Re: sleeping functions called in invalid context during resume

Ingo Molnar
2006-11-15T09:34:41Z

* Andrew Morton <akpm@osdl.org> wrote:

> > [<ffffffff80215059>] vfs_write+0xce/0x174
> > [<ffffffff802159a5>] sys_write+0x45/0x6e
> > [<ffffffff802593de>] system_call+0x7e/0x83
> > DWARF2 unwinder stuck at system_call+0x7e/0x83
> >
> > Leftover inexact backtrace:
>
> Could mean that someone somewhere forgot to release a spinlock.
>
> Ingo had a patch which would find the culprit (preempt-tracing.patch).
>
> Does it still live?

if it's really a spinlock/rwlock release that was missed, then i've got
good news: we already have that debugging infrastructure, it's called
lockdep :-)

The patch below makes use of that capability of lockdep for all
stackdumps that are printed to the console. Stephen, please apply this
patch, enable CONFIG_PROVE_LOCKING and try to trigger another message.

Ingo

---------------->
Subject: lockdep: show held locks when showing a stackdump
From: Ingo Molnar <mingo@elte.hu>

show held locks when printing a backtrace.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
arch/i386/kernel/traps.c | 1 +
arch/x86_64/kernel/traps.c | 1 +
2 files changed, 2 insertions(+)

Index: linux/arch/i386/kernel/traps.c
===================================================================
--- linux.orig/arch/i386/kernel/traps.c
+++ linux/arch/i386/kernel/traps.c
@@ -318,6 +318,7 @@ static void show_stack_log_lvl(struct ta
}
printk("\n%sCall Trace:\n", log_lvl);
show_trace_log_lvl(task, regs, esp, log_lvl);
+ debug_show_held_locks(task);
}

void show_stack(struct task_struct *task, unsigned long *esp)
Index: linux/arch/x86_64/kernel/traps.c
===================================================================
--- linux.orig/arch/x86_64/kernel/traps.c
+++ linux/arch/x86_64/kernel/traps.c
@@ -405,6 +405,7 @@ show_trace(struct task_struct *tsk, stru
printk("\nCall Trace:\n");
dump_trace(tsk, regs, stack, &print_trace_ops, NULL);
printk("\n");
+ debug_show_held_locks(tsk);
}

static void