From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793887325; b=IQr9phMyFpHaHTUx0BXfyjTpnKfEFN5rkHZzqkGxVqlX49BAREjkhvW8f4uWk0OitSbj mJejqF7ZPOrHjRagk8Txu8NDw3sbaz7C76cSwfD9f2CijBB9BWJ+ls+bfNJA4mMRD259e /fP9ILPBtcsv+bDjMYKiG2ctdLMKHbtc06Ini4M3OVATWebKzchNYAsHiNMyVhnu71u03 3/TGRTQ4zAvgP20fC4FddgxCS/12U1JGFOYr700Pn3Lm3W0tGRjourAA/OEq0OtFwqSQb fpABNjuUWjXaz000WwF9SPFb7nSv/4mMOCFEJkO+ofdljEawcGYgIlUmSAMk8rKPzHQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793887325; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=xsq3HeGsICcD9qR4LeaVPKieAjkKF0z7rahKgx3b78c=; b=M0p9Ysjv5P4s4uAFsqAc4r7YuhXRde3evJ8dfkA5aDWEx0qJe7KVmkIHMiNIXJZnCZWi 9TKm3V6SR6AheBPjuRq89yeOF+uh3V0HlKRP2bto4Czy5894ux9fP142ViM1U8Vxfv4Oz ulcYzroJLrVr4I3mFgSIIQOAgMtzBKtEPFM7KEQQTcUd3etdZ4Yg6MFQVwNGu++/Z1Mfk VxQpush+6+lt2/cSHBEmbop2+U8eGOEGryfA4oXf1bjZL+tukuA5n07O5eOu5D2rq1bj5 0BuB4Lj8jfXObYLNk/JTE6UAMnNphE5R08xPC9VFzHb2os4XEqsA5yz1MC73JVUJLeA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=VCXdsPfc; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EE69F606A32C; Thu, 5 Nov 2026 14:02:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=VCXdsPfc Received: by smtp.kernel.org (Postfix) with ESMTPSA id E023E1F000C1; Thu, 5 Nov 2026 14:01:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793887324; bh=xsq3HeGsICcD9qR4LeaVPKieAjkKF0z7rahKgx3b78c=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=VCXdsPfcQokl8f+rjLdNBL+YCFkzVLRKWrFySEE1WMzPl+ktC9vx0bBWrQsN9nihj tI18V1AdcZLO2Wp4q/XVD+jddiqq8RxzmrwGeZc2I/5xJGlBmc/lzvB9ahZ8wbsrHo 2uxI2T8kn4sNtptex1MZV2ldZjPoTKOBNL315/ys3xnd96b7/OmUqv3SMvRknBUU6n dlceNP+HUlg47v3tzKlUWNTjIKpN5HQZNGVg406HGvI1os0tGuxwamsSam0tHt6WI5 TLF6oIQU3Cawwx/shvdd/m82/qVvcUBjYJs1I074yQfHmmLWRCw4F5bVOdVN7WG+5r flUIfgaLzHqIQ== Date: Thu, 5 Nov 2026 14:01:56 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Andrew Morton , Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Suren Baghdasaryan , Vlastimil Babka , Shakeel Butt , Yonghong Song , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH 2/5] mm/khugepaged: scan mm's more efficiently under mmap_lock contention Message-ID: References: <20261103-khugepaged-latency-fix-v1-0-a07ab16ac860@kernel.org> <20261103-khugepaged-latency-fix-v1-2-a07ab16ac860@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 05, 2026 at 11:23:41AM +0100, David Hildenbrand (Arm) wrote: > I could have sworn I saw a similar patch from Nico at some point ... maybe it > was in a private discussion. Ah, yeah, it seems a fairly obvious thing to do (as often these things are), was surprised somebody hadn't already tried it. > > > Am I correct or is the short version of this change "Remember the next scan > address per MM instead of starting from address 0 whenever we continue scanning > a MM after a skip; and we might skip under mmap lock contention" ? Yes! > > I think a lot of the commit message above can be simplified. The book author part of me comes through sometimes ;) Will try and cut it down for the respin. > > Reviewed-by: David Hildenbrand (Arm) Thanks! > > -- > Cheers, > > David -- Cheers, Lorenzo