On 2022-04-21 at 08:30:50, Jason Morgan wrote:
Hi,
We have a remote repo accessed using the 'file:' protocol, mounted over Samba using drvfs into a WSL2 instance of Ubuntu 20.04.
We find a 'git push' waits forever. git version 2.25.1
I seem to recall that we've fixed some various issues with protocol
handling in the 2.29 timeframe. Is it possible you could try 2.36.0 to
see if you can reproduce it there?
Also, it would be interesting to see if there's a difference in
behaviour between setting protocol.version to 0 and setting it to 2.
That might tell us something that would help tracking this down.
Over a local LAN this works fine, but over a VPN this fails, hinting at some sort of race condition.
Output from strace hints that git is trying (and failing) to read from a closed file handle.
I don't think this is the case. If Git were trying to read from a
closed file handle, the kernel would immediately return -1 with errno
set to EBADF. Those operations won't block because there's nothing to
read.
Final output from strace:
-----------
openat(AT_FDCWD, ".git/objects/ad/065dad4384ae8c81c120c562985078d1f7b34b", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=152, ...}) = 0
mmap(NULL, 152, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000
close(3) = 0
munmap(0x7f3e0e4af000, 152) = 0
openat(AT_FDCWD, ".git/objects/30/2508dfe5201db6c000ebf17b0c69e3afb31218", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0555, st_size=214, ...}) = 0
mmap(NULL, 214, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000
close(3) = 0
munmap(0x7f3e0e4af000, 214) = 0
openat(AT_FDCWD, ".git/objects/d2/2323ec2ec40a74fbd519509662254c3cfda206", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=161, ...}) = 0
mmap(NULL, 161, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000
close(3) = 0
FD 3 is closed here...
munmap(0x7f3e0e4af000, 161) = 0
access(".git/hooks/pre-push", X_OK) = -1 ENOENT (No such file or directory)
write(4, "00953ea50e3c1f49c33f7dbbb5e3a310"..., 149) = 149
write(4, "0000", 4) = 4
pipe([3, 6]) = 0
And then it's recreated here as one part of a pipe, so it isn't closed.
fcntl(6, F_GETFD) = 0
fcntl(6, F_SETFD, FD_CLOEXEC) = 0
mmap(NULL, 8392704, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f3e0d641000
mprotect(0x7f3e0d642000, 8388608, PROT_READ|PROT_WRITE) = 0
clone(child_stack=0x7f3e0de40fb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tid=[12802], tls=0x7f3e0de41700, child_tidptr=0x7f3e0de419d0) = 12802
My guess is that in the child (which isn't shown here) that FD 6 is
hooked up to either standard output or standard error. You'd need to
follow children to see.
pipe([7, 8]) = 0
stat("/usr/lib/git-core/git", {st_mode=S_IFREG|0755, st_size=3093072, ...}) = 0
pipe([9, 10]) = 0
rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f3e0e1dae50) = 12803
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
close(10) = 0
read(9, "", 8) = 0
close(9) = 0
close(7) = 0
close(4) = 0
fcntl(8, F_GETFL) = 0x1 (flags O_WRONLY)
openat(AT_FDCWD, ".git/objects/3e", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = 4
fstat(4, {st_mode=S_IFDIR|0777, st_size=4096, ...}) = 0
getdents64(4, /* 22 entries */, 32768) = 1328
getdents64(4, /* 0 entries */, 32768) = 0
close(4) = 0
fstat(8, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
write(8, "^3ea50e3c1f49c33f7dbbb5e3a31017f"..., 83) = 83
close(8) = 0
Enumerating objects: 31, done.ts: 1
Counting objects: 100% (31/31), done.
Delta compression using up to 8 threads
Compressing objects: 100% (23/23), done.
Writing objects: 100% (23/23), 5.60 KiB | 212.00 KiB/s, done.
Total 23 (delta 14), reused 0 (delta 0)
[{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 12803
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12803, si_uid=1000, si_status=0, si_utime=2, si_stime=6} ---
read(3,
If FD 6 were wired up to something in the child and the child exited
(which, having received SIGCHLD, is a safe bet), then we'd expect this
to see this process get EOF.
It's not clear to me what's going on here, but I think this code is
ending up in connect.c (search for "transport/file"). Maybe someone
else has an idea?
