Re: panic: LK_RETRY set with incompatible flags

On 4 February 2013 16:13, Sergey Kandaurov <pluknet_at_gmail.com> wrote:
> On 4 February 2013 16:06, Andriy Gapon <avg_at_freebsd.org> wrote:
>> on 04/02/2013 13:49 Sergey Kandaurov said the following:
>>> Hi, Rick! Here is the requested info regarding witness, and a bit more.
>>> The triggered KASSERT is now different though.
>>
>> It's exactly the same problem though :-)
>> Do you have a crashdump?
>> If yes, please print **vpp.
>
> Yep, but it's in a bad form :(
> It has many bits optimized out (compiled with clang).
> I'll rebuild the kernel with -O or so and will try again.
>
> #8  0xffffffff808bc4ce in kdb_enter (why=0xffffffff80e7ed99 "panic",
>     msg=<value optimized out>) at cpufunc.h:63
> #9  0xffffffff80888fb7 in vpanic (fmt=<value optimized out>,
>     ap=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:746
> #10 0xffffffff80888e66 in kassert_panic (fmt=<value optimized out>)
>     at /usr/src/sys/kern/kern_shutdown.c:641
> #11 0xffffffff808d2259 in witness_checkorder (lock=0xfffffe00a1b44240,
> ---Type <return> to continue, or q <return> to quit---
>     flags=1,
>     file=0xffffffff81b2bb36
> "/usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c",
> line=1452,
>     interlock=<value optimized out>) at /usr/src/sys/kern/subr_witness.c:1122
> #12 0xffffffff8086c11e in __lockmgr_args (lk=0xfffffe00a1b44240,
>     flags=<value optimized out>, ilk=0xfffffe00a1b44270,
>     wmesg=0xffffffff81b2808d "zfs", pri=96, timo=51,
>     file=0xffffffff80e8e407 "/usr/src/sys/kern/vfs_default.c", line=0)
>     at /usr/src/sys/kern/kern_lock.c:511
> #13 0xffffffff8091439c in vop_stdlock (ap=<value optimized out>)
>     at lockmgr.h:97
> #14 0xffffffff80cb70c0 in VOP_LOCK1_APV (vop=<value optimized out>,
>     a=<value optimized out>) at vnode_if.c:2022
> #15 0xffffffff80932fbb in _vn_lock (vp=0xfffffe00a1b441d8,
>     flags=<value optimized out>,
>     file=0xffffffff81b2bb36
> "/usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c",
> line=1452) at vnode_if.h:859
> #16 0xffffffff81abd902 in zfs_lookup ()
>     at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:1452
> #17 0xffffffff81abdc1d in zfs_freebsd_lookup (ap=0xffffff848e6c0270)
>     at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:5864
> ---Type <return> to continue, or q <return> to quit---
> #18 0xffffffff80cb51b2 in VOP_CACHEDLOOKUP_APV (vop=<value optimized out>,
>     a=<value optimized out>) at vnode_if.c:191
> #19 0xffffffff8091177f in vfs_cache_lookup (ap=<value optimized out>)
>     at vnode_if.h:80
> #20 0xffffffff80cb50a2 in VOP_LOOKUP_APV (vop=<value optimized out>,
>     a=<value optimized out>) at vnode_if.c:125
> #21 0xffffffff80919658 in lookup (ndp=0xffffff848e6c05d8) at vnode_if.h:54
> #22 0xffffffff807dffe5 in nfsvno_namei (nd=0xffffff848e6c08c8,
>     ndp=0xffffff848e6c05d8, dp=<value optimized out>,
>     islocked=<value optimized out>, exp=<value optimized out>,
>     p=<value optimized out>, retdirp=<value optimized out>)
>     at /usr/src/sys/fs/nfsserver/nfs_nfsdport.c:413
> #23 0xffffffff807d8ffa in nfsrvd_lookup (nd=0xffffff848e6c08c8,
>     isdgram=<value optimized out>, dp=0xfffffe00a1b441d8,
>     vpp=0xffffff848e6c0810, fhp=0xffffff848e6c07f4, p=0xfffffe00a1198000,
>     exp=0xffffff848e6c07a0) at /usr/src/sys/fs/nfsserver/nfs_nfsdserv.c:517
> #24 0xffffffff807cb845 in nfsrvd_dorpc (nd=0xffffff848e6c08c8, isdgram=0,
>     p=0xfffffe00a1198000) at /usr/src/sys/fs/nfsserver/nfs_nfsdsocket.c:823
> #25 0xffffffff807d7af2 in nfssvc_program (rqst=0xfffffe00a17bb000,
>     xprt=0xfffffe00a124b200) at /usr/src/sys/fs/nfsserver/nfs_nfsdkrpc.c:347
> #26 0xffffffff80a70659 in svc_run_internal (pool=0xfffffe00067db600,
>     ismaster=0) at /usr/src/sys/rpc/svc.c:895
> #27 0xffffffff80a7155b in svc_thread_start (arg=0xffffff848e6bfc50)
> ---Type <return> to continue, or q <return> to quit---
>     at /usr/src/sys/rpc/svc.c:1200
> #28 0xffffffff80858944 in fork_exit (
>     callout=0xffffffff80a71550 <svc_thread_start>, arg=0xfffffe00067db600,
>     frame=0xffffff848e6c0c00) at /usr/src/sys/kern/kern_fork.c:991
> #29 0xffffffff80bfa86e in fork_trampoline () at exception.S:602
> #30 0x0000000000000080 in ?? ()
> #31 0x00007fffffffd820 in ?? ()
> #32 0x0000000000000001 in ?? ()
> #33 0x0000000000000000 in ?? ()
> Current language:  auto; currently minimal
>
> (kgdb) p vpp
> Cannot access memory at address 0x0
> (kgdb) p dvp
> Cannot access memory at address 0x0
>

