kernel/lib/test_lockup.c, branch linux-5.7.y

lib/test_lockup.c: fix return value of test_lockup_init()

2020-08-21T11:07:41Z

[ Upstream commit 3adf3bae0d612357da516d39e1584f1547eb6e86 ] Since filp_open() returns an error pointer, we should use IS_ERR() to check the return value and then return PTR_ERR() if failed to get the actual return value instead of always -EINVAL. E.g. without this patch: [root@localhost loongson]# ls no_such_file ls: cannot access no_such_file: No such file or directory [root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S modprobe: ERROR: could not insert 'test_lockup': Invalid argument [root@localhost loongson]# dmesg | tail -1 [ 126.100596] test_lockup: cannot find file_path With this patch: [root@localhost loongson]# ls no_such_file ls: cannot access no_such_file: No such file or directory [root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S modprobe: ERROR: could not insert 'test_lockup': Unknown symbol in module, or unknown parameter (see dmesg) [root@localhost loongson]# dmesg | tail -1 [ 95.134362] test_lockup: failed to open no_such_file: -2 Fixes: aecd42df6d39 ("lib/test_lockup.c: add parameters for locking generic vfs locks") Signed-off-by: Tiezhu Yang Signed-off-by: Andrew Morton Reviewed-by: Guenter Roeck Cc: Konstantin Khlebnikov Cc: Kees Cook Link: http://lkml.kernel.org/r/1595555407-29875-2-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

lib/test_lockup.c: add parameters for locking generic vfs locks

2020-04-07T17:43:42Z

file_path= defines file or directory to open lock_inode=Y set lock_rwsem_ptr to inode->i_rwsem lock_mapping=Y set lock_rwsem_ptr to mapping->i_mmap_rwsem lock_sb_umount=Y set lock_rwsem_ptr to sb->s_umount This gives safe and simple way to see how system reacts to contention of common vfs locks and how syscalls depend on them directly or indirectly. For example to block s_umount for 60 seconds: # modprobe test_lockup file_path=. lock_sb_umount time_secs=60 state=S This is useful for checking/testing scalability issues like this: https://lore.kernel.org/lkml/158497590858.7371.9311902565121473436.stgit@buzz/ Signed-off-by: Konstantin Khlebnikov Signed-off-by: Andrew Morton Cc: Colin Ian King Cc: Greg Kroah-Hartman Cc: Guenter Roeck Cc: Kees Cook Cc: Peter Zijlstra Cc: Petr Mladek Cc: Sasha Levin Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/158498153964.5621.83061779039255681.stgit@buzz Signed-off-by: Linus Torvalds

lib/test_lockup.c: fix spelling mistake "iteraions" -> "iterations"

2020-04-07T17:43:42Z

There is a spelling mistake in a pr_notice message. Fix it. Signed-off-by: Colin Ian King Signed-off-by: Andrew Morton Cc: Greg Kroah-Hartman Cc: Guenter Roeck Cc: Kees Cook Cc: Konstantin Khlebnikov Cc: Peter Zijlstra Cc: Petr Mladek Cc: Sasha Levin Cc: Sergey Senozhatsky Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20200221155145.79522-1-colin.king@canonical.com Signed-off-by: Linus Torvalds

