Merge branch 'linus' into locking/core, to resolve conflict

Conflicts:
	arch/arm/include/asm/percpu.h

As Stephen Rothwell noted, there's a conflict between this commit
in locking/core:

  a21ee6055c ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")

and this fresh upstream commit:

  aa54ea903a ("ARM: percpu.h: fix build error")

a21ee6055c is a simpler solution to the dependency problem and doesn't
further increase header hell - so this conflict resolution effectively
reverts aa54ea903a and uses the a21ee6055c solution.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/audit.c

@@ -1851,7 +1851,6 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 	}
 
 	audit_get_stamp(ab->ctx, &t, &serial);
-	audit_clear_dummy(ab->ctx);
 	audit_log_format(ab, "audit(%llu.%03lu:%u): ",
 			 (unsigned long long)t.tv_sec, t.tv_nsec/1000000, serial);
 

kernel/audit.h

@@ -290,13 +290,6 @@ extern int audit_signal_info_syscall(struct task_struct *t);
 extern void audit_filter_inodes(struct task_struct *tsk,
 				struct audit_context *ctx);
 extern struct list_head *audit_killed_trees(void);
-
-static inline void audit_clear_dummy(struct audit_context *ctx)
-{
-	if (ctx)
-		ctx->dummy = 0;
-}
-
 #else /* CONFIG_AUDITSYSCALL */
 #define auditsc_get_stamp(c, t, s) 0
 #define audit_put_watch(w) {}
@@ -330,7 +323,6 @@ static inline int audit_signal_info_syscall(struct task_struct *t)
 }
 
 #define audit_filter_inodes(t, c) AUDIT_DISABLED
-#define audit_clear_dummy(c) {}
 #endif /* CONFIG_AUDITSYSCALL */
 
 extern char *audit_unpack_string(void **bufp, size_t *remain, size_t len);

kernel/auditsc.c

@@ -1417,6 +1417,9 @@ static void audit_log_proctitle(void)
 	struct audit_context *context = audit_context();
 	struct audit_buffer *ab;
 
+	if (!context || context->dummy)
+		return;
+
 	ab = audit_log_start(context, GFP_KERNEL, AUDIT_PROCTITLE);
 	if (!ab)
 		return;	/* audit_panic or being filtered */

kernel/events/uprobes.c

@@ -2199,7 +2199,7 @@ static void handle_swbp(struct pt_regs *regs)
 	if (!uprobe) {
 		if (is_swbp > 0) {
 			/* No matching uprobe; signal SIGTRAP. */
-			send_sig(SIGTRAP, current, 0);
+			force_sig(SIGTRAP);
 		} else {
 			/*
 			 * Either we raced with uprobe_unregister() or we can't

kernel/sched/core.c

@@ -4119,9 +4119,6 @@ static void __sched notrace __schedule(bool preempt)
 	local_irq_disable();
 	rcu_note_context_switch(preempt);
 
-	/* See deactivate_task() below. */
-	prev_state = prev->state;
-
 	/*
 	 * Make sure that signal_pending_state()->signal_pending() below
 	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
@@ -4145,11 +4142,16 @@ static void __sched notrace __schedule(bool preempt)
 	update_rq_clock(rq);
 
 	switch_count = &prev->nivcsw;
+
 	/*
-	 * We must re-load prev->state in case ttwu_remote() changed it
-	 * before we acquired rq->lock.
+	 * We must load prev->state once (task_struct::state is volatile), such
+	 * that:
+	 *
+	 *  - we form a control dependency vs deactivate_task() below.
+	 *  - ptrace_{,un}freeze_traced() can change ->state underneath us.
 	 */
-	if (!preempt && prev_state && prev_state == prev->state) {
+	prev_state = prev->state;
+	if (!preempt && prev_state) {
 		if (signal_pending_state(prev_state, prev)) {
 			prev->state = TASK_RUNNING;
 		} else {
@@ -4163,10 +4165,12 @@ static void __sched notrace __schedule(bool preempt)
 
 			/*
 			 * __schedule()			ttwu()
-			 *   prev_state = prev->state;	  if (READ_ONCE(p->on_rq) && ...)
-			 *   LOCK rq->lock		    goto out;
-			 *   smp_mb__after_spinlock();	  smp_acquire__after_ctrl_dep();
-			 *   p->on_rq = 0;		  p->state = TASK_WAKING;
+			 *   prev_state = prev->state;    if (p->on_rq && ...)
+			 *   if (prev_state)		    goto out;
+			 *     p->on_rq = 0;		  smp_acquire__after_ctrl_dep();
+			 *				  p->state = TASK_WAKING
+			 *
+			 * Where __schedule() and ttwu() have matching control dependencies.
 			 *
 			 * After this, schedule() must not care about p->state any more.
 			 */
@@ -4481,6 +4485,7 @@ asmlinkage __visible void __sched preempt_schedule_irq(void)
 int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
 			  void *key)
 {
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
 	return try_to_wake_up(curr->private, mode, wake_flags);
 }
 EXPORT_SYMBOL(default_wake_function);

kernel/time/timer.c

@@ -43,6 +43,7 @@
 #include <linux/sched/debug.h>
 #include <linux/slab.h>
 #include <linux/compat.h>
+#include <linux/random.h>
 
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
@@ -1742,6 +1743,13 @@ void update_process_times(int user_tick)
 	scheduler_tick();
 	if (IS_ENABLED(CONFIG_POSIX_TIMERS))
 		run_posix_cpu_timers();
+
+	/* The current CPU might make use of net randoms without receiving IRQs
+	 * to renew them often enough. Let's update the net_rand_state from a
+	 * non-constant value that's not affine to the number of calls to make
+	 * sure it's updated when there's some activity (we don't care in idle).
+	 */
+	this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick);
 }
 
 /**