lockdep: Allow tuning tracing capacity constants.

Since syzkaller continues various test cases until the kernel crashes,
syzkaller tends to examine more locking dependencies than normal systems.
As a result, syzbot is reporting that the fuzz testing was terminated
due to hitting upper limits lockdep can track [1] [2] [3]. Since analysis
via /proc/lockdep* did not show any obvious culprit [4] [5], we have no
choice but allow tuning tracing capacity constants.

[1] https://syzkaller.appspot.com/bug?id=3d97ba93fb3566000c1c59691ea427370d33ea1b
[2] https://syzkaller.appspot.com/bug?id=381cb436fe60dc03d7fd2a092b46d7f09542a72a
[3] https://syzkaller.appspot.com/bug?id=a588183ac34c1437fc0785e8f220e88282e5a29f
[4] https://lkml.kernel.org/r/4b8f7a57-fa20-47bd-48a0-ae35d860f233@i-love.sakura.ne.jp
[5] https://lkml.kernel.org/r/1c351187-253b-2d49-acaf-4563c63ae7d2@i-love.sakura.ne.jp

References: https://lkml.kernel.org/r/1595640639-9310-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Dmitry Vyukov <dvyukov@google.com>

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c6d0c1d..6b96a96 100644 (file)
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1392,7 +1392,7 @@ static int add_lock_to_list(struct lock_class *this,
 /*
  * For good efficiency of modular, we use power of 2
  */
-#define MAX_CIRCULAR_QUEUE_SIZE                4096UL
+#define MAX_CIRCULAR_QUEUE_SIZE                (1UL << CONFIG_LOCKDEP_CIRCULAR_QUEUE_BITS)
 #define CQ_MASK                                (MAX_CIRCULAR_QUEUE_SIZE-1)
 
 /*

diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index de49f9e..ecb8662 100644 (file)
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -99,16 +99,16 @@ static const unsigned long LOCKF_USED_IN_IRQ_READ =
 #define MAX_STACK_TRACE_ENTRIES        262144UL
 #define STACK_TRACE_HASH_SIZE  8192
 #else
-#define MAX_LOCKDEP_ENTRIES    32768UL
+#define MAX_LOCKDEP_ENTRIES    (1UL << CONFIG_LOCKDEP_BITS)
 
-#define MAX_LOCKDEP_CHAINS_BITS        16
+#define MAX_LOCKDEP_CHAINS_BITS        CONFIG_LOCKDEP_CHAINS_BITS
 
 /*
  * Stack-trace: tightly packed array of stack backtrace
  * addresses. Protected by the hash_lock.
  */
-#define MAX_STACK_TRACE_ENTRIES        524288UL
-#define STACK_TRACE_HASH_SIZE  16384
+#define MAX_STACK_TRACE_ENTRIES        (1UL << CONFIG_LOCKDEP_STACK_TRACE_BITS)
+#define STACK_TRACE_HASH_SIZE  (1 << CONFIG_LOCKDEP_STACK_TRACE_HASH_BITS)
 #endif
 
 /*

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2779c29..f107000 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1370,6 +1370,46 @@ config LOCKDEP
 config LOCKDEP_SMALL
        bool
 
+config LOCKDEP_BITS
+       int "Bitsize for MAX_LOCKDEP_ENTRIES"
+       depends on LOCKDEP && !LOCKDEP_SMALL
+       range 10 30
+       default 15
+       help
+         Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
+
+config LOCKDEP_CHAINS_BITS
+       int "Bitsize for MAX_LOCKDEP_CHAINS"
+       depends on LOCKDEP && !LOCKDEP_SMALL
+       range 10 30
+       default 16
+       help
+         Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
+
+config LOCKDEP_STACK_TRACE_BITS
+       int "Bitsize for MAX_STACK_TRACE_ENTRIES"
+       depends on LOCKDEP && !LOCKDEP_SMALL
+       range 10 30
+       default 19
+       help
+         Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
+
+config LOCKDEP_STACK_TRACE_HASH_BITS
+       int "Bitsize for STACK_TRACE_HASH_SIZE"
+       depends on LOCKDEP && !LOCKDEP_SMALL
+       range 10 30
+       default 14
+       help
+         Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES.
+
+config LOCKDEP_CIRCULAR_QUEUE_BITS
+       int "Bitsize for elements in circular_queue struct"
+       depends on LOCKDEP
+       range 10 30
+       default 12
+       help
+         Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
+
 config DEBUG_LOCKDEP
        bool "Lock dependency engine debugging"
        depends on DEBUG_KERNEL && LOCKDEP