(2014/10/01 2:58), Oleg Nesterov wrote: > Hi Fengguang, > > On 09/30, Fengguang Wu wrote: >> >> Hi Oleg, >> >> 0day kernel testing robot got the below dmesg and the first bad commit is >> >> commit 8b4d801b2b123b6c09742f861fe44a8527b84d47 >> Author: Oleg Nesterov <[email protected]> >> AuthorDate: Thu Jun 20 17:50:06 2013 +0200 >> Commit: Ingo Molnar <[email protected]> >> CommitDate: Thu Jun 20 17:57:00 2013 +0200 >> >> hw_breakpoint: Fix cpu check in task_bp_pinned(cpu) >> >> trinity fuzzer triggered WARN_ONCE("Can't find any breakpoint >> slot") in arch_install_hw_breakpoint() but the problem is not >> arch-specific. >> >> The problem is, task_bp_pinned(cpu) checks "cpu == iter->cpu" >> but this doesn't account the "all cpus" events with iter->cpu < >> 0. >> >> This means that, say, register_user_hw_breakpoint(tsk) can >> happily create the arbitrary number > HBP_NUM of breakpoints >> which can not be activated. toggle_bp_task_slot() is equally >> wrong by the same reason and nr_task_bp_pinned[] can have >> negative entries. >> >> Simple test: >> >> # perl -e 'sleep 1 while 1' & >> # perf record -e mem:0x10,mem:0x10,mem:0x10,mem:0x10,mem:0x10 -p `pidof >> perl` >> >> Before this patch this triggers the same problem/WARN_ON(), >> after the patch it correctly fails with -ENOSPC. >> >> Reported-by: Vince Weaver <[email protected]> >> Signed-off-by: Oleg Nesterov <[email protected]> >> Acked-by: Frederic Weisbecker <[email protected]> >> Cc: <[email protected]> >> Link: http://lkml.kernel.org/r/[email protected] >> Signed-off-by: Ingo Molnar <[email protected]> >> >> +-----------------------------------------------------------------------+------------+------------+------------------+ >> | | >> 003002e04e | 8b4d801b2b | v3.17-rc7_093000 | >> +-----------------------------------------------------------------------+------------+------------+------------------+ >> | boot_successes | 60 >> | 0 | 0 | >> | boot_failures | 0 >> | 20 | 11 | >> | WARNING:at_kernel/trace/trace_kprobe.c:kprobe_trace_self_tests_init() | 0 >> | 20 | 11 | >> | backtrace:kprobe_trace_self_tests_init | 0 >> | 20 | 11 | >> | backtrace:warn_slowpath_null | 0 >> | 20 | 11 | >> | backtrace:kernel_init_freeable | 0 >> | 20 | 11 | >> +-----------------------------------------------------------------------+------------+------------+------------------+ >> >> [ 4.188679] Testing kprobe tracing: >> [ 4.189810] Could not insert probe at kprobe_trace_selftest_target+0: -22 > > __register_trace_kprobe() fails. > > No, I am very sure this can't be caused by the commit above. If nothing else, > task_bp_pinned() changed by this commit is not even called in this case.
Uh, right. I'm trying to reproduce this to analyze... Anyway, I'd like to remove the whole of kprobe_trace selftest from the kernel binary. Instead of that, we already have ftracetest scripts. We can run the test after the kernel booted. Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
