[tor-bugs] #24308 [Core Tor/Tor]: MaxMemInCellQueues minimum of 256MB is still too large for low-RAM relays (LEDE and OpenWRT routers)

[Tor Bug Tracker & Wiki]

#24308: MaxMemInCellQueues minimum of 256MB is still too large for low-RAM relays
(LEDE and OpenWRT routers)
-------------------------+-------------------------------------------------
     Reporter:  pmetras  |      Owner:  (none)
         Type:  defect   |     Status:  new
     Priority:  Medium   |  Milestone:  Tor: 0.2.9.x-final
    Component:  Core     |    Version:  Tor: 0.2.9.12
  Tor/Tor                |   Keywords:  tor-
     Severity:  Normal   |  relay,lowmem,openwrt,lede,router
Actual Points:           |  Parent ID:
       Points:           |   Reviewer:
      Sponsor:           |
-------------------------+-------------------------------------------------
 The minimum value for torrc configuration MaxMemInCellQueues of 256MB is
 still too large for memory constrained relays. I've been running a tor
 relay on my OpenWRT router for a few years reliably. I recently upgraded
 the router to use tor 0.2.9.12 where MaxMemInCellQueues is minimally
 defaulted to 256MB, even if the router only has 128 MB. Naturally, Linux
 oom-killer kills it after a few hours. I have a lot of bandwidth but I
 can't share it now...

 This is related to ticket #9686

 {{{
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.070987] Mem-Info:
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]
 active_anon:18341 inactive_anon:51 isolated_anon:0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]  active_file:35
 inactive_file:73 isolated_file:0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]  unevictable:0
 dirty:0 writeback:0 unstable:0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]
 slab_reclaimable:728 slab_unreclaimable:2804
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]  mapped:41
 shmem:1120 pagetables:102 bounce:0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.073403]  free:4723
 free_pcp:40 free_cma:0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.106437] Normal
 free:18892kB min:16384kB low:20480kB high:24576kB active_anon:73364kB
 inactive_anon:204kB active_file:
 140kB inactive_file:292kB unevictable:0kB isolated(anon):0kB
 isolated(file):0kB present:131072kB managed:125640kB mlocked:0kB dirty:0kB
 writeback:0kB mapped:164kB shmem
 :4480kB slab_reclaimable:2912kB slab_unreclaimable:11216kB
 kernel_stack:544kB pagetables:408kB unstable:0kB bounce:0kB free_pcp:160kB
 local_pcp:160kB free_cma:0kB write
 back_tmWed Nov 15 11:24:32 2017 kern.warn kernel: [221491.151989]
 lowmem_reserve[]: 0 0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.155468] Normal: 763*4kB
 (UMEH) 446*8kB (UMEH) 255*16kB (UMEH) 44*32kB (UME) 20*64kB (UMEH) 3*128kB
 (UME) 2*256kB (UH)
  1*512kB (U) 4*1024kB (UMH) 0*2048kB 0*4096kB = 18892kB
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.171705] 1228 total
 pagecache pages
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.175610] 0 pages in swap
 cache
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.179077] Swap cache
 stats: add 0, delete 0, find 0/0
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.184476] Free swap  =
 0kB
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.187482] Total swap =
 0kB
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.190505] 32768 pages RAM
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.193422] 0 pages
 HighMem/MovableOnly
 Wed Nov 15 11:24:32 2017 kern.warn kernel: [221491.197412] 1358 pages
 reserved
 Wed Nov 15 11:24:32 2017 kern.info kernel: [221491.200683] [ pid ]   uid
 tgid total_vm      rss nr_ptes nr_pmds swapents oom_score_adj name
 ...
 Wed Nov 15 11:24:32 2017 kern.info kernel: [221491.370877] [28850]    52
 28850    21220    15276      25       0        0             0 tor
 Wed Nov 15 11:24:32 2017 kern.info kernel: [221491.379539] [ 9935]     0
 9935      296        9       3       0        0             0 sleep
 Wed Nov 15 11:24:32 2017 kern.err kernel: [221491.388387] Out of memory:
 Kill process 28850 (tor) score 487 or sacrifice child
 Wed Nov 15 11:24:32 2017 kern.err kernel: [221491.396016] Killed process
 28850 (tor) total-vm:84880kB, anon-rss:61096kB, file-rss:8kB
 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24308>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online