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From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	x86@kernel.org, Paul McKenney <paulmck@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
	Alexandre Chartre <alexandre.chartre@oracle.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org
Subject: Re: [patch V3 01/23] rcu: Dont acquire lock in NMI handler in rcu_nmi_enter_common()
Date: Tue, 24 Mar 2020 16:37:55 +0100	[thread overview]
Message-ID: <20200324153754.GA20223@lenoir> (raw)
In-Reply-To: <20200320180032.523372590@linutronix.de>

On Fri, Mar 20, 2020 at 06:59:57PM +0100, Thomas Gleixner wrote:
> From: "Paul E. McKenney" <paulmck@kernel.org>
> 
> The rcu_nmi_enter_common() function can be invoked both in interrupt
> and NMI handlers.  If it is invoked from process context (as opposed
> to userspace or idle context) on a nohz_full CPU, it might acquire the
> CPU's leaf rcu_node structure's ->lock.  Because this lock is held only
> with interrupts disabled, this is safe from an interrupt handler, but
> doing so from an NMI handler can result in self-deadlock.
> 
> This commit therefore adds "irq" to the "if" condition so as to only
> acquire the ->lock from irq handlers or process context, never from
> an NMI handler.
> 
> Fixes: 5b14557b073c ("rcu: Avoid tick_dep_set_cpu() misordering")
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> Link: https://lkml.kernel.org/r/20200313024046.27622-1-paulmck@kernel.org

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

  reply	other threads:[~2020-03-24 15:38 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-20 17:59 [patch V3 00/23] x86/entry: Consolidation part II (syscalls) Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch " Thomas Gleixner
2020-03-20 17:59 ` [patch V3 01/23] rcu: Dont acquire lock in NMI handler in rcu_nmi_enter_common() Thomas Gleixner
2020-03-20 17:59   ` [RESEND][patch " Thomas Gleixner
2020-03-24 15:37   ` Frederic Weisbecker [this message]
2020-03-20 17:59 ` [patch V3 02/23] rcu: Add comments marking transitions between RCU watching and not Thomas Gleixner
2020-03-20 17:59   ` [RESEND][patch " Thomas Gleixner
2020-03-24 15:38   ` [patch " Frederic Weisbecker
2020-03-20 17:59 ` [patch V3 03/23] vmlinux.lds.h: Create section for protection against instrumentation Thomas Gleixner
2020-03-20 17:59   ` [RESEND][patch " Thomas Gleixner
2020-03-24 12:26   ` Borislav Petkov
2020-04-03  8:08   ` Alexandre Chartre
2020-03-20 18:00 ` [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-23 14:00   ` [patch " Masami Hiramatsu
2020-03-23 16:03     ` Thomas Gleixner
2020-03-24  5:49       ` Masami Hiramatsu
2020-03-24  9:47         ` Thomas Gleixner
2020-03-25 13:39           ` Masami Hiramatsu
2020-03-20 18:00 ` [patch V3 05/23] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-04-03  8:34   ` Alexandre Chartre
2020-03-20 18:00 ` [patch V3 06/23] bug: Annotate WARN/BUG/stackfail as noinstr safe Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-04-02 21:01   ` Josh Poimboeuf
2020-04-02 21:34     ` Peter Zijlstra
2020-04-02 21:43       ` Josh Poimboeuf
2020-04-02 21:49     ` Thomas Gleixner
2020-03-20 18:00 ` [patch V3 07/23] lockdep: Prepare for noinstr sections Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 08/23] x86/entry: Mark enter_from_user_mode() noinstr Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 09/23] x86/entry/common: Protect against instrumentation Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 10/23] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 11/23] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 12/23] context_tracking: Ensure that the critical path cannot be instrumented Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 13/23] lib/smp_processor_id: Move it into noinstr section Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 14/23] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 15/23] x86/entry/64: Check IF in __preempt_enable_notrace() thunk Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 16/23] x86/entry/64: Mark ___preempt_schedule_notrace() thunk noinstr Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 17/23] rcu/tree: Mark the idle relevant functions noinstr Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-24 16:09   ` Paul E. McKenney
2020-03-24 19:28     ` Thomas Gleixner
2020-03-24 19:58       ` Paul E. McKenney
2020-03-20 18:00 ` [patch V3 18/23] x86/kvm: Move context tracking where it belongs Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 19/23] x86/kvm/vmx: Add hardirq tracing to guest enter/exit Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-24 23:03   ` Peter Zijlstra
2020-03-24 23:21     ` Thomas Gleixner
2020-03-20 18:00 ` [patch V3 20/23] x86/kvm/svm: Handle hardirqs proper on " Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 21/23] context_tracking: Make guest_enter/exit_irqoff() .noinstr ready Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 22/23] x86/kvm/vmx: Move guest enter/exit into .noinstr.text Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner
2020-03-20 18:00 ` [patch V3 23/23] x86/kvm/svm: " Thomas Gleixner
2020-03-20 18:00   ` [RESEND][patch " Thomas Gleixner

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