On Wed, Feb 20, 2013 at 4:20 PM, Andrew Morton <a...@linux-foundation.org> wrote: > On Wed, 20 Feb 2013 16:17:39 -0800 > Mandeep Singh Baines <m...@chromium.org> wrote: > >> On Wed, Feb 20, 2013 at 3:24 PM, Andrew Morton >> <a...@linux-foundation.org> wrote: >> > On Wed, 20 Feb 2013 15:17:16 -0800 >> > Mandeep Singh Baines <m...@chromium.org> wrote: >> > >> >> We shouldn't try_to_freeze if locks are held. >> >> >> >> ... >> >> >> >> @@ -43,6 +44,9 @@ extern void thaw_kernel_threads(void); >> >> >> >> + if (!(current->flags & PF_NOFREEZE)) >> >> + debug_check_no_locks_held(current, >> >> + >> >> "lock held while trying to >> >> freeze"); >> >> ... >> >> >> >> + debug_check_no_locks_held(tsk, "lock held at task exit time"); >> > >> > There doesn't seem much point in adding the `msg' to >> > debug_check_no_locks_held() - the dump_stack() in >> > print_held_locks_bug() will tell us the same thing. Maybe just change >> >> dump_stack() can be confusing when there is inlining. On occasion I've >> looked at the wrong mutex_lock, for example, when there was another >> mutex_lock that was inlined. Of course, you can start objdump and >> verify the offsets. But that requires that you have the object file. >> You could have a try_to_freeze added to do_exit. I was thinking of >> adding another locks_held in the return from syscall path. > > Backtraces aren't *that* bad. We'll easily be able to tell which of > the two callsites triggered the trace. >
Let's say there was a try_to_freeze() that got inlined indirectly (multiple levels of inline) into do_exit. Wouldn't the backtraces for the regular exit check and the try_to_freeze check be identical except for the offset (do_exit+0x45 versus do_exit+0x88)? So unless you had an object file you wouldn't know which check you hit. Regards, Mandeep -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
