Environment
- App Control Agent: Version 8.7.6
- Red Hat Version 7 and 8
Symptoms
- Agent will hang, or crash due to large contiguous memory allocation failure when there is memory crunch on server
- 'b9daemon invoked oom-killer' messages similar to the following appear in the /var/log/messages file:
kernel: b9daemon invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
kernel: b9daemon cpuset=/ mems_allowed=0
kernel: CPU: 6 PID: 6708 Comm: b9daemon Tainted: P OE ------------ 3.10.0-693.21.1.el7.x86_64 #1
kernel: Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
kernel: Call Trace:
kernel: [<ffffffff816ae7c8>] dump_stack+0x19/0x1b
kernel: [<ffffffff816a9b90>] dump_header+0x90/0x229
kernel: [<ffffffff810ecec2>] ? ktime_get_ts64+0x52/0xf0
kernel: [<ffffffff8118a884>] oom_kill_process+0x254/0x3d0
kernel: [<ffffffff8118a32d>] ? oom_unkillable_task+0xcd/0x120
kernel: [<ffffffff8118a3d6>] ? find_lock_task_mm+0x56/0xc0
kernel: [<ffffffff8118b0c6>] out_of_memory+0x4b6/0x4f0
kernel: [<ffffffff816aa694>] __alloc_pages_slowpath+0x5d6/0x724
kernel: [<ffffffff811912a5>] __alloc_pages_nodemask+0x405/0x420
kernel: [<ffffffff811d5a38>] alloc_pages_current+0x98/0x110
kernel: [<ffffffff81186da7>] __page_cache_alloc+0x97/0xb0
kernel: [<ffffffff81189370>] filemap_fault+0x170/0x420
kernel: [<ffffffffc022e1e6>] ext4_filemap_fault+0x36/0x50 [ext4]
kernel: [<ffffffff811b19d8>] __do_fault+0x58/0xe0
kernel: [<ffffffff810f89f8>] ? get_futex_key+0x1c8/0x2c0
kernel: [<ffffffff811b1e7b>] do_read_fault.isra.44+0x4b/0x130
kernel: [<ffffffff811b6781>] handle_mm_fault+0x691/0xfa0
kernel: [<ffffffff810fb77a>] ? do_futex+0x12a/0x5a0
kernel: [<ffffffff816bb504>] __do_page_fault+0x154/0x450
kernel: [<ffffffff816bb835>] do_page_fault+0x35/0x90
kernel: [<ffffffff816b7768>] page_fault+0x28/0x30
Cause
The 'b9k_*' kernel module may fail allocating large contiguous memory when there is high memory stress on the server.
Resolution
Addressed in Linux Agent version 8.7.10: EP-16555: Fixed an issue where the App Control kernel module failed to allocate large amounts of contiguous memory
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