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Date: Fri, 19 Apr 2013 07:36:06 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Tommi Rantala <tt.rantala@...il.com>
Cc: netdev@...r.kernel.org, Joerg Reuter <jreuter@...na.de>,
Ralf Baechle <ralf@...ux-mips.org>,
"David S. Miller" <davem@...emloft.net>,
LKML <linux-kernel@...r.kernel.org>,
Dave Jones <davej@...hat.com>
Subject: Re: trinity locking troubles with ax25_recvmsg()
On Fri, 2013-04-19 at 14:30 +0300, Tommi Rantala wrote:
> Hello,
>
> Noticed a huge load in one of my trinity test machines:
> 14:07:10 up 6:11, 1 user, load average: 39,00, 39,01, 38,95
>
> But it is just 39x trinity child processes sitting there for couple of
> hours in D state, plus "trinity-child38" in S state:
>
> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
> ...
> root 3716 0.0 0.0 186620 3284 ? Sl 07:57 0:00 polkitd
> ttrantal 5576 0.0 0.1 22728 9124 ? DNL 12:00 0:00 trinity-child33
> ttrantal 5592 0.0 0.1 24636 8968 ? DNL 12:00 0:00 trinity-child14
> ttrantal 5593 0.0 0.1 26164 10684 ? DNL 12:00 0:00 trinity-child25
> ttrantal 5597 0.0 0.1 26620 10804 ? DNL 12:00 0:00 trinity-child4
> ttrantal 5599 0.0 0.1 31044 9268 ? DNL 12:00 0:00 trinity-child17
> ttrantal 5613 0.0 0.1 38804 8716 ? DNL 12:00 0:00 trinity-child24
> ttrantal 5621 0.0 0.2 38536 20528 ? DNL 12:00 0:00 trinity-child27
> ttrantal 5632 0.0 0.1 37508 11596 ? SNL 12:00 0:00 trinity-child38
> ttrantal 5663 0.0 0.2 31304 17656 ? DNL 12:01 0:00 trinity-child35
> ttrantal 5666 0.0 0.1 43656 13880 ? DNL 12:01 0:01 trinity-child2
> ttrantal 5689 0.0 0.3 54872 28748 ? DNL 12:01 0:00 trinity-child9
> ttrantal 5700 0.0 0.1 36600 10528 ? DN 12:01 0:00 trinity-child23
> ...
>
> [20091.121189] trinity-child38 S 0000000000000000 0 5632 1 0x00000000
> [20091.121189] ffff8802036adab8 0000000000000046 ffff8802036adfd8
> ffff88020354a3e0
> [20091.121189] ffff8802036adfd8 ffff8802036adfd8 ffff88022afe47c0
> ffff88020354a3e0
> [20091.121189] ffff88020354aab8 ffff8802036adc64 ffff88021b154b80
> ffff88021b154a40
> [20091.121189] Call Trace:
> [20091.121189] [<ffffffff822ce975>] schedule+0x55/0x60
> [20091.121189] [<ffffffff822cc1c6>] schedule_timeout+0x36/0x310
> [20091.121189] [<ffffffff811507d5>] ? trace_hardirqs_on_caller+0x155/0x1f0
> [20091.121189] [<ffffffff8115087d>] ? trace_hardirqs_on+0xd/0x10
> [20091.121189] [<ffffffff8111bc27>] ? prepare_to_wait_exclusive+0x77/0x90
> [20091.121189] [<ffffffff81ebd823>] __skb_recv_datagram+0x2e3/0x3d0
> [20091.121189] [<ffffffff81eb4fad>] ? lock_sock_nested+0x8d/0xa0
> [20091.121189] [<ffffffff81ebd1b0>] ?
