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 D633C3E9585 for ; Tue, 26 May 2026 11:43:10 +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=1779795800; cv=none; b=lVGqQvRSTLGWc9F0PCl0w919BFlaet7ZpNoxGb2DgKJ9IvZfV/5xkbIS4+fG0VTt+XKn1mKFXUyy9ismvQluKwo242mLSQG8QN5XwFxwmYvnVq7+es9u8my4qRTeHntAJODq9uYUXyrlL1PNwx9TaoQJ6mpH5rqiur4Z8U8qLlI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779795800; c=relaxed/simple; bh=proGReK3Bjp80WHoG5rgIcj2euLsuMvn3v1d5Y7Xs1M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=fyl4A2DSswLGTJ3htdDCNJmaQMr48t2OQxHTLFx1PdP3DXqL7AtZ7KhElQ70sJuP7r+vN8inB6lykWa+LT7f+PyZ8t9hO1cBy0pnI8DNF/O/dJ6kqzQf4m1MurYf0CEjQj6Ij/6Xt/fSForRfS6Dqt9/ADVr/nNdYlZouLotXEk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GE2giss5; 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="GE2giss5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D98FC1F000E9; Tue, 26 May 2026 11:43:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779795786; bh=Q8VRGHC3tlORPtYqg7Va/I23aYVh/vTeo/wVK1CMwWM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GE2giss5Wh8rI35Y9swTlRcBFd7qNiQZn7r+ZMH2GbiPpbq2NdEkd4G1PcVRtApQJ xu5rCcF/LR6ZtObpquLEgLYBm4uxIkuCd+g8LdI2pcZc5adlAaiJ0+lIU1cPq9fTy6 dHQfbHr3VD+fQ6JbwaVk1sfMQ06ySY9fytPVfY1+r1PYxKZZcOCFFbI+/uT0dGio7c ARlkqc8NA1rXBPEwjuHjGjKHMoI5aPxjzM/0hZsSFZooIcqDLQ+eFBdUPdx7yj//Gv cVPVSUxyMafe0na01QbuzDMAIOzI4ySvR3t0KsVvpy9O/PEmTIftQ+OL2yl1NAL1L2 Ces755QZ58l2A== Message-ID: Date: Tue, 26 May 2026 13:43:02 +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] mm/page_alloc: document that alloc_pages_nolock() uses RCU To: Brendan Jackman , Harry Yoo , Brendan Jackman , Andrew Morton , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan Cc: Alexei Starovoitov , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260519-nolock-rcu-comment-v1-1-4a630c8794e5@google.com> <6c089de3-34d9-4dd9-9646-f51328c77497@kernel.org> From: "Vlastimil Babka (SUSE)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/26/26 12:14 PM, Brendan Jackman wrote: > On Wed May 20, 2026 at 5:16 AM CEST, Harry Yoo wrote: >> > (I don't think there is even> any documentation of what noinstr means >> at all, let alone the connection >>> with RCU). >> >> *flips through the documentation* >> Oh, perhaps Documentation/core-api/entry.rst? > > Oh, you're right. The situation is way better than I thought, and now > I realise I have read this and it's probably where I learned about > this in the first place (I thought I learned it all from Junaid). I > apologise to the Documentation/ tree for my slander. > >>> Note this is not claiming that any cgroup code called from the allocator >>> would actually break if this restriction was violated, it could very >>> well be that there's no real way for the allocator to act on a cgroup >>> that can disappear concurrently. But, since it's likely nobody has >>> verified this one way or another, better to just be safe and declare >>> that RCU is required. Allocating from an RCU-unsafe context seems a bit >>> crazy anyway. >>> >>> Suggested-by: Junaid Shahid >> >> The email should be junaids@google.com, not jackmanb@google.com? ;) > > Damn. It looks like this already went into mm-unstable but I guess > it's not a huge deal. Things in mm-unstable can be fixed up. That's why "unstable". Acked-by: Vlastimil Babka (SUSE)