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* kernel/hung_task.c: convert simple_strtoul to kstrtouintFabian Frederick2014-06-041-1/+3
| | | | | | | | | | sysctl_hung_task_panic has been changed to unsigned int. use kstrtouint instead of obsolete simple_strtoul Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: audit/fix non-modular users of module_init in core codePaul Gortmaker2014-04-031-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Code that is obj-y (always built-in) or dependent on a bool Kconfig (built-in or absent) can never be modular. So using module_init as an alias for __initcall can be somewhat misleading. Fix these up now, so that we can relocate module_init from init.h into module.h in the future. If we don't do this, we'd have to add module.h to obviously non-modular code, and that would be a worse thing. The audit targets the following module_init users for change: kernel/user.c obj-y kernel/kexec.c bool KEXEC (one instance per arch) kernel/profile.c bool PROFILING kernel/hung_task.c bool DETECT_HUNG_TASK kernel/sched/stats.c bool SCHEDSTATS kernel/user_namespace.c bool USER_NS Note that direct use of __initcall is discouraged, vs. one of the priority categorized subgroups. As __initcall gets mapped onto device_initcall, our use of subsys_initcall (which makes sense for these files) will thus change this registration from level 6-device to level 4-subsys (i.e. slightly earlier). However no observable impact of that difference has been observed during testing. Also, two instances of missing ";" at EOL are fixed in kexec. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Eric Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hung_task: Display every hung task warningAaron Tomlin2014-01-251-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | When khungtaskd detects hung tasks, it prints out backtraces from a number of those tasks. Limiting the number of backtraces being printed out can result in the user not seeing the information necessary to debug the issue. The hung_task_warnings sysctl controls this feature. This patch makes it possible for hung_task_warnings to accept a special value to print an unlimited number of backtraces when khungtaskd detects hung tasks. The special value is -1. To use this value it is necessary to change types from ulong to int. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com [ Build warning fix. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2013-11-151-0/+11
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull KVM changes from Paolo Bonzini: "Here are the 3.13 KVM changes. There was a lot of work on the PPC side: the HV and emulation flavors can now coexist in a single kernel is probably the most interesting change from a user point of view. On the x86 side there are nested virtualization improvements and a few bugfixes. ARM got transparent huge page support, improved overcommit, and support for big endian guests. Finally, there is a new interface to connect KVM with VFIO. This helps with devices that use NoSnoop PCI transactions, letting the driver in the guest execute WBINVD instructions. This includes some nVidia cards on Windows, that fail to start without these patches and the corresponding userspace changes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (146 commits) kvm, vmx: Fix lazy FPU on nested guest arm/arm64: KVM: PSCI: propagate caller endianness to the incoming vcpu arm/arm64: KVM: MMIO support for BE guest kvm, cpuid: Fix sparse warning kvm: Delete prototype for non-existent function kvm_check_iopl kvm: Delete prototype for non-existent function complete_pio hung_task: add method to reset detector pvclock: detect watchdog reset at pvclock read kvm: optimize out smp_mb after srcu_read_unlock srcu: API for barrier after srcu read unlock KVM: remove vm mmap method KVM: IOMMU: hva align mapping page size KVM: x86: trace cpuid emulation when called from emulator KVM: emulator: cleanup decode_register_operand() a bit KVM: emulator: check rex prefix inside decode_register() KVM: x86: fix emulation of "movzbl %bpl, %eax" kvm_host: typo fix KVM: x86: emulate SAHF instruction MAINTAINERS: add tree for kvm.git Documentation/kvm: add a 00-INDEX file ...
