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From: Shakeel Butt To: Andrew Morton Cc: Michal Hocko , Tejun Heo , Johannes Weiner , Roman Gushchin , Muchun Song , Michal =?utf-8?Q?Koutn=C3=BD?= , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH] memcg: add hierarchical effective limits for v2 Message-ID: <6bs4tywynoay7q7uxgvwo5s2j2gk4osulsbdj2u4ujn55jcpne@qektqs6524xa> References: <20250205222029.2979048-1-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250205222029.2979048-1-shakeel.butt@linux.dev> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: sf8s495md31b8ca9y6gapcetq6wfstxa X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 35830160008 X-Rspam-User: X-HE-Tag: 1738880708-222815 X-HE-Meta: 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 4H6k951r tCrXitqYeJjXdtnGm3k9UznpuHAD0kunqZ2YFhCV/w2EUCu/TDMOPAfbTC7q8Lzj9T3sptJap0piJhqFCAhLskW+0lPejXHyq5OUDuy1w+4twcLmrhQCW6zXAdsv9jzFE7Mm+rBockiltFocn6L+yproNNVXHohzUqXrziOKgKHVKyA41AdmwZJA6AQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Oops, I forgot to CC Andrew. On Wed, Feb 05, 2025 at 02:20:29PM -0800, Shakeel Butt wrote: > Memcg-v1 exposes hierarchical_[memory|memsw]_limit counters in its > memory.stat file which applications can use to get their effective limit > which is the minimum of limits of itself and all of its ancestors. This > is pretty useful in environments where cgroup namespace is used and the > application does not have access to the full view of the cgroup > hierarchy. Let's expose effective limits for memcg v2 as well. > > Signed-off-by: Shakeel Butt > --- > Documentation/admin-guide/cgroup-v2.rst | 24 +++++++++++++ > mm/memcontrol.c | 48 +++++++++++++++++++++++++ > 2 files changed, 72 insertions(+) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index cb1b4e759b7e..175e9435ad5c 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1311,6 +1311,14 @@ PAGE_SIZE multiple when read back. > Caller could retry them differently, return into userspace > as -ENOMEM or silently ignore in cases like disk readahead. > > + memory.max.effective > + A read-only single value file which exists on non-root cgroups. > + > + The effective limit of the cgroup i.e. the minimum memory.max > + of all ancestors including itself. This is useful for environments > + where cgroup namespace is being used and the application does not > + have full view of the hierarchy. > + > memory.reclaim > A write-only nested-keyed file which exists for all cgroups. > > @@ -1726,6 +1734,14 @@ The following nested keys are defined. > Swap usage hard limit. If a cgroup's swap usage reaches this > limit, anonymous memory of the cgroup will not be swapped out. > > + memory.swap.max.effective > + A read-only single value file which exists on non-root cgroups. > + > + The effective limit of the cgroup i.e. the minimum memory.swap.max > + of all ancestors including itself. This is useful for environments > + where cgroup namespace is being used and the application does not > + have full view of the hierarchy. > + > memory.swap.events > A read-only flat-keyed file which exists on non-root cgroups. > The following entries are defined. Unless specified > @@ -1766,6 +1782,14 @@ The following nested keys are defined. > limit, it will refuse to take any more stores before existing > entries fault back in or are written out to disk. > > + memory.zswap.max.effective > + A read-only single value file which exists on non-root cgroups. > + > + The effective limit of the cgroup i.e. the minimum memory.zswap.max > + of all ancestors including itself. This is useful for environments > + where cgroup namespace is being used and the application does not > + have full view of the hierarchy. > + > memory.zswap.writeback > A read-write single value file. The default value is "1". > Note that this setting is hierarchical, i.e. the writeback would be > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index cae1c2e0cc71..8d21c1a44220 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4161,6 +4161,17 @@ static int memory_max_show(struct seq_file *m, void *v) > READ_ONCE(mem_cgroup_from_seq(m)->memory.max)); > } > > +static int memory_max_effective_show(struct seq_file *m, void *v) > +{ > + unsigned long max = PAGE_COUNTER_MAX; > + struct mem_cgroup *memcg = mem_cgroup_from_seq(m); > + > + for (; memcg; memcg = parent_mem_cgroup(memcg)) > + max = min(max, READ_ONCE(memcg->memory.max)); > + > + return seq_puts_memcg_tunable(m, max); > +} > + > static ssize_t memory_max_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > @@ -4438,6 +4449,11 @@ static struct cftype memory_files[] = { > .seq_show = memory_max_show, > .write = memory_max_write, > }, > + { > + .name = "max.effective", > + .flags = CFTYPE_NOT_ON_ROOT, > + .seq_show = memory_max_effective_show, > + }, > { > .name = "events", > .flags = CFTYPE_NOT_ON_ROOT, > @@ -5117,6 +5133,17 @@ static int swap_max_show(struct seq_file *m, void *v) > READ_ONCE(mem_cgroup_from_seq(m)->swap.max)); > } > > +static int swap_max_effective_show(struct seq_file *m, void *v) > +{ > + unsigned long max = PAGE_COUNTER_MAX; > + struct mem_cgroup *memcg = mem_cgroup_from_seq(m); > + > + for (; memcg; memcg = parent_mem_cgroup(memcg)) > + max = min(max, READ_ONCE(memcg->swap.max)); > + > + return seq_puts_memcg_tunable(m, max); > +} > + > static ssize_t swap_max_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > @@ -5166,6 +5193,11 @@ static struct cftype swap_files[] = { > .seq_show = swap_max_show, > .write = swap_max_write, > }, > + { > + .name = "swap.max.effective", > + .flags = CFTYPE_NOT_ON_ROOT, > + .seq_show = swap_max_effective_show, > + }, > { > .name = "swap.peak", > .flags = CFTYPE_NOT_ON_ROOT, > @@ -5308,6 +5340,17 @@ static int zswap_max_show(struct seq_file *m, void *v) > READ_ONCE(mem_cgroup_from_seq(m)->zswap_max)); > } > > +static int zswap_max_effective_show(struct seq_file *m, void *v) > +{ > + unsigned long max = PAGE_COUNTER_MAX; > + struct mem_cgroup *memcg = mem_cgroup_from_seq(m); > + > + for (; memcg; memcg = parent_mem_cgroup(memcg)) > + max = min(max, READ_ONCE(memcg->zswap_max)); > + > + return seq_puts_memcg_tunable(m, max); > +} > + > static ssize_t zswap_max_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > @@ -5362,6 +5405,11 @@ static struct cftype zswap_files[] = { > .seq_show = zswap_max_show, > .write = zswap_max_write, > }, > + { > + .name = "zswap.max.effective", > + .flags = CFTYPE_NOT_ON_ROOT, > + .seq_show = zswap_max_effective_show, > + }, > { > .name = "zswap.writeback", > .seq_show = zswap_writeback_show, > -- > 2.43.5 >