Re: panic: mutex Giant owned at nfs_syscalls.c:556

On 03/03/2008, Kostik Belousov <kostikbel_at_gmail.com> wrote:
[snip]
>  To summarize, I need both the tcpdump and kernel/witness messages from
>  the panic.
>

I'm sorry. Here it is.
http://pluknet.nm.ru/dev/tcpdump-nfsserver-full.raw

The messages (same as unread msgbuf in initial posting, hand-scribed):
panic: mutex Giant owned at
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_syscalls.c:556
KDB: enter: panic
[thread pid 601 tid 100055 ]
Stopped at kdb_enter+0x3a: movl $0,kdb_why
db> show locks
exclusive sleep mutex nfsd_mtx r = 0 (0xc2e0af40) locked _at_
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_syscalls.c:501
exclusive sleep mutex Giant r = 0 (0xc07e6410) locked _at_
/usr/src/sys/kern/vfs_lookup.c:663

>  Nevertheless, the patch below might help with the panic during
>  the unlinking (not tested).
>
>  diff --git a/sys/nfsserver/nfs_serv.c b/sys/nfsserver/nfs_serv.c
>  index 446651d..87e1aaa 100644
>  --- a/sys/nfsserver/nfs_serv.c
>  +++ b/sys/nfsserver/nfs_serv.c
>  _at__at_ -2146,7 +2146,7 _at__at_ nfsrv_remove(struct nfsrv_descript *nfsd, struct nfssvc_sock *slp,
>         nfsfh_t nfh;
>         fhandle_t *fhp;
>         struct mount *mp = NULL;
>  -       int vfslocked;
>  +       int vfslocked, vfslocked1;
>
>         nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
>         ndclear(&nd);
>  _at__at_ -2168,7 +2168,11 _at__at_ nfsrv_remove(struct nfsrv_descript *nfsd, struct nfssvc_sock *slp,
>         nd.ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF | MPSAFE;
>         error = nfs_namei(&nd, fhp, len, slp, nam, &md, &dpos,
>                 &dirp, v3,  &dirfor, &dirfor_ret, td, FALSE);
>  -       vfslocked = NDHASGIANT(&nd);
>  +       vfslocked1 = NDHASGIANT(&nd);
>  +       if (vfslocked && vfslocked1)
>  +               VFS_UNLOCK_GIANT(vfslocked1);
>  +       if (vfslocked || vfslocked1)
>  +               vfslocked = 1;
>         if (dirp && !v3) {
>                 vrele(dirp);
>                 dirp = NULL;
>
>

Now the last lock triplex looks like:
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2161
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 1106
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 673
vfslocked unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 916
vfslocked1 unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2173
^^^
vfslocked unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2238

And no panic. Thanks.

wbr,
pluknet