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As Andrew noted, my previous patch ("debug lockups: Improve lockup
detection") broke/removed SysRq-L support from architecture that do
not provide a __trigger_all_cpu_backtrace implementation.
Restore a fallback path and clean up the SysRq-L machinery a bit:
- Rename the arch method to arch_trigger_all_cpu_backtrace()
- Simplify the define
- Document the method a bit - in the hope of more architectures
adding support for it.
[ The patch touches Sparc code for the rename. ]
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
LKML-Reference: <20090802140809.7ec4bb6b.akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When debugging a recent lockup bug i found various deficiencies
in how our current lockup detection helpers work:
- SysRq-L is not very efficient as it uses a workqueue, hence
it cannot punch through hard lockups and cannot see through
most soft lockups either.
- The SysRq-L code depends on the NMI watchdog - which is off
by default.
- We dont print backtraces from the RCU code's built-in
'RCU state machine is stuck' debug code. This debug
code tends to be one of the first (and only) mechanisms
that show that a lockup has occured.
This patch changes the code so taht we:
- Trigger the NMI backtrace code from SysRq-L instead of using
a workqueue (which cannot punch through hard lockups)
- Trigger print-all-CPU-backtraces from the RCU lockup detection
code
Also decouple the backtrace printing code from the NMI watchdog:
- Dont use variable size cpumasks (it might not be initialized
and they are a bit more fragile anyway)
- Trigger an NMI immediately via an IPI, instead of waiting
for the NMI tick to occur. This is a lot faster and can
produce more relevant backtraces. It will also work if the
NMI watchdog is disabled.
- Dont print the 'dazed and confused' message when we print
a backtrace from the NMI
- Do a show_regs() plus a dump_stack() to get maximum info
out of the dump. Worst-case we get two stacktraces - which
is not a big deal. Sometimes, if register content is
corrupted, the precise stack walker in show_regs() wont
give us a full backtrace - in this case dump_stack() will
do it.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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commit d6580a9f15238b87e618310c862231ae3f352d2d ("kexec: sysrq: simplify
sysrq-c handler") changed the behavior of sysrq-c to unconditional
dereference of NULL pointer. So in cases with CONFIG_KEXEC, where
crash_kexec() was directly called from sysrq-c before, now it can be said
that a step of "real oops" was inserted before starting kdump.
However, in contrast to oops via SysRq-c from keyboard which results in
panic due to in_interrupt(), oops via "echo c > /proc/sysrq-trigger" will
not become panic unless panic_on_oops=1. It means that even if dump is
properly configured to be taken on panic, the sysrq-c from proc interface
might not start crashdump while the sysrq-c from keyboard can start
crashdump. This confuses traditional users of kdump, i.e. people who
expect sysrq-c to do common behavior in both of the keyboard and proc
interface.
This patch brings the keyboard and proc interface behavior of sysrq-c in
line, by forcing panic_on_oops=1 before oops in sysrq-c handler.
And some updates in documentation are included, to clarify that there is
no longer dependency with CONFIG_KEXEC, and that now the system can just
crash by sysrq-c if no dump mechanism is configured.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Brayan Arraes <brayan@yack.com.br>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Currently the sysrq-c handler is bit over-engineered. Its behavior is
dependent on a few compile time and run time factors that alter its
behavior which is really unnecessecary.
If CONFIG_KEXEC is not configured, sysrq-c, crashes the system with a NULL
pointer dereference. If CONFIG_KEXEC is configured, it calls crash_kexec
directly, which implies that the kexec kernel will either be booted (if
its been previously loaded), or it will simply do nothing (the no kexec
kernel has been loaded).
It would be much easier to just simplify the whole thing to dereference a
NULL pointer all the time regardless of configuration. That way, it will
always try to crash the system, and if a kexec kernel has been loaded into
reserved space, it will still boot from the page fault trap handler
(assuming panic_on_oops is set appropriately).
