From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F17722DF151; Fri, 20 Feb 2026 19:50:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771617022; cv=none; b=GDDh/AW6maJ9Bh4HNkwoMTdG5PyDkyQNQ4XgC6vJ68IADLr2j734sbOdBvIjWOZNgd78++xaTtgUUPD1KEnVWn8gcZl7MEu5k6TsIkCRI/6UqujF0QMO5RLZ5B3TvUFa64crwBv0PSDZD5IUQSr7pP8cFwKrhaOdN3BCWtyx2KQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771617022; c=relaxed/simple; bh=46rZAlhHO0tSGik7S4Qgw3kaq49VkdGzybXEmAOjuGQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CTw9W3s1+7CYrV445Itie1Hj+46AruxLk/jELYHljp5ztknuOs51/uvZjaTxrCElOvvZltzGLpf5/MF3MZtag4LWo/uw1o3Ega0khWRMMHVG7B7AXXP7UH4BT3p4+wM9UlL6MXCy61NMkwm/JXYuQ6yQCwdE0Oso5rqD7XzA5RE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rDrzAl6u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rDrzAl6u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 894C6C116C6; Fri, 20 Feb 2026 19:50:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771617021; bh=46rZAlhHO0tSGik7S4Qgw3kaq49VkdGzybXEmAOjuGQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rDrzAl6uzNk5PgAfQyn3GzfGAdo3ATRFHQCZOX9KPp0pgrSmVBW+LUM8tUzr3IOmo pKrPFvz6yEGZTIfbLtskbXiZsK3wgfOKYXFybTyaA7T8LMMosacAC4t3NwlYQVOKGT abSdcwQBm6B7qsu3MtuXIFUiNf7Ves0t47+Zd4n6y1dbvdEIDFiqSN5hNZXi8QMYs7 qPV9uHZg+jPEwLM+TXQLAEN8teZatZVDQ19orS+kk6V9piJb5RBoujarc6nsgeQ72r O6GZESNyS7LwjcUVfJDjuAgq6s++irzvYrnoLKLtTfO6vSa20tgmgubVukycwPJ/1I aaMDInQr6f/Zw== Date: Fri, 20 Feb 2026 09:50:20 -1000 From: Tejun Heo To: Amir Goldstein Cc: "T.J. Mercier" , gregkh@linuxfoundation.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, jack@suse.cz, shuah@kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 2/3] kernfs: Send IN_DELETE_SELF and IN_IGNORED Message-ID: References: <20260220055449.3073-1-tjmercier@google.com> <20260220055449.3073-3-tjmercier@google.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hello, On Fri, Feb 20, 2026 at 07:15:56PM +0200, Amir Goldstein wrote: ... > > Adding a comment with the above content would probably be useful. It also > > might be worthwhile to note that fanotify recursive monitoring wouldn't work > > reliably as cgroups can go away while inodes are not attached. > > Sigh.. it's a shame to grow more weird semantics. Yeah, I mean, kernfs *is* weird. > But I take this back to the POV of "remote" vs. "local" vfs notifications. > the IN_DELETE_SELF events added by this change are actually > "local" vfs notifications. > > If we would want to support monitoring cgroups fs super block > for all added/removed cgroups with fanotify, we would be able > to implement this as "remote" notifications and in this case, adding > explicit fsnotify() calls could make sense. Yeah, that can be useful. For cgroupfs, there would probably need to be a way to scope it so that it can be used on delegation boundaries too (which we can require to coincide with cgroup NS boundaries). Would it be possible to make FAN_MNT_ATTACH work for that? Thanks. -- tejun