From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933130AbeAXKnE (ORCPT ); Wed, 24 Jan 2018 05:43:04 -0500 Received: from terminus.zytor.com ([65.50.211.136]:54759 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932999AbeAXKnC (ORCPT ); Wed, 24 Jan 2018 05:43:02 -0500 Date: Wed, 24 Jan 2018 02:38:50 -0800 From: tip-bot for Peter Zijlstra Message-ID: Cc: tglx@linutronix.de, tj@kernel.org, peterz@infradead.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mingo@kernel.org Reply-To: tglx@linutronix.de, tj@kernel.org, peterz@infradead.org, hpa@zytor.com, mingo@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org In-Reply-To: <20180122215328.GP3397@worktop> References: <20180122215328.GP3397@worktop> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched/core: Fix cpu.max vs. cpuhotplug deadlock Git-Commit-ID: ce48c146495a1a50e48cdbfbfaba3e708be7c07c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ce48c146495a1a50e48cdbfbfaba3e708be7c07c Gitweb: https://git.kernel.org/tip/ce48c146495a1a50e48cdbfbfaba3e708be7c07c Author: Peter Zijlstra AuthorDate: Mon, 22 Jan 2018 22:53:28 +0100 Committer: Ingo Molnar CommitDate: Wed, 24 Jan 2018 10:03:44 +0100 sched/core: Fix cpu.max vs. cpuhotplug deadlock Tejun reported the following cpu-hotplug lock (percpu-rwsem) read recursion: tg_set_cfs_bandwidth() get_online_cpus() cpus_read_lock() cfs_bandwidth_usage_inc() static_key_slow_inc() cpus_read_lock() Reported-by: Tejun Heo Tested-by: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180122215328.GP3397@worktop Signed-off-by: Ingo Molnar --- include/linux/jump_label.h | 7 +++++++ kernel/jump_label.c | 12 +++++++++--- kernel/sched/fair.c | 4 ++-- 3 files changed, 18 insertions(+), 5 deletions(-) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index c7b368c..e0340ca 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -160,6 +160,8 @@ extern void arch_jump_label_transform_static(struct jump_entry *entry, extern int jump_label_text_reserved(void *start, void *end); extern void static_key_slow_inc(struct static_key *key); extern void static_key_slow_dec(struct static_key *key); +extern void static_key_slow_inc_cpuslocked(struct static_key *key); +extern void static_key_slow_dec_cpuslocked(struct static_key *key); extern void jump_label_apply_nops(struct module *mod); extern int static_key_count(struct static_key *key); extern void static_key_enable(struct static_key *key); @@ -222,6 +224,9 @@ static inline void static_key_slow_dec(struct static_key *key) atomic_dec(&key->enabled); } +#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key) +#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key) + static inline int jump_label_text_reserved(void *start, void *end) { return 0; @@ -416,6 +421,8 @@ extern bool ____wrong_branch_error(void); #define static_branch_inc(x) static_key_slow_inc(&(x)->key) #define static_branch_dec(x) static_key_slow_dec(&(x)->key) +#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key) +#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key) /* * Normal usage; boolean enable/disable. diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 8594d24..b451709 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -79,7 +79,7 @@ int static_key_count(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_count); -static void static_key_slow_inc_cpuslocked(struct static_key *key) +void static_key_slow_inc_cpuslocked(struct static_key *key) { int v, v1; @@ -180,7 +180,7 @@ void static_key_disable(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_disable); -static void static_key_slow_dec_cpuslocked(struct static_key *key, +static void __static_key_slow_dec_cpuslocked(struct static_key *key, unsigned long rate_limit, struct delayed_work *work) { @@ -211,7 +211,7 @@ static void __static_key_slow_dec(struct static_key *key, struct delayed_work *work) { cpus_read_lock(); - static_key_slow_dec_cpuslocked(key, rate_limit, work); + __static_key_slow_dec_cpuslocked(key, rate_limit, work); cpus_read_unlock(); } @@ -229,6 +229,12 @@ void static_key_slow_dec(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_slow_dec); +void static_key_slow_dec_cpuslocked(struct static_key *key) +{ + STATIC_KEY_CHECK_USE(key); + __static_key_slow_dec_cpuslocked(key, 0, NULL); +} + void static_key_slow_dec_deferred(struct static_key_deferred *key) { STATIC_KEY_CHECK_USE(key); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2fe3aa8..26a71eb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4365,12 +4365,12 @@ static inline bool cfs_bandwidth_used(void) void cfs_bandwidth_usage_inc(void) { - static_key_slow_inc(&__cfs_bandwidth_used); + static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used); } void cfs_bandwidth_usage_dec(void) { - static_key_slow_dec(&__cfs_bandwidth_used); + static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used); } #else /* HAVE_JUMP_LABEL */ static bool cfs_bandwidth_used(void)