lib/test_lockup: test module to generate lockups

2020-04-07T17:43:42Z

CONFIG_TEST_LOCKUP=m adds module "test_lockup" that helps to make sure that watchdogs and lockup detectors are working properly. Depending on module parameters test_lockup could emulate soft or hard lockup, "hung task", hold arbitrary lock, allocate bunch of pages. Also it could generate series of lockups with cooling-down periods, in this way it could be used as "ping" for locks or page allocator. Loop checks signals between iteration thus could be stopped by ^C. # modinfo test_lockup ... parm: time_secs:lockup time in seconds, default 0 (uint) parm: time_nsecs:nanoseconds part of lockup time, default 0 (uint) parm: cooldown_secs:cooldown time between iterations in seconds, default 0 (uint) parm: cooldown_nsecs:nanoseconds part of cooldown, default 0 (uint) parm: iterations:lockup iterations, default 1 (uint) parm: all_cpus:trigger lockup at all cpus at once (bool) parm: state:wait in 'R' running (default), 'D' uninterruptible, 'K' killable, 'S' interruptible state (charp) parm: use_hrtimer:use high-resolution timer for sleeping (bool) parm: iowait:account sleep time as iowait (bool) parm: lock_read:lock read-write locks for read (bool) parm: lock_single:acquire locks only at one cpu (bool) parm: reacquire_locks:release and reacquire locks/irq/preempt between iterations (bool) parm: touch_softlockup:touch soft-lockup watchdog between iterations (bool) parm: touch_hardlockup:touch hard-lockup watchdog between iterations (bool) parm: call_cond_resched:call cond_resched() between iterations (bool) parm: measure_lock_wait:measure lock wait time (bool) parm: lock_wait_threshold:print lock wait time longer than this in nanoseconds, default off (ulong) parm: disable_irq:disable interrupts: generate hard-lockups (bool) parm: disable_softirq:disable bottom-half irq handlers (bool) parm: disable_preempt:disable preemption: generate soft-lockups (bool) parm: lock_rcu:grab rcu_read_lock: generate rcu stalls (bool) parm: lock_mmap_sem:lock mm->mmap_sem: block procfs interfaces (bool) parm: lock_rwsem_ptr:lock rw_semaphore at address (ulong) parm: lock_mutex_ptr:lock mutex at address (ulong) parm: lock_spinlock_ptr:lock spinlock at address (ulong) parm: lock_rwlock_ptr:lock rwlock at address (ulong) parm: alloc_pages_nr:allocate and free pages under locks (uint) parm: alloc_pages_order:page order to allocate (uint) parm: alloc_pages_gfp:allocate pages with this gfp_mask, default GFP_KERNEL (uint) parm: alloc_pages_atomic:allocate pages with GFP_ATOMIC (bool) parm: reallocate_pages:free and allocate pages between iterations (bool) Parameters for locking by address are unsafe and taints kernel. With CONFIG_DEBUG_SPINLOCK=y they at least check magics for embedded spinlocks. Examples: task hang in D-state: modprobe test_lockup time_secs=1 iterations=60 state=D task hang in io-wait D-state: modprobe test_lockup time_secs=1 iterations=60 state=D iowait softlockup: modprobe test_lockup time_secs=1 iterations=60 state=R hardlockup: modprobe test_lockup time_secs=1 iterations=60 state=R disable_irq system-wide hardlockup: modprobe test_lockup time_secs=1 iterations=60 state=R \ disable_irq all_cpus rcu stall: modprobe test_lockup time_secs=1 iterations=60 state=R \ lock_rcu touch_softlockup lock mmap_sem / block procfs interfaces: modprobe test_lockup time_secs=1 iterations=60 state=S lock_mmap_sem lock tasklist_lock for read / block forks: TASKLIST_LOCK=$(awk '$3 == "tasklist_lock" {print "0x"$1}' /proc/kallsyms) modprobe test_lockup time_secs=1 iterations=60 state=R \ disable_irq lock_read lock_rwlock_ptr=$TASKLIST_LOCK lock namespace_sem / block vfs mount operations: NAMESPACE_SEM=$(awk '$3 == "namespace_sem" {print "0x"$1}' /proc/kallsyms) modprobe test_lockup time_secs=1 iterations=60 state=S \ lock_rwsem_ptr=$NAMESPACE_SEM lock cgroup mutex / block cgroup operations: CGROUP_MUTEX=$(awk '$3 == "cgroup_mutex" {print "0x"$1}' /proc/kallsyms) modprobe test_lockup time_secs=1 iterations=60 state=S \ lock_mutex_ptr=$CGROUP_MUTEX ping cgroup_mutex every second and measure maximum lock wait time: modprobe test_lockup cooldown_secs=1 iterations=60 state=S \ lock_mutex_ptr=$CGROUP_MUTEX reacquire_locks measure_lock_wait [linux@roeck-us.net: rename disable_irq to fix build error] Link: http://lkml.kernel.org/r/20200317133614.23152-1-linux@roeck-us.net Signed-off-by: Konstantin Khlebnikov Signed-off-by: Guenter Roeck Signed-off-by: Andrew Morton Cc: Sasha Levin Cc: Petr Mladek Cc: Kees Cook Cc: Peter Zijlstra Cc: Greg Kroah-Hartman Cc: Steven Rostedt Cc: Sergey Senozhatsky Cc: Dmitry Monakhov Cc: Guenter Roeck Link: http://lkml.kernel.org/r/158132859146.2797.525923171323227836.stgit@buzz Signed-off-by: Linus Torvalds