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Date: Mon, 29 Feb 2016 13:05:40 +0800
From: kernel test robot <ying.huang@...ux.intel.com>
TO: Brian Bloniarz <brian.bloniarz@...il.com>
CC: 0day robot <fengguang.wu@...el.com>
Subject: [lkp] [n_tty] dd9a6fee68: INFO: possible circular locking
dependency detected ]
FYI, we noticed the below changes on
https://github.com/0day-ci/linux Brian-Bloniarz/Re-n_tty-Check-the-other-end-of-pty-pair-before-returning-EAGAIN-on-a-read/20160229-070452
commit dd9a6fee6830f16f602b1aa2e85d6307acd04945 ("n_tty: Check the other end of pty pair before returning EAGAIN on a read()")
+----------------------------------------------------+----------+------------+
| | v4.5-rc6 | dd9a6fee68 |
+----------------------------------------------------+----------+------------+
| boot_successes | 128 | 2 |
| boot_failures | 9 | 6 |
| invoked_oom-killer:gfp_mask=0x | 9 | 1 |
| Mem-Info | 9 | 2 |
| Out_of_memory:Kill_process | 9 | 1 |
| backtrace:vfs_write | 1 | |
| backtrace:SyS_write | 1 | |
| backtrace:do_execveat_common | 1 | |
| backtrace:compat_SyS_execve | 1 | |
| backtrace:vfs_read | 1 | 4 |
| backtrace:SyS_read | 1 | 4 |
| backtrace:compat_process_vm_rw | 1 | |
| backtrace:compat_SyS_process_vm_readv | 1 | |
| backtrace:_do_fork | 1 | |
| backtrace:SyS_clone | 1 | |
| page_allocation_failure:order:#,mode | 0 | 1 |
| warn_alloc_failed+0x | 0 | 1 |
| backtrace:kswapd | 0 | 1 |
| INFO:possible_circular_locking_dependency_detected | 0 | 4 |
| backtrace:flush_to_ldisc | 0 | 4 |
+----------------------------------------------------+----------+------------+
[ 17.523349] mount (2393) used greatest stack depth: 12392 bytes left
[ 17.684314]
[ 17.684972] ======================================================
[ 17.686059] [ INFO: possible circular locking dependency detected ]
[ 17.687174] 4.5.0-rc6-00001-gdd9a6fe #64 Not tainted
[ 17.688127] -------------------------------------------------------
[ 17.689216] bootlogd/2434 is trying to acquire lock:
[ 17.690167] ((&buf->work)){+.+...}, at: [<ffffffff810b205c>] flush_work+0x5/0x23d
[ 17.692006]
[ 17.692006] but task is already holding lock:
[ 17.693433] (&tty->termios_rwsem){++++..}, at: [<ffffffff81600f90>] n_tty_read+0xd0/0x882
[ 17.695346]
[ 17.695346] which lock already depends on the new lock.
[ 17.695346]
[ 17.697370]
[ 17.697370] the existing dependency chain (in reverse order) is:
[ 17.698961]
-> #2 (&tty->termios_rwsem){++++..}:
[ 17.700507] [<ffffffff810e508f>] lock_acquire+0x147/0x1e2
[ 17.701621] [<ffffffff81c85f97>] down_read+0x48/0x90
[ 17.702696] [<ffffffff81600486>] n_tty_receive_buf_common+0x46/0x8c0
[ 17.703900] [<ffffffff81600d14>] n_tty_receive_buf2+0x14/0x16
[ 17.705046] [<ffffffff816038e3>] flush_to_ldisc+0xcb/0x125
[ 17.706167] [<ffffffff810b3a03>] process_one_work+0x2b8/0x5b2
[ 17.707339] [<ffffffff810b48d5>] worker_thread+0x28b/0x37d
[ 17.708454] [<ffffffff810b9776>] kthread+0xfb/0x103
[ 17.709511] [<ffffffff81c8849f>] ret_from_fork+0x3f/0x70
[ 17.710614]
-> #1 (&buf->lock){+.+...}:
[ 17.712070] [<ffffffff810e508f>] lock_acquire+0x147/0x1e2
[ 17.713185] [<ffffffff81c83fde>] mutex_lock_nested+0x79/0x35f
[ 17.714328] [<ffffffff81603863>] flush_to_ldisc+0x4b/0x125
[ 17.715443] [<ffffffff810b3a03>] process_one_work+0x2b8/0x5b2
[ 17.716587] [<ffffffff810b48d5>] worker_thread+0x28b/0x37d
[ 17.717700] [<ffffffff810b9776>] kthread+0xfb/0x103
[ 17.718752] [<ffffffff81c8849f>] ret_from_fork+0x3f/0x70
