Echoing values into /proc/sysrq-trigger seems to be a popular way to get
information out of the kernel. However, dumping information about
thousands of processes, or hundreds of CPUs to serial console can result
in IRQs being blocked for minutes, resulting in various kinds of cascade
failures.
The most common failure is due to interrupts being blocked for a very
long time. This can lead to things like failed IO requests, and other
things the system cannot easily recover from.
This problem is easily fixable by making __handle_sysrq use RCU instead
of spin_lock_irqsave.
This leaves the warning that RCU grace periods have not elapsed for a
long time, but the system will come back from that automatically.
It also leaves sysrq-from-irq-context when the sysrq keys are pressed,
but that is probably desired since people want that to work in
situations where the system is already hosed.
The callers of register_sysrq_key and unregister_sysrq_key appear to be
capable of sleeping.
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Madper Xie <cxie@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
... instead of naked numbers.
Stuff in sysrq.c used to set it to 8 which is supposed to mean above
default level so set it to DEBUG instead as we're terminating/killing all
tasks and we want to be verbose there.
Also, correct the check in x86_64_start_kernel which should be >= as
we're clearly issuing the string there for all debug levels, not only
the magical 10.
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Joe Perches <joe@perches.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE)
into a Kconfig variable.
Original version by Bastian Blank <waldi@debian.org>.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull input updates from Dmitry Torokhov:
"A new driver for slidebar on Ideapad laptops and a bunch of assorted
driver fixes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (32 commits)
Input: add SYN_MAX and SYN_CNT constants
Input: max11801_ts - convert to devm
Input: egalax-ts - fix typo and improve text
Input: MAINTAINERS - change maintainer for cyttsp driver
Input: cyttsp4 - kill 'defined but not used' compiler warnings
Input: add driver for slidebar on Lenovo IdeaPad laptops
Input: omap-keypad - set up irq type from DT
Input: omap-keypad - enable wakeup capability for keypad.
Input: omap-keypad - clear interrupts on open
Input: omap-keypad - convert to threaded IRQ
Input: omap-keypad - use bitfiled instead of hardcoded values
Input: cyttsp4 - remove useless NULL test from cyttsp4_watchdog_timer()
Input: wacom - fix error return code in wacom_probe()
Input: as5011 - fix error return code in as5011_probe()
Input: keyboard, serio - simplify use of devm_ioremap_resource
Input: tegra-kbc - simplify use of devm_ioremap_resource
Input: htcpen - fix incorrect placement of __initdata
Input: qt1070 - add power management ops
Input: wistron_btns - add MODULE_DEVICE_TABLE
Input: wistron_btns - mark the Medion MD96500 keymap as tested
...
Adding a simple device tree binding for the specification of key
sequences. Definition of the keys found in the sequence are located in
'include/uapi/linux/input.h'.
For the sysrq driver, holding the sequence of keys down for a specific
amount of time will reset the system.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Pull input updates from Dmitry Torokhov:
"First round of updates for the input subsystem.
You will get a new touchsreen driver for Cypress 4th generation
devices, a driver for a special controller implementing PS/2 protocol
in OLPC devices, and a driver for power key for SiRFprimaII PWRC.
HID and bcm5497 now support for the 2013 MacBook Air.
EVIOCGKEY and the rest of evdev ioctls now flush events of matching
type from the client's event queue so that clients can be sure any
events received after issuing EVIOCG* ioctl are new events.
And a host of cleanups and improvements in other drivers"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (87 commits)
Input: cyttsp4 - kfree xfer_buf on error path in probe()
Input: tps6507x-ts - select INPUT_POLLDEV
Input: bcm5974 - add support for the 2013 MacBook Air
HID: apple: Add support for the 2013 Macbook Air
Input: cyttsp4 - leak on error path in probe()
Input: cyttsp4 - silence NULL dereference warning
Input: cyttsp4 - silence shift wrap warning
Input: tps6507x-ts - convert to polled input device infrastructure
ARM: davinci: da850-evm: remove vref from touchscreen platform data
Input: cyttsp4 - SPI driver for Cypress TMA4XX touchscreen devices
Input: cyttsp4 - I2C driver for Cypress TMA4XX touchscreen devices
Input: cyttsp4 - add core driver for Cypress TMA4XX touchscreen devices
Input: cyttsp - I2C driver split into two modules
Input: add OLPC AP-SP driver
Input: nspire-keypad - remove redundant dev_err call in nspire_keypad_probe()
Input: tps6507x-ts - remove vref from platform data
Input: tps6507x-ts - use bool for booleans
Input: tps6507x-ts - remove bogus unreachable code
Input: samsung-keypad - let device core setup the default pin configuration
Input: wacom_i2c - implement hovering capability
...
Attempt to reboot the system gracefully when a key combo is detected.
