Hi,

On 10/10/20 3:38 AM, Muchun Song wrote:

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.

  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 +--
 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(-)

Thanks for finding that.

Please update Documentation/filesystems/proc.rst "meminfo" section also.

-- 
~Randy

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