Sometimes there are severe contentions on the mmap_lock and we want
see it in the -l/--lock-addr output.  However it cannot symbolize
the mmap_lock because it's allocated dynamically without symbols.

Stephane and Hao gave me an idea separately to display mmap_lock by
following the current->mm pointer.  I added a flag to mark mmap_lock
after comparing the lock address so that it can show them differently.
With this change it can show mmap_lock like below:

  $ sudo ./perf lock con -abl -- sleep 10
   contended   total wait     max wait     avg wait            address   symbol
   ...
       16344    312.30 ms      2.22 ms     19.11 us   ffff8cc702595640
       17686    310.08 ms      1.49 ms     17.53 us   ffff8cc7025952c0
           3     84.14 ms     45.79 ms     28.05 ms   ffff8cc78114c478   mmap_lock
        3557     76.80 ms     68.75 us     21.59 us   ffff8cc77ca3af58
           1     68.27 ms     68.27 ms     68.27 ms   ffff8cda745dfd70
           9     54.53 ms      7.96 ms      6.06 ms   ffff8cc7642a48b8   mmap_lock
       14629     44.01 ms     60.00 us      3.01 us   ffff8cc7625f9ca0
        3481     42.63 ms    140.71 us     12.24 us   ffffffff937906ac   vmap_area_lock
       16194     38.73 ms     42.15 us      2.39 us   ffff8cd397cbc560
          11     38.44 ms     10.39 ms      3.49 ms   ffff8ccd6d12fbb8   mmap_lock
           1      5.43 ms      5.43 ms      5.43 ms   ffff8cd70018f0d8
        1674      5.38 ms    422.93 us      3.21 us   ffffffff92e06080   tasklist_lock
         581      4.51 ms    130.68 us      7.75 us   ffff8cc9b1259058
           5      3.52 ms      1.27 ms    703.23 us   ffff8cc754510070
         112      3.47 ms     56.47 us     31.02 us   ffff8ccee38b3120
         381      3.31 ms     73.44 us      8.69 us   ffffffff93790690   purge_vmap_area_lock
         255      3.19 ms     36.35 us     12.49 us   ffff8d053ce30c80

Note that mmap_lock was renamed some time ago and it needs to support
old kernels with a different name 'mmap_sem'.
Suggested-by: Hao Luo <haoluo@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230313204825.2665483-2-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>