Also dmesg is full of this:

nginx[9184]: segfault at 27 ip 0000000000447606 sp 00007fff9972a8b0 error 4 in nginx[400000+b6000]
nginx[9599]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9579]: segfault at 117 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9600]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9639]: segfault at ea78 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9659]: segfault at 19 ip 0000000000447606 sp 00007fff9972a8b0 error 4 in nginx[400000+b6000]
nginx[9601]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9662]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9663]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]
nginx[9661]: segfault at 19 ip 0000000000447606 sp 00007fff9972b7f0 error 4 in nginx[400000+b6000]