linux-stable.git/drivers/tty/sysrq.c, branch linux-4.9.y

sysrq: Remove duplicated sysrq message

2020-03-11T06:53:04+00:00

commit c3fee60908db4a8594f2e4a2131998384b8fa006 upstream.

The commit 97f5f0cd8cd0a0544 ("Input: implement SysRq as a separate input
handler") added pr_fmt() definition. It caused a duplicated message
prefix in the sysrq header messages, for example:

[  177.053931] sysrq: SysRq : Show backtrace of all active CPUs
[  742.864776] sysrq: SysRq : HELP : loglevel(0-9) reboot(b) crash(c)

Fixes: 97f5f0cd8cd0a05 ("Input: implement SysRq as a separate input handler")
Signed-off-by: Petr Mladek 
Reviewed-by: Sergey Senozhatsky 
Cc: Tommi Rantala  
Signed-off-by: Greg Kroah-Hartman

sysrq: Restore original console_loglevel when sysrq disabled

2020-03-11T06:53:04+00:00

commit 075e1a0c50f59ea210561d0d0fedbd945615df78 upstream.

The sysrq header line is printed with an increased loglevel
to provide users some positive feedback.

The original loglevel is not restored when the sysrq operation
is disabled. This bug was introduced in 2.6.12 (pre-git-history)
by the commit ("Allow admin to enable only some of the Magic-Sysrq
functions").

Signed-off-by: Petr Mladek 
Reviewed-by: Sergey Senozhatsky 
Reviewed-by: Steven Rostedt (VMware) 
Cc: Tommi Rantala 
Signed-off-by: Greg Kroah-Hartman

sysrq : fix Show Regs call trace on ARM

2017-12-09T21:01:49+00:00

[ Upstream commit b00bebbc301c8e1f74f230dc82282e56b7e7a6db ]

When kernel configuration SMP,PREEMPT and DEBUG_PREEMPT are enabled,
echo 1 >/proc/sys/kernel/sysrq
echo p >/proc/sysrq-trigger
kernel will print call trace as below:

sysrq: SysRq : Show Regs
BUG: using __this_cpu_read() in preemptible [00000000] code: sh/435
caller is __this_cpu_preempt_check+0x18/0x20
Call trace:
[] dump_backtrace+0x0/0x1d0
[] show_stack+0x24/0x30
[] dump_stack+0x90/0xb0
[] check_preemption_disabled+0x100/0x108
[] __this_cpu_preempt_check+0x18/0x20
[] sysrq_handle_showregs+0x1c/0x40
[] __handle_sysrq+0x12c/0x1a0
[] write_sysrq_trigger+0x60/0x70
[] proc_reg_write+0x90/0xd0
[] __vfs_write+0x48/0x90
[] vfs_write+0xa4/0x190
[] SyS_write+0x54/0xb0
[] el0_svc_naked+0x24/0x28

This can be seen on a common board like an r-pi3.
This happens because when echo p >/proc/sysrq-trigger,
get_irq_regs() is called outside of IRQ context,
if preemption is enabled in this situation,kernel will
print the call trace. Since many prior discussions on
the mailing lists have made it clear that get_irq_regs
either just returns NULL or stale data when used outside
of IRQ context,we simply avoid calling it outside of
IRQ context.

Signed-off-by: Jibin Xu 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

sysrq: attach sysrq handler correctly for 32-bit kernel

2017-01-19T19:18:03+00:00

commit 802c03881f29844af0252b6e22be5d2f65f93fd0 upstream.

The sysrq input handler should be attached to the input device which has
a left alt key.

On 32-bit kernels, some input devices which has a left alt key cannot
attach sysrq handler.  Because the keybit bitmap in struct input_device_id
for sysrq is not correctly initialized.  KEY_LEFTALT is 56 which is
greater than BITS_PER_LONG on 32-bit kernels.

I found this problem when using a matrix keypad device which defines
a KEY_LEFTALT (56) but doesn't have a KEY_O (24 == 56%32).

Cc: Jiri Slaby 
Signed-off-by: Akinobu Mita 
Acked-by: Dmitry Torokhov 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

mm: oom: add memcg to oom_control

2016-07-26T23:19:19+00:00

It's a part of oom context just like allocation order and nodemask, so
let's move it to oom_control instead of passing it in the argument list.

Link: http://lkml.kernel.org/r/40e03fd7aaf1f55c75d787128d6d17c5a71226c2.1464358556.git.vdavydov@virtuozzo.com
Signed-off-by: Vladimir Davydov 
Acked-by: Michal Hocko 
Acked-by: Johannes Weiner 
Cc: Tetsuo Handa 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysrq: Fix warning in sysrq generated crash.

2015-12-30T00:29:18+00:00

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:[] 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 
Reviewed-by: Rik van Riel 
Signed-off-by: Paul E. McKenney

drivers/tty: make sysrq.c slightly more explicitly non-modular

2015-10-04T16:27:56+00:00

The Kconfig currently controlling compilation of this code is:

config.debug:config MAGIC_SYSRQ
      bool "Magic SysRq key"

...meaning that it currently is not being built as a module by anyone.

Lets remove the traces of modularity we can so that when reading the
driver there is less doubt it is builtin-only.

Since module_init translates to device_initcall in the non-modular
case, the init ordering remains unchanged with this commit.

We don't delete the module.h include since other parts of the file are
using content from there.

Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Signed-off-by: Paul Gortmaker 
Signed-off-by: Greg Kroah-Hartman

mm, oom: pass an oom order of -1 when triggered by sysrq

2015-09-08T22:35:28+00:00

The force_kill member of struct oom_control isn't needed if an order of -1
is used instead.  This is the same as order == -1 in struct
compact_control which requires full memory compaction.

This patch introduces no functional change.

Signed-off-by: David Rientjes 
Cc: Sergey Senozhatsky 
Cc: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, oom: organize oom context into struct

2015-09-08T22:35:28+00:00

There are essential elements to an oom context that are passed around to
multiple functions.

Organize these elements into a new struct, struct oom_control, that
specifies the context for an oom condition.

This patch introduces no functional change.

Signed-off-by: David Rientjes 
Acked-by: Michal Hocko 
Cc: Sergey Senozhatsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2015-07-01T17:49:25+00:00

Pull module updates from Rusty Russell:
 "Main excitement here is Peter Zijlstra's lockless rbtree optimization
  to speed module address lookup.  He found some abusers of the module
  lock doing that too.

  A little bit of parameter work here too; including Dan Streetman's
  breaking up the big param mutex so writing a parameter can load
  another module (yeah, really).  Unfortunately that broke the usual
  suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were
  appended too"

* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits)
  modules: only use mod->param_lock if CONFIG_MODULES
  param: fix module param locks when !CONFIG_SYSFS.
  rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
  module: add per-module param_lock
  module: make perm const
  params: suppress unused variable error, warn once just in case code changes.
  modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'.
  kernel/module.c: avoid ifdefs for sig_enforce declaration
  kernel/workqueue.c: remove ifdefs over wq_power_efficient
  kernel/params.c: export param_ops_bool_enable_only
  kernel/params.c: generalize bool_enable_only
  kernel/module.c: use generic module param operaters for sig_enforce
  kernel/params: constify struct kernel_param_ops uses
  sysfs: tightened sysfs permission checks
  module: Rework module_addr_{min,max}
  module: Use __module_address() for module_address_lookup()
  module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING
  module: Optimize __module_address() using a latched RB-tree
  rbtree: Implement generic latch_tree
  seqlock: Introduce raw_read_seqcount_latch()
  ...