From: Greg Kroah-Hartman Date: Tue, 13 Dec 2016 12:31:37 +0000 (-0800) Subject: 4.9-stable patches X-Git-Tag: v4.4.39~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=637743e2f9315dce57eb737f641425c8f138b205;p=thirdparty%2Fkernel%2Fstable-queue.git 4.9-stable patches added patches: hotplug-make-register-and-unregister-notifier-api-symmetric.patch --- diff --git a/queue-4.9/hotplug-make-register-and-unregister-notifier-api-symmetric.patch b/queue-4.9/hotplug-make-register-and-unregister-notifier-api-symmetric.patch new file mode 100644 index 00000000000..bbf9f305a86 --- /dev/null +++ b/queue-4.9/hotplug-make-register-and-unregister-notifier-api-symmetric.patch @@ -0,0 +1,111 @@ +From 777c6e0daebb3fcefbbd6f620410a946b07ef6d0 Mon Sep 17 00:00:00 2001 +From: Michal Hocko +Date: Wed, 7 Dec 2016 14:54:38 +0100 +Subject: hotplug: Make register and unregister notifier API symmetric + +From: Michal Hocko + +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: [] raw_notifier_chain_register+0x1b/0x40 + +[ 145.122628] Call Trace: +[ 145.125086] [] __register_cpu_notifier+0x18/0x20 +[ 145.131350] [] zswap_pool_create+0x273/0x400 +[ 145.137268] [] __zswap_param_set+0x1fc/0x300 +[ 145.143188] [] ? trace_hardirqs_on+0xd/0x10 +[ 145.149018] [] ? kernel_param_lock+0x28/0x30 +[ 145.154940] [] ? __might_fault+0x4f/0xa0 +[ 145.160511] [] zswap_compressor_param_set+0x17/0x20 +[ 145.167035] [] param_attr_store+0x5c/0xb0 +[ 145.172694] [] module_attr_store+0x1d/0x30 +[ 145.178443] [] sysfs_kf_write+0x4f/0x70 +[ 145.183925] [] kernfs_fop_write+0x149/0x180 +[ 145.189761] [] __vfs_write+0x18/0x40 +[ 145.194982] [] vfs_write+0xb2/0x1a0 +[ 145.200122] [] SyS_write+0x52/0xa0 +[ 145.205177] [] 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: 47e627bc8c9a ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU") +Reported-and-tested-by: Yu Zhao +Signed-off-by: Michal Hocko +Cc: linux-mm@kvack.org +Cc: Andrew Morton +Cc: Dan Streetman +Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org +Signed-off-by: Thomas Gleixner +Signed-off-by: Greg Kroah-Hartman + +--- + include/linux/cpu.h | 15 ++++----------- + kernel/cpu.c | 2 +- + 2 files changed, 5 insertions(+), 12 deletions(-) + +--- a/include/linux/cpu.h ++++ b/include/linux/cpu.h +@@ -93,22 +93,16 @@ extern bool cpuhp_tasks_frozen; + { .notifier_call = fn, .priority = pri }; \ + __register_cpu_notifier(&fn##_nb); \ + } +-#else /* #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */ +-#define cpu_notifier(fn, pri) do { (void)(fn); } while (0) +-#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0) +-#endif /* #else #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */ + +-#ifdef CONFIG_HOTPLUG_CPU + extern int register_cpu_notifier(struct notifier_block *nb); + extern int __register_cpu_notifier(struct notifier_block *nb); + extern void unregister_cpu_notifier(struct notifier_block *nb); + extern void __unregister_cpu_notifier(struct notifier_block *nb); +-#else + +-#ifndef MODULE +-extern int register_cpu_notifier(struct notifier_block *nb); +-extern int __register_cpu_notifier(struct notifier_block *nb); +-#else ++#else /* #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE) */ ++#define cpu_notifier(fn, pri) do { (void)(fn); } while (0) ++#define __cpu_notifier(fn, pri) do { (void)(fn); } while (0) ++ + static inline int register_cpu_notifier(struct notifier_block *nb) + { + return 0; +@@ -118,7 +112,6 @@ static inline int __register_cpu_notifie + { + return 0; + } +-#endif + + static inline void unregister_cpu_notifier(struct notifier_block *nb) + { +--- a/kernel/cpu.c ++++ b/kernel/cpu.c +@@ -659,7 +659,6 @@ void __init cpuhp_threads_init(void) + kthread_unpark(this_cpu_read(cpuhp_state.thread)); + } + +-#ifdef CONFIG_HOTPLUG_CPU + EXPORT_SYMBOL(register_cpu_notifier); + EXPORT_SYMBOL(__register_cpu_notifier); + void unregister_cpu_notifier(struct notifier_block *nb) +@@ -676,6 +675,7 @@ void __unregister_cpu_notifier(struct no + } + EXPORT_SYMBOL(__unregister_cpu_notifier); + ++#ifdef CONFIG_HOTPLUG_CPU + /** + * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU + * @cpu: a CPU id diff --git a/queue-4.9/series b/queue-4.9/series new file mode 100644 index 00000000000..56787218976 --- /dev/null +++ b/queue-4.9/series @@ -0,0 +1 @@ +hotplug-make-register-and-unregister-notifier-api-symmetric.patch