NFS Mbuf malloc(M_WAITOK) with locks held

Hi all,

I'm seeing the following two code paths leading to a malloc with locks
held on a 5.3-BETA2 machine which is both an NFS server and an NFS
client...

malloc(M_WAITOK) of "Mbuf", forcing M_NOWAIT with the following non-sleepable locks held:
exclusive sleep mutex nfsd_mtx r = 0 (0xc08eed00) locked _at_ /usr/src/sys/nfsserver/nfs_srvsock.c:712
KDB: stack backtrace:
kdb_backtrace(1,1,1,1a,c101fb00) at kdb_backtrace+0x29
witness_warn(5,0,c0809b40,c07ef018,0) at witness_warn+0x19a
uma_zalloc_arg(c101fb00,dc799bec,2) at uma_zalloc_arg+0x41
nfsm_disct(dc799c38,dc799c3c,28,0,c1d38c00) at nfsm_disct+0xa2
nfsm_dissect_xx(28,dc799c38,dc799c3c) at nfsm_dissect_xx+0x31
nfs_getreq(c2a88e00,c1881000,1,c08eed00,0) at nfs_getreq+0x49
nfsrv_dorec(c1acb300,c1881000,dc799cac,dc799ca4,0) at nfsrv_dorec+0xc3
nfssvc_nfsd(c16336e0,c07efaa5,121,c175406c,c1754000) at nfssvc_nfsd+0x1df
nfssvc(c16336e0,dc799d14,2,0,296) at nfssvc+0x18c
syscall(2f,2f,2f,bfbfeec4,4) at syscall+0x217
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (155, FreeBSD ELF32, nfssvc), eip = 0x280cbb87, esp = 0xbfbfeb1c, ebp = 0xbfbfeb38 ---

and

malloc(M_WAITOK) of "Mbuf", forcing M_NOWAIT with the following non-sleepable locks held:
exclusive sleep mutex nfsd_mtx r = 0 (0xc08eed00) locked _at_ /usr/src/sys/nfsserver/nfs_serv.c:1103
KDB: stack backtrace:
kdb_backtrace(1,1,1,d,c101fb00) at kdb_backtrace+0x29
witness_warn(5,0,c0809b40,c07ef018,dc799a2c) at witness_warn+0x19a
uma_zalloc_arg(c101fb00,dc799a3c,2) at uma_zalloc_arg+0x41
nfsm_disct(dc799ac4,dc799ac8,14,d,46) at nfsm_disct+0xa2
nfsm_dissect_xx(14,dc799ac4,dc799ac8) at nfsm_dissect_xx+0x31
nfsrv_write(c1915d00,c1acb300,c16336e0,dc799ca8,dc799ca4) at
nfsrv_write+0x1e2
nfssvc_nfsd(c16336e0,c07efaa5,121,c175406c,c1754000) at nfssvc_nfsd+0x3d5
nfssvc(c16336e0,dc799d14,2,0,296) at nfssvc+0x18c
syscall(2f,2f,2f,bfbfeec4,4) at syscall+0x217
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (155, FreeBSD ELF32, nfssvc), eip = 0x280cbb87, esp = 0xbfbfeb1c, ebp = 0xbfbfeb38 ---

/usr/src/sys/nfsserver/nfs_serv.c:
     $FreeBSD: src/sys/nfsserver/nfs_serv.c,v 1.147 2004/06/17 17:16:52 phk Exp $
/usr/src/sys/nfsserver/nfs_srvsock.c:
     $FreeBSD: src/sys/nfsserver/nfs_srvsock.c,v 1.92 2004/07/24 02:07:09

While some locking related changes went into nfs_serv.c 1.148, as far as I
can see they don't affect the code path I'm seeing (and only touched Giant
locking, whereas I'm seeing issues relating to nfsd_mtx). Regardless, I'll
take this machine to current RELENG_5 and see if I still see the messages.

Gavin