> csum_partial_copy_fromiovecend+0x220/0x220
> [20091.121189] [<ffffffff81ebd93d>] skb_recv_datagram+0x2d/0x30
> [20091.121189] [<ffffffff8205ef68>] ax25_recvmsg+0x78/0x260
> [20091.121189] [<ffffffff81ead2f2>] sock_aio_read+0x132/0x170
> [20091.121189] [<ffffffff8120f308>] do_sync_read+0x98/0xf0
> [20091.121189] [<ffffffff8120f9ad>] vfs_read+0xbd/0x180
> [20091.121189] [<ffffffff8120fe80>] sys_read+0x50/0xa0
> [20091.121189] [<ffffffff822d1da9>] system_call_fastpath+0x16/0x1b
> [20091.121189] trinity-child35 D 0000000000000000 0 5663 1 0x00000004
> [20091.121189] ffff880210a2fe68 0000000000000046 ffff880210a2ffd8
> ffff88022afe0000
> [20091.121189] ffff880210a2ffd8 ffff880210a2ffd8 ffff88022aa823e0
> ffff88022afe0000
> [20091.121189] ffff880210a2fe58 ffff88021b154a90 ffff88021b154a40
> ffff88021b154ae0
> [20091.121189] Call Trace:
> [20091.121189] [<ffffffff81001000>] ? _stext+0xe48/0xe48
> [20091.121189] [<ffffffff822ce975>] schedule+0x55/0x60
> [20091.121189] [<ffffffff81eb162e>] __lock_sock+0x6e/0xa0
> [20091.121189] [<ffffffff8111bd70>] ? abort_exclusive_wait+0xb0/0xb0
> [20091.121189] [<ffffffff81eb4f5e>] ? lock_sock_nested+0x3e/0xa0
> [20091.121189] [<ffffffff81eb4f72>] lock_sock_nested+0x52/0xa0
> [20091.121189] [<ffffffff81001000>] ? _stext+0xe48/0xe48
> [20091.121189] [<ffffffff8205f17b>] ax25_listen+0x2b/0x70
> [20091.121189] [<ffffffff81eafca7>] sys_listen+0x57/0x80
> [20091.121189] [<ffffffff822d1da9>] system_call_fastpath+0x16/0x1b
> [20091.121189] [<ffffffff81001000>] ? _stext+0xe48/0xe48
> [20091.121189] trinity-child15 D 0000000000000000 0 5781 1 0x00000004
> [20091.121189] ffff8801f992fd58 0000000000000046 ffff8801f992ffd8
> ffff8801f9c723e0
> [20091.121189] ffff8801f992ffd8 ffff8801f992ffd8 ffff88020354c7c0
> ffff8801f9c723e0
> [20091.121189] ffff8801f992fd48 ffff88021b154a90 ffff88021b154a40
> ffff88021b154ae0
> [20091.121189] Call Trace:
> [20091.121189] [<ffffffff822ce975>] schedule+0x55/0x60
> [20091.121189] [<ffffffff81eb162e>] __lock_sock+0x6e/0xa0
> [20091.121189] [<ffffffff8111bd70>] ? abort_exclusive_wait+0xb0/0xb0
> [20091.121189] [<ffffffff81eb4f5e>] ? lock_sock_nested+0x3e/0xa0
> [20091.121189] [<ffffffff81eb4f72>] lock_sock_nested+0x52/0xa0
> [20091.121189] [<ffffffff812112db>] ? get_empty_filp+0x13b/0x1e0
> [20091.121189] [<ffffffff8205fb28>] ax25_accept+0x78/0x280
> [20091.121189] [<ffffffff8111bd70>] ? abort_exclusive_wait+0xb0/0xb0
> [20091.121189] [<ffffffff81eafdf8>] sys_accept4+0x128/0x200
> [20091.121189] [<ffffffff8115087d>] ? trace_hardirqs_on+0xd/0x10
> [20091.121189] [<ffffffff822d06fb>] ? _raw_spin_unlock_irq+0x2b/0x50
> [20091.121189] [<ffffffff822d1dd5>] ? sysret_check+0x22/0x5d
> [20091.121189] [<ffffffff811507d5>] ? trace_hardirqs_on_caller+0x155/0x1f0
> [20091.121189] [<ffffffff814c222e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [20091.121189] [<ffffffff81eafedb>] sys_accept+0xb/0x10
> [20091.121189] [<ffffffff822d1da9>] system_call_fastpath+0x16/0x1b
