Re: [PATCH 0/5 v1] mm, oom: Introduce per numa node oom for CONSTRAINT_MEMORY_POLICY

[Suren Baghdasaryan <surenb@google.com>]

On Wed, May 11, 2022 at 9:47 PM Gang Li <ligang.bdlg@bytedance.com> wrote:
>
> TLDR:
> If a mempolicy is in effect(oc->constraint == CONSTRAINT_MEMORY_POLICY), out_of_memory() will
> select victim on specific node to kill. So that kernel can avoid accidental killing on NUMA system.
>
> Problem:
> Before this patch series, oom will only kill the process with the highest memory usage.
> by selecting process with the highest oom_badness on the entire system to kill.
>
> This works fine on UMA system, but may have some accidental killing on NUMA system.
>
> As shown below, if process c.out is bind to Node1 and keep allocating pages from Node1,
> a.out will be killed first. But killing a.out did't free any mem on Node1, so c.out
> will be killed then.
>
> A lot of our AMD machines have 8 numa nodes. In these systems, there is a greater chance
> of triggering this problem.
>
> OOM before patches:
> ```
> Per-node process memory usage (in MBs)
> PID             Node 0        Node 1      Total
> ----------- ---------- ------------- ----------
> 3095 a.out     3073.34          0.11    3073.45(Killed first. Maximum memory consumption)
> 3199 b.out      501.35       1500.00    2001.35
> 3805 c.out        1.52 (grow)2248.00    2249.52(Killed then. Node1 is full)
> ----------- ---------- ------------- ----------
> Total          3576.21       3748.11    7324.31
> ```
>
> Solution:
> We store per node rss in mm_rss_stat for each process.
>
> If a page allocation with mempolicy in effect(oc->constraint == CONSTRAINT_MEMORY_POLICY)
> triger oom. We will calculate oom_badness with rss counter for the corresponding node. Then
> select the process with the highest oom_badness on the corresponding node to kill.
>
> OOM after patches:
> ```
> Per-node process memory usage (in MBs)
> PID             Node 0        Node 1     Total
> ----------- ---------- ------------- ----------
> 3095 a.out     3073.34          0.11    3073.45
> 3199 b.out      501.35       1500.00    2001.35
> 3805 c.out        1.52 (grow)2248.00    2249.52(killed)
> ----------- ---------- ------------- ----------
> Total          3576.21       3748.11    7324.31
> ```

You included lots of people but missed Michal Hocko. CC'ing him and
please include him in the future postings.

>
> Gang Li (5):
>   mm: add a new parameter `node` to `get/add/inc/dec_mm_counter`
>   mm: add numa_count field for rss_stat
>   mm: add numa fields for tracepoint rss_stat
>   mm: enable per numa node rss_stat count
>   mm, oom: enable per numa node oom for CONSTRAINT_MEMORY_POLICY
>
>  arch/s390/mm/pgtable.c        |   4 +-
>  fs/exec.c                     |   2 +-
>  fs/proc/base.c                |   6 +-
>  fs/proc/task_mmu.c            |  14 ++--
>  include/linux/mm.h            |  59 ++++++++++++-----
>  include/linux/mm_types_task.h |  16 +++++
>  include/linux/oom.h           |   2 +-
>  include/trace/events/kmem.h   |  27 ++++++--
>  kernel/events/uprobes.c       |   6 +-
>  kernel/fork.c                 |  70 +++++++++++++++++++-
>  mm/huge_memory.c              |  13 ++--
>  mm/khugepaged.c               |   4 +-
>  mm/ksm.c                      |   2 +-
>  mm/madvise.c                  |   2 +-
>  mm/memory.c                   | 116 ++++++++++++++++++++++++----------
>  mm/migrate.c                  |   2 +
>  mm/migrate_device.c           |   2 +-
>  mm/oom_kill.c                 |  59 ++++++++++++-----
>  mm/rmap.c                     |  16 ++---
>  mm/swapfile.c                 |   4 +-
>  mm/userfaultfd.c              |   2 +-
>  21 files changed, 317 insertions(+), 111 deletions(-)
>
> --
> 2.20.1
>