If the reste combination is pressed the 2nd time we assume that graceful
reboot failed and perform emergency reboot. This fucntionality is useful
when UI is stuck but the system is otherwise working fine.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
The usage of strict_strtoul() is not preferred, because
strict_strtoul() is obsolete. Thus, kstrtoul() should be
used.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull input updates from Dmitry Torokhov:
"Assorted fixes and cleanups to the existing drivers plus a new driver
for IMS Passenger Control Unit device they use for ther in-flight
entertainment system."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (44 commits)
Input: trackpoint - Optimize trackpoint init to use power-on reset
Input: apbps2 - convert to devm_ioremap_resource()
Input: ALPS - use %ph to print buffers
ARM - shmobile: Armadillo800EVA: Move st1232 reset pin handling
Input: st1232 - add reset pin handling
Input: st1232 - convert to devm_* infrastructure
Input: MT - handle semi-mt devices in core
Input: adxl34x - use spi_get_drvdata()
Input: ad7877 - use spi_get_drvdata() and spi_set_drvdata()
Input: ads7846 - use spi_get_drvdata() and spi_set_drvdata()
Input: ims-pcu - fix a memory leak on error
Input: sysrq - supplement reset sequence with timeout functionality
Input: tegra-kbc - support for defining row/columns based on SoC
Input: imx_keypad - switch to using managed resources
Input: arc_ps2 - add support for device tree
Input: mma8450 - fix signed 12bits to 32bits conversion
Input: eeti_ts - remove redundant null check
Input: edt-ft5x06 - remove redundant null check before kfree
Input: ad714x - add CONFIG_PM_SLEEP to suspend/resume functions
Input: adxl34x - add CONFIG_PM_SLEEP to suspend/resume functions
...
Some devices have too few buttons, which it makes it hard to have
a reset combo that won't trigger automatically. As such a
timeout functionality that requires the combination to be held for
a given amount of time before triggering is introduced.
If a key combo is recognized and held for a 'timeout' amount of time,
the system triggers a reset. If the timeout value is omitted the
driver simply ignores the functionality.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Currently help message of /proc/sysrq-trigger highlight its
upper-case characters, like below:
SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
memory-full-oom-kill(F) kill-all-tasks(I) ...
this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.
This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.
This patch fix it.
Thanks the comments from Andrew and Randy.
Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When taking an address of an extern array, gcc quite naturally should be
able to say "an address of an object can never be NULL" and just
optimize away the test entirely.
However, the new alternate sysrq reset code (commit 154b7a489a5b:
"Input: sysrq - allow specifying alternate reset sequence") did exactly
that, and declared platform_sysrq_reset_seq[] as a weak array, and
expecting that testing the address of the array would show whether it
actually got linked against something or not.
And that doesn't work with all gcc versions. Clearly it works with
*some* versions of gcc, and maybe it's even supposed to work, but it
really is a very fragile concept.
So instead of testing the address of the weak variable, just create a
weak instance of that array that is empty. If some platform then has a
real platform_sysrq_reset_seq[] that overrides our weak one, the linker
will switch to that one, and it all works without any run-time
conditionals at all.
Reported-by: Dave Airlie <airlied@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull input updates from Dmitry Torokhov:
"Two new touchpad drivers - Cypress APA I2C Trackpad and Cypress PS/2
touchpad and a big update to ALPS driver from Kevin Cernekee that adds
support for "Rushmore" touchpads and paves way for adding support for
"Dolphin" touchpads.
There is also a new input driver for Goldfish emulator and also
Android keyreset driver was folded into SysRq code.
A few more drivers were updated with device tree bindings and others
got some small cleanups and fixes."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (55 commits)
Input: cyttsp-spi - remove duplicate MODULE_ALIAS()
Input: tsc2005 - add MODULE_ALIAS
Input: tegra-kbc - require CONFIG_OF, remove platform data
Input: synaptics - initialize pointer emulation usage
Input: MT - do not apply filtering on emulated events
Input: bma150 - make some defines public and fix some comments
Input: bma150 - fix checking pm_runtime_get_sync() return value
Input: ALPS - enable trackstick on Rushmore touchpads
Input: ALPS - add support for "Rushmore" touchpads
Input: ALPS - make the V3 packet field decoder "pluggable"
Input: ALPS - move pixel and bitmap info into alps_data struct
Input: ALPS - fix command mode check
Input: ALPS - rework detection of Pinnacle AGx touchpads
Input: ALPS - move {addr,nibble}_command settings into alps_set_defaults()
Input: ALPS - use function pointers for different protocol handlers
Input: ALPS - rework detection sequence
Input: ALPS - introduce helper function for repeated commands
Input: ALPS - move alps_get_model() down below hw_init code
Input: ALPS - copy "model" info into alps_data struct
Input: ALPS - document the alps.h data structures
...
Move rt scheduler definitions out of include/linux/sched.h into
new file include/linux/sched/rt.h
Signed-off-by: Clark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch adds keyreset functionality to the sysrq driver. It allows
certain button/key combinations to be used in order to trigger emergency
reboots.
Redefining the '__weak platform_sysrq_reset_seq' variable is required
to trigger the feature. Alternatively keys can be passed to the driver
via a module parameter.
