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Subject: Re: [PATCH] mm: proc: add Sock to /proc/meminfo
To:     Muchun Song <songmuchun@bytedance.com>, gregkh@linuxfoundation.org,
        rafael@kernel.org, mst@redhat.com, jasowang@redhat.com,
        davem@davemloft.net, kuba@kernel.org, adobriyan@gmail.com,
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Cc:     linux-kernel@vger.kernel.org,
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        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
References: <20201010103854.66746-1-songmuchun@bytedance.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <f6dfa37f-5991-3e96-93b8-737f60128151@infradead.org>
Date:   Sat, 10 Oct 2020 09:36:15 -0700
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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 <songmuchun@bytedance.com>
> ---
>  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