[tor-bugs] #26181 [Core Tor/Tor]: Systemd fails to load included service files tor at .service or tor at default.service + DisableAllSwap Fix

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#26181: Systemd fails to load included service files tor at .service or
tor at default.service + DisableAllSwap Fix
--------------------------+------------------------------------
 Reporter:  d3m0nkingx    |          Owner:  (none)
     Type:  defect        |         Status:  new
 Priority:  Very High     |      Milestone:  Tor: 0.3.3.x-final
Component:  Core Tor/Tor  |        Version:  Tor: 0.3.3.6
 Severity:  Major         |     Resolution:
 Keywords:                |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:
--------------------------+------------------------------------

Comment (by d3m0nkingx):

 * '''$ systemctl set-property tor.service !MemoryLimit=64M'''

 Also set the memory limit to 64 Megabytes rather than allowing all
 available. Setting less than 47MB resulted in tor having an oom and kernel
 kills the process:

 out_of_memory+0x2ce/0x4f0

 kernel:  mem_cgroup_out_of_memory+0x4b/0x80

 kernel:  mem_cgroup_oom_synchronize+0x2e8/0x320

 kernel:  ? mem_cgroup_css_online+0x40/0x40

 kernel:  pagefault_out_of_memory+0x36/0x7b

 kernel:  mm_fault_error+0x90/0x180

 kernel:  !__do_page_fault+0x4a5/0x4d0

 kernel:  do_page_fault+0x2d/0xf0

 kernel:  ? page_fault+0x2f/0x50

 kernel:  page_fault+0x45/0x50

 kernel: RIP: 0033:0x7efc1d3de786

 kernel: RSP: 002!b:00007ffcd6ed4e50 EFLAGS: 00010206

 kernel: RAX: 000000000001c001 RBX: 00007efc1d720b20 RCX: 0000000000000021

 kernel: RDX: 0000559948ceefe0 RSI: 0000559948cef000 RDI: 0000000000000000

 kernel: RBP: 0000000000000021 R08: 0000559948ceef50 R09: 2e33363120746100

 kernel: R10: 2e3637312e323731 R11: ffffffffffffffff R12: 00007efc1d720b78

 kernel: R13: 00007efc1d720b78 R14: 0000000000002710 R15: 00007efc1d720b88

 kernel: Task in /system.slice/tor.service killed as a result of limit of
 /system.slice/tor.service

 kernel: memory: usage 1024kB, limit 1024kB, failcnt 162

 kernel: memory+swap: usage 0kB, limit 9007199254740988kB, failcnt 0

 kernel: kmem: usage 224kB, limit 9007199254740988kB, failcnt 0

 kernel: Memory cgroup stats for /system.slice/tor.service: !cache:0KB
 !rss:792KB rss_!huge:0KB !shmem:0KB mapped_!file:0KB !dirty:0

 kernel: [ pid ]   uid  tgid total_vm      rss pgtables_bytes swapents
 oom_score_adj name

 kernel: [ 5884]     0  5884    11802     2277   139264        0
 0 tor

 kernel: Memory cgroup out of memory: Kill process 5884 (tor) score 1 or
 sacrifice child

 __'''kernel: Killed process 5884 (tor)'''__ '''!total-vm:47208kB''',
 !anon-rss:800kB, !file-rss:8308kB, !shmem-rss:0kB

 kernel: oom_reaper: reaped process 5884 (tor), now !anon-rss:540kB, !file-
 rss:7016kB, !shmem-rss:0kB

 systemd![1]: tor.service: Control process exited, code=killed status=9

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26181#comment:4>
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