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Tue, 3 Mar 2020 14:20:33 -0500 (EST) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Originaldate: Tue Mar 3, 2020 at 8:50 AM Originalfrom: "Shakeel Butt" Original: =?utf-8?q?Hi_Daniel, =0D=0A=0D=0AOn_Mon,_Mar_2,_2020_at_5:42_PM_Daniel_Xu_?= =?utf-8?q?_wrote:=0D=0A>=0D=0A>_User_extended_attributes_a?= =?utf-8?q?re_useful_as_metadata_storage_for_kernfs=0D=0A>_consumers_like_?= =?utf-8?q?cgroups._Especially_in_the_case_of_cgroups,_it_is_useful=0D=0A>?= =?utf-8?q?_to_have_a_central_metadata_store_that_multiple_processes/servi?= =?utf-8?q?ces_can=0D=0A>_use_to_coordinate_actions.=0D=0A>=0D=0A>_A_concr?= =?utf-8?q?ete_example_is_for_userspace_out_of_memory_killers._We_want_to?= =?utf-8?q?=0D=0A>_let_delegated_cgroup_subtree_owners_(running_as_non-roo?= =?utf-8?q?t)_to_be_able_to=0D=0A>_say_"please_avoid_killing_this_cgroup".?= =?utf-8?q?_In_server_environments_this_is=0D=0A>_less_important_as_everyo?= =?utf-8?q?ne_is_running_as_root.=0D=0A=0D=0AI_would_recommend_removing_th?= =?utf-8?q?e_"everyone_is_running_as_root"_statement=0D=0Aas_it_is_not_gen?= =?utf-8?q?erally_true.=0D=0A=0D=0AShakeel=0D=0A?= In-Reply-To: Date: Tue, 03 Mar 2020 11:20:32 -0800 Cc: "Cgroups" , "Tejun Heo" , "Li Zefan" , "Johannes Weiner" , "LKML" , "Greg Kroah-Hartman" , "Kernel Team" Subject: Re: [PATCH 0/2] Support user xattrs in cgroupfs From: "Daniel Xu" To: "Shakeel Butt" Message-Id: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue Mar 3, 2020 at 8:50 AM, Shakeel Butt wrote: > Hi Daniel, > >=20 > On Mon, Mar 2, 2020 at 5:42 PM Daniel Xu wrote: > > > > User extended attributes are useful as metadata storage for kernfs > > consumers like cgroups. Especially in the case of cgroups, it is useful > > to have a central metadata store that multiple processes/services can > > use to coordinate actions. > > > > A concrete example is for userspace out of memory killers. We want to > > let delegated cgroup subtree owners (running as non-root) to be able to > > say "please avoid killing this cgroup". In server environments this is > > less important as everyone is running as root. > >=20 > I would recommend removing the "everyone is running as root" statement > as it is not generally true. > >=20 > Shakeel Good point, thanks. From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel Xu" Subject: Re: [PATCH 0/2] Support user xattrs in cgroupfs Date: Tue, 03 Mar 2020 11:20:32 -0800 Message-ID: References: Content-Transfer-Encoding: quoted-printable Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dxuuu.xyz; h= content-transfer-encoding:content-type:in-reply-to:date:cc :subject:from:to:message-id; s=fm2; bh=FJ6KELxyo/zYZfyW+0Pn8m70T 4Tx2JSVTx48BzYMJvg=; b=tkLGfZkSv5J9psMO+WQWVj4I6UVu6g4z0tOr6y64Q qasyR5Q7LFNOS3wRB1Fts5bIDy7jD6TnGYbt+QVV3wjIhzY5xzKPydwZGckLaWCv iZN3EUeGwRvu65muDaE60yATilaeeEYLUxIvyWCe08GETO4Hp6O0isa1rpaaoM2c Gex1JZn7kNhZnmJhCsHFOwzMK2ylg5NgqK50fMt4C+8v9RJ02un+mOtLf+4iB7FZ 9h08uWg/Kl2rJ5nytZZhT4JXuKH5QGKsfUUw9NsXDYyNcQFEU7Lxr80NWb5kQvyX LtT7YAGyMQbu/s5aG881J7UR5CjYgftzAzqPwV/aVyvPA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=FJ6KEL xyo/zYZfyW+0Pn8m70T4Tx2JSVTx48BzYMJvg=; b=hy/0/NtTPq7PPl0uM4niAG Os5W20Gk/M2MwlNSZ/RxvXdWcQEE93Ilam/7BN+uUm4qeFiWW4lpWhCxBhKBWoDC b42sPcbuwWU/LLmwGAE2lGmti6noCFUSjjj0ZXNMhtHVgTH8TC723SbGZdagCDMB LR22vsFb7I0pumNzENvll+8iJ7thsaUXedFPzRFckiBjpr7LhfYp5q2Fb3tifKKC WX5TJNBdxUhaQWozRsKVGFafjtvsXLCr/479LMPQMjG6BCH5wcAD1uKEfDnI2CaD EI7T3r0f5iVSi6y5m3cjQZhH4UAH2F2IF2c2iNtr4+v8hMh+mi7BzuZDrn3Wgvvw == In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: Shakeel Butt Cc: Cgroups , Tejun Heo , Li Zefan , Johannes Weiner , LKML , Greg Kroah-Hartman , Kernel Team On Tue Mar 3, 2020 at 8:50 AM, Shakeel Butt wrote: > Hi Daniel, > >=20 > On Mon, Mar 2, 2020 at 5:42 PM Daniel Xu wrote: > > > > User extended attributes are useful as metadata storage for kernfs > > consumers like cgroups. Especially in the case of cgroups, it is useful > > to have a central metadata store that multiple processes/services can > > use to coordinate actions. > > > > A concrete example is for userspace out of memory killers. We want to > > let delegated cgroup subtree owners (running as non-root) to be able to > > say "please avoid killing this cgroup". In server environments this is > > less important as everyone is running as root. > >=20 > I would recommend removing the "everyone is running as root" statement > as it is not generally true. > >=20 > Shakeel Good point, thanks.