mm, tracing: Print symbol name for call_site in trace events

mm, tracing: Print symbol name for call_site in trace events

To improve the readability of raw slab trace points, print the call_site ip
using '%pS'. Then we can grep events with function names.

[002] ....   808.188897: kmem_cache_free: call_site=putname+0x47/0x50 ptr=00000000cef40c80
[002] ....   808.188898: kfree: call_site=security_cred_free+0x42/0x50 ptr=0000000062400820
[002] ....   808.188904: kmem_cache_free: call_site=put_cred_rcu+0x88/0xa0 ptr=0000000058d74ef8
[002] ....   808.188913: kmem_cache_alloc: call_site=prepare_creds+0x26/0x100 ptr=0000000058d74ef8 bytes_req=168 bytes_alloc=576 gfp_flags=GFP_KERNEL
[002] ....   808.188917: kmalloc: call_site=security_prepare_creds+0x77/0xa0 ptr=0000000062400820 bytes_req=8 bytes_alloc=336 gfp_flags=GFP_KERNEL|__GFP_ZERO
[002] ....   808.188920: kmem_cache_alloc: call_site=getname_flags+0x4f/0x1e0 ptr=00000000cef40c80 bytes_req=4096 bytes_alloc=4480 gfp_flags=GFP_KERNEL
[002] ....   808.188925: kmem_cache_free: call_site=putname+0x47/0x50 ptr=00000000cef40c80
[002] ....   808.188926: kfree: call_site=security_cred_free+0x42/0x50 ptr=0000000062400820
[002] ....   808.188931: kmem_cache_free: call_site=put_cred_rcu+0x88/0xa0 ptr=0000000058d74ef8

Link: http://lkml.kernel.org/r/20190914103215.23301-1-changbin.du@gmail.com
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>