From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BC4F942E8FF for ; Thu, 2 Jul 2026 13:20:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782998402; cv=none; b=nVRFmWgNdJLjG8wtg5BoH47y4+38b95WaGca12XYh37xjIUASeIVgyZ/jpWMf/hs9OTqdHgM6zOMqsOTyEyf23vmgqJ2WB9js2BZxEljq6ceT3exqIGhoa3zoI2/CJ+ZdfJ8pWU8rKLvn87x0N4v3AWsBOrVoyVg//GNsMns6aw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782998402; c=relaxed/simple; bh=HmfkqVk4R3yRomoRMxzwquh4EhnfiOtrlu/DXGVuXNY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CLfsLEWds1x3PABK+1s0T1Hv/PzhccBon4H8HE4vydmvNfyIaqzKCdV98yK7DFhYbYgUN/z0snTpD8Dz55BqJS/mA1uvxcC8vCDOrHoCVSlK7QqOd528xrO0VVcvxnJGM8eybWobMrLo0T/iRWVYsvbfQE8XWjHiiHOgn+kFMfI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CGXO6T6x; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CGXO6T6x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 178441F00A3A; Thu, 2 Jul 2026 13:19:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782998400; bh=dRxaeNPnGQ0zViJtDVvZTezJFXLd8iqfnNeVWlkksh8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=CGXO6T6xfGoFTxtpyNjLn7XuGtESkZA1HoAysOFugchG4rG3R7GA+uAqGb2cSscpS 3elCGKYQQNdduE6fZQI7VPNQ2X2aOICI3DuFlgmUVvkrqT915gKiIynukGpLVNgu3c epCLySq07HK96EZ+5nBpySxqvhcflj9E25e65XTq67IKJZyBVo3tc66zLPE3as0h0g 3wvlFO6prwZ9+sXKSz15JMxuA37KhCKyjRje6VlhePlkUeM82Q4f+UbZDLxmZ1G3WB VNko7QAocVA/mTGMZ2oc/nJvXIYQx4Lg5A1ZfB8EjuXcmC5rSNPhhzvc2TKVklhNqA zTw2tHq8mvHuw== Message-ID: <1b6b2074-4575-4c54-a950-fda4b9154169@kernel.org> Date: Thu, 2 Jul 2026 15:19:55 +0200 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 v5 1/5] mm: move mirrored memory overlap checking to the outer loop To: "Liu, Yuan1" , Oscar Salvador , Mike Rapoport , Wei Yang Cc: "linux-mm@kvack.org" , "Hu, Yong" , "Zou, Nanhai" , Tim Chen , "Zhuo, Qiuxu" , "Chen, Yu C" , "Deng, Pan" , "Li, Tianyou" , Chen Zhang , "Zeng, Jason" , "linux-kernel@vger.kernel.org" References: <20260520093457.3719960-1-yuan1.liu@intel.com> <20260520093457.3719960-2-yuan1.liu@intel.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/26/26 10:26, Liu, Yuan1 wrote: > >> -----Original Message----- >> From: David Hildenbrand (Arm) >> Sent: Thursday, June 25, 2026 8:05 PM >> To: Liu, Yuan1 ; Oscar Salvador ; >> Mike Rapoport ; Wei Yang >> Cc: linux-mm@kvack.org; Hu, Yong ; Zou, Nanhai >> ; Tim Chen ; Zhuo, Qiuxu >> ; Chen, Yu C ; Deng, Pan >> ; Li, Tianyou ; Chen Zhang >> ; Zeng, Jason ; linux- >> kernel@vger.kernel.org >> Subject: Re: [PATCH v5 1/5] mm: move mirrored memory overlap checking to >> the outer loop >> >> On 5/20/26 11:34, Yuan Liu wrote: >>> Move the overlap memmap initialization check from memmap_init_range() >>> to memmap_init(), and replace the per-PFN check with a memblock-based >>> check. >>> >>> Reviewed-by: Wei Yang >>> Reviewed-by: Jason Zeng >>> Signed-off-by: Yuan Liu >>> --- >> >> IIRC, with the patch from Mike+Wei this patch here should no longer be >> required, >> right? >> >> https://lore.kernel.org/r/20260625073941.145014-1-rppt@kernel.org > > Hi David > > Yes, we don't need the overlap-related patch anymore. The zone contiguity optimization will build on top of Mike's and Wei's changes, and I'll update the patches accordingly. > > These days I've been revisiting the issue where pages_with_online_memmap overcounts subsection hole pages in early sections. > > We previously attempted to address this with a patch [1], but I think the concern raised by Sashiko [2] is valid, so we may not be able to use patch [1]. > > I can think of the following alternative approach, which can avoid changing semantics of pfn_valid() or first_valid_pfn(): > > Basically we calculate pages_with_online_memmap by iterating over subsections in each zone during memmap_init(), to see pfn_to_online_page(start_pfn) is true or not. > If it is true, then the whole subsection will be counted into pages_with_online_memmap. We really should strive for a solution that doesn't walk any PFN ranges to perform a pfn_to_online_page(). -- Cheers, David