On 13.05.2013 01:20, Stanislav Meduna wrote: > So it looks like the problem happens inside the put_user, > maybe a pagefault? The buf is an address on the stack: Yep, this is a page fault. I added tracing of the mm_fault_error handle_mm_fault handle_pte_fault do_page_fault functions The result is 0....0 62811.755379: bprint: timerfd_read: timerfd_read after unlock, res=0 0d...0 62811.755382: function: do_page_fault 0....0 62811.755386: function: handle_mm_fault 0....0 62811.755389: function: handle_pte_fault 0d...0 62811.755394: function: do_page_fault 0....0 62811.755396: function: handle_mm_fault 0....0 62811.755398: function: handle_pte_fault 0d...0 62811.755402: function: do_page_fault 0....0 62811.755404: function: handle_mm_fault 0....0 62811.755406: function: handle_pte_fault > Viewing the ps -o min_flt,maj_flt for the task shows 969701 > minor faults (that do not increment - I will check this when > the hang happens again) and 0 major ones. The number of minor faults of the thread jumped to 1433400 and the process recovered after 2.77 seconds. The trace file is at http://www.meduna.org/tmp/trace.mmfaulthang.dat.gz Thanks -- Stano -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
