linux-kernel - Re: 4d004099a6 ("lockdep: Fix lockdep recursion"): BUG: using __this_cpu_read() in preemptible [00000000] code: trinity-c6/526

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Message-ID: <20201019183355.GS2611@hirez.programming.kicks-ass.net>
Date:   Mon, 19 Oct 2020 20:33:55 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     kernel test robot <lkp@...el.com>
Cc:     LKP <lkp@...ts.01.org>, linux-kernel@...r.kernel.org,
        Ingo Molnar <mingo@...nel.org>, philip.li@...el.com
Subject: Re: 4d004099a6 ("lockdep: Fix lockdep recursion"):  BUG: using
 __this_cpu_read() in preemptible [00000000] code: trinity-c6/526

On Tue, Oct 20, 2020 at 12:55:46AM +0800, kernel test robot wrote:
> [   92.898145] BUG: using __this_cpu_read() in preemptible [00000000] code: trinity-c6/526

> [   92.903305] Call Trace:
> [   92.905182]  __this_cpu_preempt_check+0xf/0x11
> [   92.905968]  lockdep_hardirqs_on_prepare+0x2c/0x18f
> [   92.906853]  trace_hardirqs_on+0x49/0x53
> [   92.907578]  __bad_area_nosemaphore+0x3a/0x134

Hurph, that's a spurious local_irq_enable(). I suppose this'll fix it.

---
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 3e99dfef8408..9f818145ef7d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4057,9 +4057,6 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
 	if (unlikely(in_nmi()))
 		return;
 
-	if (unlikely(__this_cpu_read(lockdep_recursion)))
-		return;
-
 	if (unlikely(lockdep_hardirqs_enabled())) {
 		/*
 		 * Neither irq nor preemption are disabled here
@@ -4070,6 +4067,9 @@ void lockdep_hardirqs_on_prepare(unsigned long ip)
 		return;
 	}
 
+	if (unlikely(__this_cpu_read(lockdep_recursion)))
+		return;
+
 	/*
 	 * We're enabling irqs and according to our state above irqs weren't
 	 * already enabled, yet we find the hardware thinks they are in fact
@@ -4126,9 +4126,6 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
 		goto skip_checks;
 	}
 
-	if (unlikely(__this_cpu_read(lockdep_recursion)))
-		return;
-
 	if (lockdep_hardirqs_enabled()) {
 		/*
 		 * Neither irq nor preemption are disabled here
@@ -4139,6 +4136,9 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
 		return;
 	}
 
+	if (unlikely(__this_cpu_read(lockdep_recursion)))
+		return;
+
 	/*
 	 * We're enabling irqs and according to our state above irqs weren't
 	 * already enabled, yet we find the hardware thinks they are in fact