On 17 April 2012 20:28, Kirk McKusick <mckus...@freebsd.org> wrote:
> Author: mckusick
> Date: Tue Apr 17 16:28:22 2012
> New Revision: 234386
> URL: http://svn.freebsd.org/changeset/base/234386
>
> Log:
> Replace the MNT_VNODE_FOREACH interface with MNT_VNODE_FOREACH_ALL.
> The primary changes are that the user of the interface no longer
> needs to manage the mount-mutex locking and that the vnode that
> is returned has its mutex locked (thus avoiding the need to check
> to see if its is DOOMED or other possible end of life senarios).
>
> To minimize compatibility issues for third-party developers, the
> old MNT_VNODE_FOREACH interface will remain available so that this
> change can be MFC'ed to 9. Following the MFC to 9, MNT_VNODE_FOREACH
> will be removed in head.
>
> The reason for this update is to prepare for the addition of the
> MNT_VNODE_FOREACH_ACTIVE interface that will loop over just the
> active vnodes associated with a mount point (typically less than
> 1% of the vnodes associated with the mount point).
>
> Reviewed by: kib
> Tested by: Peter Holm
> MFC after: 2 weeks
>
Hi.
This commit crashes on old nfsclient. Looks like this change is missed.
Index: nfsclient/nfs_vfsops.c
===================================================================
--- nfsclient/nfs_vfsops.c (revision 235051)
+++ nfsclient/nfs_vfsops.c (working copy)
@@ -1452,6 +1452,7 @@
MNT_IUNLOCK(mp);
return (EBADF);
}
+ MNT_IUNLOCK(mp);
/*
* Force stale buffer cache information to be flushed.
[...]
>
> Modified: head/sys/nfsclient/nfs_vfsops.c
> ==============================================================================
> --- head/sys/nfsclient/nfs_vfsops.c Tue Apr 17 14:54:00 2012
> (r234385)
> +++ head/sys/nfsclient/nfs_vfsops.c Tue Apr 17 16:28:22 2012
> (r234386)
> @@ -1457,19 +1457,15 @@ nfs_sync(struct mount *mp, int waitfor)
> * Force stale buffer cache information to be flushed.
> */
> loop:
> - MNT_VNODE_FOREACH(vp, mp, mvp) {
> - VI_LOCK(vp);
> - MNT_IUNLOCK(mp);
> + MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
Now this call results in malloc() and MNT_ILOCK(mp) inside
__mnt_vnode_first_all().
But MNT_ILOCK(mp) is already done few lines above (probably because
its MNT_IUNLOCK() counterpart was missed in this commit?).
[...]
> +struct vnode *
> +__mnt_vnode_first_all(struct vnode **mvp, struct mount *mp)
> +{
> + struct vnode *vp;
> +
To the moment it already holds MNT_ILOCK(mp) from
sys/nfsclient/nfs_vfsops.c:1445
> + *mvp = malloc(sizeof(struct vnode), M_VNODE_MARKER, M_WAITOK |
> M_ZERO);
> + MNT_ILOCK(mp);
> + MNT_REF(mp);
> + (*mvp)->v_type = VMARKER;
> +
> + vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
> + while (vp != NULL && (vp->v_type == VMARKER ||
> + (vp->v_iflag & VI_DOOMED) != 0))
> + vp = TAILQ_NEXT(vp, v_nmntvnodes);
> +
> + /* Check if we are done */
> + if (vp == NULL) {
> + *mvp = NULL;
> + MNT_REL(mp);
> + MNT_IUNLOCK(mp);
> + free(*mvp, M_VNODE_MARKER);
> + return (NULL);
> + }
> + (*mvp)->v_mount = mp;
> + TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, *mvp, v_nmntvnodes);
> + VI_LOCK(vp);
> + MNT_IUNLOCK(mp);
> + return (vp);
> +}
[...]
uma_zalloc_arg: zone "1024" with the following non-sleepable locks held:
exclusive sleep mutex struct mount mtx (struct mount mtx) r = 0
(0xfffffe0002907750) locked @ /usr/src/sys/nfsclient/nfs_vfsops.c:1445
KDB: stack backtrace:
db_trace_self_wrapper() at 0xffffffff802c75aa = db_trace_self_wrapper+0x2a
kdb_backtrace() at 0xffffffff80476547 = kdb_backtrace+0x37
_witness_debugger() at 0xffffffff8048d48c = _witness_debugger+0x2c
witness_warn() at 0xffffffff8048e274 = witness_warn+0x2c4
uma_zalloc_arg() at 0xffffffff8068be24 = uma_zalloc_arg+0x384
malloc() at 0xffffffff80425026 = malloc+0xc6
__mnt_vnode_first_all() at 0xffffffff804dd3f9 = __mnt_vnode_first_all+0x29
nfs_sync() at 0xffffffff805f231d = nfs_sync+0x8d
sys_sync() at 0xffffffff804e8906 = sys_sync+0x146
amd64_syscall() at 0xffffffff806c780c = amd64_syscall+0x38c
Xfast_syscall() at 0xffffffff806b2c47 = Xfast_syscall+0xf7
--- syscall (36, FreeBSD ELF64, sys_sync), rip = 0x800a95a0c, rsp =
0x7fffffffd958, rbp = 0x7fffffffdd50 ---
panic: _mtx_lock_sleep: recursed on non-recursive mutex struct mount
mtx @ /usr/src/sys/kern/vfs_subr.c:4595
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at 0xffffffff802c75aa = db_trace_self_wrapper+0x2a
kdb_backtrace() at 0xffffffff80476547 = kdb_backtrace+0x37
panic() at 0xffffffff8043bc3e = panic+0x1ce
_mtx_lock_sleep() at 0xffffffff80429058 = _mtx_lock_sleep+0x538
_mtx_lock_flags() at 0xffffffff804291e4 = _mtx_lock_flags+0x184
__mnt_vnode_first_all() at 0xffffffff804dd413 = __mnt_vnode_first_all+0x43
nfs_sync() at 0xffffffff805f231d = nfs_sync+0x8d
sys_sync() at 0xffffffff804e8906 = sys_sync+0x146
amd64_syscall() at 0xffffffff806c780c = amd64_syscall+0x38c
Xfast_syscall() at 0xffffffff806b2c47 = Xfast_syscall+0xf7
--- syscall (36, FreeBSD ELF64, sys_sync), rip = 0x800a95a0c, rsp =
0x7fffffffd958, rbp = 0x7fffffffdd50 ---
KDB: enter: panic
[ thread pid 1268 tid 100085 ]
Stopped at 0xffffffff8047620b = kdb_enter+0x3b: movq
$0,0x75d252(%rip)
db>
--
wbr,
pluknet
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