Repository files (latest commit first)

Filename	Latest commit message	Latest commit date
Tejun Heo 85fbd722ad libata, freezer: avoid block device removal while system is frozen ... Freezable kthreads and workqueues are fundamentally problematic in that they effectively introduce a big kernel lock widely used in the kernel and have already been the culprit of several deadlock scenarios. This is the latest occurrence. During resume, libata rescans all the ports and revalidates all pre-existing devices. If it determines that a device has gone missing, the device is removed from the system which involves invalidating block device and flushing bdi while holding driver core layer locks. Unfortunately, this can race with the rest of device resume. Because freezable kthreads and workqueues are thawed after device resume is complete and block device removal depends on freezable workqueues and kthreads (e.g. bdi_wq, jbd2) to make progress, this can lead to deadlock - block device removal can't proceed because kthreads are frozen and kthreads can't be thawed because device resume is blocked behind block device removal. 839a8e8660 ("writeback: replace custom worker pool implementation with unbound workqueue") made this particular deadlock scenario more visible but the underlying problem has always been there - the original forker task and jbd2 are freezable too. In fact, this is highly likely just one of many possible deadlock scenarios given that freezer behaves as a big kernel lock and we don't have any debug mechanism around it. I believe the right thing to do is getting rid of freezable kthreads and workqueues. This is something fundamentally broken. For now, implement a funny workaround in libata - just avoid doing block device hot[un]plug while the system is frozen. Kernel engineering at its finest. :( v2: Add EXPORT_SYMBOL_GPL(pm_freezing) for cases where libata is built as a module. v3: Comment updated and polling interval changed to 10ms as suggested by Rafael. v4: Add #ifdef CONFIG_FREEZER around the hack as pm_freezing is not defined when FREEZER is not configured thus breaking build. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Tomaž Šolc <tomaz.solc@tablix.org> Reviewed-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Link: https://bugzilla.kernel.org/show_bug.cgi?id=62801 Link: http://lkml.kernel.org/r/20131213174932.GA27070@htj.dyndns.org Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Len Brown <len.brown@intel.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: stable@vger.kernel.org Cc: kbuild test robot <fengguang.wu@intel.com>		2013-12-19 13:50:32 -05:00
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cpu	sched: Add NEED_RESCHED to the preempt_count	2013-09-25 14:07:49 +02:00
debug	kdb: Add support for external NMI handler to call KGDB/KDB	2013-10-03 18:47:54 +02:00
events	list: introduce list_next_entry() and list_prev_entry()	2013-11-13 12:09:23 +09:00
gcov	gcov: reuse kbasename helper	2013-11-13 12:09:34 +09:00
irq	Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-11-19 10:40:00 -08:00
locking	locking/lockdep: Mark __lockdep_count_forward_deps() as static	2013-11-13 13:50:17 +01:00
power	Merge branch 'pm-sleep'	2013-11-19 01:07:08 +01:00
printk	printk.c: comments should refer to /proc/vmcore instead of /proc/vmcoreinfo	2013-11-13 12:09:14 +09:00
rcu	This batch of changes is mostly clean ups and small bug fixes.	2013-11-16 12:23:18 -08:00
sched	sched/fair: Avoid integer overflow	2013-11-13 13:33:55 +01:00
time	Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-11-12 10:36:00 +09:00
trace	This batch of changes is mostly clean ups and small bug fixes.	2013-11-16 12:23:18 -08:00
.gitignore
acct.c
async.c
audit.c	Merge git://git.infradead.org/users/eparis/audit	2013-11-21 19:18:14 -08:00
audit.h	audit: call audit_bprm() only once to add AUDIT_EXECVE information	2013-11-05 11:15:03 -05:00
audit_tree.c
audit_watch.c
auditfilter.c	audit: do not reject all AUDIT_INODE filter types	2013-11-05 11:09:16 -05:00
auditsc.c	audit: fix type of sessionid in audit_set_loginuid()	2013-11-06 11:47:24 -05:00
backtracetest.c
bounds.c	kernel/bounds: avoid circular dependencies in generated headers	2013-11-19 14:20:12 -08:00
capability.c	xfs: update for v3.12-rc1	2013-09-09 11:19:09 -07:00
cgroup.c	consolidate simple ->d_delete() instances	2013-11-15 22:04:17 -05:00
cgroup_freezer.c	cgroup: make css_for_each_descendant() and friends include the origin css in the iteration	2013-08-08 20:11:27 -04:00
compat.c
configs.c
context_tracking.c	Linux 3.12-rc4	2013-10-09 12:36:13 +02:00
cpu.c	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-11-14 16:55:11 +09:00
cpu_pm.c
cpuset.c	Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2013-09-03 18:25:03 -07:00
crash_dump.c
cred.c
delayacct.c	kernel/delayacct.c: remove redundant checking in __delayacct_add_tsk()	2013-11-13 12:09:12 +09:00
dma.c
