From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Dan Streetman <ddstreet@ieee.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 4.4 15/16] hotplug: Make register and unregister notifier API symmetric
Date: Tue, 13 Dec 2016 09:16:01 -0800 [thread overview]
Message-ID: <20161213171519.624992520@linuxfoundation.org> (raw)
In-Reply-To: <20161213171518.862135257@linuxfoundation.org>
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michal Hocko <mhocko@suse.com>
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: 47e627bc8c9a ("[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>
---
include/linux/cpu.h | 15 ++++-----------
kernel/cpu.c | 3 +--
2 files changed, 5 insertions(+), 13 deletions(-)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -131,22 +131,16 @@ enum {
{ .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;
@@ -156,7 +150,6 @@ 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
@@ -223,8 +223,6 @@ static int cpu_notify(unsigned long val,
return __cpu_notify(val, v, -1, NULL);
}
-#ifdef CONFIG_HOTPLUG_CPU
-
static void cpu_notify_nofail(unsigned long val, void *v)
{
BUG_ON(cpu_notify(val, v));
@@ -246,6 +244,7 @@ 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
next prev parent reply other threads:[~2016-12-13 17:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20161213171600epcas4p21d6115c640ff49376b44fb19568af7f4@epcas4p2.samsung.com>
2016-12-13 17:15 ` [PATCH 4.4 00/16] 4.4.39-stable review Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared Greg Kroah-Hartman
2016-12-13 23:59 ` Andrew Donnellan
2016-12-14 1:01 ` Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 02/16] parisc: Purge TLB before setting PTE Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 03/16] parisc: Remove unnecessary TLB purges from flush_dcache_page_asm and flush_icache_page_asm Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 04/16] parisc: Fix TLB related boot crash on SMP machines Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 05/16] zram: restrict add/remove attributes to root only Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 06/16] locking/rtmutex: Prevent dequeue vs. unlock race Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 07/16] locking/rtmutex: Use READ_ONCE() in rt_mutex_owner() Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 08/16] perf/x86: Fix full width counter, counter overflow Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 09/16] crypto: mcryptd - Check mcryptd algorithm compatibility Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 10/16] can: raw: raw_setsockopt: limit number of can_filter that can be set Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 12/16] arm64: futex.h: Add missing PAN toggling Greg Kroah-Hartman
2016-12-13 17:15 ` [PATCH 4.4 13/16] m68k: Fix ndelay() macro Greg Kroah-Hartman
2016-12-13 17:16 ` [PATCH 4.4 14/16] batman-adv: Check for alloc errors when preparing TT local data Greg Kroah-Hartman
2016-12-13 17:16 ` Greg Kroah-Hartman [this message]
2016-12-13 17:16 ` [PATCH 4.4 16/16] crypto: rsa - Add Makefile dependencies to fix parallel builds Greg Kroah-Hartman
2016-12-13 19:31 ` [PATCH 4.4 00/16] 4.4.39-stable review Shuah Khan
2016-12-14 4:11 ` Guenter Roeck
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