netbsd-8 hang on tstile

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello
on an up-to-date netbsd-8 Xen3 i386PAE kernel I see hangs on tstile.
Hung processes shows the same pattern, they sleep in fstrans_start():
sleepq_block(0,0,c0596900,c0639b6c,c534e802,40,c03dbcfe,75,c5356340,c534e800) at netbsd:sleepq_block+0xe6
turnstile_block(c59847f0,1,c078b6c0,c0639b6c,de8b9b70,c59847f0,c5db6020,c59a2008,0,c59a2008) at netbsd:turnstile_block+0x29d
mutex_vector_enter(c078b6c0,c0cb8fe0,c055570c,de8b9b84,c05349d7,c575ed04,1,c59a2008,de8b9ba4,c0493ff8) at netbsd:mutex_vector_enter+0x28c
fstrans_start(c59a2008,0,de8b9ba8,10,c055cf2c,c575ed04,20002,20002,c575ed04,0) at netbsd:fstrans_start+0x3b6
VOP_LOCK(c575ed04,20002,22000,0,c03dc2e7,c0746e1a,de8b9d0c,20002,c575ed04,de8b9c88) at netbsd:VOP_LOCK+0x48
vn_lock(c575ed04,20002,4,0,de8b9c14,c03af32d,de8b9edc,3,0,5) at netbsd:vn_lock+0x7f
namei_tryemulroot(0,c012a96a,c532c240,de8b9ce8,c041f909,c532c2b4,de8b9d0c,de8b9d34,0,0) at netbsd:namei_tryemulroot+0x14f
namei(de8b9d0c,1,3,de8b9d10,c042266a,0,c532c240,de8b9d20,c04211d6,0) at netbsd:namei+0x27
check_exec(c5db6020,de8b9dc8,c5f558a8,de8b9da4,9cf21000,de8b9dac,c0114f1a,bad054d0,de8b9ddc,bf7fef58) at netbsd:check_exec+0x40
execve_loadvm(bf7feab8,c03c95a0,de8b9dc8,c5a6f000,c6460c00,c700b008,404,0,0,0) at netbsd:execve_loadvm+0x233
execve1(c5db6020,bf7fef58,bad054d0,bf7feab8,c03c95a0,de8b9f9c,c0113572,c5db6020, de8b9f68,de8b9f60) at netbsd:execve1+0x3c
sys_execve(c5db6020,de8b9f68,de8b9f60,c63d8290,0,c0636ddc,de8b9f68,0,0,bf7fef58) at netbsd:sys_execve+0x31
syscall() at netbsd:syscall+0x82

I guess the culprit is:
2650     1 3   2         0           c5f92a80          python2.7 psrlz
(an anita process, actually)
sleepq_block(1,0,c059af17,c0639f80,c0640804,c5356340,c5358a80,c063f93c,6406c2,c0
59af17) at netbsd:sleepq_block+0x1cd
kpause(c059af17,0,1,0,c5448590,c5cec008,de5e7b5c,c048355a,c5330a28,de5e7b6c) at 
n
etbsd:kpause+0xf2
pserialize_perform(c5330a28,de5e7b6c,c0484a6f,c638e8c0,0,c055cf2c,c5cec008,504,0,de5e7b7c) at netbsd:pserialize_perform+0x10a
fstrans_setstate(c5cec008,0,fffffffe,c0115914,c5cec008,c5cec008,de5e7b94,c047a2c0,c5cec008,2) at netbsd:fstrans_setstate+0x3a
genfs_suspendctl(c5cec008,2,de5e7bb0,de5e7bd4,de5e7bb0,c0483fc4,c5cec008,2,de5e7bd4,de5e7bd4) at netbsd:genfs_suspendctl+0x3a
VFS_SUSPENDCTL(c5cec008,2,de5e7bd4,de5e7bd4,504,de5e7be4,c0486fd6,c5cec008,504,0) at netbsd:VFS_SUSPENDCTL+0x20
vfs_resume(c5cec008,504,0,de5e7bd4,c011599f,4,c5cec008,c5e978e4,c5e978e4,c5f92a80) at netbsd:vfs_resume+0x74
vrevoke(c5e978e4,de5e7c14,c049370a,de5e7c04,0,0,c055d160,c5e978e4,1,0) at netbsd:vrevoke+0x96
genfs_revoke(de5e7c04,0,0,c055d160,c5e978e4,1,0,de5e7cc4,c044dea9,c5e978e4) at netbsd:genfs_revoke+0x1a
VOP_REVOKE(c5e978e4,1,c5353f00,504,0,74,c5e978e4,0,190,ffffffff) at netbsd:VOP_REVOKE+0x4a
pty_grant_slave(c5f92a80,504,0,c5cec008,0,10,c055cf2c,c5c271bc,20002,20002) at netbsd:pty_grant_slave+0xc9
ptmioctl(a501,0,48087446,c6922008,3,c5f92a80,c5f92a80,48087446,c055c260,3) at netbsd:ptmioctl+0xdd
cdev_ioctl(a501,0,48087446,c6922008,3,c5f92a80,a501,c5c271bc,c5c271bc,c5fd22c0) at netbsd:cdev_ioctl+0xd0
spec_ioctl(de5e7da0,c0115914,c5df9bc0,c055d1f0,c5c271bc,48087446,c6922008,3,c5eac9c0,48087446) at netbsd:spec_ioctl+0x90
VOP_IOCTL(c5c271bc,48087446,c6922008,3,c5eac9c0,c5e74380,c6fbe790,fffffffe,c0115914,0) at netbsd:VOP_IOCTL+0x3e
vn_ioctl(c5fd22c0,48087446,c6922008,c5f8eb74,c5fd22c0,ffffffff,ffffffff,0,0,c6922008) at netbsd:vn_ioctl+0x9f
sys_ioctl(c5f92a80,de5e7f68,de5e7f60,c63d8788,0,c0636d78,de5e7f68,0,0,7) at netbsd:sys_ioctl+0x10a
syscall() at netbsd:syscall+0x82

This is reproductible, restarting my automatic test script hangs the same
way. This i plain ffs, no wapbl.

Any idea ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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