From: "tip-bot2 for Marco Elver" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
Marco Elver <elver@google.com>, Ingo Molnar <mingo@kernel.org>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: locking/core] kcsan: Make KCSAN compatible with new IRQ state tracking
Date: Sat, 11 Jul 2020 10:09:57 -0000 [thread overview]
Message-ID: <159446219784.4006.13350341271966090231.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200624113246.GA170324@elver.google.com>
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 248591f5d257a19c1cba9ab9da3536bfbc2f0149
Gitweb: https://git.kernel.org/tip/248591f5d257a19c1cba9ab9da3536bfbc2f0149
Author: Marco Elver <elver@google.com>
AuthorDate: Wed, 24 Jun 2020 13:32:46 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 10 Jul 2020 12:00:00 +02:00
kcsan: Make KCSAN compatible with new IRQ state tracking
The new IRQ state tracking code does not honor lockdep_off(), and as
such we should again permit tracing by using non-raw functions in
core.c. Update the lockdep_off() comment in report.c, to reflect the
fact there is still a potential risk of deadlock due to using printk()
from scheduler code.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200624113246.GA170324@elver.google.com
---
kernel/kcsan/core.c | 5 ++---
kernel/kcsan/report.c | 9 +++++----
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 15f6794..732623c 100644
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -397,8 +397,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
}
if (!kcsan_interrupt_watcher)
- /* Use raw to avoid lockdep recursion via IRQ flags tracing. */
- raw_local_irq_save(irq_flags);
+ local_irq_save(irq_flags);
watchpoint = insert_watchpoint((unsigned long)ptr, size, is_write);
if (watchpoint == NULL) {
@@ -539,7 +538,7 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
kcsan_counter_dec(KCSAN_COUNTER_USED_WATCHPOINTS);
out_unlock:
if (!kcsan_interrupt_watcher)
- raw_local_irq_restore(irq_flags);
+ local_irq_restore(irq_flags);
out:
user_access_restore(ua_flags);
}
diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
index ac5f834..6b2fb1a 100644
--- a/kernel/kcsan/report.c
+++ b/kernel/kcsan/report.c
@@ -606,10 +606,11 @@ void kcsan_report(const volatile void *ptr, size_t size, int access_type,
goto out;
/*
- * With TRACE_IRQFLAGS, lockdep's IRQ trace state becomes corrupted if
- * we do not turn off lockdep here; this could happen due to recursion
- * into lockdep via KCSAN if we detect a race in utilities used by
- * lockdep.
+ * Because we may generate reports when we're in scheduler code, the use
+ * of printk() could deadlock. Until such time that all printing code
+ * called in print_report() is scheduler-safe, accept the risk, and just
+ * get our message out. As such, also disable lockdep to hide the
+ * warning, and avoid disabling lockdep for the rest of the kernel.
*/
lockdep_off();
next prev parent reply other threads:[~2020-07-11 10:10 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 8:36 [PATCH v4 0/8] lockdep: Change IRQ state tracking to use per-cpu variables Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 1/8] lockdep: Prepare for NMI IRQ state tracking Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 2/8] x86/entry: Fix NMI vs " Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 3/8] sparc64: Fix asm/percpu.h build error Peter Zijlstra
2020-06-23 21:35 ` David Miller
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 4/8] powerpc64: Break asm/percpu.h vs spinlock_types.h dependency Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 5/8] s390: Break cyclic percpu include Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 6/8] arm: " Peter Zijlstra
2020-06-23 9:02 ` Will Deacon
2020-06-24 17:53 ` Peter Zijlstra
2020-06-25 7:31 ` Will Deacon
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 7/8] lockdep: Change hardirq{s_enabled,_context} to per-cpu variables Peter Zijlstra
2020-06-23 15:00 ` Ahmed S. Darwish
2020-06-23 15:24 ` Peter Zijlstra
2020-06-23 16:13 ` Ahmed S. Darwish
2020-06-23 16:37 ` Peter Zijlstra
2020-06-23 17:59 ` Marco Elver
2020-06-23 18:12 ` Peter Zijlstra
2020-06-23 18:39 ` Marco Elver
2020-06-23 19:13 ` Marco Elver
2020-06-23 19:41 ` Peter Zijlstra
2020-06-23 20:08 ` Peter Zijlstra
2020-06-23 20:24 ` Peter Zijlstra
2020-06-23 20:33 ` Peter Zijlstra
2020-06-24 9:00 ` Peter Zijlstra
2020-06-24 10:17 ` Marco Elver
2020-06-24 12:31 ` Peter Zijlstra
2020-06-24 11:32 ` Marco Elver
2020-06-24 15:18 ` Peter Zijlstra
2020-07-11 10:09 ` tip-bot2 for Marco Elver [this message]
2020-06-30 5:59 ` Ahmed S. Darwish
2020-06-30 9:40 ` Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-06-23 8:36 ` [PATCH v4 8/8] lockdep: Remove lockdep_hardirq{s_enabled,_context}() argument Peter Zijlstra
2020-07-11 10:09 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
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