From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AEF09C64ED6 for ; Sun, 26 Feb 2023 03:44:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230017AbjBZDoy (ORCPT ); Sat, 25 Feb 2023 22:44:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229842AbjBZDoQ (ORCPT ); Sat, 25 Feb 2023 22:44:16 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A32851689D; Sat, 25 Feb 2023 19:43:52 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4B3B560BCC; Sun, 26 Feb 2023 03:42:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1E8EC433EF; Sun, 26 Feb 2023 03:42:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677382973; bh=GJWmifj/956RQriLz9gCxLRgbfqs+WR2rBHhH8HJapM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iMlOb7bM9kmsP7AV3abd1yO4u01tXZH0P1+y+s+yGe999bvOhbyljtW3eLMURqVsm MCKXJGqxeY3zQMJrbtBa++KNK/LcAgZtDLHwmf84jEmoQdowSfjZDGrdhtDTMweQAY dbKrKC+AZx4DT0F30A/oL/9w+nwQdxv8Lmb6cRsQUtgIYTTUlzB82QQ+S4+UOpwYFr sDGLC85TGd2sbeiJaurMLP+rXmV4lvvw5TxojmqxekwfgQlMVJz1s7z3K7/QQRnP7K 1gw5QB5kspw1UoiDcRs6RWqzbJUDAhKqaCASLyEKC6Qn13/CISMhhdrO2Bo1D/Jisq jjxGaBGfV2kfg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Sasha Levin , frederic@kernel.org, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, pmladek@suse.com, mcgrof@kernel.org, keescook@chromium.org, akpm@linux-foundation.org, gpiccoli@igalia.com, andriy.shevchenko@linux.intel.com, yangtiezhu@loongson.cn, tangmeng@uniontech.com, daniel.vetter@ffwll.ch, catalin.marinas@arm.com, mark.rutland@arm.com, svens@linux.ibm.com, jpoimboe@kernel.org Subject: [PATCH AUTOSEL 6.2 20/21] cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG Date: Sat, 25 Feb 2023 22:41:49 -0500 Message-Id: <20230226034150.771411-20-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226034150.771411-1-sashal@kernel.org> References: <20230226034150.771411-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra [ Upstream commit 5a5d7e9badd2cb8065db171961bd30bd3595e4b6 ] In order to avoid WARN/BUG from generating nested or even recursive warnings, force rcu_is_watching() true during WARN/lockdep_rcu_suspicious(). Notably things like unwinding the stack can trigger rcu_dereference() warnings, which then triggers more unwinding which then triggers more warnings etc.. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230126151323.408156109@infradead.org Signed-off-by: Sasha Levin --- include/linux/context_tracking.h | 27 +++++++++++++++++++++++++++ kernel/locking/lockdep.c | 3 +++ kernel/panic.c | 5 +++++ lib/bug.c | 15 ++++++++++++++- 4 files changed, 49 insertions(+), 1 deletion(-) diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index dcef4a9e4d63e..d4afa8508a806 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -130,9 +130,36 @@ static __always_inline unsigned long ct_state_inc(int incby) return arch_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state)); } +static __always_inline bool warn_rcu_enter(void) +{ + bool ret = false; + + /* + * Horrible hack to shut up recursive RCU isn't watching fail since + * lots of the actual reporting also relies on RCU. + */ + preempt_disable_notrace(); + if (rcu_dynticks_curr_cpu_in_eqs()) { + ret = true; + ct_state_inc(RCU_DYNTICKS_IDX); + } + + return ret; +} + +static __always_inline void warn_rcu_exit(bool rcu) +{ + if (rcu) + ct_state_inc(RCU_DYNTICKS_IDX); + preempt_enable_notrace(); +} + #else static inline void ct_idle_enter(void) { } static inline void ct_idle_exit(void) { } + +static __always_inline bool warn_rcu_enter(void) { return false; } +static __always_inline void warn_rcu_exit(bool rcu) { } #endif /* !CONFIG_CONTEXT_TRACKING_IDLE */ #endif diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index e3375bc40dadc..50d4863974e7a 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -55,6 +55,7 @@ #include #include #include +#include #include @@ -6555,6 +6556,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) { struct task_struct *curr = current; int dl = READ_ONCE(debug_locks); + bool rcu = warn_rcu_enter(); /* Note: the following can be executed concurrently, so be careful. */ pr_warn("\n"); @@ -6595,5 +6597,6 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s) lockdep_print_held_locks(curr); pr_warn("\nstack backtrace:\n"); dump_stack(); + warn_rcu_exit(rcu); } EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious); diff --git a/kernel/panic.c b/kernel/panic.c index 463c9295bc28a..487f5b03bf835 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -679,6 +680,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, void warn_slowpath_fmt(const char *file, int line, unsigned taint, const char *fmt, ...) { + bool rcu = warn_rcu_enter(); struct warn_args args; pr_warn(CUT_HERE); @@ -693,11 +695,13 @@ void warn_slowpath_fmt(const char *file, int line, unsigned taint, va_start(args.args, fmt); __warn(file, line, __builtin_return_address(0), taint, NULL, &args); va_end(args.args); + warn_rcu_exit(rcu); } EXPORT_SYMBOL(warn_slowpath_fmt); #else void __warn_printk(const char *fmt, ...) { + bool rcu = warn_rcu_enter(); va_list args; pr_warn(CUT_HERE); @@ -705,6 +709,7 @@ void __warn_printk(const char *fmt, ...) va_start(args, fmt); vprintk(fmt, args); va_end(args); + warn_rcu_exit(rcu); } EXPORT_SYMBOL(__warn_printk); #endif diff --git a/lib/bug.c b/lib/bug.c index c223a2575b721..e0ff219899902 100644 --- a/lib/bug.c +++ b/lib/bug.c @@ -47,6 +47,7 @@ #include #include #include +#include extern struct bug_entry __start___bug_table[], __stop___bug_table[]; @@ -153,7 +154,7 @@ struct bug_entry *find_bug(unsigned long bugaddr) return module_find_bug(bugaddr); } -enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) +static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *regs) { struct bug_entry *bug; const char *file; @@ -209,6 +210,18 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) return BUG_TRAP_TYPE_BUG; } +enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) +{ + enum bug_trap_type ret; + bool rcu = false; + + rcu = warn_rcu_enter(); + ret = __report_bug(bugaddr, regs); + warn_rcu_exit(rcu); + + return ret; +} + static void clear_once_table(struct bug_entry *start, struct bug_entry *end) { struct bug_entry *bug; -- 2.39.0