| * hung_task: add method to reset detectorMarcelo Tosatti2013-11-061-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | In certain occasions it is possible for a hung task detector positive to be false: continuation from a paused VM, for example. Add a method to reset detection, similar as is done with other kernel watchdogs. Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
* | hung_task debugging: Add tracepoint to report the hangOleg Nesterov2013-10-311-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently check_hung_task() prints a warning if it detects the problem, but it is not convenient to watch the system logs if user-space wants to be notified about the hang. Add the new trace_sched_process_hang() into check_hung_task(), this way a user-space monitor can easily wait for the hang and potentially resolve a problem. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Dave Sullivan <dsulliva@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20131019161828.GA7439@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | hung_task: Change sysctl_hung_task_check_count to 'int'Li Zefan2013-09-231-1/+1
|/ | | | | | | | | | | | | | | | | As 'sysctl_hung_task_check_count' is 'unsigned long' when this value is assigned to max_count in check_hung_uninterruptible_tasks(), it's truncated to 'int' type. This causes a minor artifact: if we write 2^32 to sysctl.hung_task_check_count, hung task detection will be effectively disabled. With this fix, it will still truncate the user input to 32 bits, but reading sysctl.hung_task_check_count reflects the actual truncated value. Signed-off-by: Li Zefan <lizefan@huawei.com> Acked-by: Ingo Molnar <mingo@kernel.org> Link: http://lkml.kernel.org/r/523FFF4E.9050401@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* hung_task debugging: Print more info when reporting the problemOleg Nesterov2013-08-021-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | printk(KERN_ERR) from check_hung_task() likely means we have a bug, but unlike BUG_ON()/WARN_ON ()it doesn't show the kernel version, this complicates the bug-reports investigation. Add the additional pr_err() to print tainted/release/version like dump_stack_print_info() does, the output becomes: INFO: task perl:504 blocked for more than 2 seconds. Not tainted 3.11.0-rc1-10367-g136bb46-dirty #1763 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ... While at it, turn the old printk's into pr_err(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: ahecox@redhat.com Cc: Christopher Williams <cww@redhat.com> Cc: dwysocha@redhat.com Cc: gavin@redhat.com Cc: Mandeep Singh Baines <msb@chromium.org> Cc: nshi@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130801165941.GA17544@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* hung task debugging: Inject NMI when hung and going to panicSasha Levin2012-04-251-1/+3
| | | | | | | | | | | | | | | | | Send an NMI to all CPUs when a hung task is detected and the hung task code is configured to panic. This gives us a fairly uptodate snapshot of all CPUs in the system. This lets us get stack trace of all CPUs which makes life easier trying to debug a deadlock, and the NMI doesn't change anything since the next step is a kernel panic. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1331848040-1676-1-git-send-email-levinsasha928@gmail.com [ extended the changelog a bit ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* hung_task: fix the broken rcu_lock_break() logicOleg Nesterov2012-03-051-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | check_hung_uninterruptible_tasks()->rcu_lock_break() introduced by "softlockup: check all tasks in hung_task" commit ce9dbe24 looks absolutely wrong. - rcu_lock_break() does put_task_struct(). If the task has exited it is not safe to even read its ->state, nothing protects this task_struct. - The TASK_DEAD checks are wrong too. Contrary to the comment, we can't use it to check if the task was unhashed. It can be unhashed without TASK_DEAD, or it can be valid with TASK_DEAD. For example, an autoreaping task can do release_task(current) long before it sets TASK_DEAD in do_exit(). Or, a zombie task can have ->state == TASK_DEAD but release_task() was not called, and in this case we must not break the loop. Change this code to check pid_alive() instead, and do this before we drop the reference to the task_struct. Note: while_each_thread() under rcu_read_lock() is not really safe, it can livelock. This will be fixed later, but fortunately in this case the "max_count" logic saves us anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Mandeep Singh Baines <msb@google.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* hung_task: fix false positive during vforkMandeep Singh Baines2012-01-031-4/+10
| | | | | | | | | | | | | | | | | vfork parent uninterruptibly and unkillably waits for its child to exec/exit. This wait is of unbounded length. Ignore such waits in the hung_task detector. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Reported-by: Sasha Levin <levinsasha928@gmail.com> LKML-Reference: <1325344394.28904.43.camel@lappy> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: John Kacur <jkacur@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel: Map most files to use export.h instead of module.hPaul Gortmaker2011-10-311-1/+1
| | | | | | | | | | | | | | | | The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* watchdog, hung_task_timeout: Add Kconfig configurable defaultJeff Mahoney2011-04-281-1/+1
