From: Roman Gushchin <guro@fb.com>
To: Qian Cai <cai@lca.pw>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Shakeel Butt <shakeelb@google.com>, <linux-mm@kvack.org>,
Vlastimil Babka <vbabka@suse.cz>, <kernel-team@fb.com>,
<linux-kernel@vger.kernel.org>, <catalin.marinas@arm.com>
Subject: Re: [PATCH v6 00/19] The new cgroup slab memory controller
Date: Sun, 21 Jun 2020 16:34:29 -0700 [thread overview]
Message-ID: <20200621233429.GA293939@carbon.DHCP.thefacebook.com> (raw)
In-Reply-To: <20200621225752.GB2034@lca.pw>
On Sun, Jun 21, 2020 at 06:57:52PM -0400, Qian Cai wrote:
> On Mon, Jun 08, 2020 at 04:06:35PM -0700, Roman Gushchin wrote:
> > This is v6 of the slab cgroup controller rework.
> >
> > The patchset moves the accounting from the page level to the object
> > level. It allows to share slab pages between memory cgroups.
> > This leads to a significant win in the slab utilization (up to 45%)
> > and the corresponding drop in the total kernel memory footprint.
> > The reduced number of unmovable slab pages should also have a positive
> > effect on the memory fragmentation.
> >
> > The patchset makes the slab accounting code simpler: there is no more
> > need in the complicated dynamic creation and destruction of per-cgroup
> > slab caches, all memory cgroups use a global set of shared slab caches.
> > The lifetime of slab caches is not more connected to the lifetime
> > of memory cgroups.
> >
> > The more precise accounting does require more CPU, however in practice
> > the difference seems to be negligible. We've been using the new slab
> > controller in Facebook production for several months with different
> > workloads and haven't seen any noticeable regressions. What we've seen
> > were memory savings in order of 1 GB per host (it varied heavily depending
> > on the actual workload, size of RAM, number of CPUs, memory pressure, etc).
> >
> > The third version of the patchset added yet another step towards
> > the simplification of the code: sharing of slab caches between
> > accounted and non-accounted allocations. It comes with significant
> > upsides (most noticeable, a complete elimination of dynamic slab caches
> > creation) but not without some regression risks, so this change sits
> > on top of the patchset and is not completely merged in. So in the unlikely
> > event of a noticeable performance regression it can be reverted separately.
>
> Reverting this series and its dependency [1], i.e.,
>
> git revert --no-edit 05923a2ccacd..07666ee77fb4
>
> on the top of next-20200621 fixed an issue where kmemleak could report
> thousands of leaks like this below using this .config (if ever matters),
>
> https://github.com/cailca/linux-mm/blob/master/x86.config
>
> unreferenced object 0xffff888ff2bf6200 (size 512):
Hi Qian!
My wild guess is that kmemleak is getting confused by modifying the lowest
bit of page->mem_cgroup/obhj_cgroups pointer:
struct page {
...
union {
struct mem_cgroup *mem_cgroup;
struct obj_cgroup **obj_cgroups;
};
...
}
We're using the lowest bit to distinguish between a "normal" mem_cgroup
pointer and a vector of obj_cgroup pointers.
This pointer to obj_cgroup vector is saved only here, so if we're modifying
the address, I guess it's what makes kmemleak think that there is a leak.
Or do you have a real leak?
Thanks!
