Messages in this thread | | | Date | Tue, 24 Jun 2008 15:01:26 +0800 | From | hyl <> | Subject | [patch][RFC] an early patch for x86_64 preempt-rt kernel cause more __might_sleep warnings |
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Hi, John
[Sorry resend this mail, with pure text format and CC to Linux-kernel. ]
I saw you submitted a patch for X86_64 to prevent a oops, here is the hyper-link i google: http://marc.info/?l=git-commits-head&m=113979973412652&w=2
There is an obvious problem for your patch , see my comment at "=====>"
/* runs on IST stack. */ asmlinkage void __kprobes do_debug(struct pt_regs * regs, unsigned long error_code) {
- conditional_sti(regs); + preempt_conditional_sti(regs);
force_sig_info(SIGTRAP, &info, tsk);=====> /*this function try spin_lock_irqsave(&t->sighand->siglock, flags); generate more warnings*/
clear_dr7: set_debugreg(0UL, 7); + preempt_conditional_cli(regs); return;
clear_TF_reenable: set_tsk_thread_flag(tsk, TIF_SINGLESTEP); regs->eflags &= ~TF_MASK; + preempt_conditional_cli(regs);
}
here is the trace result, founded on linux2.6.25.4 with realtime patch(not only do_debug, do_int3,do_stack_segment also has same problem ):
BUG: sleeping function called from invalid context usermode-agent(2302) at kernel/rtmutex.c:626
in_atomic():1 [00000001], irqs_disabled():0
Call Trace: <#DB> [<ffffffff80227177>] __might_sleep+0x107/0x110 [<ffffffff804ec510>] __rt_spin_lock+0x30/0x60 [<ffffffff804ec549>] rt_spin_lock+0x9/0x10
[<ffffffff8023cf2f>] force_sig_info+0x2f/0xd0 [<ffffffff8020cdab>] do_debug+0x17b/0x220 [<ffffffff804ed1b3>] debug+0x93/0x9f <<EOE>>
Posssible way to resolve such problem:
1. relpace task->sighand->siglock as raw_spin_lock_t but this will reduce the preemptive kernel code size
2. if possible, call preempt_conditional_cli before call force_sig_info but we must sure the John's bug not be re-introduce by such action
please don't hesitate to tell me the best solution if you got the good idea.
Best Wishes hyl
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