| | | | | | | | | | | | | | | | | | This patch allows the default value for sysctl_hung_task_timeout_secs to be set at build time. The feature carries virtually no overhead, so it makes sense to keep it enabled. On heavily loaded systems, though, it can end up triggering stack traces when there is no bug other than the system being underprovisioned. We use this patch to keep the hung task facility available but disabled at boot-time. The default of 120 seconds is preserved. As a note, commit e162b39a may have accidentally reverted commit fb822db4, which raised the default from 120 seconds to 480 seconds. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Acked-by: Mandeep Singh Baines <msb@google.com> Link: http://lkml.kernel.org/r/4DB8600C.8080000@suse.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockup detector: Fix grammar by adding a missing "to" in the commentsJohn Kacur2010-08-171-1/+1
| | | | | | | | | | This fixes a minor grammar problem in the comments in hung_task.c Signed-off-by: John Kacur <jkacur@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1281021054-4228-2-git-send-email-jkacur@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* lockdep: Remove __debug_show_held_locksJohn Kacur2010-08-171-1/+1
| | | | | | | | | | | There is no longer any functional difference between __debug_show_held_locks() and debug_show_held_locks(), so remove the former. Signed-off-by: John Kacur <jkacur@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1281021054-4228-1-git-send-email-jkacur@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: Fix hung_task_check_count sysctlAnton Blanchard2009-11-271-1/+1
| | | | | | | | | | | | | | | | | I'm seeing spikes of up to 0.5ms in khungtaskd on a large machine. To reduce this source of jitter I tried setting hung_task_check_count to 0: # echo 0 > /proc/sys/kernel/hung_task_check_count which didn't have the intended response. Change to a post increment of max_count, so a value of 0 means check 0 tasks. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: msb@google.com LKML-Reference: <20091127022820.GU32182@kryten> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sysctl: remove "struct file *" argument of ->proc_handlerAlexey Dobriyan2009-09-241-2/+2
| | | | | | | | | | | | | | | | | | | | | It's unused. It isn't needed -- read or write flag is already passed and sysctl shouldn't care about the rest. It _was_ used in two places at arch/frv for some reason. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: David Howells <dhowells@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: ensure the task has been switched out onceFrederic Weisbecker2009-02-111-1/+7
| | | | | | | | | | | | | | | | | | When we check if a task has been switched out since the last scan, we might have a race condition on the following scenario: - the task is freshly created and scheduled - it puts its state to TASK_UNINTERRUPTIBLE and is not yet switched out - check_hung_task() scans this task and will report a false positive because t->nvcsw + t->nivcsw == t->last_switch_count == 0 Add a check for such cases. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: remove timestamp checking from hung_taskMandeep Singh Baines2009-02-091-39/+9
| | | | | | | | | | Impact: saves sizeof(long) bytes per task_struct By guaranteeing that sysctl_hung_task_timeout_secs have elapsed between tasklist scans we can avoid using timestamps. Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: convert read_lock in hung_task to rcu_read_lockMandeep Singh Baines2009-02-051-2/+2
| | | | | | | | | Since the tasklist is protected by rcu list operations, it is safe to convert the read_lock()s to rcu_read_lock(). Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: check all tasks in hung_taskMandeep Singh Baines2009-02-051-2/+37
| | | | | | | | | | | | | | | | | | | | | | | Impact: extend the scope of hung-task checks Changed the default value of hung_task_check_count to PID_MAX_LIMIT. hung_task_batch_count added to put an upper bound on the critical section. Every hung_task_batch_count checks, the rcu lock is never held for a too long time. Keeping the critical section small minimizes time preemption is disabled and keeps rcu grace periods small. To prevent following a stale pointer, get_task_struct is called on g and t. To verify that g and t have not been unhashed while outside the critical section, the task states are checked. The design was proposed by Frédéric Weisbecker. Signed-off-by: Mandeep Singh Baines <msb@google.com> Suggested-by: Frédéric Weisbecker <fweisbec@gmail.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: fix potential race in hung_task when resetting timeoutMandeep Singh Baines2009-01-181-8/+16
| | | | | | | | | | | | | | Impact: fix potential false panic A potential race exists if sysctl_hung_task_timeout_secs is reset to 0 while inside check_hung_uniterruptible_tasks(). If check_task() is entered, a comparison with 0 will result in a false hung_task being detected. If sysctl_hung_task_panic is set, the system will panic. Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: decouple hung tasks check from softlockup detectionMandeep Singh Baines2009-01-161-0/+198
Decoupling allows: * hung tasks check to happen at very low priority * hung tasks check and softlockup to be enabled/disabled independently at compile and/or run-time * individual panic settings to be enabled disabled independently at compile and/or run-time * softlockup threshold to be reduced without increasing hung tasks poll frequency (hung task check is expensive relative to softlock watchdog) * hung task check to be zero over-head when disabled at run-time Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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