diff options
| author | Ani Sinha <ani@arista.com> | 2015-12-17 17:15:10 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-17 09:35:28 +0100 |
| commit | 6321e175356326f16d5d7d066c067f48483f5317 (patch) | |
| tree | 36813723c53a0805c0e4c5cb12e8da776bb61845 /drivers/tty/sysrq.c | |
| parent | 6f61bd5c4ff5c2b6a63113bff6c4a4bace2b9a3a (diff) | |
sysrq: Fix warning in sysrq generated crash.
commit 984cf355aeaa8f2eda3861b50d0e8d3e3f77e83b upstream.
Commit 984d74a72076a1 ("sysrq: rcu-ify __handle_sysrq") replaced
spin_lock_irqsave() calls with rcu_read_lock() calls in sysrq. Since
rcu_read_lock() does not disable preemption, faulthandler_disabled() in
__do_page_fault() in x86/fault.c returns false. When the code later calls
might_sleep() in the pagefault handler, we get the following warning:
BUG: sleeping function called from invalid context at ../arch/x86/mm/fault.c:1187
in_atomic(): 0, irqs_disabled(): 0, pid: 4706, name: bash
Preemption disabled at:[<ffffffff81484339>] printk+0x48/0x4a
To fix this, we release the RCU read lock before we crash.
Tested this patch on linux 3.18 by booting off one of our boards.
Fixes: 984d74a72076a1 ("sysrq: rcu-ify __handle_sysrq")
Signed-off-by: Ani Sinha <ani@arista.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/sysrq.c')
| -rw-r--r-- | drivers/tty/sysrq.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index b07f864f68e8..ed27fda13387 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -133,6 +133,12 @@ static void sysrq_handle_crash(int key) { char *killer = NULL; + /* we need to release the RCU read lock here, + * otherwise we get an annoying + * 'BUG: sleeping function called from invalid context' + * complaint from the kernel before the panic. + */ + rcu_read_unlock(); panic_on_oops = 1; /* force panic */ wmb(); *killer = 1; |