That was from f 16. And as Andriy suggested in private (thanks Andriy!)
those pointers could be reached from ap in f 17.
On the other hand, zfs_lookup() is large, and *vpp might be
rewritten several times there. Here it is:

(kgdb) f 17
#17 0xffffffff81abdc1d in zfs_freebsd_lookup (ap=0xffffff848e6c0270)
    at /usr/src/sys/modules/zfs/../../cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c:5864
5864            return (zfs_lookup(ap->a_dvp, nm, ap->a_vpp, cnp,
cnp->cn_nameiop,
(kgdb) p ap->a_vpp
$4 = (struct vnode **) 0xffffff848e6c0618
(kgdb) p *ap->a_vpp
$5 = (struct vnode *) 0xfffffe00a1b441d8
(kgdb) p **ap->a_vpp
$6 = {v_tag = 0xffffffff81b2808d "zfs", v_op = 0xffffffff81b35808,
  v_data = 0xfffffe00a188f000, v_mount = 0xfffffe0015a5f000, v_nmntvnodes = {
    tqe_next = 0xfffffe00a1b44000, tqe_prev = 0xfffffe00a1b443d0}, v_un = {
    vu_mount = 0x0, vu_socket = 0x0, vu_cdev = 0x0, vu_fifoinfo = 0x0},
  v_hashlist = {le_next = 0x0, le_prev = 0x0}, v_cache_src = {lh_first = 0x0},
  v_cache_dst = {tqh_first = 0x0, tqh_last = 0xfffffe00a1b44228},
  v_cache_dd = 0x0, v_lock = {lock_object = {
      lo_name = 0xffffffff81b2808d "zfs", lo_flags = 91947008, lo_data = 0,
      lo_witness = 0xffffff80006d2700}, lk_lock = 18446741877389099008,
    lk_exslpfail = 0, lk_timo = 51, lk_pri = 96}, v_interlock = {
    lock_object = {lo_name = 0xffffffff80e873f0 "vnode interlock",
      lo_flags = 16973824, lo_data = 0, lo_witness = 0xffffff80006c9600},
    mtx_lock = 4}, v_vnlock = 0xfffffe00a1b44240, v_actfreelist = {
    tqe_next = 0xfffffe000bd363b0, tqe_prev = 0xfffffe0015a5f078}, v_bufobj = {
    bo_mtx = {lock_object = {lo_name = 0xffffffff80e8f3d5 "bufobj interlock",
        lo_flags = 16973824, lo_data = 0, lo_witness = 0xffffff80006d0580},
      mtx_lock = 4}, bo_ops = 0xffffffff8121cc30,
    bo_object = 0xfffffe00a1872780, bo_synclist = {le_next = 0x0,
      le_prev = 0x0}, bo_private = 0xfffffe00a1b441d8,
    __bo_vnode = 0xfffffe00a1b441d8, bo_clean = {bv_hd = {tqh_first = 0x0,
        tqh_last = 0xfffffe00a1b442f8}, bv_root = 0x0, bv_cnt = 0},
    bo_dirty = {bv_hd = {tqh_first = 0x0, tqh_last = 0xfffffe00a1b44318},
      bv_root = 0x0, bv_cnt = 0}, bo_numoutput = 0, bo_flag = 0,
---Type <return> to continue, or q <return> to quit---
    bo_bsize = 131072}, v_pollinfo = 0x0, v_label = 0x0, v_lockf = 0x0,
  v_rl = {rl_waiters = {tqh_first = 0x0, tqh_last = 0xfffffe00a1b44360},
    rl_currdep = 0x0}, v_cstart = 0, v_lasta = 0, v_lastw = 0, v_clen = 0,
  v_holdcnt = 4, v_usecount = 4, v_iflag = 512, v_vflag = 0, v_writecount = 0,
  v_hash = 10597441, v_type = VDIR}

Anyway, new kernel is almost ready. Stay tuned :).

-- 
wbr,
pluknet