From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f169.google.com (mail-yb1-f169.google.com [209.85.219.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 727421E9B04 for ; Wed, 25 Jun 2025 21:52:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750888326; cv=none; b=YGe3Kgd8L6i6XVIz5Xd3gssu2EaBu7+tZ7SKbk78TiJYL0fCQQsbHBXekKH3A1hX/Q8bQDXAaIRmh7Mv8sA4J53Uj0v99WGInBuP8iG3T+RUqkNRGjqbgGmhbCzCWW/XFlhoK+OfQu4d1SNEO+ebZwu0jbvqpKmPuLrYvfPXJvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750888326; c=relaxed/simple; bh=8gWLbwOk5igz/abwJ7DtKa+yMldSLIe+QHXq01J5WwQ=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=o5Tkc0c2tXC+Mz4zMZxJTEnf3VZJ3DITA5CpBRQHOtdc8mzvHUTP9OOSrevUgUurbz6Dm5D51Zi/+5b9otgrt0lTCogI6SFkkQGEzISk3HCvkt+feYcq8s+Y+G+ZD10DjbVzJMUmA6kp4aGgWclvqCuSinHRRKLeHvKlTQWQMUE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=s7ADR9Ql; arc=none smtp.client-ip=209.85.219.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="s7ADR9Ql" Received: by mail-yb1-f169.google.com with SMTP id 3f1490d57ef6-e81f8679957so259699276.2 for ; Wed, 25 Jun 2025 14:52:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1750888324; x=1751493124; darn=vger.kernel.org; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=zn3wkl/8rFNEaRV9dGBaoEQ5JkNSFdHxBuYwPyRc1yU=; b=s7ADR9Qlp4VeuBh/gR7Yw0SfVhLnu/LFuq7H6dKxqrHnR3ik+1e1E/6Bu264F45IGH PBBQbbVi0MFGLV38mU17dZqd2qhgWXp09VKpCAnQ4SyaqpUrji/RGmj0AWn8lrgbCFjf //FJbCRxc3yAaLOEXuh8nI/zk9DEgErlT+GeJrv76WyU2ZW13W9Uh2RlMqAoYlJ/AE6Y uwEtt1l1pvdCMAVly2TVisKyHWySGDjeTXmGynZvnpP265yqStfjOfu4cgkuDlj55PrQ +clZnA+9a5GfyWbWplnwCBJ8NSZSb3sSvxWJJfi4cY6zvAEucdjVbP31q+fhzwZhIlip WAXA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750888324; x=1751493124; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zn3wkl/8rFNEaRV9dGBaoEQ5JkNSFdHxBuYwPyRc1yU=; b=kODS4sPUmRxiWgQbW3MSv++746yEPPvoVySmNoD392PCBr2rXy5HS1qoHE73U5Uohl 3UTHgZdcsGfrVzq6V4W94kw8v0qqMjMTtlrRPMG//KCWQ+fz5jGWf8TH1hp7EqTaPOyh zZMHpyhmi+iXc0znnqQel21Q26CuCY8KLwTqYk6RL3Mw3peW0uJXXp8xxbemUQzxIAFX v2EEeQ6wQ0XvYjhmJlzBxYWUmJk9Q8Fo5EpW5GDGmJMJq4NzgfxT1Vt8qJKxBDRdT5Qc TcjoGBhN3pDiNebZZ7TNVmZtxTBP23//XGl8tglFCvjdfJBYC6jqDMlJtAT8PzhupHid 5Z0Q== X-Forwarded-Encrypted: i=1; AJvYcCXe6XM0xasWAH0PlbJ82xc/FNDQGFrlfi3erellX9wlj01I5MJXhdVVXwctQj0OLUWZKJZxxzm11uEn6WY=@vger.kernel.org X-Gm-Message-State: AOJu0Ywb4ZOpj5+iKV207Bzp+59PwOy3BWU2+Wa298IbSEJuzNWcjvNT 5OKgAuWrVhuhi9Fa5Lcpkjj+FzopbW97DL7v8ifvLb3VnRT1TuQJp9GYTeeqcg4rdg== X-Gm-Gg: ASbGnct1PBjZVmtLiRlKVqqA786QhGWYhcsirqn198wXIwOF6tL0/jAVxxqJyzxkxpq McJpFQvWg3Cy1kvB0GsPUwlen8YrlvWFwgE5nlqD53Ef+9RaHwP2PyNUPJcozU+zFW8bRG8hVmq bUtDYKj8PJyB1FNfAXTOCHnNj0VQLcO+A0q6lqNc8ZlkTWBwOdGgkY9sfiJF1kX2xQCUuIj5koR 0db/SqcKgBS3QZIfEfi/h/I8qJqc60vsY5jVmkmkSlpqnM83HYm4rQE6k1fsy6qyFv0nelrxUAY 73MwEHEgoDxJC6qhcyXOUU1jEg8VJm67DYE17BZhwWgO/833/+qIRequ/5+iHXwCCLD76LYcQmC c3EhjS411i/dKSMMPzBkykK8/yW1ijPKQ9/2fJuW2vX0j9XM= X-Google-Smtp-Source: AGHT+IHca06mCSOznvqnZXmdMtIDiuoPO9Ny+dcngUNKJ1qC16ANTlTIwNA4GvPhmZA93uvUS/bCCQ== X-Received: by 2002:a05:6902:1106:b0:e82:3d1f:29f4 with SMTP id 3f1490d57ef6-e86018ef30emr6124620276.39.1750888324147; Wed, 25 Jun 2025 14:52:04 -0700 (PDT) Received: from darker.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id 3f1490d57ef6-e842aaed6e4sm3886264276.20.2025.06.25.14.52.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Jun 2025 14:52:03 -0700 (PDT) Date: Wed, 25 Jun 2025 14:51:52 -0700 (PDT) From: Hugh Dickins To: David Hildenbrand cc: Lorenzo Stoakes , Hugh Dickins , Baolin Wang , akpm@linux-foundation.org, ziy@nvidia.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, zokeefe@google.com, shy828301@gmail.com, usamaarif642@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 0/2] fix MADV_COLLAPSE issue if THP settings are disabled In-Reply-To: <8691d74b-67ee-4e26-81ac-f6bf1725361e@redhat.com> Message-ID: <3ec483b4-9f13-daa4-68ac-2af3eabe8583@google.com> References: <75c02dbf-4189-958d-515e-fa80bb2187fc@google.com> <9cb94544-f65a-4394-b1e2-bfb226ead31c@redhat.com> <8691d74b-67ee-4e26-81ac-f6bf1725361e@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 25 Jun 2025, David Hildenbrand wrote: > > I know, See my other mail, the problem is rather if there is no somebody > relying on never+MADV_COLLAPSE from doing the MADV_COLLAPSE-documented thing. > > It's a mess. > > (I have the suspicion that Hugh might know of such a user :) ) I've not yet read my way through this firestorm I've raised, but on this point: no, I don't know of such a user. You'll be suspecting that I know of some such use by Google: no, I haven't even investigated to see if that's the case; I think not, I think we're not neverers, but cannot check at the moment (and might have got in a muddle with the defrag options). I never(!) bothered to investigate that, because if Google does rely on this behaviour, it is very easy for Google to maintain its own variation from whatever is decided here (though management won't like me saying so). My concern is for everyone else who read the madvise MADV_COLLAPSE manpage. Hugh