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-ae35d860f...@i-love.sakura.ne.jp [5] https://lkml.kernel.org/r/1c351187-253b-2d49-acaf-4563c63ae...@i-love.sakura.ne.jp Reported-by: syzbot <syzbot+cd0ec5211ac07c18c...@syzkaller.appspotmail.com> Reported-by: syzbot <syzbot+91fd909b6e62ebe06...@syzkaller.appspotmail.com> Reported-by: syzbot <syzbot+62ebe501c1ce9a91f...@syzkaller.appspotmail.com> References: https://lkml.kernel.org/r/1595640639-9310-1-git-send-email-penguin-ker...@i-love.sakura.ne.jp Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Acked-by: Dmitry Vyukov <dvyu...@google.com> --- kernel/locking/lockdep.c | 2 +- kernel/locking/lockdep_internals.h | 8 +++--- lib/Kconfig.debug | 40 ++++++++++++++++++++++++++++++ 3 files changed, 45 insertions(+), 5 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index bdaf4829098c..65b3777e8089 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1391,7 +1391,7 @@ 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 de49f9e1c11b..ecb8662e7a4e 100644 --- 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 7937265ef879..4cb84b499636 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1332,6 +1332,46 @@ 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 -- 2.18.4
