Linux segfault meaning

yanyg@t430:~/platform/build$ sudo cat /var/log/messages | grep segfault
Mar  3 22:35:23 t430 kernel: [259968.485176] test_memory[25547]: segfault at 0 ip 0000561ca344c481 sp 00007fff51370480 error 6 in test_memory[561ca343e000+3e000]
Mar  3 22:36:01 t430 kernel: [260006.883227] test_memory[27588]: segfault at 0 ip 000055937db1f496 sp 00007ffd3ecafef0 error 6 in test_memory[55937db11000+3e000]
Mar  3 22:36:12 t430 kernel: [260017.962634] test_memory[28159]: segfault at 0 ip 000055c8ac8c4496 sp 00007ffec8b966b0 error 6 in test_memory[55c8ac8b6000+3e000]
Mar  3 22:38:37 t430 kernel: [260162.515243] test_memory[1919]: segfault at 0 ip 0000561b33b8b496 sp 00007fffdb075e90 error 4 in test_memory[561b33b7d000+3e000]
Mar  3 22:43:01 t430 kernel: [260426.348912] test_memory[13029]: segfault at 0 ip 0000564c5bc9f486 sp 00007ffe05d4e3b0 error 4 in test_memory[564c5bc91000+3e000]
Mar  3 22:45:51 t430 kernel: [260596.608846] test_memory[21028]: segfault at 0 ip 000056186403d4db sp 00007fff77c5fb50 error 6 in test_memory[56186402f000+3e000]
Mar  3 22:48:37 t430 kernel: [260762.502445] test_memory[26497]: segfault at 0 ip 0000560b14cc84db sp 00007fffbd248ef0 error 6 in test_memory[560b14cba000+3e000]

/*
 * Page fault error code bits:
 *
 *   bit 0 ==    0: no page found       1: protection fault
 *   bit 1 ==    0: read access         1: write access
 *   bit 2 ==    0: kernel-mode access  1: user-mode access
 *   bit 3 ==                           1: use of reserved bit detected
 *   bit 4 ==                           1: fault was an instruction fetch
 *   bit 5 ==                           1: protection keys block access
 */
enum x86_pf_error_code {
        X86_PF_PROT     =               1 << 0,
        X86_PF_WRITE    =               1 << 1,
        X86_PF_USER     =               1 << 2,
        X86_PF_RSVD     =               1 << 3,
        X86_PF_INSTR    =               1 << 4,
        X86_PF_PK       =               1 << 5,
};