Dave Jones wrote:
> Whilst printk'ing to both console and serial console, I got this...
> (2.6.18rc1)
>
> Dave
>
>
> BUG: sleeping function called from invalid context at kernel/sched.c:4438
> in_atomic():0, irqs_disabled():1
>
> Call Trace:
> [<ffffffff80271db8>] show_trace+0xaa/0x23d
> [<ffffffff80271f60>] dump_stack+0x15/0x17
> [<ffffffff8020b9f8>] __might_sleep+0xb2/0xb4
> [<ffffffff8029232e>] __cond_resched+0x15/0x55
> [<ffffffff80267eb8>] cond_resched+0x3b/0x42
> [<ffffffff80268c64>] console_conditional_schedule+0x12/0x14
> [<ffffffff80368159>] fbcon_redraw+0xf6/0x160
> [<ffffffff80369c58>] fbcon_scroll+0x5d9/0xb52
> [<ffffffff803a43c4>] scrup+0x6b/0xd6
> [<ffffffff803a4453>] lf+0x24/0x44
> [<ffffffff803a7ff8>] vt_console_print+0x166/0x23d
> [<ffffffff80295528>] __call_console_drivers+0x65/0x76
> [<ffffffff80295597>] _call_console_drivers+0x5e/0x62
> [<ffffffff80217e3f>] release_console_sem+0x14b/0x232
> [<ffffffff8036acd6>] fb_flashcursor+0x279/0x2a6
> [<ffffffff80251e3f>] run_workqueue+0xa8/0xfb
> [<ffffffff8024e5e0>] worker_thread+0xef/0x122
> [<ffffffff8023660f>] kthread+0x100/0x136
> [<ffffffff8026419e>] child_rip+0x8/0x12
>
>
Looks like the printk buffer was flushed on release_console_sem() while
the irqs are disabled. But the console (fbcon) thinks that it's still
okay to schedule() which triggered might_sleep().
Would the attached patch help? It disables console scheduling before
calling the console drivers.
Tony
diff --git a/kernel/printk.c b/kernel/printk.c
index 9940030..f98576d 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -780,6 +780,9 @@ void release_console_sem(void)
up(&secondary_console_sem);
return;
}
+
+ console_may_schedule = 0;
+
for ( ; ; ) {
spin_lock_irqsave(&logbuf_lock, flags);
wake_klogd |= log_start - log_end;
@@ -793,7 +796,6 @@ void release_console_sem(void)
local_irq_restore(flags);
}
console_locked = 0;
- console_may_schedule = 0;
up(&console_sem);
spin_unlock_irqrestore(&logbuf_lock, flags);
if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) {
-
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