This functionality comes from the keyreset driver submitted by
Arve Hjønnevåg in the Android kernel.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
With hotpluggable and memoryless nodes, it's possible that node 0 will
not be online, so use the first online node's zonelist rather than
hardcoding node 0 to pass a zonelist with all zones to the oom killer.
Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Change send_sig_all() to use do_send_sig_info(SEND_SIG_FORCED) instead
of force_sig(SIGKILL). With the recent changes we do not need force_ to
kill the CLONE_NEWPID tasks.
And this is more correct. force_sig() can race with the exiting thread,
while do_send_sig_info(group => true) kill the whole process.
Some more notes from Oleg Nesterov:
> Just one note. This change makes no difference for sysrq_handle_kill().
> But it obviously changes the behaviour sysrq_handle_term(). I think
> this is fine, if you want to really kill the task which blocks/ignores
> SIGTERM you can use sysrq_handle_kill().
>
> Even ignoring the reasons why force_sig() is simply wrong here,
> force_sig(SIGTERM) looks strange. The task won't be killed if it has
> a handler, but SIG_IGN can't help. However if it has the handler
> but blocks SIGTERM temporary (this is very common) it will be killed.
Also,
> force_sig() can't kill the process if the main thread has already
> exited. IOW, it is trivial to create the process which can't be
> killed by sysrq.
So, this patch fixes the issue.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The oom killer chooses not to kill a thread if:
- an eligible thread has already been oom killed and has yet to exit,
and
- an eligible thread is exiting but has yet to free all its memory and
is not the thread attempting to currently allocate memory.
SysRq+F manually invokes the global oom killer to kill a memory-hogging
task. This is normally done as a last resort to free memory when no
progress is being made or to test the oom killer itself.
For both uses, we always want to kill a thread and never defer. This
patch causes SysRq+F to always kill an eligible thread and can be used to
force a kill even if another oom killed thread has failed to exit.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Keyboard struct lifetime is easy, but the locking is not and is completely
ignored by the existing code. Tackle this one head on
- Make the kbd_table private so we can run down all direct users
- Hoick the relevant ioctl handlers into the keyboard layer
- Lock them with the keyboard lock so they don't change mid keypress
- Add helpers for things like console stop/start so we isolate the poking
around properly
- Tweak the braille console so it still builds
There are a couple of FIXME locking cases left for ioctls that are so hideous
they should be addressed in a later patch. After this patch the kbd_table is
private and all the keyboard jiggery pokery is in one place.
This update fixes speakup and also a memory leak in the original.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There's a real possibility of killing kernel threads that might
have issued use_mm(), so kthread's mm might become non-NULL.
This patch fixes the issue by checking for PF_KTHREAD (just as
get_task_mm()).
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysrq should grab the tasklist lock, otherwise calling force_sig() is
not safe, as it might race with exiting task, which ->sighand might be
set to NULL already.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export
kill_bdev as well, so brd doesn't have to open code it. Reduce
buffer_head.h requirement accordingly.
Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving. The small comment replacing it says enough.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit ddd588b5dd ("oom: suppress nodes that are not allowed from
meminfo on oom kill") moved lib/show_mem.o out of lib/lib.a, which
resulted in build warnings on all architectures that implement their own
versions of show_mem():
lib/lib.a(show_mem.o): In function `show_mem':
show_mem.c:(.text+0x1f4): multiple definition of `show_mem'
arch/sparc/mm/built-in.o:(.text+0xd70): first defined here
The fix is to remove __show_mem() and add its argument to show_mem() in
all implementations to prevent this breakage.
Architectures that implement their own show_mem() actually don't do
anything with the argument yet, but they could be made to filter nodes
that aren't allowed in the current context in the future just like the
generic implementation.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: James Bottomley <James.Bottomley@hansenpartnership.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: wacom - pass touch resolution to clients through input_absinfo
Input: wacom - add 2 Bamboo Pen and touch models
Input: sysrq - ensure sysrq_enabled and __sysrq_enabled are consistent
Input: sparse-keymap - fix KEY_VSW handling in sparse_keymap_setup
Input: tegra-kbc - add tegra keyboard driver
Input: gpio_keys - switch to using request_any_context_irq
Input: serio - allow registered drivers to get status flag
Input: ct82710c - return proper error code for ct82c710_open
Input: bu21013_ts - added regulator support
Input: bu21013_ts - remove duplicate resolution parameters
Input: tnetv107x-ts - don't treat NULL clk as an error
Input: tnetv107x-keypad - don't treat NULL clk as an error
Fix up trivial conflicts in drivers/input/keyboard/Makefile due to
additions of tc3589x/Tegra drivers
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: fix typo in keycode validation supporting large scancodes
Input: aiptek - tighten up permissions on sysfs attributes
Input: sysrq - pass along lone Alt + SysRq
The tty code should be in its own subdirectory and not in the char
driver with all of the cruft that is currently there.
Based on work done by Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Rik van Riel