Messages in this thread |  | | | Date | Tue, 24 Oct 2006 13:46:50 +0100 | | From | John Levon <> | | Subject | Re: oprofile can cause an NMI to schedule (was: [RT] scheduling and oprofile) |
| |
On Mon, Oct 23, 2006 at 10:24:34PM -0400, Steven Rostedt wrote:
> > caller is rt_mutex_slowlock+0x156/0x1dd > > [<c032051a>] schedule+0x65/0xd2 (8) > > [<c0321338>] rt_mutex_slowlock+0x156/0x1dd (12) > > [<c032142a>] rt_mutex_lock+0x24/0x28 (72) > > [<c0134904>] rt_down_read+0x38/0x3b (20) > > [<c0322a89>] do_page_fault+0xe3/0x52d (12) > > [<c03229a6>] do_page_fault+0x0/0x52d (76) > > [<c01033bb>] error_code+0x4f/0x54 (8) > > [<c01ce6d0>] __copy_from_user_ll+0x55/0x7c (44) > > [<f89be7ef>] dump_user_backtrace+0x2e/0x56 [oprofile] (24) > > [<c0134869>] rt_up_read+0x3e/0x41 (20) > > [<f89be864>] x86_backtrace+0x4a/0x5a [oprofile] (20) > > [<f89bd53a>] oprofile_add_sample+0x73/0x89 [oprofile] (20) > > [<f89beea3>] athlon_check_ctrs+0x22/0x4a [oprofile] (32) > > [<f89be8c5>] nmi_callback+0x18/0x1b [oprofile] (28) > > [<c01041ff>] do_nmi+0x24/0x33 (12) > > [<c0103462>] nmi_stack_correct+0x1d/0x22 (16) > > > > It seems strange to me that oprofile would be calling > > '__copy_from_user_ll' in this context. I can see why the > > changes made for RT locking expose this. But, doesn't this > > issue also exist on non-RT (default) kernels? What happens > > when we generate a page fault in this context on non-RT kernels? > > > > As Mike has pointed out here, oprofile _can_ cause the nmi to schedule.
in_atomic() is supposed to be true in this context, so the test in do_page_fault() catches it.
john - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |