Michal Hocko 1c0f4e0ebb hotplug: Make register and unregister notifier API symmetric ... commit 777c6e0daebb3fcefbbd6f620410a946b07ef6d0 upstream. Yu Zhao has noticed that __unregister_cpu_notifier only unregisters its notifiers when HOTPLUG_CPU=y while the registration might succeed even when HOTPLUG_CPU=n if MODULE is enabled. This means that e.g. zswap might keep a stale notifier on the list on the manual clean up during the pool tear down and thus corrupt the list. Resulting in the following [ 144.964346] BUG: unable to handle kernel paging request at ffff880658a2be78 [ 144.971337] IP: [<ffffffffa290b00b>] raw_notifier_chain_register+0x1b/0x40 <snipped> [ 145.122628] Call Trace: [ 145.125086] [<ffffffffa28e5cf8>] __register_cpu_notifier+0x18/0x20 [ 145.131350] [<ffffffffa2a5dd73>] zswap_pool_create+0x273/0x400 [ 145.137268] [<ffffffffa2a5e0fc>] __zswap_param_set+0x1fc/0x300 [ 145.143188] [<ffffffffa2944c1d>] ? trace_hardirqs_on+0xd/0x10 [ 145.149018] [<ffffffffa2908798>] ? kernel_param_lock+0x28/0x30 [ 145.154940] [<ffffffffa2a3e8cf>] ? __might_fault+0x4f/0xa0 [ 145.160511] [<ffffffffa2a5e237>] zswap_compressor_param_set+0x17/0x20 [ 145.167035] [<ffffffffa2908d3c>] param_attr_store+0x5c/0xb0 [ 145.172694] [<ffffffffa290848d>] module_attr_store+0x1d/0x30 [ 145.178443] [<ffffffffa2b2b41f>] sysfs_kf_write+0x4f/0x70 [ 145.183925] [<ffffffffa2b2a5b9>] kernfs_fop_write+0x149/0x180 [ 145.189761] [<ffffffffa2a99248>] __vfs_write+0x18/0x40 [ 145.194982] [<ffffffffa2a9a412>] vfs_write+0xb2/0x1a0 [ 145.200122] [<ffffffffa2a9a732>] SyS_write+0x52/0xa0 [ 145.205177] [<ffffffffa2ff4d97>] entry_SYSCALL_64_fastpath+0x12/0x17 This can be even triggered manually by changing /sys/module/zswap/parameters/compressor multiple times. Fix this issue by making unregister APIs symmetric to the register so there are no surprises. Fixes: 47e627bc8c ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU") Reported-and-tested-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: linux-mm@kvack.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Streetman <ddstreet@ieee.org> Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-12-15 08:49:23 -08:00
..
bpf	bpf, inode: disallow userns mounts	2016-06-24 10:18:17 -07:00
configs	kconfig: tinyconfig: provide whole choice blocks to avoid warnings	2016-09-24 10:07:42 +02:00
debug
events	perf/core: Fix pmu::filter_match for SW-led groups	2016-10-07 15:23:41 +02:00
gcov
irq	genirq/generic_chip: Add irq_unmap callback	2016-10-31 04:13:59 -06:00
livepatch	livepatch: x86: fix relocation computation with kASLR	2015-11-11 17:36:04 +01:00
locking	locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()	2016-12-15 08:49:22 -08:00
power	PM / sleep: fix device reference leak in test_suspend	2016-11-26 09:54:53 +01:00
printk	printk: fix parsing of "brl=" option	2016-10-07 15:23:43 +02:00
rcu	rcu: Fix soft lockup for rcu_nocb_kthread	2016-12-08 07:15:24 +01:00
sched	sched/core: Fix a race between try_to_wake_up() and a woken up task	2016-09-24 10:07:42 +02:00
time	timekeeping: Fix __ktime_get_fast_ns() regression	2016-10-16 17:36:14 +02:00
trace	tracing: Move mutex to protect against resetting of seq data	2016-09-30 10:18:38 +02:00
.gitignore	certs: add .gitignore to stop git nagging about x509_certificate_list	2015-10-21 15:18:35 +01:00
acct.c
async.c
audit.c	mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd	2015-11-06 17:50:42 -08:00
audit.h	audit: audit_tree_match can be boolean	2015-11-04 08:23:51 -05:00
audit_fsnotify.c
audit_tree.c	audit: audit_tree_match can be boolean	2015-11-04 08:23:51 -05:00
audit_watch.c	audit: fix exe_file access in audit_exe_compare	2016-09-24 10:07:36 +02:00
auditfilter.c	audit: fix comment block whitespace	2015-11-04 08:23:51 -05:00
auditsc.c	audit: fix a double fetch in audit_log_single_execve_arg()	2016-08-20 18:09:22 +02:00
backtracetest.c
bounds.c
capability.c	kernel: Add noaudit variant of ns_capable()	2016-09-15 08:27:50 +02:00
cgroup.c	cgroup: avoid false positive gcc-6 warning	2016-11-10 16:36:36 +01:00
