On Sat, Jul 27, 2019 at 6:12 PM Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > On Sat, Jul 27, 2019 at 12:02 PM Andrii Nakryiko <andriin@xxxxxx> wrote: > > > > This patch set makes a number of changes to test_progs selftest, which is > > a collection of many other tests (and sometimes sub-tests as well), to provide > > better testing experience and allow to start convering many individual test > > programs under selftests/bpf into a single and convenient test runner. > > I really like the patches, but something isn't right: Argh... Uninitialized `int ret` in test__vprintf(). Should be initialized to zero, otherwise in some corner cases when log buffer is completely full and ret's initial value is sufficiently large negative number, it can underflow env.log_cnt, silently skipping one log output, and then crashing on next one. You've somehow encountered a fascinating series of conditions that I've never stumbled upon running my code dozens of times. Fixing, sorry about that! > #16 raw_tp_writable_reject_nbd_invalid:OK > #17 raw_tp_writable_test_run:OK > #18 reference_tracking:OK > [ 87.715996] test_progs[2200]: segfault at 2f ip 00007f56aeea347b sp > 00007ffce9720980 error 4 in libc-2.23.so[7f56aee5b000+198000] > [ 87.717316] Code: ff ff 44 89 8d 30 fb ff ff e8 01 74 fd ff 44 8b > 8d 30 fb ff ff 4c 8b 85 28 fb ff ff e9 fd eb ff ff 31 c0 48 83 c9 ff > 4c 89 df <f2> ae c7 85 28 fb ff ff 00 00 00 00 48 89 c8 48 f7 d0 4c 8f > [ 87.719493] audit: type=1701 audit(1564276195.971:5): auid=0 uid=0 > gid=0 ses=1 subj=kernel pid=2200 comm="test_progs" > exe="/data/users/ast/net-next/tools/testing/selftests/bpf/test_progs" > sig=11 res=1 > Segmentation fault (core dumped) > > Under gdb fault is different: > #23 stacktrace_build_id:OK > Detaching after fork from child process 2276. > Detaching after fork from child process 2278. > [ 149.013116] perf: interrupt took too long (6799 > 6713), lowering > kernel.perf_event_max_sample_rate to 29000 > [ 149.014634] perf: interrupt took too long (8511 > 8498), lowering > kernel.perf_event_max_sample_rate to 23000 > [ 149.017038] perf: interrupt took too long (10649 > 10638), lowering > kernel.perf_event_max_sample_rate to 18000 > [ 149.021901] perf: interrupt took too long (13322 > 13311), lowering > kernel.perf_event_max_sample_rate to 15000 > [ 149.042946] perf: interrupt took too long (16660 > 16652), lowering > kernel.perf_event_max_sample_rate to 12000 > Detaching after fork from child process 2279. > #24 stacktrace_build_id_nmi:OK > #25 stacktrace_map:OK > #26 stacktrace_map_raw_tp:OK > > Program received signal SIGSEGV, Segmentation fault. > 0x00007ffff723f47b in vfprintf () from /usr/lib/libc.so.6 > (gdb) bt > #0 0x00007ffff723f47b in vfprintf () from /usr/lib/libc.so.6 > #1 0x00007ffff72655a9 in vsnprintf () from /usr/lib/libc.so.6 > #2 0x0000000000403100 in test__vprintf (fmt=0x426754 "%s:PASS:%s %d > nsec\n", args=0x7fffffffe878) at test_progs.c:114 > #3 0x000000000040325c in test__printf (fmt=fmt@entry=0x426754 > "%s:PASS:%s %d nsec\n") at test_progs.c:147 > #4 0x000000000042222d in test_task_fd_query_rawtp () at > prog_tests/task_fd_query_rawtp.c:19 > #5 0x0000000000402c76 in main (argc=<optimized out>, argv=<optimized > out>) at test_progs.c:501 > (gdb) info threads > Id Target Id Frame > * 1 Thread 0x7ffff7fea700 (LWP 2245) "test_progs" > 0x00007ffff723f47b in vfprintf () from /usr/lib/libc.so.6
