ANDROID: sched: Fix SCHED_WARN_ON()

SCHED_WARN_ON() uses WARN_ONCE() and WARN_ONCE() uses printk(). Using
printk() from certain code paths in the process scheduler is not allowed
because printk() acquires the console_lock and this may cause printk()
to sleep. Sleeping is not allowed from many paths in the process
scheduler. Hence make sure that SCHED_WARN_ON() uses printk_deferred()
instead of printk().

This CL has the ANDROID: prefix because SCHED_WARN_ON() has been removed
from the upstream kernel. This CL fixes e.g. the following lockdep
complaint:

======================================================
WARNING: possible circular locking dependency detected
6.12.45-android16-5-maybe-dirty-4k #1 Tainted: G        W  OE
------------------------------------------------------
swapper/4/0 is trying to acquire lock:
ffffffc082179768 (console_owner){-...}-{0:0}, at: console_lock_spinning_enable+0x44/0x80

but task is already holding lock:
ffffff8b33d30a18 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x188/0x116c

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #5 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x50/0x70
       __task_rq_lock+0x74/0x154
       wake_up_new_task+0x110/0x40c
       kernel_clone+0x28c/0x508
       user_mode_thread+0x60/0x8c
       rest_init+0x28/0x1b8
       start_kernel+0x390/0x4b0
       __primary_switched+0x88/0x94

-> #4 (&p->pi_lock){-.-.}-{2:2}:
       _raw_spin_lock_irqsave+0x64/0xac
       try_to_wake_up+0x6c/0xa18
       default_wake_function+0x20/0x38
       autoremove_wake_function+0x1c/0x64
       __wake_up+0xac/0xfc
       rpm_suspend+0x484/0x668
       pm_runtime_work+0x8c/0xa8
       process_one_work+0x26c/0x65c
       worker_thread+0x33c/0x498
       kthread+0x110/0x134
       ret_from_fork+0x10/0x20

-> #3 (&dev->power.wait_queue){....}-{2:2}:
       _raw_spin_lock_irqsave+0x64/0xac
       __wake_up+0x34/0xfc
       rpm_resume+0x4e8/0x5c8
       __pm_runtime_resume+0x6c/0xb0
       dt_idle_attach_cpu+0x70/0x9c
       psci_cpuidle_probe+0x270/0x494
       platform_probe+0xa0/0xe0
       really_probe+0x114/0x454
       __driver_probe_device+0xa4/0x160
       driver_probe_device+0x44/0x23c
       __device_attach_driver+0x15c/0x1f4
       bus_for_each_drv+0x10c/0x168
       __device_attach+0xc0/0x1a0
       device_initial_probe+0x14/0x24
       bus_probe_device+0x94/0x120
       device_add+0x298/0x498
       platform_device_add+0x80/0x24c
       platform_device_register_full+0x144/0x154
       psci_idle_init+0x74/0xc4
       do_one_initcall+0x124/0x464
       do_initcall_level+0xa8/0xd4
       do_initcalls+0x74/0xf0
       do_basic_setup+0x1c/0x28
       kernel_init_freeable+0x154/0x204
       kernel_init+0x20/0x1ac
       ret_from_fork+0x10/0x20

-> #2 (&dev->power.lock){-.-.}-{2:2}:
       _raw_spin_lock_irqsave+0x64/0xac
       __pm_runtime_resume+0x5c/0xb0
       __uart_start+0x4c/0x120
       uart_write+0xe8/0x304
       n_tty_write+0x310/0x4c8
       file_tty_write+0x154/0x32c
       redirected_tty_write+0x94/0xe0
       vfs_write+0x2e8/0x3ac
       ksys_write+0x78/0xe8
       __arm64_sys_write+0x1c/0x2c
       invoke_syscall+0x58/0x10c
       el0_svc_common+0xa8/0xdc
       do_el0_svc+0x1c/0x28
       el0_svc+0x50/0xd4
       el0t_64_sync_handler+0x70/0xbc
       el0t_64_sync+0x1bc/0x1c0

-> #1 (&port_lock_key){-...}-{2:2}:
       _raw_spin_lock_irqsave+0x64/0xac
       google_serial8250_console_write+0xe0/0x8f0 [google_8250_base]
       univ8250_console_write+0x2c/0x40 [google_8250]
       console_flush_all+0x210/0x420
       console_unlock+0x84/0x12c
       vprintk_emit+0x12c/0x1b8
       vprintk_default+0x44/0x70
       vprintk+0xe4/0x164
       _printk+0x54/0x80
       register_console+0x428/0x524
       serial_core_register_port+0x664/0x8b8
       serial_ctrl_register_port+0x10/0x20
       uart_add_one_port+0x10/0x20
       google_serial8250_register_8250_port+0x834/0xa1c [google_8250]
       dw8250_probe+0x550/0x5f0 [google_8250_dw]
       platform_probe+0xa0/0xe0
       really_probe+0x114/0x454
       __driver_probe_device+0xa4/0x160
       driver_probe_device+0x44/0x23c
       __driver_attach+0x124/0x278
       bus_for_each_dev+0x104/0x160
       driver_attach+0x24/0x34
       bus_add_driver+0x144/0x2d4
       driver_register+0x68/0x104
       __platform_driver_register+0x20/0x30
       0xffffffc07ed1e03c
       do_one_initcall+0x124/0x464
       do_init_module+0x58/0x2f4
       load_module+0x12c8/0x14b0
       __arm64_sys_finit_module+0x238/0x33c
       invoke_syscall+0x58/0x10c
       el0_svc_common+0xa8/0xdc
       do_el0_svc+0x1c/0x28
       el0_svc+0x50/0xd4
       el0t_64_sync_handler+0x70/0xbc
       el0t_64_sync+0x1bc/0x1c0