[akpm@linux-foundation.org: build fix]
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Brayan Arraes <brayan@yack.com.br>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge reason: this branch was on an -rc4 base, merge it up to -rc6
to get the latest upstream fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Commit 79e539453b34e35f39299a899d263b0a1f1670bd introduced a
regression where you cannot use sysrq 'g' to enter kgdb. The solution
is to move the intel fb sysrq over to V for video instead of G for
graphics. The SMP VOYAGER code to register for the sysrq-v is not
anywhere to be found in the mainline kernel, so the comments in the
code were cleaned up as well.
This patch also cleans up the sysrq definitions for kgdb to make it
generic for the kernel debugger, such that the sysrq 'g' can be used
in the future to enter a gdbstub or another kernel debugger.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Merge reason: This brach was on -rc1, refresh it to almost-rc4 to pick up
the latest upstream fixes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Remove duplicated #include in drivers/char/sysrq.c.
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge reason: we have gathered quite a few conflicts, need to merge upstream
Conflicts:
arch/powerpc/kernel/Makefile
arch/x86/ia32/ia32entry.S
arch/x86/include/asm/hardirq.h
arch/x86/include/asm/unistd_32.h
arch/x86/include/asm/unistd_64.h
arch/x86/kernel/cpu/common.c
arch/x86/kernel/irq.c
arch/x86/kernel/syscall_table_32.S
arch/x86/mm/iomap_32.c
include/linux/sched.h
kernel/Makefile
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
include/linux/slub_def.h
lib/Kconfig.debug
mm/slob.c
mm/slub.c
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* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
[S390] cio: online_store - trigger recognition for boxed devices
[S390] cio: disallow online setting of device in transient state
[S390] cio: introduce notifier for boxed state
[S390] cio: introduce ccw_device_schedule_sch_unregister
[S390] cio: wake up on failed recognition
[S390] fix hypfs build failure
[PATCH] sysrq: include interrupt.h instead of irq.h
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Now that the filesystem freeze operation has been elevated to the VFS, and
is just an ioctl away, some sort of safety net for unintentionally frozen
root filesystems may be in order.
The timeout thaw originally proposed did not get merged, but perhaps
something like this would be useful in emergencies.
For example, freeze /path/to/mountpoint may freeze your root filesystem if
you forgot that you had that unmounted.
I chose 'j' as the last remaining character other than 'h' which is sort
of reserved for help (because help is generated on any unknown character).
I've tested this on a non-root fs with multiple (nested) freezers, as well
as on a system rendered unresponsive due to a frozen root fs.
[randy.dunlap@oracle.com: emergency thaw only if CONFIG_BLOCK enabled]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With "cpumask: update irq_desc to use cpumask_var_t"
we get this build failure on s390:
CC drivers/char/sysrq.o
In file included from drivers/char/sysrq.c:38:
include/linux/irq.h: In function 'init_alloc_desc_masks':
include/linux/irq.h:442: error: dereferencing pointer to incomplete type
drivers/char/sysrq.c should include interrupt.h instead of irq.h.
Cc: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Conflicts:
include/linux/syscalls.h
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Add an explanitory comment as to why we modify the kernel console loglevel
rather than simply moving sysrq messages to KERN_EMERG level.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Conflicts:
include/linux/kernel_stat.h
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Eliminate sysrq terse help mode; make sysrq help messages more meaningful
(more explicit/verbose). Make the sysrq action letter clearer by listing
it explicitly in more sysrq help messages (when it is not simple/clear).
The SysRq help message now looks like this:
SysRq : HELP : loglevel(0-9) reBoot terminate-all-tasks(E) memory-full-oom-kill(F) kill-all-tasks(I) saK show-backtrace-all-active-cpus(L) show-memory-usage(M) nice-all-RT-tasks(N) powerOff show-registers(P) show-all-timers(Q) unRaw Sync show-task-states(T) Unmount show-blocked-tasks(W)
Addresses http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=330403.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: <jidanni@jidanni.org>
Cc: <330403@bugs.debian.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Conflicts:
fs/exec.c
include/linux/init_task.h
Simple context conflicts.
