Not able to run pwru with --filter-dst-port option due to OOM about pwru

[brb]

@YutaroHayakawa Thanks for the investigation! Mind opening the PR to add your findings to KNOWN_ISSUES.md (the file needs to be created)?

[brb]

Could you show dmesg output?

[achilles-git]

[   69.777400] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/user.slice/user-1000.slice/session-4.scope,task=pwru,pid=1624,uid=0
[   69.778302] Out of memory: Killed process 1624 (pwru) total-vm:777540kB, anon-rss:70648kB, file-rss:0kB, shmem-rss:0kB, UID:0 pgtables:232kB oom_score_adj:0
[   69.784610] oom_reaper: reaped process 1624 (pwru), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

Ohk
i have 2GB memory and no application is running
is that not sufficient ??

[brb]

I remember @ti-mo mentioning somewhere that cilium/ebpf kprobe orchestration code consumes a lot of mem per kprobe. @ti-mo?

[ti-mo]

kprobe orchestration code consumes a lot of mem per kprobe

Not sure where this is coming from. I mentioned parsing vmlinux BTF makes enormous amounts of allocations in its current state (around 500MB on my machine), which might cause trouble running pwru on nodes with smaller memory budgets.

[YutaroHayakawa]

@achilles-git Do you happen to have many messages from audit subsystem in dmesg? In that case, what happens when you try with setenforce Permissive (if the situation allows)?

===
When SELinux is enabled, in some cases, an audit message is generated per eBPF program invocation. Since pwru attaches the BPF program for hundreds or thousands of functions, many messages are generated in a very short time.

As a result, auditd cannot catch up to the speed and the message will be queued up to the backlog memory inside the kernel. Then, OOM killer works.

Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1955585
Fix: https://lore.kernel.org/all/[email protected]/

===
I could reproduce the issue with Fedora 34 box.

$ uname -a
Linux fedora 5.11.12-300.fc34.x86_64 #1 SMP Wed Apr 7 16:31:13 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

$ sudo ./pwru --filter-dst-port=11211
2022/02/14 06:29:26 Attaching kprobes...
87 / 1333 [------->______________________________________________________________________________________________________] 6.53% 28 p/sKilled

$ dmesg
[  232.680704] audit_log_start: 13274 callbacks suppressed
[  232.680706] audit: audit_backlog=65 > audit_backlog_limit=64
[  232.681686] audit: audit_lost=1228717 audit_rate_limit=0 audit_backlog_limit=64
[  232.682072] audit: backlog limit exceeded
[  232.682407] audit: audit_backlog=65 > audit_backlog_limit=64
[  232.682729] audit: audit_lost=1228718 audit_rate_limit=0 audit_backlog_limit=64
[  232.683095] audit: backlog limit exceeded
[  232.683442] audit: audit_backlog=65 > audit_backlog_limit=64
[  232.683769] audit: audit_lost=1228719 audit_rate_limit=0 audit_backlog_limit=64
[  232.684128] audit: backlog limit exceeded
[  232.684431] audit: audit_backlog=65 > audit_backlog_limit=64
[  236.816357] pwru invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=0
[  236.816822] CPU: 0 PID: 2136 Comm: pwru Not tainted 5.11.12-300.fc34.x86_64 #1
[  236.817258] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  236.817737] Call Trace:
[  236.818110]  dump_stack+0x6b/0x83
[  236.818490]  dump_header+0x4a/0x1f3
[  236.818859]  oom_kill_process.cold+0xb/0x10
[  236.819240]  out_of_memory+0x229/0x4c0
[  236.819638]  __alloc_pages_slowpath.constprop.0+0xbf0/0xcc0
[  236.820054]  __alloc_pages_nodemask+0x30a/0x340
[  236.820443]  pagecache_get_page+0x192/0x470
[  236.820828]  filemap_fault+0x6bd/0xa50
[  236.821198]  ext4_filemap_fault+0x2d/0x40
[  236.821574]  __do_fault+0x36/0x100
[  236.821936]  handle_mm_fault+0x1174/0x1970
[  236.822309]  do_user_addr_fault+0x19f/0x480
[  236.822687]  exc_page_fault+0x67/0x150
[  236.823057]  ? asm_exc_page_fault+0x8/0x30
[  236.823440]  asm_exc_page_fault+0x1e/0x30
[  236.823814] RIP: 0033:0x42fbe0
[  236.824175] Code: Unable to access opcode bytes at RIP 0x42fbb6.
[  236.824589] RSP: 002b:000000c000041ec8 EFLAGS: 00010202
[  236.824996] RAX: 000000c000033400 RBX: 0000000000000017 RCX: 000000c000033400
[  236.825438] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000003720f59a77
[  236.825882] RBP: 000000c000041ee0 R08: 00000000000008b2 R09: 0000000000000000
[  236.826329] R10: 0000000000000000 R11: 0000000000000246 R12: 000000c000041950
[  236.826782] R13: 000000c000032000 R14: 000000c0000004e0 R15: 00007ff583df5034
[  236.827278] Mem-Info:
[  236.827582] active_anon:224 inactive_anon:30787 isolated_anon:0
                active_file:351 inactive_file:227 isolated_file:0
                unevictable:0 dirty:3 writeback:0
                slab_reclaimable:4134 slab_unreclaimable:76903
                mapped:529 shmem:440 pagetables:803 bounce:0
                free:1921 free_pcp:25 free_cma:0

[YutaroHayakawa]

Created the one.

#52