Commit 78944e549d36673eb6265a2411574e79c28e23dc
Committed by
Linus Torvalds
Linus Torvalds
1 parent
38cbcdc0a7
Exists in
master
and in
4 other branches
[PATCH] vt: printk: Fix framebuffer console triggering might_sleep assertion
Reported by: Dave Jones Whilst printk'ing to both console and serial console, I got this... (2.6.18rc1) 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 This can occur when release_console_sem() is called but the log buffer still has contents that need to be flushed. The console drivers are called while the console_may_schedule flag is still true. The might_sleep() is triggered when fbcon calls console_conditional_schedule(). Fix by setting console_may_schedule to zero earlier, before the call to the console drivers. Signed-off-by: Antonino Daplas <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Showing 1 changed file with 3 additions and 1 deletions Side-by-side Diff
kernel/printk.c
| ... | ... | @@ -799,6 +799,9 @@ |
| 799 | 799 | up(&secondary_console_sem); |
| 800 | 800 | return; |
| 801 | 801 | } |
| 802 | + | |
| 803 | + console_may_schedule = 0; | |
| 804 | + | |
| 802 | 805 | for ( ; ; ) { |
| 803 | 806 | spin_lock_irqsave(&logbuf_lock, flags); |
| 804 | 807 | wake_klogd |= log_start - log_end; |
| ... | ... | @@ -812,7 +815,6 @@ |
| 812 | 815 | local_irq_restore(flags); |
| 813 | 816 | } |
| 814 | 817 | console_locked = 0; |
| 815 | - console_may_schedule = 0; | |
| 816 | 818 | up(&console_sem); |
| 817 | 819 | spin_unlock_irqrestore(&logbuf_lock, flags); |
| 818 | 820 | if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) { |