elfcore.c	switch elf_core_write_extra_phdrs() to dump_emit()	2013-11-09 00:16:23 -05:00
exec_domain.c
exit.c
extable.c	extable: skip sorting if the table is empty	2013-09-11 15:58:25 -07:00
fork.c	mm: implement split page table lock for PMD level	2013-11-15 09:32:15 +09:00
freezer.c	libata, freezer: avoid block device removal while system is frozen	2013-12-19 13:50:32 -05:00
futex.c	locking: Move the rtmutex code to kernel/locking/	2013-11-06 09:23:59 +01:00
futex_compat.c
groups.c	userns: Kill nsown_capable it makes the wrong thing easy	2013-08-30 23:44:11 -07:00
hrtimer.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
hung_task.c	Here are the 3.13 KVM changes. There was a lot of work on the PPC	2013-11-15 13:51:36 +09:00
irq_work.c
itimer.c
jump_label.c	static_key: WARN on usage before jump_label_init was called	2013-10-19 19:45:35 -04:00
kallsyms.c
kcmp.c
Kconfig.freezer
Kconfig.hz	kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS	2013-11-15 09:32:22 +09:00
Kconfig.locks
Kconfig.preempt
kexec.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2013-11-15 16:47:22 -08:00
kmod.c	kernel/kmod.c: check for NULL in call_usermodehelper_exec()	2013-09-30 14:31:02 -07:00
kprobes.c	kprobes: use KSYM_NAME_LEN to size identifier buffers	2013-11-13 12:09:26 +09:00
ksysfs.c	kernel: replace strict_strto*() with kstrto*()	2013-09-12 15:38:03 -07:00
kthread.c	kthread: make kthread_create() killable	2013-11-13 12:08:59 +09:00
latencytop.c
Makefile	Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security	2013-11-21 19:46:00 -08:00
module-internal.h	KEYS: Separate the kernel signature checking keyring from module signing	2013-09-25 17:17:01 +01:00
module.c	Mainly boring here, too. rmmod --wait finally removed, though.	2013-11-15 13:27:50 +09:00
module_signing.c	keys: change asymmetric keys to use common hash definitions	2013-10-25 17:15:18 -04:00
notifier.c
nsproxy.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2013-09-07 14:35:32 -07:00
padata.c	padata - Register hotcpu notifier after initialization	2013-08-29 14:37:59 +10:00
panic.c	kernel/panic.c: reduce 1 byte usage for print tainted buffer	2013-11-13 12:09:35 +09:00
params.c	kernel/params: fix handling of signed integer types	2013-09-28 12:35:52 -07:00
pid.c	pidns: fix free_pid() to handle the first fork failure	2013-09-30 14:31:03 -07:00
pid_namespace.c	pid_namespace: make freeing struct pid_namespace rcu-delayed	2013-10-24 23:43:29 -04:00
posix-cpu-timers.c
posix-timers.c
profile.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
ptrace.c	exec/ptrace: fix get_dumpable() incorrect tests	2013-11-13 12:09:33 +09:00
range.c
reboot.c	kernel/reboot.c: re-enable the function of variable reboot_default	2013-09-24 17:00:26 -07:00
relay.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
res_counter.c	memcg: reduce function dereference	2013-09-12 15:38:02 -07:00
resource.c
seccomp.c
signal.c	constify copy_siginfo_to_user{,32}()	2013-11-09 00:16:29 -05:00
smp.c	kernel: fix generic_exec_single indentation	2013-11-15 09:32:22 +09:00
smpboot.c	kernel: delete __cpuinit usage from all core kernel files	2013-07-14 19:36:59 -04:00
smpboot.h
softirq.c	revert "softirq: Add support for triggering softirq work on softirqs"	2013-11-15 09:32:22 +09:00
stacktrace.c
stop_machine.c	stop_machine: Fix race between stop_two_cpus() and stop_cpus()	2013-11-11 12:43:38 +01:00
sys.c	kernel/sys.c: remove obsolete #include <linux/kexec.h>	2013-11-13 12:09:13 +09:00
sys_ni.c
sysctl.c	Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-11-14 16:30:30 +09:00
sysctl_binary.c	kernel/sysctl_binary.c: use scnprintf() instead of snprintf()	2013-11-13 12:09:33 +09:00
system_certificates.S	kernel/system_certificate.S: use real contents instead of macro GLOBAL()	2013-10-30 12:58:00 +00:00
system_keyring.c	KEYS: Make the system 'trusted' keyring viewable by userspace	2013-09-25 17:17:01 +01:00
task_work.c	task_work: documentation	2013-09-11 15:58:27 -07:00
taskstats.c	genetlink: only pass array to genl_register_family_with_ops()	2013-11-19 16:39:05 -05:00
test_kprobes.c
time.c
timeconst.bc
timer.c	sched: Introduce preempt_count accessor functions	2013-09-25 14:07:32 +02:00
tracepoint.c
tsacct.c
uid16.c	userns: Kill nsown_capable it makes the wrong thing easy	2013-08-30 23:44:11 -07:00
up.c	kernel: provide a __smp_call_function_single stub for !CONFIG_SMP	2013-11-15 09:32:22 +09:00
user-return-notifier.c
user.c	KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches	2013-09-24 10:35:19 +01:00
user_namespace.c	KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches	2013-09-24 10:35:19 +01:00
utsname.c	userns: Kill nsown_capable it makes the wrong thing easy	2013-08-30 23:44:11 -07:00
utsname_sysctl.c
watchdog.c	watchdog: update watchdog_thresh properly	2013-09-24 17:00:25 -07:00
workqueue.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2013-09-06 09:36:28 -07:00
workqueue_internal.h