FYI, we noticed the below changes on https://git.kernel.org/pub/scm/linux/kernel/git/sergeh/linux-security 2016-01-04/cgroupns.lockfix.rb commit 1552ecad0cce46249034ac21a5f4de1a7e438d18 ("cgroup: introduce cgroup namespaces") +-----------------------------------------------------------------------------+------------+------------+ | | f2a74e2f95 | 1552ecad0c | +-----------------------------------------------------------------------------+------------+------------+ | boot_successes | 10 | 4 | | boot_failures | 0 | 4 | | INFO:suspicious_RCU_usage | 0 | 4 | | BUG:sleeping_function_called_from_invalid_context_at_kernel/locking/mutex.c | 0 | 4 | | INFO:lockdep_is_turned_off | 0 | 4 | | WARNING:at_kernel/softirq.c:#__local_bh_enable_ip() | 0 | 4 | | backtrace:vfs_read | 0 | 4 | | backtrace:SyS_read | 0 | 4 | +-----------------------------------------------------------------------------+------------+------------+ [ 55.044030] mount.nfs (3519) used greatest stack depth: 11584 bytes left [ 56.148911] [ 56.149300] =============================== [ 56.150062] [ INFO: suspicious RCU usage. ] [ 56.151432] 4.4.0-rc1-00024-g1552eca #1 Not tainted [ 56.152911] ------------------------------- [ 56.154282] include/linux/rcupdate.h:560 Illegal context switch in RCU read-side critical section! [ 56.157290] [ 56.157290] other info that might help us debug this: [ 56.157290] [ 56.160443] [ 56.160443] rcu_scheduler_active = 1, debug_locks = 0 [ 56.162772] 3 locks held by cat/3847: [ 56.164038] #0: (&p->lock){+.+.+.}, at: [] seq_read+0x3c/0x350 [ 56.167012] #1: (sched_debug_lock){......}, at: [] print_cpu+0x585/0x9c6 [ 56.170123] #2: (rcu_read_lock){......}, at: [] print_cfs_stats+0x5/0x143 [ 56.173245] [ 56.173245] stack backtrace: [ 56.175284] CPU: 0 PID: 3847 Comm: cat Not tainted 4.4.0-rc1-00024-g1552eca #1 [ 56.177729] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 56.180438] 0000000000000000 ffff88003c19fb70 ffffffff81505768 ffff88003c2a5100 [ 56.183292] ffff88003c19fba0 ffffffff810d85d6 ffffffff82079d0f 0000000000000269 [ 56.186135] 0000000000000000 00000000001d6300 ffff88003c19fbc8 ffffffff810b83de [ 56.188969] Call Trace: [ 56.190068] [] dump_stack+0x4b/0x63 [ 56.191581] [] lockdep_rcu_suspicious+0xf7/0x100 [ 56.193276] [] ___might_sleep+0x58/0x200 [ 56.194854] [] __might_sleep+0x75/0x7c [ 56.196416] [] mutex_lock_nested+0x3e/0x35f [ 56.198040] [] ? sched_clock+0x9/0xd [ 56.199570] [] ? local_clock+0x20/0x22 [ 56.201124] [] cgroup_path_ns+0x2c/0x72 [ 56.202685] [] ? cgroup_path_ns+0x2c/0x72 [ 56.204375] [] task_group_path+0x4a/0x53 [ 56.205949] [] print_cfs_rq+0x52/0xb79 [ 56.207507] [] print_cfs_stats+0xcb/0x143 [ 56.209101] [] print_cpu+0x594/0x9c6 [ 56.210624] [] sched_debug_show+0x17/0x22 [ 56.212229] [] seq_read+0x26a/0x350 [ 56.213731] [] proc_reg_read+0x48/0x67 [ 56.215280] [] ? proc_reg_write+0x67/0x67 [ 56.216866] [] __vfs_read+0x26/0xb9 [ 56.218375] [] ? up_read+0x1f/0x35 [ 56.219861] [] ? __do_page_fault+0x3aa/0x424 [ 56.221508] [] vfs_read+0xa0/0x12e [ 56.222999] [] SyS_read+0x51/0x92 [ 56.224479] [] entry_SYSCALL_64_fastpath+0x12/0x76 [ 56.226192] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:617 [ 56.229101] in_atomic(): 1, irqs_disabled(): 1, pid: 3847, name: cat [ 56.230798] INFO: lockdep is turned off. [ 56.232285] irq event stamp: 1812 [ 56.233502] hardirqs last enabled at (1811): [] sched_debug_header+0x63/0x4a5 [ 56.236352] hardirqs last disabled at (1812): [] _raw_spin_lock_irqsave+0x27/0x88 [ 56.239178] softirqs last enabled at (1346): [] __do_softirq+0x2ce/0x3bc [ 56.241888] softirqs last disabled at (1221): [] irq_exit+0x47/0x9b [ 56.244521] CPU: 0 PID: 3847 Comm: cat Not tainted 4.4.0-rc1-00024-g1552eca #1 [ 56.246950] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 56.249649] 0000000000000000 ffff88003c19fba0 ffffffff81505768 ffff88003c2a5100 [ 56.252582] ffff88003c19fbc8 ffffffff810b857f ffffffff82079d0f 0000000000000269 [ 56.255437] 0000000000000000 ffff88003c19fbf0 ffffffff810b85fb ffffffff8227c4a0 [ 56.258293] Call Trace: [ 56.259372] [] dump_stack+0x4b/0x63 [ 56.260877] [] ___might_sleep+0x1f9/0x200 [ 56.262476] [] __might_sleep+0x75/0x7c [ 56.264076] [] mutex_lock_nested+0x3e/0x35f [ 56.265722] [] ? sched_clock+0x9/0xd [ 56.267254] [] ? local_clock+0x20/0x22 [ 56.268802] [] cgroup_path_ns+0x2c/0x72 [ 56.270372] [] ? cgroup_path_ns+0x2c/0x72 [ 56.271955] [] task_group_path+0x4a/0x53 [ 56.273537] [] print_cfs_rq+0x52/0xb79 [ 56.275089] [] print_cfs_stats+0xcb/0x143 [ 56.276684] [] print_cpu+0x594/0x9c6 [ 56.278208] [] sched_debug_show+0x17/0x22 [ 56.279802] [] seq_read+0x26a/0x350 [ 56.281313] [] proc_reg_read+0x48/0x67 [ 56.282855] [] ? proc_reg_write+0x67/0x67 [ 56.284445] [] __vfs_read+0x26/0xb9 [ 56.285947] [] ? up_read+0x1f/0x35 [ 56.287443] [] ? __do_page_fault+0x3aa/0x424 [ 56.289067] [] vfs_read+0xa0/0x12e [ 56.290557] [] SyS_read+0x51/0x92 [ 56.292043] [] entry_SYSCALL_64_fastpath+0x12/0x76 [ 56.293761] ------------[ cut here ]------------ [ 56.295180] WARNING: CPU: 0 PID: 3847 at kernel/softirq.c:150 __local_bh_enable_ip+0x45/0xb4() [ 56.298176] Modules linked in: snd_pcsp [ 56.299668] CPU: 0 PID: 3847 Comm: cat Not tainted 4.4.0-rc1-00024-g1552eca #1 [ 56.302095] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 56.304768] 0000000000000000 ffff88003c19fbe8 ffffffff81505768 0000000000000000 [ 56.307588] ffff88003c19fc20 ffffffff810939e9 ffffffff81098485 0000000000000201 [ 56.310408] ffffffff81124687 0000000000000000 00000000001d6300 ffff88003c19fc30 [ 56.313226] Call Trace: [ 56.314296] [] dump_stack+0x4b/0x63 [ 56.315786] [] warn_slowpath_common+0x99/0xb2 [ 56.317427] [] ? __local_bh_enable_ip+0x45/0xb4 [ 56.319091] [] ? cgroup_path_ns+0x5b/0x72 [ 56.320762] [] warn_slowpath_null+0x1a/0x1c [ 56.322371] [] __local_bh_enable_ip+0x45/0xb4 [ 56.323996] [] _raw_spin_unlock_bh+0x35/0x38 [ 56.325611] [] cgroup_path_ns+0x5b/0x72 [ 56.327159] [] task_group_path+0x4a/0x53 [ 56.328712] [] print_cfs_rq+0x52/0xb79 [ 56.330251] [] print_cfs_stats+0xcb/0x143 [ 56.331822] [] print_cpu+0x594/0x9c6 [ 56.333328] [] sched_debug_show+0x17/0x22 [ 56.334894] [] seq_read+0x26a/0x350 [ 56.336390] [] proc_reg_read+0x48/0x67 [ 56.337915] [] ? proc_reg_write+0x67/0x67 [ 56.339593] [] __vfs_read+0x26/0xb9 [ 56.341091] [] ? up_read+0x1f/0x35 [ 56.342564] [] ? __do_page_fault+0x3aa/0x424 [ 56.344180] [] vfs_read+0xa0/0x12e [ 56.345489] [] SyS_read+0x51/0x92 [ 56.346433] [] entry_SYSCALL_64_fastpath+0x12/0x76 [ 56.347526] ---[ end trace 44f5e154b5cac1f9 ]--- [ 56.347526] ---[ end trace 44f5e154b5cac1f9 ]--- To reproduce: git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git cd lkp-tests bin/lkp install job.yaml # job file is attached in this email bin/lkp run job.yaml Thanks, Kernel Test Robot