Correct David's email addr. Add Christoph Hellwig. Regards, - jay Jay Lan wrote:
We ran into a system hang problem at sys_ptrace. The system may hang if a user attempts to "strace" a pthreaded application that is making frequent calls to pthread_create & pthread_exit. The hang is caused by a task sleeping (yield()) while holding the tasklist_lock. Note that the problem appears to exist ONLY on IA64. IA64 has an ARCH-specific implementation of sys_ptrace(). The failing path is: sys_ptrace read_lock(&tasklist_lock); find_thread_for_addr(child, addr); thread_matches(p, addr) ptrace_check_attach(thread, 0) wait_task_inactive(child); yield(); Failures always show 1 task sleeping with the backtrace listed above, plus tasks on all cpus spinning waiting to write_lock the tasklist lock. Sleeping Stack traceback for pid 31069 0xe00000343b800000 31069 0 3 R 0xe00000343b8003a0 strace 0xa000000100981c60 schedule+0x2460 0xa00000010007d4d0 sys_sched_yield+0x110 0xa000000100982120 yield+0x40 0xa000000100082f10 wait_task_inactive+0x170 0xa0000001000a2570 ptrace_check_attach+0x1d0 0xa00000010002e9b0 sys_ptrace+0x1f0 0xa00000010000c900 ia64_ret_from_syscall CPU 0 0xe00000343b5f0000 4973 0 3 C 0xe00000343b5f03a0 thdcrex 0xa00000010000caa0 ia64_leave_kernel 0xa00000010053d0a0 _raw_write_lock+0x120 0xa0000001009854d0 _write_lock_irq+0x30 0xa000000100093a00 do_exit+0xae0 0xa000000100094560 sys_exit+0x20 0xa00000010000c900 ia64_ret_from_syscall CPU 1 0xe000003038880000 4972 0 1 R 0xe0000030388803a0 thdcrex 0xa00000010000caa0 ia64_leave_kernel 0xa00000010053d0a0 _raw_write_lock+0x120 0xa0000001009854d0 _write_lock_irq+0x30 0xa0000001000880e0 copy_process+0x1f80 0xa000000100088e30 do_fork+0x150 0xa00000010000c160 sys_clone2+0x60 0xa00000010000c900 ia64_ret_from_syscall Regards, - jay - : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
- : send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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