FYI, we noticed the below changes on git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git since-3.18 commit 407bf4d3b56d3d36920a401cd88691f3f6c093cc ("sched: Debug nested sleeps") I think this is expected behavior, some migh_sleep warning show in dmesg. +------------------------------------------------------------------+------------+------------+ | | 6866a948ce | 407bf4d3b5 | +------------------------------------------------------------------+------------+------------+ | boot_successes | 9 | 0 | | boot_failures | 9 | 30 | | Out_of_memory:Kill_process | 9 | | | backtrace:do_mount | 2 | | | backtrace:compat_SyS_mount | 2 | | | Kernel_panic-not_syncing:Out_of_memory_and_no_killable_processes | 2 | | | backtrace:vfs_read | 2 | | | backtrace:SyS_read | 2 | | | backtrace:do_sys_open | 1 | | | backtrace:compat_SyS_open | 1 | | | backtrace:do_fork | 4 | | | backtrace:SyS_clone | 4 | | | WARNING:at_drivers/block/floppy.c:#schedule_bh() | 1 | | | backtrace:do_execve_common | 3 | | | backtrace:compat_SyS_execve | 3 | | | WARNING:at_kernel/sched/core.c:#__might_sleep() | 0 | 30 | | backtrace:rfcomm_run | 0 | 29 | +------------------------------------------------------------------+------------+------------+ [ 32.821749] Bluetooth: RFCOMM TTY layer initialized [ 32.823450] Bluetooth: RFCOMM socket layer initialized [ 32.825557] ------------[ cut here ]------------ [ 32.826714] WARNING: CPU: 0 PID: 232 at kernel/sched/core.c:7193 __might_sleep+0x6f/0xa9() [ 32.829296] do not call blocking ops when !TASK_RUNNING; state=1 set at [] rfcomm_run+0x122/0x1005 [ 32.831873] Modules linked in: [ 32.832928] CPU: 0 PID: 232 Comm: krfcommd Not tainted 3.18.0 #1922 [ 32.834668] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 32.835998] 0000000000000009 ffff88000b26bc58 ffffffff82d5df90 00000000001cf5b0 [ 32.838613] ffff88000b26bca8 ffff88000b26bc98 ffffffff810c7209 ffffea00002702b8 [ 32.840983] ffffffff810e65d1 ffffffff8386bf13 000000000000026d 0000000000000000 [ 32.843919] Call Trace: [ 32.844787] [] dump_stack+0x4e/0x68 [ 32.846210] [] warn_slowpath_common+0xa2/0xbc [ 32.847591] [] ? __might_sleep+0x6f/0xa9 [ 32.849319] [] warn_slowpath_fmt+0x46/0x48 [ 32.850673] [] ? rfcomm_session_add+0x2b/0xdd [ 32.852680] [] ? rfcomm_run+0x122/0x1005 [ 32.854011] [] ? rfcomm_run+0x122/0x1005 [ 32.855356] [] __might_sleep+0x6f/0xa9 [ 32.856845] [] ? rfcomm_check_accept+0x8b/0x8b [ 32.858291] [] mutex_lock_nested+0x2f/0x3e4 [ 32.859663] [] ? init_timer_key+0x97/0xd2 [ 32.861321] [] ? rfcomm_check_accept+0x8b/0x8b [ 32.862735] [] rfcomm_run+0x167/0x1005 [ 32.864414] [] ? __schedule+0x3f5/0x5e4 [ 32.865881] [] ? rfcomm_check_accept+0x8b/0x8b [ 32.867790] [] kthread+0xe0/0xe8 [ 32.869022] [] ? _raw_spin_unlock_irq+0x2d/0x3e [ 32.870951] [] ? __kthread_parkme+0xad/0xad [ 32.872632] [] ret_from_fork+0x7c/0xb0 [ 32.873934] [] ? __kthread_parkme+0xad/0xad [ 32.875531] ---[ end trace a2de474b76db3d65 ]--- [ 32.876812] Bluetooth: RFCOMM ver 1.11 Thanks, Fengguang