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 104E41098792 for ; Fri, 20 Mar 2026 14:33:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7865C6B0155; Fri, 20 Mar 2026 10:33:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 736E96B0158; Fri, 20 Mar 2026 10:33:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6261B6B0159; Fri, 20 Mar 2026 10:33:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 4FE466B0155 for ; Fri, 20 Mar 2026 10:33:55 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id F21C61A0229 for ; Fri, 20 Mar 2026 14:33:54 +0000 (UTC) X-FDA: 84566685588.15.466EB7F Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf07.hostedemail.com (Postfix) with ESMTP id 4EC1B40013 for ; Fri, 20 Mar 2026 14:33:53 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=m040ISdA; spf=pass (imf07.hostedemail.com: domain of vbabka@kernel.org designates 172.105.4.254 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=1774017233; 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=2F3LmFYgz/IO1qdw8D5sw1nCML0e7Tg4mGt3tYCtNas=; b=F4kQn8k+XJ1X5DXxjkGf2H6rCn390EEC3P8TsqspQQWD6unYMnhb+w45otwADtiDqpaQdl oAOCiGCdZVAlYLpJ36MJaq7dKSQZ+Um+Gk8P3f4M4nZI/einkNoNOu2egMVuvPWNrTZgjH dftYDsls2L520qd5t3rq4yP09Hq+49E= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=m040ISdA; spf=pass (imf07.hostedemail.com: domain of vbabka@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=vbabka@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774017233; a=rsa-sha256; cv=none; b=VeTN3IxgD57LJ7SHCfFPVk2+j8pL0rTJORJ1lkkHa7RNowjef2hRHAEYmv9Y1dv3ZgJ5nw P0E0lt+GOohpxJ037nzmlzC1pyjRGeSXRBGUzDYlYse42Y0tnTzS6mYKwz2kW6VRyISmTw TrziAiEqfU97N4lcoS2OlsICt/Xdq3Q= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 966DE61865; Fri, 20 Mar 2026 14:33:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56BC8C4CEF7; Fri, 20 Mar 2026 14:33:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774017232; bh=woNciVcFPVPKMQT5S/73G3cJUwtRkApIxOo1qnPR/fA=; h=Date:Subject:To:References:From:In-Reply-To:From; b=m040ISdArhiK15Wt+g2CXOlAvu3bmHrRHpsjRNyEr+5iQN0VHvwWEumgevnywYjgK 7RWgfS9f7qIpRldtep2k0MvPI0QGqwKqCkowgyPujUSov0ZTUfaNdgWzIENX/xaDfl 7KwtQ6jZ/xdWEyJiuF0eTiDqfIjbOAFNn46yoa/BTGzlgCGZrV/+ZgYsk39dWsQjPN FVFgBH4utS0kC2+I0NUEdiK2vL204Cde0ej3BOxGLMSKBAewmL8+8P4xEz3Pjq2opg e9UWBA1ff3zHWLPMxoUWuPcHIvLstFIWFd76R/3VL243g31wdj13Plvlj75qRli5Jk 7cC+vmQ/cIGEA== Message-ID: <38379a16-d596-4266-ac3b-1dbee5356add@kernel.org> Date: Fri, 20 Mar 2026 15:33:46 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] vmalloc: Optimize vfree Content-Language: en-US To: "David Hildenbrand (Arm)" , Muhammad Usama Anjum , Andrew Morton , 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> From: "Vlastimil Babka (SUSE)" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 4EC1B40013 X-Rspamd-Server: rspam08 X-Stat-Signature: t88stq3kqhhbqniuj4ta4kpdm9n74q9x X-HE-Tag: 1774017233-161227 X-HE-Meta: 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 atphIAeG jgHFcaDLktx3ixLPS8lMJwNBLJOdhVb1nqek3YDyszMn1XYIcmVbjpivBRYHFdehmwcMe88KY3E2WC9zShgHhN4Rvcfqmox6FokZ23R5b3lHb4qib5Lr0zyQEvyK//MTG1YLTF1aMU1zS7Q3lhHiw92H8yi67+05i7vAdnmOvnQ2KBYKNiSYP0S2zpm5cyDUt+Hd25pj6VxPJQAw8+aWGamv0FznSo4cCHJZLc+N9uIi51/DkqP7Q5TSd+o6FzmVp7rFq8L9x6E/QQXn31UipqXU7O3iLtJAW6Sx0oakChWZLX2vr15i2la3KBqVRDXoDTWpELo3RZ5HevA4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/20/26 09:39, David Hildenbrand (Arm) wrote: > On 3/16/26 16:49, Vlastimil Babka wrote: >>> 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"? > > Are we sure that pages cannot cross nodes etc? It could happen that we > have a contig range that spans zones/nodes/etc ... Hmm single order-3 allocation can't but we could be unlucky and get the last order-3 from zone X and first order-3 from adjacent zone Y. In that case the loop would need to also check same zone/node. > Anyhow, should we try to decouple both things, providing a > core-mm function to do the page freeing? > > We do have something similar, optimized unpinning of large folios, > in unpin_user_pages_dirty_lock(). This here is a bit different. > > > So what I am thinking about for this code here to do: > > if (!(vm->flags & VM_MAP_PUT_PAGES)) { > for (i = 0; i < vm->nr_pages; i++) > mod_lruvec_page_state(vm->pages[i], NR_VMALLOC, -1); > } > free_pages_bulk(vm->pages, vm->nr_pages); > > > We could optimize the first loop to do batching where possible as well. > > > free_pages_bulk() would match alloc_pages_bulk() > > void free_pages_bulk(struct page **page_array, unsigned long nr_pages) > > Internally we'd do the contig handling. > > Was that already discussed? AFAIU some of Zi's replies hinted at this direction. It would make sense, yeah.