On Sun, Oct 11, 2020 at 9:53 PM Mike Rapoport [off-list ref] wrote:

On Sat, Oct 10, 2020 at 06:38:54PM +0800, Muchun Song wrote:

quoted

The amount of memory allocated to sockets buffer can become significant.
However, we do not display the amount of memory consumed by sockets
buffer. In this case, knowing where the memory is consumed by the kernel
is very difficult. On our server with 500GB RAM, sometimes we can see
25GB disappear through /proc/meminfo. After our analysis, we found the
following memory allocation path which consumes the memory with page_owner
enabled.

I have a high lelel question.
There is accounting of the socket memory for memcg that gets called from
the networking layer. Did you check if the same call sites can be used
for the system-wide accounting as well?

I also think about this. But we did not pass the `struct page` parameter to
the sock accounting memcg API. So we did not know the NUMA node
which allocated the socket buffer memory and cannot do node-level
statistics. In addition, there is another problem. If the user sends a 4096-byte
message, we only charge one page to the memcg but the system allocates 8
pages. So if we reuse the same call sites for the system-wide accounting,
the statistical count we get is always smaller than the actual situation.

quoted

  849698 times:
  Page allocated via order 3, mask 0x4052c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP)
   __alloc_pages_nodemask+0x11d/0x290
   skb_page_frag_refill+0x68/0xf0
   sk_page_frag_refill+0x19/0x70
   tcp_sendmsg_locked+0x2f4/0xd10
   tcp_sendmsg+0x29/0xa0
   sock_sendmsg+0x30/0x40
   sock_write_iter+0x8f/0x100
   __vfs_write+0x10b/0x190
   vfs_write+0xb0/0x190
   ksys_write+0x5a/0xd0
   do_syscall_64+0x5d/0x110
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Muchun Song <redacted>
---
 drivers/base/node.c      |  2 ++
 drivers/net/virtio_net.c |  3 +--

Is virtio-net the only dirver that requred an update?

Yeah, only virtio-net needs an update. Because only it uses the
skb_page_frag_refill() API.

quoted

 fs/proc/meminfo.c        |  1 +
 include/linux/mmzone.h   |  1 +
 include/linux/skbuff.h   | 43 ++++++++++++++++++++++++++++++++++++++--
 kernel/exit.c            |  3 +--
 mm/page_alloc.c          |  7 +++++--
 mm/vmstat.c              |  1 +
 net/core/sock.c          |  8 ++++----
 net/ipv4/tcp.c           |  3 +--
 net/xfrm/xfrm_state.c    |  3 +--
 11 files changed, 59 insertions(+), 16 deletions(-)

-- 
Yours,
Muchun