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Impact: update documentation and help messages
We have a conventional method of explicitly stating the
sysrq action key in a sysrq help message, so change
dump-ftrace-buffer to use that method and add it to
Documentation/sysrq.txt.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Implement the core kernel bits of Performance Counters subsystem.
The Linux Performance Counter subsystem provides an abstraction of
performance counter hardware capabilities. It provides per task and per
CPU counters, and it provides event capabilities on top of those.
Performance counters are accessed via special file descriptors.
There's one file descriptor per virtual counter used.
The special file descriptor is opened via the perf_counter_open()
system call:
int
perf_counter_open(u32 hw_event_type,
u32 hw_event_period,
u32 record_type,
pid_t pid,
int cpu);
The syscall returns the new fd. The fd can be used via the normal
VFS system calls: read() can be used to read the counter, fcntl()
can be used to set the blocking mode, etc.
Multiple counters can be kept open at a time, and the counters
can be poll()ed.
See more details in Documentation/perf-counters.txt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Impact: add SysRq-z support to dump trace buffers
Allows one to force an ftrace dump from sysrq
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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SysRq-Q also dumps information about the clockevent devices.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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I fell into the trap recently that it only dumps hrtimers instead of
all timers. Fix the documentation.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: torvalds@linux-foundation.org
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Move it into sysrq.c, along with the rest of the sysrq implementation.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It is written in the Documentation/sysrq.txt that oom-killer is enabled
when we set "64" in /proc/sys/kernel/sysrq:
<Documentation/sysrq.txt>
Here is the list of possible values in /proc/sys/kernel/sysrq:
64 - enable signalling of processes (term, kill, oom-kill)
^^^^^^^^
but enable_mask is not set in sysrq_moom_op.
Signed-off-by: Naohiro Ooiwa <nooiwa@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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drivers/char/sysrq.c: In function 'sysrq_showregs_othercpus':
drivers/char/sysrq.c:218: error: too many arguments to function 'smp_call_function'
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When a cpu really is stuck in the kernel, it can be often
impossible to figure out which cpu is stuck where. The
worst case is when the stuck cpu has interrupts disabled.
Therefore, implement a global cpu state capture that uses
SMP message interrupts which are not disabled by the
normal IRQ enable/disable APIs of the kernel.
As long as we can get a sysrq 'y' to the kernel, we can
get a dump. Even if the console interrupt cpu is wedged,
we can trigger it from userspace using /proc/sysrq-trigger
The output is made compact so that this facility is more
useful on high cpu count systems, which is where this
facility will likely find itself the most useful :)
Signed-off-by: David S. Miller <davem@davemloft.net>
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SysRQ-P is not always useful on SMP systems, since it usually ends up showing
the backtrace of a CPU that is doing just fine, instead of the backtrace of
the CPU that is having problems.
This patch adds SysRQ show-all-cpus(L), which shows the backtrace of every
active CPU in the system. It skips idle CPUs because some SMP systems are
just too large and we already know what the backtrace of the idle task looks
like.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Rik van Riel <riel@redhat.com>
Randy Dunlap <randy.dunlap@oracle.com>
Cc: <lwoodman@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Introduce a node_zonelist() helper function. It is used to lookup the
appropriate zonelist given a node and a GFP mask. The patch on its own is a
cleanup but it helps clarify parts of the two-zonelist-per-node patchset. If
necessary, it can be merged with the next patch in this set without problems.
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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is_init() is an ambiguous name for the pid==1 check. Split it into
is_global_init() and is_container_init().
A cgroup init has it's tsk->pid == 1.
A global init also has it's tsk->pid == 1 and it's active pid namespace
is the init_pid_ns. But rather than check the active pid namespace,
compare the task structure with 'init_pid_ns.child_reaper', which is
initialized during boot to the /sbin/init process and never changes.
Changelog:
2.6.22-rc4-mm2-pidns1:
- Use 'init_pid_ns.child_reaper' to determine if a given task is the
global init (/sbin/init) process. This would improve performance
and remove dependence on the task_pid().
2.6.21-mm2-pidns2:
- [Sukadev Bhattiprolu] Changed is_container_init() calls in {powerpc,
ppc,avr32}/traps.c for the _exception() call to is_global_init().
