Ani Sinha 6321e17535 sysrq: Fix warning in sysrq generated crash. ...

commit 984cf355ae upstream.

Commit 984d74a720 ("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: 984d74a720 ("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>

2018-01-17 09:35:28 +01:00

..

hvc

Merge tag 'tty-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2015-11-04 21:35:12 -08:00

ipwireless

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2015-04-14 09:50:27 -07:00

serial

serial: 8250: Preserve DLD[7:4] for PORT_XR17V35X

2017-12-09 18:42:40 +01:00

vt

vt: fix unchecked __put_user() in tioclinux ioctls

2017-07-21 07:44:57 +02:00

amiserial.c

tty: amiserial.c: move assignment out of if () block

2015-05-10 19:04:16 +02:00

bfin_jtag_comm.c

TTY: bfin_jtag_comm: remove incorrect wait_until_sent operation

2015-03-07 03:44:14 +01:00

cyclades.c

tty: Remove ASYNC_CLOSING checks in open()/hangup() methods

2015-10-17 21:11:29 -07:00

ehv_bytechan.c

tty: remove unused variable sprop

2015-02-03 15:52:13 -08:00

goldfish.c

Revert "tty: goldfish: Fix a parameter of a call to free_irq"

2017-10-21 17:09:06 +02:00

isicom.c

tty/isicom: fix big-endian compile warning

2015-02-02 10:11:25 -08:00

Kconfig

ttyFDC: Implement KGDB IO operations.

2015-03-31 12:04:13 +02:00

Makefile

TTY: Add MIPS EJTAG Fast Debug Channel TTY driver

2015-03-31 12:04:12 +02:00

metag_da.c

tty/metag_da: Avoid module_init/module_exit in non-modular code

2015-06-16 14:12:31 -04:00

mips_ejtag_fdc.c

ttyFDC: Fix build problems due to use of module_{init,exit}

2015-10-17 21:29:21 -07:00

moxa.c

TTY: fix decimal printf format specifiers prefixed with 0x

2014-09-08 15:51:35 -07:00

moxa.h

tty: move a number of tty drivers from drivers/char/ to drivers/tty/

2011-02-22 16:14:56 -08:00

mxser.c

tty: mxser: Fix build warning introduced by dfc7b837c7 (Re: linux-next: build warning after merge of the tty.current tree)

2013-05-22 10:26:02 -07:00

mxser.h

Fix common misspellings

2011-03-31 11:26:23 -03:00

n_gsm.c

TTY: n_gsm, fix false positive WARN_ON

2016-06-01 12:15:52 -07:00

n_hdlc.c

tty: n_hdlc: get rid of racy n_hdlc.tbuf

2017-03-15 09:57:10 +08:00

n_r3964.c

tty: r3964: Replace/remove bogus tty lock use

2015-10-17 21:11:29 -07:00

n_tracerouter.c

n_tracerouter: stop including <asm-generic/bug>

2015-10-15 00:21:10 +02:00

n_tracesink.c

n_tracesink: stop including <asm-generic/bug>

2015-10-15 00:21:11 +02:00

n_tracesink.h

n_tracerouter and n_tracesink ldisc additions.

2011-05-13 16:31:00 -07:00

n_tty.c

n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD)

2018-01-02 20:33:28 +01:00

nozomi.c

tty: nozomi: avoid a harmless gcc warning

2017-04-30 05:49:27 +02:00

pty.c

tty: pty: Fix ldisc flush after userspace become aware of the data already

2017-05-20 14:27:02 +02:00

rocket_int.h

tty: move a number of tty drivers from drivers/char/ to drivers/tty/

2011-02-22 16:14:56 -08:00

rocket.c

tty: Remove tty_port::close_wait

2015-10-17 21:11:29 -07:00

rocket.h

tty: rocket: fix comment of ROCKET_SPD_HI

2015-05-24 12:49:16 -07:00

synclink_gt.c

tty: Remove ASYNC_CLOSING checks in open()/hangup() methods

2015-10-17 21:11:29 -07:00

synclink.c

tty: synclink, fix indentation

2015-10-17 21:14:06 -07:00

synclinkmp.c

tty: Remove ASYNC_CLOSING checks in open()/hangup() methods

2015-10-17 21:11:29 -07:00

sysrq.c

sysrq: Fix warning in sysrq generated crash.

2018-01-17 09:35:28 +01:00

tty_audit.c

tty: audit: Fix audit source

2015-11-20 16:19:54 -08:00

tty_buffer.c

tty: fix __tty_insert_flip_char regression

2017-09-27 11:00:13 +02:00

tty_io.c

tty: Drop krefs for interrupted tty lock

2017-06-14 13:16:26 +02:00

tty_ioctl.c

tty: Fix tty_send_xchar() lock order inversion

2015-11-20 16:19:54 -08:00

tty_ldisc.c

tty: Prevent ldisc drivers from re-using stale tty fields

2016-11-21 10:06:40 +01:00

tty_ldsem.c

tty: tty_ldsem.c: move assignment out of if () block

2015-05-10 19:04:18 +02:00

tty_mutex.c

tty: Drop krefs for interrupted tty lock

2017-06-14 13:16:26 +02:00

tty_port.c

tty: Abstract tty buffer work

2015-10-17 21:32:21 -07:00