[ 17.719855]
-> #0 ((&buf->work)){+.+...}:
[ 17.721333] [<ffffffff810e423d>] __lock_acquire+0x12dd/0x1932
[ 17.722489] [<ffffffff810e508f>] lock_acquire+0x147/0x1e2
[ 17.723598] [<ffffffff810b2091>] flush_work+0x3a/0x23d
[ 17.724683] [<ffffffff816011c8>] n_tty_read+0x308/0x882
[ 17.725771] [<ffffffff815fb87b>] tty_read+0x8b/0xcd
[ 17.726830] [<ffffffff811e0a70>] __vfs_read+0x26/0xb9
[ 17.727910] [<ffffffff811e1668>] vfs_read+0xa0/0x12e
[ 17.728974] [<ffffffff811e241e>] SyS_read+0x51/0x92
[ 17.730032] [<ffffffff81c88132>] entry_SYSCALL_64_fastpath+0x12/0x72
[ 17.731237]
[ 17.731237] other info that might help us debug this:
[ 17.731237]
[ 17.733255] Chain exists of:
(&buf->work) --> &buf->lock --> &tty->termios_rwsem
[ 17.735644] Possible unsafe locking scenario:
[ 17.735644]
[ 17.737064] CPU0 CPU1
[ 17.737969] ---- ----
[ 17.738873] lock(&tty->termios_rwsem);
[ 17.739832] lock(&buf->lock);
[ 17.740966] lock(&tty->termios_rwsem);
[ 17.742181] lock((&buf->work));
[ 17.743081]
[ 17.743081] *** DEADLOCK ***
[ 17.743081]
[ 17.744901] 3 locks held by bootlogd/2434:
[ 17.745761] #0: (&tty->ldisc_sem){++++.+}, at: [<ffffffff81c8734d>] ldsem_down_read+0x37/0x3c
[ 17.747838] #1: (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81600fbb>] n_tty_read+0xfb/0x882
[ 17.749898] #2: (&tty->termios_rwsem){++++..}, at: [<ffffffff81600f90>] n_tty_read+0xd0/0x882
[ 17.751912]
[ 17.751912] stack backtrace:
[ 17.753200] CPU: 0 PID: 2434 Comm: bootlogd Not tainted 4.5.0-rc6-00001-gdd9a6fe #64
[ 17.754825] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[ 17.756559] 0000000000000000 ffff88000c27fa90 ffffffff8153530b ffffffff82f923c0
[ 17.758372] ffffffff82f906b0 ffff88000c27fad0 ffffffff810e1a0d ffff88000b6b8000
[ 17.760189] ffff88000b6b88e0 ffff88000b6b88a8 0000000000000003 0000000000000003
[ 17.762011] Call Trace:
[ 17.762709] [<ffffffff8153530b>] dump_stack+0x85/0xbe
[ 17.763685] [<ffffffff810e1a0d>] print_circular_bug+0x287/0x295
[ 17.764741] [<ffffffff810e423d>] __lock_acquire+0x12dd/0x1932
[ 17.765780] [<ffffffff810b205c>] ? flush_work+0x5/0x23d
[ 17.766780] [<ffffffff810e2420>] ? check_irq_usage+0x99/0xaa
[ 17.767808] [<ffffffff810e508f>] lock_acquire+0x147/0x1e2
[ 17.768812] [<ffffffff810e508f>] ? lock_acquire+0x147/0x1e2
[ 17.769835] [<ffffffff810b205c>] ? flush_work+0x5/0x23d
[ 17.770819] [<ffffffff810b2091>] flush_work+0x3a/0x23d
[ 17.771792] [<ffffffff810b205c>] ? flush_work+0x5/0x23d
[ 17.772781] [<ffffffff810e2ad7>] ? mark_held_locks+0x5e/0x74
[ 17.773816] [<ffffffff81c877f4>] ? _raw_spin_unlock_irqrestore+0x47/0x5d
[ 17.774951] [<ffffffff810e2c6a>] ? trace_hardirqs_on_caller+0x17d/0x199
[ 17.776080] [<ffffffff810e2c93>] ? trace_hardirqs_on+0xd/0xf
[ 17.777116] [<ffffffff816011c8>] n_tty_read+0x308/0x882
[ 17.778099] [<ffffffff810d9af7>] ? abort_exclusive_wait+0x9a/0x9a
[ 17.779171] [<ffffffff815fb87b>] tty_read+0x8b/0xcd
[ 17.780126] [<ffffffff811e0a70>] __vfs_read+0x26/0xb9
[ 17.781098] [<ffffffff810de7a1>] ? up_read+0x1f/0x35
[ 17.782085] [<ffffffff8108b9d1>] ? __do_page_fault+0x3aa/0x424
[ 17.783187] [<ffffffff811e1668>] vfs_read+0xa0/0x12e
[ 17.784147] [<ffffffff811e241e>] SyS_read+0x51/0x92
[ 17.785100] [<ffffffff81c88132>] entry_SYSCALL_64_fastpath+0x12/0x72
Kernel tests: Boot OK!
Thanks,
Kernel Test Robot
View attachment "config-4.5.0-rc6-00001-gdd9a6fe" of type "text/plain" (108713 bytes)
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