From: Richard Palethorpe <rpalethorpe@suse.de> To: "Michal Koutný" <mkoutny@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org>, Roman Gushchin <guro@fb.com>, ltp@lists.linux.it, Andrew Morton <akpm@linux-foundation.org>, Shakeel Butt <shakeelb@google.com>, Christoph Lameter <cl@linux.com>, Michal Hocko <mhocko@kernel.org>, Tejun Heo <tj@kernel.org>, Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] mm: memcg/slab: Stop reparented obj_cgroups from charging root Date: Mon, 19 Oct 2020 09:45:32 +0100 [thread overview] Message-ID: <87lfg2ob83.fsf@suse.de> (raw) In-Reply-To: <20201016171502.GA102311@blackbook> Hello, Michal Koutný <mkoutny@suse.com> writes: > On Fri, Oct 16, 2020 at 10:53:08AM -0400, Johannes Weiner <hannes@cmpxchg.org> wrote: >> The central try_charge() function charges recursively all the way up >> to and including the root. > Except for use_hiearchy=0 (which is the case here as Richard > wrote). The reparenting is hence somewhat incompatible with > new_parent.use_hiearchy=0 :-/ > Yes and it also seems new_parent.use_hierarch=0 -> new_child.use_hierarchy=0 and new_parent.use_hierarch=0 -> new_child.use_hierarchy=1 are considered valid on cgroupsV1. The kernel will also allow more descendants on new_child.use_hierarchy=0, but sets broken_hierarchy=1. However this will not stop the stack trace occuring (AFAICT) when the reparenting happens between two descendants. >> We should clean this up one way or another: either charge the root or >> don't, but do it consistently. > I agree this'd be good to unify. One upside of excluding root memcg from > charging is that users are spared from the charging overhead when memcg > tree is not created. (Actually, I thought that was the reason for this > exception.) > > Michal -- Thank you, Richard.
next prev parent reply other threads:[~2020-10-19 8:45 UTC|newest] Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-10-14 19:07 Richard Palethorpe 2020-10-14 20:08 ` Roman Gushchin 2020-10-16 5:40 ` Richard Palethorpe 2020-10-16 9:47 ` Michal Koutný 2020-10-16 10:41 ` Richard Palethorpe 2020-10-16 15:05 ` Richard Palethorpe 2020-10-16 17:26 ` Michal Koutný 2020-10-16 14:53 ` Johannes Weiner 2020-10-16 17:02 ` Roman Gushchin 2020-10-16 17:15 ` Michal Koutný 2020-10-19 8:45 ` Richard Palethorpe [this message] 2020-10-19 9:58 ` [PATCH v3] " Richard Palethorpe 2020-10-19 16:58 ` Shakeel Butt 2020-10-20 5:52 ` Richard Palethorpe 2020-10-20 13:49 ` Richard Palethorpe 2020-10-20 16:56 ` Shakeel Butt 2020-10-21 20:32 ` Roman Gushchin 2020-10-20 17:24 ` Michal Koutný 2020-10-22 7:04 ` Richard Palethorpe 2020-10-22 12:28 ` [PATCH v4] " Richard Palethorpe 2020-10-22 16:37 ` Shakeel Butt 2020-10-22 17:25 ` Roman Gushchin 2020-10-22 23:59 ` Shakeel Butt 2020-10-23 0:40 ` Roman Gushchin 2020-10-23 15:44 ` Johannes Weiner 2020-10-23 16:41 ` Shakeel Butt 2020-10-26 7:32 ` Richard Palethorpe 2020-10-26 23:14 ` Roman Gushchin 2020-10-19 22:28 ` [RFC PATCH] " Roman Gushchin 2020-10-20 6:04 ` Richard Palethorpe 2020-10-20 12:02 ` Richard Palethorpe 2020-10-20 14:48 ` Richard Palethorpe 2020-10-20 16:27 ` Michal Koutný 2020-10-20 17:07 ` Roman Gushchin 2020-10-20 18:18 ` Johannes Weiner 2020-10-21 19:33 ` Roman Gushchin 2020-10-23 16:30 ` Johannes Weiner 2020-11-10 1:27 ` Roman Gushchin 2020-11-10 15:11 ` Shakeel Butt 2020-11-10 19:13 ` Roman Gushchin 2020-11-20 17:46 ` Michal Koutný 2020-11-03 13:22 ` Michal Hocko 2020-11-03 21:30 ` Roman Gushchin 2020-10-20 16:55 ` Shakeel Butt 2020-10-20 17:17 ` Roman Gushchin
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