> [20091.121189] trinity-child37 D 0000000000000000 0 5788 1 0x00000004
> [20091.121189] ffff8801fccabb78 0000000000000046 ffff8801fccabfd8
> ffff88022aa70000
> [20091.121189] ffff8801fccabfd8 ffff8801fccabfd8 ffff8801f9840000
> ffff88022aa70000
> [20091.121189] ffff8801fccabb68 ffff88021b154a90 ffff88021b154a40
> ffff88021b154ae0
> [20091.121189] Call Trace:
> [20091.121189] [<ffffffff822ce975>] schedule+0x55/0x60
> [20091.121189] [<ffffffff81eb162e>] __lock_sock+0x6e/0xa0
> [20091.121189] [<ffffffff8111bd70>] ? abort_exclusive_wait+0xb0/0xb0
> [20091.121189] [<ffffffff81eb4f5e>] ? lock_sock_nested+0x3e/0xa0
> [20091.121189] [<ffffffff81eb4f72>] lock_sock_nested+0x52/0xa0
> [20091.121189] [<ffffffff8143d450>] ? sock_has_perm+0x180/0x1e0
> [20091.121189] [<ffffffff8143d2d0>] ? selinux_setprocattr+0x790/0x790
> [20091.121189] [<ffffffff8205ef2d>] ax25_recvmsg+0x3d/0x260
> [20091.121189] [<ffffffff81ead97c>] sock_recvmsg+0xbc/0xf0
> [20091.121189] [<ffffffff8106b555>] ? native_sched_clock+0x35/0x80
> [20091.121189] [<ffffffff8106b5a9>] ? sched_clock+0x9/0x10
> [20091.121189] [<ffffffff81eb039e>] sys_recvfrom+0xde/0x150
> [20091.121189] [<ffffffff8115087d>] ? trace_hardirqs_on+0xd/0x10
> [20091.121189] [<ffffffff822d06fb>] ? _raw_spin_unlock_irq+0x2b/0x50
> [20091.121189] [<ffffffff822d1dd5>] ? sysret_check+0x22/0x5d
> [20091.121189] [<ffffffff811507d5>] ? trace_hardirqs_on_caller+0x155/0x1f0
> [20091.121189] [<ffffffff814c222e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [20091.121189] [<ffffffff822d1da9>] system_call_fastpath+0x16/0x1b
> [...]
>
>
> [20091.121189] Showing all locks held in the system:
> [20091.121189] 1 lock held by getty/3568:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by getty/3574:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by getty/3581:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by getty/3585:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by getty/3588:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by getty/3637:
> [20091.121189] #0: (&ldata->atomic_read_lock){+.+...}, at:
> [<ffffffff81582808>] n_tty_read+0x2b8/0x980
> [20091.121189] 1 lock held by trinity-child38/5632:
> [20091.121189] #0: (sk_lock-AF_AX25){+.+.+.}, at:
> [<ffffffff8205ef2d>] ax25_recvmsg+0x3d/0x260
> [20091.121189] 2 locks held by bash/6823:
> [20091.121189] #0: (sysrq_key_table_lock){......}, at:
> [<ffffffff8158a52e>] __handle_sysrq+0x2e/0x1b0
> [20091.121189] #1: (tasklist_lock){.+.+..}, at: [<ffffffff81151b7c>]
> debug_show_all_locks+0x5c/0x260
> [20091.121189]
>
>
> Looking at e.g. net/ax25/af_ax25.c and net/x25/af_x25.c side-by-side,
> one glaring difference is that in x25 we release_sock() just before
> skb_recv_datagram(), but not in ax25.
This code is probably not used anymore, and if used, its used for a few
sockets.
There is no need trying to make it faster.
Lets hope there is no bug in x25 because of the release_sock().
--
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