This way, we kill only the cgroup if the cgroup's init has a
bug rather than force a kernel panic.
[akpm@linux-foundation.org: fix comment]
[sukadev@us.ibm.com: Use is_global_init() in arch/m32r/mm/fault.c]
[bunk@stusta.de: kernel/pid.c: remove unused exports]
[sukadev@us.ibm.com: Fix capability.c to work with threaded init]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Acked-by: Pavel Emelianov <xemul@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Herbert Poetzel <herbert@13thfloor.at>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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As of now, the kernel defaults to non-unicode and XLATE for the keyboard.
We've been changing this in Fedora, but that requires patching the defaults
in the kernel.
The attached introduces CONFIG_VT_UNICODE, which sets the console in
unicode mode by default on boot, including both the virtual terminal and
the keyboard driver.
Signed-off-by: Bill Nottingham <notting@redhat.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Move the OOM killer's extern function prototypes to include/linux/oom.h and
include it where necessary.
[clg@fr.ibm.com: build fix]
Cc: Andrea Arcangeli <andrea@suse.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remove includes of <linux/smp_lock.h> where it is not used/needed.
Suggested by Al Viro.
Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add SysRq-Q to print pending timers and other timer info.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Somewhere in the rewrite of the work queues my cleanup of SAK handling
got broken. Maybe I didn't retest it properly or possibly the API
was changing so fast I missed something. Regardless currently
triggering a SAK now generates an ugly BUG_ON and kills the kernel.
Thanks to Alexey Dobriyan <adobriyan@openvz.org> for spotting this.
This modifies the use of SAK_work to initialize it when the data
structure it resides in is initialized, and to simply call
schedule_work when we need to generate a SAK. I update both
data structures that have a SAK_work member for consistency.
All of the old PREPARE_WORK calls that are now gone.
If we call schedule_work again before it has processed it
has generated the first SAK it will simply ignore the duplicate
schedule_work request.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This does several things.
- It moves looking up of the current foreground console into process
context where we can safely take the semaphore that protects this
operation.
- It uses the new flavor of work queue processing.
- This generates a factor of do_SAK, __do_SAK that runs immediately.
- This calls __do_SAK with the console semaphore held ensuring nothing
else happens to the console while we process the SAK operation.
- With the console SAK processing moved into process context this
patch removes the xchg operations that I used to attempt to attomically
update struct pid, because of the strange locking used in the SAK processing.
With SAK using the normal console semaphore nothing special is needed.
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Change SysRq showBlockedTasks from sysrq-X to sysrq-W and show that in the
Help message.
It was previously done via X, but X is already used for Xmon on ppc & powerpc
platforms and this collision needs to be avoided.
All callers of register_sysrq_key() are now marked in the sysrq op/key table.
I didn't mark 'h' as Help because Help is just printed for any unknown key,
such as '?'.
Added some omitted sysrq key entries in the sysrq.txt file.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Most distributions enable sysrq support but set it to 0 by default. Add a
sysrq_always_enabled boot option to always-enable sysrq keys. Useful for
debugging - without having to modify the disribution's config files (which
might not be possible if the kernel is on a live CD, etc.).
Also, while at it, clean up the sysrq interfaces.
[bunk@stusta.de: make sysrq_always_enabled_setup() static]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add SysRq-X support: show blocked (TASK_UNINTERRUPTIBLE) tasks only.
Useful for debugging IO stalls.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pass the work_struct pointer to the work function rather than context data.
The work function can use container_of() to work out the data.
For the cases where the container of the work_struct may go away the moment the
pending bit is cleared, it is made possible to defer the release of the
structure by deferring the clearing of the pending bit.
To make this work, an extra flag is introduced into the management side of the
work_struct. This governs auto-release of the structure upon execution.
Ordinarily, the work queue executor would release the work_struct for further
scheduling or deallocation by clearing the pending bit prior to jumping to the
work function. This means that, unless the driver makes some guarantee itself
that the work_struct won't go away, the work function may not access anything
else in the work_struct or its container lest they be deallocated.. This is a
problem if the auxiliary data is taken away (as done by the last patch).