-> #0 (console_owner){-...}-{0:0}:
       __lock_acquire+0x150c/0x2e24
       lock_acquire+0x13c/0x2f0
       console_lock_spinning_enable+0x6c/0x80
       console_flush_all+0x1dc/0x420
       console_unlock+0x84/0x12c
       vprintk_emit+0x12c/0x1b8
       vprintk_default+0x44/0x70
       vprintk+0xe4/0x164
       _printk+0x54/0x80
       __warn_printk+0x10c/0x1d4
       sub_running_bw+0x164/0x1a8
       task_non_contending+0x29c/0x4b0
       dequeue_dl_entity+0x1f0/0x260
       pick_task_dl+0x7c/0x1c4
       __schedule+0x554/0x116c
       schedule_idle+0x24/0x48
       do_idle+0x2f0/0x338
       cpu_startup_entry+0x34/0x3c
       secondary_start_kernel+0x138/0x1a8
       __secondary_switched+0xc0/0xc4

other info that might help us debug this:

Chain exists of:
  console_owner --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->__lock);
                               lock(&p->pi_lock);
                               lock(&rq->__lock);
  lock(console_owner);

 *** DEADLOCK ***

3 locks held by swapper/4/0:
 #0: ffffff8b33d30a18 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x188/0x116c
 #1: ffffffc082179790 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x124/0x1b8
 #2: ffffffc082109238 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire+0x0/0x40

stack backtrace:
Call trace:
 dump_backtrace+0xfc/0x17c
 show_stack+0x18/0x28
 dump_stack_lvl+0x40/0x104
 dump_stack+0x18/0x3c
 print_circular_bug+0x32c/0x334
 check_noncircular+0x158/0x178
 __lock_acquire+0x150c/0x2e24
 lock_acquire+0x13c/0x2f0
 console_lock_spinning_enable+0x6c/0x80
 console_flush_all+0x1dc/0x420
 console_unlock+0x84/0x12c
 vprintk_emit+0x12c/0x1b8
 vprintk_default+0x44/0x70
 vprintk+0xe4/0x164
 _printk+0x54/0x80
 __warn_printk+0x10c/0x1d4
 sub_running_bw+0x164/0x1a8
 task_non_contending+0x29c/0x4b0
 dequeue_dl_entity+0x1f0/0x260
 pick_task_dl+0x7c/0x1c4
 __schedule+0x554/0x116c
 schedule_idle+0x24/0x48
 do_idle+0x2f0/0x338
 cpu_startup_entry+0x34/0x3c
 secondary_start_kernel+0x138/0x1a8
 __secondary_switched+0xc0/0xc4
libbinder.BackendUnifiedServiceManager: Thread Pool max thread count is 0. Cannot cache binder as linkToDeath cannot be implemented. serviceName: android.hardware.boot.IBootControl/default
dl_rq->running_bw > old
WARNING: CPU: 4 PID: 0 at kernel/sched/deadline.c:265 sub_running_bw+0x164/0x1a8

Bug: 416505362
Change-Id: I4c7fbcb48c242e37a3451c6400e4e298bf1466dd
Signed-off-by: Bart Van Assche <bvanassche@google.com>

Author: Bart Van Assche

kernel/printk/printk_safe.c

@@ -31,12 +31,14 @@ void __printk_deferred_enter(void)
 	cant_migrate();
 	__printk_safe_enter();
 }
+EXPORT_SYMBOL(__printk_deferred_enter);
 
 void __printk_deferred_exit(void)
 {
 	cant_migrate();
 	__printk_safe_exit();
 }
+EXPORT_SYMBOL(__printk_deferred_exit);
 
 bool is_printk_legacy_deferred(void)
 {

kernel/sched/sched.h

@@ -36,6 +36,7 @@
 #include <linux/hrtimer_api.h>
 #include <linux/interrupt.h>
 #include <linux/irq_work.h>
+#include <linux/irqflags.h>
 #include <linux/jiffies.h>
 #include <linux/kref_api.h>
 #include <linux/kthread.h>
@@ -95,7 +96,26 @@ struct cpuidle_state;
 #include "cpudeadline.h"
 
 #ifdef CONFIG_SCHED_DEBUG
+#ifdef CONFIG_PROVE_LOCKING
+# define SCHED_WARN_ON(x)				\
+	({						\
+		bool __ret = false;			\
+							\
+		if (unlikely(x)) {			\
+			unsigned long __flags;		\
+							\
+			local_irq_save(__flags);	\
+			printk_deferred_enter();	\
+			WARN_ONCE(true, #x);		\
+			printk_deferred_exit();		\
+			local_irq_restore(__flags);	\
+			__ret = true;			\
+		}					\
+		unlikely(__ret);			\
+	})
+#else
 # define SCHED_WARN_ON(x)      WARN_ONCE(x, #x)
+#endif
 #else
 # define SCHED_WARN_ON(x)      ({ (void)(x), 0; })
 #endif