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From: Johannes Weiner <hannes@cmpxchg.org>
To: Roman Gushchin <guro@fb.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Shakeel Butt <shakeelb@google.com>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	linux-kernel@vger.kernel.org, kernel-team@fb.com,
	Bharata B Rao <bharata@linux.ibm.com>,
	Yafang Shao <laoar.shao@gmail.com>
Subject: Re: [PATCH v2 08/28] mm: fork: fix kernel_stack memcg stats for various stack implementations
Date: Mon, 3 Feb 2020 11:12:00 -0500	[thread overview]
Message-ID: <20200203161200.GB1697@cmpxchg.org> (raw)
In-Reply-To: <20200127173453.2089565-9-guro@fb.com>

On Mon, Jan 27, 2020 at 09:34:33AM -0800, Roman Gushchin wrote:
> Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio
> the space for task stacks can be allocated using __vmalloc_node_range(),
> alloc_pages_node() and kmem_cache_alloc_node(). In the first and the
> second cases page->mem_cgroup pointer is set, but in the third it's
> not: memcg membership of a slab page should be determined using the
> memcg_from_slab_page() function, which looks at
> page->slab_cache->memcg_params.memcg . In this case, using
> mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
> page->mem_cgroup pointer is NULL even for pages charged to a non-root
> memory cgroup.
> 
> In order to fix it, let's introduce a mod_memcg_obj_state() helper,
> which takes a pointer to a kernel object as a first argument, uses
> mem_cgroup_from_obj() to get a RCU-protected memcg pointer and
> calls mod_memcg_state(). It allows to handle all possible
> configurations (CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE
> values) without spilling any memcg/kmem specifics into fork.c .

The change looks good to me, but it sounds like this is a bug with
actual consequences to userspace. Can you elaborate on that in the
changelog please? Maybe add a Fixes: line, if applicable?


  reply	other threads:[~2020-02-03 16:12 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 17:34 [PATCH v2 00/28] The new cgroup slab memory controller Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 01/28] mm: kmem: cleanup (__)memcg_kmem_charge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 02/28] mm: kmem: cleanup memcg_kmem_uncharge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 03/28] mm: kmem: rename memcg_kmem_(un)charge() into memcg_kmem_(un)charge_page() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 04/28] mm: kmem: switch to nr_pages in (__)memcg_kmem_charge_memcg() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 05/28] mm: memcg/slab: cache page number in memcg_(un)charge_slab() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 06/28] mm: kmem: rename (__)memcg_kmem_(un)charge_memcg() to __memcg_kmem_(un)charge() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 07/28] mm: memcg/slab: introduce mem_cgroup_from_obj() Roman Gushchin
2020-02-03 16:05   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 08/28] mm: fork: fix kernel_stack memcg stats for various stack implementations Roman Gushchin
2020-02-03 16:12   ` Johannes Weiner [this message]
2020-01-27 17:34 ` [PATCH v2 09/28] mm: memcg/slab: rename __mod_lruvec_slab_state() into __mod_lruvec_obj_state() Roman Gushchin
2020-02-03 16:13   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 10/28] mm: memcg: introduce mod_lruvec_memcg_state() Roman Gushchin
2020-02-03 17:39   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 11/28] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-02-03 17:44   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 12/28] mm: vmstat: use s32 for vm_node_stat_diff in struct per_cpu_nodestat Roman Gushchin
2020-02-03 17:58   ` Johannes Weiner
2020-02-03 18:25     ` Roman Gushchin
2020-02-03 20:34       ` Johannes Weiner
2020-02-03 22:28         ` Roman Gushchin
2020-02-03 22:39           ` Johannes Weiner
2020-02-04  1:44             ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 13/28] mm: vmstat: convert slab vmstat counter to bytes Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 14/28] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 15/28] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-02-03 19:31   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 16/28] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-02-03 18:27   ` Johannes Weiner
2020-02-03 18:34     ` Roman Gushchin
2020-02-03 20:46       ` Johannes Weiner
2020-02-03 21:19         ` Roman Gushchin
2020-02-03 22:29           ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 17/28] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-02-03 19:53   ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 18/28] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 19/28] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 20/28] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 21/28] mm: memcg/slab: use a single set of kmem_caches for all memory cgroups Roman Gushchin
2020-02-03 19:50   ` Johannes Weiner
2020-02-03 20:58     ` Roman Gushchin
2020-02-03 22:17       ` Johannes Weiner
2020-02-03 22:38         ` Roman Gushchin
2020-02-04  1:15         ` Roman Gushchin
2020-02-04  2:47           ` Johannes Weiner
2020-02-04  4:35             ` Roman Gushchin
2020-02-04 18:41               ` Johannes Weiner
2020-02-05 15:58                 ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 22/28] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 23/28] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 24/28] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 25/28] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 26/28] tools/cgroup: add slabinfo.py tool Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 27/28] tools/cgroup: make slabinfo.py compatible with new slab controller Roman Gushchin
2020-01-30  2:17   ` Bharata B Rao
2020-01-30  2:44     ` Roman Gushchin
2020-01-31 22:24     ` Roman Gushchin
2020-02-12  5:21       ` Bharata B Rao
2020-02-12 20:42         ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 28/28] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-01-30  2:06 ` [PATCH v2 00/28] The new cgroup slab memory controller Bharata B Rao
2020-01-30  2:41   ` Roman Gushchin
2020-08-12 23:16     ` Pavel Tatashin
2020-08-12 23:18       ` Pavel Tatashin
2020-08-13  0:04       ` Roman Gushchin
2020-08-13  0:31         ` Pavel Tatashin
2020-08-28 16:47           ` Pavel Tatashin
2020-09-01  5:28             ` Bharata B Rao
2020-09-01 12:52               ` Pavel Tatashin
2020-09-02  6:23                 ` Bharata B Rao
2020-09-02 12:34                   ` Pavel Tatashin
2020-09-02  9:53             ` Vlastimil Babka
2020-09-02 10:39               ` David Hildenbrand
2020-09-02 12:42                 ` Pavel Tatashin
2020-09-02 13:50                   ` Michal Hocko
2020-09-02 14:20                     ` Pavel Tatashin
2020-09-03 18:09                       ` David Hildenbrand
2020-09-02 11:26               ` Michal Hocko
2020-09-02 12:51                 ` Pavel Tatashin
2020-09-02 13:51                   ` Michal Hocko
2020-09-02 11:32               ` Michal Hocko
2020-09-02 12:53                 ` Pavel Tatashin
2020-09-02 13:52                   ` Michal Hocko

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