However, if the pending bit is *not* cleared before jumping to the work
function, then the work function *may* access the work_struct and its container
with no problems. But then the work function must itself release the
work_struct by calling work_release().
In most cases, automatic release is fine, so this is the default. Special
initiators exist for the non-auto-release case (ending in _NAR).
Signed-Off-By: David Howells <dhowells@redhat.com>
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drivers/char/sysrq.c: In function `sysrq_handle_crashdump':
drivers/char/sysrq.c:98: warning: implicit declaration of function `get_irq_regs'
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
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SysRq : Emergency Sync
Emergency Sync complete
SysRq : Emergency Remount R/O
Emergency Remount complete
SysRq : Resetting
BUG: warning at kernel/lockdep.c:1816/trace_hardirqs_on() (Not tainted)
Call Trace:
[<ffffffff8026d56d>] show_trace+0xae/0x319
[<ffffffff8026d7ed>] dump_stack+0x15/0x17
[<ffffffff802a68d1>] trace_hardirqs_on+0xbc/0x13d
[<ffffffff803a8eec>] sysrq_handle_reboot+0x9/0x11
[<ffffffff803a8f8d>] __handle_sysrq+0x99/0x130
[<ffffffff803a903b>] handle_sysrq+0x17/0x19
[<ffffffff803a36ee>] kbd_event+0x32e/0x57d
[<ffffffff80401e35>] input_event+0x42d/0x45b
[<ffffffff804063eb>] atkbd_interrupt+0x44d/0x53d
[<ffffffff803fe5c5>] serio_interrupt+0x49/0x86
[<ffffffff803ff2a4>] i8042_interrupt+0x202/0x21a
[<ffffffff80210cf0>] handle_IRQ_event+0x2c/0x64
[<ffffffff802bfd8b>] __do_IRQ+0xaf/0x114
[<ffffffff8026ea24>] do_IRQ+0xf8/0x107
[<ffffffff8025f886>] ret_from_intr+0x0/0xf
DWARF2 unwinder stuck at ret_from_intr+0x0/0xf
Leftover inexact backtrace:
<IRQ> <EOI> [<ffffffff80258e36>] mwait_idle+0x3f/0x54
[<ffffffff8024a33a>] cpu_idle+0xa2/0xc5
[<ffffffff8026c34e>] rest_init+0x2b/0x2d
[<ffffffff809708bc>] start_kernel+0x24a/0x24c
[<ffffffff8097028b>] _sinittext+0x28b/0x292
Since we're shutting down anyway, don't bother being smart,
just turn the thing off.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This is an updated version of Eric Biederman's is_init() patch.
(http://lkml.org/lkml/2006/2/6/280). It applies cleanly to 2.6.18-rc3 and
replaces a few more instances of ->pid == 1 with is_init().
Further, is_init() checks pid and thus removes dependency on Eric's other
patches for now.
Eric's original description:
There are a lot of places in the kernel where we test for init
because we give it special properties. Most significantly init
must not die. This results in code all over the kernel test
->pid == 1.
Introduce is_init to capture this case.
With multiple pid spaces for all of the cases affected we are
looking for only the first process on the system, not some other
process that has pid == 1.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: <lxc-devel@lists.sourceforge.net>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Print all lock-classes on SysRq-D.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Generic lock debugging:
- generalized lock debugging framework. For example, a bug in one lock
subsystem turns off debugging in all lock subsystems.
- got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
the mutex/rtmutex debugging code: it caused way too much prototype
hackery, and lockdep will give the same information anyway.
- ability to do silent tests
- check lock freeing in vfree too.
- more finegrained debugging options, to allow distributions to
turn off more expensive debugging features.
There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes. (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)
Here are the current debugging options:
CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y
which do:
config DEBUG_MUTEXES
bool "Mutex debugging, basic checks"
config DEBUG_LOCK_ALLOC
bool "Detect incorrect freeing of live mutexes"
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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sysrq.c is fairly revolting. Fix.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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