apr testsuite: Spinning forever in sys_futex() [SIGSTOP does not work]
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From: Kyle Moffett on 16 Jul 2010 21:20 Hi all, In the "apr" testsuite, the "testatomic" test seems to get 4 processes completely stuck in sys_futex. If I "kill -STOP" the process it continues to run, chewing CPU. It seems that "kill -KILL" works, though... Because of the "kill -STOP" problem, I can't attach to it with GDB to see where it's stuck, but I can dump /proc/$PID/stack repeatedly to see where it seems to be spinning in the kernel. My kernel version is 2.6.32.15 plus arch/powerpc board-support patches. In particular, I seem to have the following callchains (starting at sys_futex): do_futex futex_lock_pi __switch_to futex_lock_pi_atomic cmpxchg_futex_value_locked handle_page_fault do_page_fault fault_in_user_writeable get_user_pages __get_user_pages __cond_resched __switch_to get_futex_key __lock_page sync_page __switch_to drop_futex_key_refs iput 0x48026000 resume_kernel __switch_to resume_kernel __switch_to I noticed this particular problem while working on a Debian "PowerPCSPE" port [0], so it's entirely possible that my EGLIBC build is slightly broken, but even that should not make it completely impossible to "kill -STOP" a process. My particular boards use the "P2020" chipset (mpc85xx/e500v2 family). Any advice on how to further debug this would be much appreciated! Cheers, Kyle Moffett [0] http://wiki.debian.org/PowerPCSPEPort -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |