Re: #1775: fuse tests hang

[Chicken Trac]

#1775: fuse tests hang
-----------------------------------------------+----------------------
            Reporter:  Mario Domenech Goulart  |      Owner:  evhan
                Type:  defect                  |     Status:  assigned
            Priority:  minor                   |  Milestone:  someday
           Component:  extensions              |    Version:
          Resolution:                          |   Keywords:  fuse
Estimated difficulty:                          |
-----------------------------------------------+----------------------

Comment (by Mario Domenech Goulart):

 Attempting to unload the fuse kernel module causes:

 {{{
 [Wed Oct 27 20:28:46 2021] Disabling lock debugging due to kernel taint
 [Wed Oct 27 20:28:46 2021]
 =============================================================================
 [Wed Oct 27 20:28:46 2021] BUG fuse_inode (Tainted: G  R  U           ):
 Objects remaining in fuse_inode on __kmem_cache_shutdown()
 [Wed Oct 27 20:28:46 2021]
 -----------------------------------------------------------------------------

 [Wed Oct 27 20:28:46 2021] INFO: Slab 0x000000001779a0bd objects=19
 used=18 fp=0x0000000095932986 flags=0xfffffc0010200
 [Wed Oct 27 20:28:46 2021] CPU: 0 PID: 42390 Comm: rmmod Tainted: G  R BU
 5.10.0-8-amd64 #1 Debian 5.10.46-5
 [Wed Oct 27 20:28:46 2021] Hardware name: LENOVO 20GG001KUS/20GG001KUS,
 BIOS N1LET90W (1.90 ) 11/11/2020
 [Wed Oct 27 20:28:46 2021] Call Trace:
 [Wed Oct 27 20:28:46 2021]  dump_stack+0x6b/0x83
 [Wed Oct 27 20:28:46 2021]  slab_err+0xb7/0xdc
 [Wed Oct 27 20:28:46 2021]  ? kernel_poison_pages+0xc0/0xc0
 [Wed Oct 27 20:28:46 2021]  ? slub_cpu_dead+0xa0/0xa0
 [Wed Oct 27 20:28:46 2021]  __kmem_cache_shutdown.cold+0x31/0xfe
 [Wed Oct 27 20:28:46 2021]  kmem_cache_destroy+0x53/0x110
 [Wed Oct 27 20:28:46 2021]  fuse_exit+0x29/0x2e [fuse]
 [Wed Oct 27 20:28:46 2021]  __do_sys_delete_module+0x190/0x300
 [Wed Oct 27 20:28:46 2021]  do_syscall_64+0x33/0x80
 [Wed Oct 27 20:28:46 2021]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
 [Wed Oct 27 20:28:46 2021] RIP: 0033:0x7f5d534887d7
 [Wed Oct 27 20:28:46 2021] Code: 73 01 c3 48 8b 0d b9 f6 0b 00 f7 d8 64 89
 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00
 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 89 f6 0b 00 f7 d8 64 89 01
 48
 [Wed Oct 27 20:28:46 2021] RSP: 002b:00007ffecd151eb8 EFLAGS: 00000206
 ORIG_RAX: 00000000000000b0
 [Wed Oct 27 20:28:46 2021] RAX: ffffffffffffffda RBX: 000055ca8f2b0760
 RCX: 00007f5d534887d7
 [Wed Oct 27 20:28:46 2021] RDX: 000055ca8f2b0860 RSI: 0000000000000a00
 RDI: 000055ca8f2b07c8
 [Wed Oct 27 20:28:46 2021] RBP: 0000000000000200 R08: 000055ca8f2b07e0
 R09: 00007f5d53548be0
 [Wed Oct 27 20:28:46 2021] R10: 000055ca8f2b1760 R11: 0000000000000206
 R12: 00007ffecd1520e8
 [Wed Oct 27 20:28:46 2021] R13: 00007ffecd1528d9 R14: 000055ca8f2b02a0
 R15: 000055ca8f2b0760
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000a4069606 @offset=0
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000db760b9f @offset=832
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000004fbcb2d4 @offset=1664
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x0000000054e6106f @offset=2496
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000003ecd50ed @offset=3328
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000004d60ea7b @offset=4160
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000006e39884a @offset=5824
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000006e5e8a15 @offset=6656
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000738d55e2 @offset=7488
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x0000000042644689 @offset=8320
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x0000000020afe7b0 @offset=9152
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000db14db06 @offset=9984
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000f5e6ea8a @offset=10816
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000000db8fe50 @offset=11648
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000000542a9e5 @offset=12480
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x0000000037060d99 @offset=13312
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x000000007503a134 @offset=14144
 [Wed Oct 27 20:28:46 2021] INFO: Object 0x00000000dbc4ef19 @offset=14976
 }}}

 After that the system is mostly unusable:

 {{{
 $ sudo sync ; echo $?
 Killed
 137
 }}}

 Not sure if it is directly related to the fuse egg (probably not), but
 apparently the egg causes process that use it to go into a weird state.  I
 suppose trying to remove the kernel module when such processes are running
 triggers some edge case in the kernel code, which leads to that kernel
 backtrace.

 Just in case, I've added the fuse egg to the skip list of salmonella tests
 for they time being, as once they hang they cannot be killed.

-- 
Ticket URL: <https://bugs.call-cc.org/ticket/1775#comment:3>
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