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 11C7C1A682F for ; Wed, 15 Jul 2026 04:05:25 +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=1784088328; cv=none; b=N3V86IVpRCgdY6wOXbjpQC9xdqVTfcDCxwi/774WTaB6l0dgK9mSDf9gDtdZnqFPkVGvOS6MH+wvsLCbXaUa4SabWpMYgrmf13Q5426gvUDFxkRjkG4E9Pl1qt9BQ3scsTMRYQOL1pHFg3L3TvubMQeZQO1nJE8RMnFE4xaVzkM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784088328; c=relaxed/simple; bh=JleE5ZWx9SjpMJn0oHA2QSPbxd8mp4PaHdJxoION0bY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=euaBvMDq3zWgK1dwV74/hvyItnbyok/xO5ajgPolz3y913m56BAO79uiCj9ybmGIo7ONVsJF541MkaSAG6+IBBwYEyX08PHcrUaAAryvfl/efUU8jxg+bk+RBegMywarfBQo1paelRSPSvxcxB9wfH4vvJQSDY7qqXuef+nKlFY= 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; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=Be6daMTs; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="Be6daMTs" 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 7FA7E339; Tue, 14 Jul 2026 21:05:20 -0700 (PDT) Received: from [10.164.18.40] (unknown [10.164.18.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D24F23F7D8; Tue, 14 Jul 2026 21:05:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784088324; bh=JleE5ZWx9SjpMJn0oHA2QSPbxd8mp4PaHdJxoION0bY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Be6daMTs1IbU1CSoetXmxbaEoBz8AoymrrC01Gu2ZMKnuQTFZg2itQMyvkNGJewjG W00xD+NdY68zakgWc9vHhmLYz2D0EOw8R5GaE/MwzP4v6IMDxG+eCYgDl+6Ojz1itL dUS8pwTSACiNa/1z7jgbTix7dOW1TdVfVZn1Jrzk= Message-ID: <90194352-7389-4942-a33f-37ed4df7c51e@arm.com> Date: Wed, 15 Jul 2026 09:35:18 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 0/6] mm/vmalloc: Speed up ioremap, vmalloc and vmap with contiguous memory To: Dev Jain , Wen Jiang , Andrew Morton Cc: catalin.marinas@arm.com, linux-mm@kvack.org, urezki@gmail.com, will@kernel.org, Xueyuan.chen21@gmail.com, ajd@linux.ibm.com, david@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, rppt@kernel.org, ryan.roberts@arm.com, Wen Jiang References: <20260709073823.6643-1-jiangwen6@xiaomi.com> <20260709160805.26e63bae89dd03cf2951104e@linux-foundation.org> <929dedc2-eea3-4153-be6d-d2dd727fed89@arm.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 14/07/26 4:47 PM, Dev Jain wrote: > > > On 14/07/26 2:06 pm, Anshuman Khandual wrote: >> >> >> On 10/07/26 2:24 PM, Wen Jiang wrote: >>> On Fri, 10 Jul 2026 at 07:08, Andrew Morton wrote: >>>> >>>> On Thu, 9 Jul 2026 15:38:17 +0800 Wen Jiang wrote: >>>> >>>>> This patchset accelerates ioremap, vmalloc, and vmap when the memory >>>>> is physically fully or partially contiguous. >>>> >>>> Thanks, I added this to mm.git's mm-new branch for wider testing. >>>> >>>> AI review asked some questions, and some of them are new since the v5 >>>> series: >>>> https://sashiko.dev/#/patchset/20260709073823.6643-1-jiangwen6@xiaomi.com >>> >>> Hi Andrew, >>> >>> I've gone through the Sashiko findings: >>> >>> - Patch 1 (find_num_contig): Over-interpretation. No new hugetlbfs hstate >>> is added. The extra sizes are only used by init_mm kernel mappings via. >> >> But not sure if that is a right approach. If these multi CONT_PTE >> sized mappings need to be supported in vmalloc() but without adding >> corresponding HugeTLB sizes, probably these required helpers could >> just be factored outside HugeTLB. > > The problem is that the existing vmalloc-huge code reuses the hugetlb helpers > because it is easier that way. > > If you really look at it, num_contig_ptes(), set_huge_pte_at() and arch_make_huge_pte() > do not have anything to do with hugetlbfs, but with huge mappings. It is unfortunate > that these helpers are sitting in hugetlbpage.c . Really these functions should be > pulled out of CONFIG_HUGETLBFS and put into some common header - but I can't think > of a clean solution to this. > set_huge_pte_at() and arch_make_huge_pte() are provided by subscribing platforms to be used in generic HugeTLB. But later these callbacks started getting used in generic vmalloc() as well. Although arch_vmap_pte_range_map_size() first narrows down supported size from HugeTLB list. Basically vmalloc huge mapping support is still a subset of HugeTLB support. Hence we should not add new vmalloc based huge size support without first adding that up in HugeTLB. Otherwise set_huge_pte_at() and arch_make_huge_pte() need moved outside generic HugeTLB as well. > So I think for this series, the least we can do is add a comment to clarify that these > helpers can be used by non-hugetlbfs mm code to set multiple huge mappings at the PTE level. For these helpers to be used outside HugeTLB (without prerequisite) - Move them outside generic HugeTLB - Drop #ifdef CONFIG_HUGETLB_PAGE in vmalloc.c Not sure if a comment would be sufficient here. > > >>> >>> - Patch 5/6 (NULL page): Invalid input. vmap() expects a fully populated >>> array of valid struct page pointers. >>> >>> - Patch 6 (32-bit count << PAGE_SHIFT overflow): Pre-existing. This was >>> already discussed in the V3 thread, and a separate fix was proposed >>> there. >>> >>> Thanks, >>> Wen >> >