https://github.com/torvalds/linux
Revision 093e5840ae76f1082633503964d035f40ed0216d authored by Sebastian Andrzej Siewior on 21 December 2015, 17:17:10 UTC, committed by Ingo Molnar on 06 January 2016, 10:01:07 UTC
In the following commit:
7675104990ed ("sched: Implement lockless wake-queues")
we gained lockless wake-queues.
The -RT kernel managed to lockup itself with those. There could be multiple
attempts for task X to enqueue it for a wakeup _even_ if task X is already
running.
The reason is that task X could be runnable but not yet on CPU. The the
task performing the wakeup did not leave the CPU it could performe
multiple wakeups.
With the proper timming task X could be running and enqueued for a
wakeup. If this happens while X is performing a fork() then its its
child will have a !NULL `wake_q` member copied.
This is not a problem as long as the child task does not participate in
lockless wakeups :)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 7675104990ed ("sched: Implement lockless wake-queues")
Link: http://lkml.kernel.org/r/20151221171710.GA5499@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent be958bd
Tip revision: 093e5840ae76f1082633503964d035f40ed0216d authored by Sebastian Andrzej Siewior on 21 December 2015, 17:17:10 UTC
sched/core: Reset task's lockless wake-queues on fork()
sched/core: Reset task's lockless wake-queues on fork()
Tip revision: 093e584
| File | Mode | Size |
|---|---|---|
| Kbuild | -rw-r--r-- | 787 bytes |
| Kbuild.asm | -rw-r--r-- | 1016 bytes |
| auxvec.h | -rw-r--r-- | 218 bytes |
| bitsperlong.h | -rw-r--r-- | 516 bytes |
| errno-base.h | -rw-r--r-- | 1.5 KB |
| errno.h | -rw-r--r-- | 5.5 KB |
| fcntl.h | -rw-r--r-- | 5.2 KB |
| int-l64.h | -rw-r--r-- | 670 bytes |
| int-ll64.h | -rw-r--r-- | 816 bytes |
| ioctl.h | -rw-r--r-- | 3.1 KB |
| ioctls.h | -rw-r--r-- | 3.6 KB |
| ipcbuf.h | -rw-r--r-- | 940 bytes |
| kvm_para.h | -rw-r--r-- | 96 bytes |
| mman-common.h | -rw-r--r-- | 2.8 KB |
| mman.h | -rw-r--r-- | 937 bytes |
| msgbuf.h | -rw-r--r-- | 1.5 KB |
| param.h | -rw-r--r-- | 305 bytes |
| poll.h | -rw-r--r-- | 795 bytes |
| posix_types.h | -rw-r--r-- | 2.2 KB |
| resource.h | -rw-r--r-- | 1.8 KB |
| sembuf.h | -rw-r--r-- | 1.2 KB |
| setup.h | -rw-r--r-- | 127 bytes |
| shmbuf.h | -rw-r--r-- | 1.7 KB |
| shmparam.h | -rw-r--r-- | 168 bytes |
| siginfo.h | -rw-r--r-- | 8.9 KB |
| signal-defs.h | -rw-r--r-- | 802 bytes |
| signal.h | -rw-r--r-- | 2.6 KB |
| socket.h | -rw-r--r-- | 1.9 KB |
| sockios.h | -rw-r--r-- | 376 bytes |
| stat.h | -rw-r--r-- | 2.5 KB |
| statfs.h | -rw-r--r-- | 1.7 KB |
| swab.h | -rw-r--r-- | 439 bytes |
| termbits.h | -rw-r--r-- | 4.5 KB |
| termios.h | -rw-r--r-- | 1.3 KB |
| types.h | -rw-r--r-- | 170 bytes |
| ucontext.h | -rw-r--r-- | 294 bytes |
| unistd.h | -rw-r--r-- | 28.9 KB |
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