The patch titled
Subject: memcg: add per-memcg total kernel memory stat
has been added to the -mm tree. Its filename is
memcg-add-per-memcg-total-kernel-memory-stat.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/memcg-add-per-memcg-total-kernel-memory-stat.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/memcg-add-per-memcg-total-kernel-memory-stat.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
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------------------------------------------------------
From: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Subject: memcg: add per-memcg total kernel memory stat
Currently memcg stats show several types of kernel memory: kernel stack,
page tables, sock, vmalloc, and slab. However, there are other
allocations with __GFP_ACCOUNT (or supersets such as GFP_KERNEL_ACCOUNT)
that are not accounted in any of those stats, a few examples are:
- various kvm allocations (e.g. allocated pages to create vcpus)
- io_uring
- tmp_page in pipes during pipe_write()
- bpf ringbuffers
- unix sockets
Keeping track of the total kernel memory is essential for the ease of
migration from cgroup v1 to v2 as there are large discrepancies between
v1's kmem.usage_in_bytes and the sum of the available kernel memory stats
in v2. Adding separate memcg stats for all __GFP_ACCOUNT kernel
allocations is an impractical maintenance burden as there a lot of those
all over the kernel code, with more use cases likely to show up in the
future.
Therefore, add a "kernel" memcg stat that is analogous to kmem page
counter, with added benefits such as using rstat infrastructure which
aggregates stats more efficiently. Additionally, this provides a lighter
alternative in case the legacy kmem is deprecated in the future
Link: https://lkml.kernel.org/r/20220201200823.3283171-1-yosryahmed@xxxxxxxxxx
Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Acked-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 5 ++++
include/linux/memcontrol.h | 1
mm/memcontrol.c | 24 ++++++++++++++++------
3 files changed, 24 insertions(+), 6 deletions(-)
--- a/Documentation/admin-guide/cgroup-v2.rst~memcg-add-per-memcg-total-kernel-memory-stat
+++ a/Documentation/admin-guide/cgroup-v2.rst
@@ -1317,6 +1317,11 @@ PAGE_SIZE multiple when read back.
vmalloc (npn)
Amount of memory used for vmap backed memory.
+ kernel (npn)
+ Amount of total kernel memory, including
+ (kernel_stack, pagetables, percpu, vmalloc, slab) in
+ addition to other kernel memory use cases.
+
shmem
Amount of cached filesystem data that is swap-backed,
such as tmpfs, shm segments, shared anonymous mmap()s
--- a/include/linux/memcontrol.h~memcg-add-per-memcg-total-kernel-memory-stat
+++ a/include/linux/memcontrol.h
@@ -34,6 +34,7 @@ enum memcg_stat_item {
MEMCG_SOCK,
MEMCG_PERCPU_B,
MEMCG_VMALLOC,
+ MEMCG_KMEM,
MEMCG_NR_STAT,
};
--- a/mm/memcontrol.c~memcg-add-per-memcg-total-kernel-memory-stat
+++ a/mm/memcontrol.c
@@ -1376,6 +1376,7 @@ static const struct memory_stat memory_s
{ "percpu", MEMCG_PERCPU_B },
{ "sock", MEMCG_SOCK },
{ "vmalloc", MEMCG_VMALLOC },
+ { "kernel", MEMCG_KMEM },
{ "shmem", NR_SHMEM },
{ "file_mapped", NR_FILE_MAPPED },
{ "file_dirty", NR_FILE_DIRTY },
@@ -2979,6 +2980,19 @@ static void memcg_free_cache_id(int id)
ida_simple_remove(&memcg_cache_ida, id);
}
+static void mem_cgroup_kmem_record(struct mem_cgroup *memcg,
+ int nr_pages)
+{
+ mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
+ if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+ if (nr_pages > 0)
+ page_counter_charge(&memcg->kmem, nr_pages);
+ else
+ page_counter_uncharge(&memcg->kmem, -nr_pages);
+ }
+}
+
+
/*
* obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg
* @objcg: object cgroup to uncharge
@@ -2991,8 +3005,7 @@ static void obj_cgroup_uncharge_pages(st
memcg = get_mem_cgroup_from_objcg(objcg);
- if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
- page_counter_uncharge(&memcg->kmem, nr_pages);
+ mem_cgroup_kmem_record(memcg, -nr_pages);
refill_stock(memcg, nr_pages);
css_put(&memcg->css);
@@ -3018,8 +3031,7 @@ static int obj_cgroup_charge_pages(struc
if (ret)
goto out;
- if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
- page_counter_charge(&memcg->kmem, nr_pages);
+ mem_cgroup_kmem_record(memcg, nr_pages);
out:
css_put(&memcg->css);
@@ -6801,8 +6813,8 @@ static void uncharge_batch(const struct
page_counter_uncharge(&ug->memcg->memory, ug->nr_memory);
if (do_memsw_account())
page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory);
- if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && ug->nr_kmem)
- page_counter_uncharge(&ug->memcg->kmem, ug->nr_kmem);
+ if (ug->nr_kmem)
+ mem_cgroup_kmem_record(ug->memcg, -ug->nr_kmem);
memcg_oom_recover(ug->memcg);
}
_
Patches currently in -mm which might be from yosryahmed@xxxxxxxxxx are
memcg-add-per-memcg-total-kernel-memory-stat.patch
