generic/204 is crashing on linux-next when testing f2fs

["Theodore Tso" <tytso@mit.edu>]

(fstests cc'ed so I can a get handy-dandy lore.kernel.org URL for the
 exclude file with the background for the test exclusion.)

Hi, I've been running xfstests on ext4, xfs, btrfs, and f2fs on
linux-next[1], and for the past week or two, the tests have been
hanging due to a BUG getting triggered on either f2fs/encrypt[2] or
f2fs/compress[3] test configrations.

[1] Using the command: "gce-xfstests ltm -c ext4/all,xfs/all,btrfs/all,f2fs/all -g auto --repo https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next --watch fs-next"
[2] https://github.com/tytso/xfstests-bld/blob/master/test-appliance/files/root/fs/f2fs/cfg/encrypt
[3] https://github.com/tytso/xfstests-bld/blob/master/test-appliance/files/root/fs/f2fs/cfg/compress

Interestingly, after the BUG_ON things get wedged so badly that
"systemctl" hangs forever.  So apparently whatever is going wrong, it
causes the systemd to malfunction in a profound way.  As a result, the
test VM hangs for days until I get around to aborting the VM.

For now, I'll exclude generic/204 from the f2fs configs in my test
appliance; if you have a chance to take a look at this and let me know
when it might be safe to re-neable generic/204 for f2fs, that would be
great.  Thanks!

BTW, if you'd be interestedr receiving the daily ouptut of the
gce-xfstests run for f2fs, let me know.  That can be arranged...

	     	     	       	  - Ted

P.S.  Here's the dmesg output from a run this morning using the
linux-next kernel 6.18.0-xfstests-g781b8d22e5d5:

[ 1011.282502] run fstests generic/204 at 2025-12-01 22:27:28
[ 1011.604590] F2FS-fs (dm-1): f2fs_recover_fsync_data: recovery fsync data, check_only: 0
[ 1011.605016] F2FS-fs (dm-1): Mounted with checkpoint version = 55cbed75
[ 1065.186351] ------------[ cut here ]------------
[ 1065.191112] kernel BUG at fs/f2fs/segment.c:2872!
[ 1065.195977] Oops: invalid opcode: 0000 [#1] SMP PTI
[ 1065.201170] CPU: 0 UID: 0 PID: 390275 Comm: umount Tainted: G        W           6.18.0-xfstests-g781b8d22e5d5 #1 PREEMPT(none) 
[ 1065.212886] Tainted: [W]=WARN
[ 1065.216868] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
[ 1065.226646] RIP: 0010:get_new_segment+0x28d/0x2b0
[ 1065.231684] Code: e4 ff ff ff e9 5f ff ff ff ba 08 00 00 00 31 f6 4c 89 e7 e8 25 14 fe ff 4c 89 ef e8 6d ea 6c 00 b8 8b ff ff ff e9 3e ff ff ff <0f> 0b 83 7c 24 04 01 0f 85 4e fe ff ff 41 39 ee 0f 82 45 fe ff ff
[ 1065.250635] RSP: 0018:ffffb3d684a2b860 EFLAGS: 00010246
[ 1065.255988] RAX: 0000000000000031 RBX: ffffb3d684a2b8b4 RCX: 0000000000000031
[ 1065.263230] RDX: 0000000000000000 RSI: 0000000000000031 RDI: ffff8e76c1d3e290
[ 1065.270556] RBP: 0000000000000001 R08: ffff8e76c1d3e288 R09: 0000000000000000
[ 1065.277801] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8e76c6b1f000
[ 1065.285090] R13: ffff8e7729c2308c R14: 0000000000000000 R15: ffff8e7729c23080
[ 1065.292362] FS:  00007fb977a5f840(0000) GS:ffff8e78090e8000(0000) knlGS:0000000000000000
[ 1065.301096] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1065.307080] CR2: 00007fef85ee165c CR3: 000000015b64e006 CR4: 00000000003706f0
[ 1065.314528] Call Trace:
[ 1065.317324]  <TASK>
[ 1065.319547]  new_curseg+0xb5/0x220
[ 1065.323166]  f2fs_allocate_data_block+0x51e/0x750
[ 1065.328026]  do_write_page+0x57/0x280
[ 1065.331823]  f2fs_do_write_node_page+0x38/0x70
[ 1065.336395]  __write_node_folio+0x2d1/0x4e0
[ 1065.340723]  f2fs_sync_node_pages+0x428/0x550
[ 1065.345209]  block_operations+0x33e/0x450
[ 1065.349518]  f2fs_write_checkpoint+0x103/0x5e0
[ 1065.354119]  kill_f2fs_super+0x14b/0x190
[ 1065.358297]  deactivate_locked_super+0x33/0xb0
[ 1065.362918]  cleanup_mnt+0xea/0x180
[ 1065.366582]  task_work_run+0x5c/0xa0
[ 1065.370323]  exit_to_user_mode_loop+0xb1/0xd0
[ 1065.374850]  do_syscall_64+0x155/0x160
[ 1065.378830]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 1065.384054] RIP: 0033:0x7fb977cb8217
[ 1065.387743] Code: 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 b1 5b 0d 00 f7 d8 64 89 02 b8
[ 1065.406622] RSP: 002b:00007ffc531c8d48 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[ 1065.414317] RAX: 0000000000000000 RBX: 0000564b0abc7af8 RCX: 00007fb977cb8217
[ 1065.421570] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000564b0abce710
[ 1065.428834] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 1065.436085] R10: 0000000000000008 R11: 0000000000000246 R12: 00007fb977e1826c
[ 1065.443415] R13: 0000564b0abce710 R14: 0000564b0abc7e30 R15: 0000564b0abc79f0
[ 1065.450667]  </TASK>
[ 1065.453067] ---[ end trace 0000000000000000 ]---
[ 1065.457915] RIP: 0010:get_new_segment+0x28d/0x2b0
[ 1065.462751] Code: e4 ff ff ff e9 5f ff ff ff ba 08 00 00 00 31 f6 4c 89 e7 e8 25 14 fe ff 4c 89 ef e8 6d ea 6c 00 b8 8b ff ff ff e9 3e ff ff ff <0f> 0b 83 7c 24 04 01 0f 85 4e fe ff ff 41 39 ee 0f 82 45 fe ff ff
[ 1065.481788] RSP: 0018:ffffb3d684a2b860 EFLAGS: 00010246
[ 1065.487199] RAX: 0000000000000031 RBX: ffffb3d684a2b8b4 RCX: 0000000000000031
[ 1065.494559] RDX: 0000000000000000 RSI: 0000000000000031 RDI: ffff8e76c1d3e290
[ 1065.501898] RBP: 0000000000000001 R08: ffff8e76c1d3e288 R09: 0000000000000000
[ 1065.509183] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8e76c6b1f000
[ 1065.516459] R13: ffff8e7729c2308c R14: 0000000000000000 R15: ffff8e7729c23080
[ 1065.523744] FS:  00007fb977a5f840(0000) GS:ffff8e78090e8000(0000) knlGS:0000000000000000
[ 1065.532160] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1065.538091] CR2: 00007fef85ee165c CR3: 000000015b64e006 CR4: 00000000003706f0
[ 1065.545412] note: umount[390275] exited with preempt_count 1