Git 2.55.0/next/seen NO_RUST fsmonitor BUG_vfl crash

Git 2.55.0/next/seen NO_RUST fsmonitor BUG_vfl crash

[Đoàn Trần Công Danh]

Hello,

With Git 2.55.0 built without Rust (NO_RUST = Yes), also observed
with seen and next branches.

Running ./t7527-builtin-fsmonitor.sh will run into crash on:

not ok 43 - Matrix[uc:false][fsm:true] move_directory_up
#
#			matrix_clean_up_repo &&
#			$fn &&
#			if test $uc = false && test $fsm = false
#			then
#				git status --porcelain=v1 >.git/expect.$fn
#			else
#				git status --porcelain=v1 >.git/actual.$fn &&
#				test_cmp .git/expect.$fn .git/actual.$fn
#			fi
#

With backtrace:


#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at ./nptl/pthread_kill.c:44
#1  0x00007fad081c724f in __pthread_kill_internal (signo=6, threadid=<optimized out>) at ./nptl/pthread_kill.c:89
#2  0x00007fad08177fe2 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007fad08160efc in __GI_abort () at ./stdlib/abort.c:73
#4  0x0000561637c48e71 in BUG_vfl (file=0x561637fc98b0 "compat/fsmonitor/fsm-listen-linux.c", line=144, fmt=0x561637fc9890 "double remove of watch for '%s'", params=0x7fad03929b38)
    at usage.c:343
#5  BUG_fl (file=file@entry=0x561637fc98b0 "compat/fsmonitor/fsm-listen-linux.c", line=line@entry=144, fmt=fmt@entry=0x561637fc9890 "double remove of watch for '%s'") at usage.c:360
#6  0x0000561637f490bf in remove_watch (w=0x561675350240, data=data@entry=0x56167533b050) at compat/fsmonitor/fsm-listen-linux.c:144
#7  0x0000561637f49f22 in rename_dir (cookie=<optimized out>, path=0x561675352260 "/home/sgn/src/git/t/trash directory.t7527-builtin-fsmonitor/T1/T3", data=<optimized out>)
    at compat/fsmonitor/fsm-listen-linux.c:246
#8  process_event (path=0x561675352260 "/home/sgn/src/git/t/trash directory.t7527-builtin-fsmonitor/T1/T3", event=0x7fad03929de0, batch=<synthetic pointer>, cookie_list=0x7fad03929d60,
    state=0x7ffdb01840c0) at compat/fsmonitor/fsm-listen-linux.c:559
#9  handle_events (state=state@entry=0x7ffdb01840c0) at compat/fsmonitor/fsm-listen-linux.c:661
#10 0x0000561637f4a73f in fsm_listen__loop (state=state@entry=0x7ffdb01840c0) at compat/fsmonitor/fsm-listen-linux.c:728
#11 0x0000561637ca8e65 in fsm_listen__thread_proc (_state=0x7ffdb01840c0) at builtin/fsmonitor--daemon.c:1194
#12 0x00007fad081c5579 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:448
#13 0x00007fad0823f858 in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78


[System Info]
git version:
git version 2.55.0.551.g10ab9bd069f7d
cpu: x86_64
built from commit: 10ab9bd069f7d523b2392c7b471a6a7af88a5740
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
rust: disabled
feature: fsmonitor--daemon
gettext: enabled
libcurl: 8.21.0
OpenSSL: OpenSSL 3.6.3 9 Jun 2026
zlib: 1.3.2
SHA-1: SHA1_DC
SHA-256: SHA256_BLK
default-ref-format: files
default-hash: sha1
uname: Linux 7.0.14_1 #1 SMP PREEMPT_DYNAMIC Sat Jun 27 23:57:22 UTC 2026 x86_64
compiler info: gnuc: 14.2
libc info: glibc: 2.41
$SHELL (typically, interactive shell): /bin/zsh

-- 
Danh