Public issue detail

Runaway CPU investigation for cc1: unknown userspace loop at bitmap_set_bit(bitmap_head*, int)

cc1 is stuck in a likely unclassified userspace loop: 2.04% of sampled CPU passed through bitmap_set_bit(bitmap_head*, int), with repeated write x88, mmap x1.

highscore: 106reports: 1

Last seen: 2026-10-13 06:02 UTC. Public JSON: /v1/issues/019fa11d-a82b-79e0-891c-85e9b734e4a0

Technical snapshot

This is the clearest retained userspace thread cluster Fixer captured while the process was spinning.

Representative thread backtrace

  • Command: /usr/libexec/gcc/x86_64-linux-gnu/14/cc1 -quiet -I ../../liblwgeom/../deps/ryu/.. -I /usr/local/include -I /usr/include/x86_64-linux-gnu -I /usr/include/webp -I /usr/include/p11-kit-1 -I /usr/include/libxml2 -I /usr/include -I /usr/include/json-c -I . -I ../../liblwgeom -I /usr/include -imultiarch x86_64-linux-gnu -D NDEBUG -D PIC -D PIC -isystem /usr/include/mit-krb5 ../../liblwgeom/measures.c -quiet -dumpdir .libs/ -dumpbase measures.c -dumpbase-ext .c -mtune=generic -march=x86-64 -g -O2 -O2 -Wall -std=gnu11 -fno-math-errno -fno-signed-zeros -fPIC -fasynchronous-unwind-tables -o /tmp/ccUGbAT0.s
  • Why Fixer classified it this way: The process is demonstrably CPU-hot, but the current syscall and symbol sample does not point to a single dominant loop family yet.
  • Wait site: 0
  • Hot path: bitmap_set_bit(bitmap_head*, int) (2.04% sampled CPU)
  • Repeated loop: write -> write -> write
  • Top syscalls: write x88, mmap x1
  • Kernel: 7.1.8+deb14.1-amd64
  • Distribution: debian
preempt_schedule_thunk
task_work_run
irqentry_exit
asm_sysvec_apic_timer_interrupt

Possible duplicates

These are suggestions based on sanitized trigram similarity plus structured fields like package, subsystem, classification, and wait site. They are not auto-merged.

Runaway CPU investigation for lto1: unknown userspace loop at bitmap_set_bit(bitmap_head*, int)

possible duplicate

lto1 is stuck in a likely unclassified userspace loop: 2.51% of sampled CPU passed through bitmap_set_bit(bitmap_head*, int), with repeated thread backtraces show 1 thread(s) around 0x000000000162a9f7 in constrain_operands(int, unsigned long) ().

highscore: 106reports: 1similarity: 97%

Why this looks related: same classification, same subsystem, same wait site

Last seen: 2026-09-30 11:46 UTC. Public page: /issues/019fa772-cf3b-7890-82d2-60e7dba39362. Public JSON: /v1/issues/019fa772-cf3b-7890-82d2-60e7dba39362

Runaway CPU investigation for po2xml: unknown userspace loop at unresolved offset in libpcre2-16.so.0.14.0

possible duplicate

po2xml is stuck in a likely unclassified userspace loop: 53.94% of sampled CPU passed through unresolved offset, with repeated write x2, exit_group x1, fstat x1.

highscore: 106reports: 1similarity: 75%

Why this looks related: same classification, same subsystem, same wait site

Last seen: 2026-10-19 03:46 UTC. Public page: /issues/01a0f656-df4b-7fc2-acb4-c03fc6235e66. Public JSON: /v1/issues/01a0f656-df4b-7fc2-acb4-c03fc6235e66

Runaway CPU investigation for llama-server: unknown userspace loop at uvm_spin_loop

possible duplicate

llama-server is stuck in a likely unclassified userspace loop: 23.95% of sampled CPU passed through uvm_spin_loop, with repeated no dominant syscall sample was captured.

highscore: 106reports: 1similarity: 75%

Why this looks related: same classification, same subsystem, same wait site

Last seen: 2026-10-22 21:36 UTC. Public page: /issues/01a0b753-7de3-74d2-bfee-879445fd371b. Public JSON: /v1/issues/01a0b753-7de3-74d2-bfee-879445fd371b

Runaway CPU investigation for clang: unknown userspace loop at clang::Lexer::LexTokenInternal(clang::Token&, bool)

possible duplicate

clang is stuck in a likely unclassified userspace loop: 1.91% of sampled CPU passed through clang::Lexer::LexTokenInternal(clang::Token&, bool), with repeated write x2, close x1, exit_group x1.

highscore: 106reports: 1similarity: 75%

Why this looks related: same classification, same subsystem, same wait site

Last seen: 2026-10-20 04:50 UTC. Public page: /issues/019ff123-7d66-7253-bc62-d7ba8c5bd3e8. Public JSON: /v1/issues/019ff123-7d66-7253-bc62-d7ba8c5bd3e8

Published attempts

No public attempts have been published for this issue yet.

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