cgroup_freezer.c	cgroup: fix handling of multi-destination migration from subtree_control enabling	2015-12-03 10:18:21 -05:00
cgroup_pids.c	cgroup_pids: don't account for the root cgroup	2015-12-03 10:18:21 -05:00
compat.c
configs.c
context_tracking.c	context_tracking: avoid irq_save/irq_restore on guest entry and exit	2015-11-10 12:06:23 +01:00
cpu.c	hotplug: Make register and unregister notifier API symmetric	2016-12-15 08:49:23 -08:00
cpu_pm.c
cpuset.c	cpuset: handle race between CPU hotplug and cpuset_hotplug_work	2016-10-07 15:23:40 +02:00
crash_dump.c
cred.c	cred: Reject inodes with invalid ids in set_create_file_as()	2016-09-15 08:27:49 +02:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	wait/ptrace: assume __WALL if the child is traced	2016-06-07 18:14:35 -07:00
extable.c
fork.c	kernel/fork: fix CLONE_CHILD_CLEARTID regression in nscd	2016-10-07 15:23:46 +02:00
freezer.c
futex.c	futex: Acknowledge a new waiter in counter before plist	2016-05-04 14:48:43 -07:00
futex_compat.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 12:01:16 -08:00
groups.c
hung_task.c
irq_work.c	treewide: Remove old email address	2015-11-23 09:44:58 +01:00
jump_label.c	locking/static_key: Fix concurrent static_key_slow_inc()	2016-07-27 09:47:29 -07:00
kallsyms.c
kcmp.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 12:01:16 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c	kexec: use file name as the output message prefix	2015-11-06 17:50:42 -08:00
kexec_core.c	kexec: use file name as the output message prefix	2015-11-06 17:50:42 -08:00
kexec_file.c	kexec: fix double-free when failing to relocate the purgatory	2016-09-24 10:07:36 +02:00
kexec_internal.h
kmod.c	kmod: don't run async usermode helper as a child of kworker thread	2015-10-23 17:55:10 +09:00
kprobes.c
ksysfs.c
kthread.c
latencytop.c
Makefile
membarrier.c
memremap.c	devm_memremap: Fix error value when memremap failed	2016-03-03 15:07:08 -08:00
module-internal.h
module.c	module: Invalidate signatures on force-loaded modules	2016-08-20 18:09:27 +02:00
module_signing.c	KEYS: Merge the type-specific data with the payload data	2015-10-21 15:18:36 +01:00
notifier.c
nsproxy.c
padata.c
panic.c	printk: do cond_resched() between lines while outputting to consoles	2016-02-17 12:30:57 -08:00
params.c	Nothing exciting, minor tweaks and cleanups.	2015-11-09 15:53:39 -08:00
pid.c	pidns: fix NULL dereference in __task_pid_nr_ns()	2015-11-24 12:03:55 -08:00
pid_namespace.c
profile.c
ptrace.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 12:01:16 -08:00
range.c
reboot.c
relay.c
resource.c	kernel/resource.c: fix muxed resource handling in __request_region()	2016-03-03 15:07:29 -08:00
seccomp.c	seccomp: always propagate NO_NEW_PRIVS on tsync	2016-03-03 15:07:25 -08:00
signal.c	kernel/signal.c: unexport sigsuspend()	2015-11-20 16:17:32 -08:00
smp.c	mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd	2015-11-06 17:50:42 -08:00
smpboot.c	stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()	2015-10-20 10:23:55 +02:00
smpboot.h
softirq.c
stacktrace.c
stop_machine.c	kernel: remove stop_machine() Kconfig dependency	2015-12-12 10:15:34 -08:00
sys.c	prctl: take mmap sem for writing to protect against others	2016-02-25 12:01:25 -08:00
sys_ni.c	mm: mlock: add new mlock system call	2015-11-05 19:34:48 -08:00
sysctl.c	sysctl: handle error writing UINT_MAX to u32 fields	2016-10-07 15:23:46 +02:00
sysctl_binary.c	fs/coredump: prevent fsuid=0 dumps into user-controlled directories	2016-04-12 09:08:58 -07:00
task_work.c
taskstats.c
test_kprobes.c
torture.c	torture: Consolidate cond_resched_rcu_qs() into stutter_wait()	2015-10-06 11:25:01 -07:00
tracepoint.c	tracepoint: Give priority to probes of tracepoints	2015-10-25 21:33:54 -04:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
watchdog.c	watchdog: don't run proc_watchdog_update if new value is same as old	2016-04-12 09:08:54 -07:00
workqueue.c	workqueue: fix rebind bound workers warning	2016-05-18 17:06:50 -07:00
workqueue_internal.h