) 74.58% | > | | pcpu_alloc_test: p:1, h:0, l:500000 (usec) | 500824.67 | 4.35% | > | | random_size_align_alloc_test: p:1, h:0, l:500000 (usec) | 1637554.67 | (I) 76.99% | > | | random_size_alloc_test: p:1, h:0, l:500000 (usec) | 4556288.67 | (I) 72.23% | > | | vm_map_ram_test: p:1, h:0, l:500000 (usec) | 107371.00 | -0.70% | > +-----------------+----------------------------------------------------------+-------------------+--------------------+ > > Fixes: a06157804399 ("mm/vmalloc: request large order pages from buddy allocator") > Closes: https://lore.kernel.org/all/66919a28-bc81-49c9-b68f-dd7c73395a0d@arm.com/ > Signed-off-by: Ryan Roberts > Co-developed-by: Muhammad Usama Anjum > Signed-off-by: Muhammad Usama Anjum > --- > Changes since v1: > - Rebase on mm-new > - Rerun benchmarks > --- > mm/vmalloc.c | 34 +++++++++++++++++++++++++--------- > 1 file changed, 25 insertions(+), 9 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index c607307c657a6..8b935395fb068 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3459,18 +3459,34 @@ void vfree(const void *addr) > > if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS)) > vm_reset_perms(vm); > - for (i = 0; i < vm->nr_pages; i++) { > - struct page *page = vm->pages[i]; > + > + if (vm->nr_pages) { > + bool account = !(vm->flags & VM_MAP_PUT_PAGES); > + unsigned long start_pfn, pfn; > + struct page *page = vm->pages[0]; > + int nr = 1; > > BUG_ON(!page); > - /* > - * High-order allocs for huge vmallocs are split, so > - * can be freed as an array of order-0 allocations > - */ > - if (!(vm->flags & VM_MAP_PUT_PAGES)) > + start_pfn = page_to_pfn(page); > + if (account) > mod_lruvec_page_state(page, NR_VMALLOC, -1); > - __free_page(page); > - cond_resched(); > + > + for (i = 1; i < vm->nr_pages; i++) { > + page = vm->pages[i]; > + BUG_ON(!page); We shouldn't be adding BUG_ON()'s. Rather demote also the pre-existing one to VM_WARN_ON_ONCE() and skip gracefully. > + if (account) > + mod_lruvec_page_state(page, NR_VMALLOC, -1); I think we should be able to batch this too to use "nr"? > + pfn = page_to_pfn(page); > + if (start_pfn + nr == pfn) { > + nr++; > + continue; > + } > + __free_contig_range(start_pfn, nr); > + start_pfn = pfn; > + nr = 1; > + cond_resched();> + } > + __free_contig_range(start_pfn, nr); > } > kvfree(vm->pages); > kfree(vm);