perf: memory leak

Occasionally I'm seeing perf processes whose memory continues growing forever. Here's one example for `/proc/pid/status` of such a perf - it shows that anonymous memory takes up most of the space (700mb). This perf process is at least 2 weeks old.
```
ame: perf
Umask: 0022
State: S (sleeping)
Tgid: 3966
Ngid: 0
Pid: 3966
PPid: 3825
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 64
Groups: 0 1001
NStgid: 3966
NSpid: 3966
NSpgid: 3966
NSsid: 3665
VmPeak: 732316 kB
VmSize: 732208 kB
VmLck: 0 kB
VmPin: 5136 kB
VmHWM: 707368 kB
VmRSS: 707368 kB
RssAnon: 702548 kB
RssFile: 4820 kB
RssShmem: 0 kB
VmData: 712220 kB
VmStk: 132 kB
VmExe: 11512 kB
VmLib: 4 kB
VmPTE: 1452 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
CoreDumping: 0
THP_enabled: 1
Threads: 2
SigQ: 0/15540
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000008000000
SigIgn: 0000000000000004
SigCgt: 0000000180014c02
CapInh: 0000000000000000
CapPrm: 0000003fffffffff
CapEff: 0000003fffffffff
CapBnd: 0000003fffffffff
CapAmb: 0000000000000000
NoNewPrivs: 0
Seccomp: 0
Speculation_Store_Bypass: thread vulnerable
Cpus_allowed: 3
Cpus_allowed_list: 0-1
Mems_allowed: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
Mems_allowed_list: 0
voluntary_ctxt_switches: 130270
nonvoluntary_ctxt_switches: 1686839
```

What's interesting - there are 2 perf processes (one for DWARF and one for FP) and both have roughly the same amount of used memory. Something causes perf to continue accumulating memory over time, we need to figure it out and either restart perf from time to time, or configure it to prevent this from happening.