next prev parent reply other threads:[~2020-06-21 23:34 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-08 23:06 [PATCH v6 00/19] The new cgroup slab memory controller Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 01/19] mm: memcg: factor out memcg- and lruvec-level changes out of __mod_lruvec_state() Roman Gushchin
2020-06-17 1:52 ` Shakeel Butt
2020-06-17 2:50 ` Roman Gushchin
2020-06-17 2:59 ` Shakeel Butt
2020-06-17 3:19 ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 02/19] mm: memcg: prepare for byte-sized vmstat items Roman Gushchin
2020-06-17 2:57 ` Shakeel Butt
2020-06-17 3:19 ` Roman Gushchin
2020-06-17 15:55 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 03/19] mm: memcg: convert vmstat slab counters to bytes Roman Gushchin
2020-06-17 3:03 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 04/19] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-06-17 3:08 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 05/19] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-06-18 0:47 ` Shakeel Butt
2020-06-18 14:55 ` Shakeel Butt
2020-06-18 19:51 ` Roman Gushchin
2020-06-19 1:08 ` Roman Gushchin
2020-06-19 1:18 ` Shakeel Butt
2020-06-19 1:31 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 06/19] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-06-19 15:42 ` Shakeel Butt
2020-06-19 21:38 ` Roman Gushchin
2020-06-19 22:16 ` Shakeel Butt
2020-06-19 22:52 ` Roman Gushchin
2020-06-20 22:50 ` Andrew Morton
2020-06-08 23:06 ` [PATCH v6 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-06-19 16:36 ` Shakeel Butt
2020-06-20 0:25 ` Roman Gushchin
2020-06-20 0:31 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 08/19] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-06-20 0:16 ` Shakeel Butt
2020-06-20 1:19 ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 09/19] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-06-20 0:54 ` Shakeel Butt
2020-06-20 1:29 ` Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 10/19] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-06-22 17:12 ` Shakeel Butt
2020-06-22 18:01 ` Roman Gushchin
2020-06-22 18:09 ` Shakeel Butt
2020-06-22 18:25 ` Roman Gushchin
2020-06-22 18:38 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 11/19] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-06-20 1:19 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 12/19] mm: memcg/slab: use a single set of kmem_caches for all accounted allocations Roman Gushchin
2020-06-22 16:56 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 13/19] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-06-22 17:29 ` Shakeel Butt
2020-06-22 17:40 ` Roman Gushchin
2020-06-22 18:03 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 14/19] mm: memcg/slab: remove memcg_kmem_get_cache() Roman Gushchin
2020-06-22 18:42 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 15/19] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-06-22 17:36 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 16/19] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-06-22 17:32 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 17/19] mm: memcg/slab: use a single set of kmem_caches for all allocations Roman Gushchin
2020-06-17 23:35 ` Andrew Morton
2020-06-18 0:35 ` Roman Gushchin
2020-06-18 7:33 ` Vlastimil Babka
2020-06-18 19:54 ` Roman Gushchin
2020-06-22 19:21 ` Shakeel Butt
2020-06-22 20:37 ` Roman Gushchin
2020-06-22 21:04 ` Shakeel Butt
2020-06-22 21:13 ` Roman Gushchin
2020-06-22 21:28 ` Shakeel Butt
2020-06-22 21:58 ` Roman Gushchin
2020-06-22 22:05 ` Shakeel Butt
2020-06-08 23:06 ` [PATCH v6 18/19] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-06-08 23:06 ` [PATCH v6 19/19] tools/cgroup: add memcg_slabinfo.py tool Roman Gushchin
2020-06-17 1:46 ` [PATCH v6 00/19] The new cgroup slab memory controller Shakeel Butt
2020-06-17 2:41 ` Roman Gushchin
2020-06-17 3:05 ` Shakeel Butt
2020-06-17 3:32 ` Roman Gushchin
2020-06-17 11:24 ` Vlastimil Babka
2020-06-17 14:31 ` Mel Gorman
2020-06-20 0:57 ` Roman Gushchin
2020-06-18 1:29 ` Roman Gushchin
2020-06-18 8:43 ` Jesper Dangaard Brouer
2020-06-18 9:31 ` Jesper Dangaard Brouer
2020-06-19 1:30 ` Roman Gushchin
2020-06-19 8:32 ` Jesper Dangaard Brouer
2020-06-19 1:27 ` Roman Gushchin
2020-06-19 9:39 ` Jesper Dangaard Brouer
2020-06-19 18:47 ` Roman Gushchin
2020-06-18 9:27 ` Mike Rapoport
2020-06-18 20:43 ` Roman Gushchin
2020-06-21 22:57 ` Qian Cai
2020-06-21 23:34 ` Roman Gushchin [this message]
[not found] ` <7DEA68BC-3B9A-46FA-8103-AE6B72324591@lca.pw>
2020-06-22 3:07 ` Roman Gushchin
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