On Sat, Jan 02, 2021 at 12:02:23AM +0200, Konstantin Belousov wrote:
> On Fri, Jan 01, 2021 at 06:44:00PM +0000, Alexey Dokuchaev wrote:
> > On Tue, Sep 15, 2020 at 10:19:16PM +0000, Konstantin Belousov wrote:
> > > New Revision: 365787
> > > URL: https://svnweb.freebsd.org/changeset/base/365787
> > >
> > > Log:
> > > Add tmpfs page cache read support.
> > >
> > > Or it could be explained as lockless (for vnode lock) reads. Reads
> > > are performed from the node tn_obj object. Tmpfs regular vnode object
> > > lifecycle is significantly different from the normal OBJT_VNODE: it is
> > > alive as far as ref_count > 0.
> >
> > This causes panics for me when building ports in the tmpfs-backed tinderbox.
> > Easily reproducible:
> >
> > 1) ./tc tinderbuild ... -b "$@"
> > 2) tail -f .../tmp/make.log4 # on the adjacent console
> > 3) wait until the build job finishes
> > 4) ^C in the "tail" window -> crash
>
> What exactly 'crash' is?
The usual "Fatal trap 12: page fault while in kernel mode" panic.
> Provide literal transcription of the kernel messages and not your
> interpretation of them.
Sorry, I've just quickly copied function names off the screen since my
debug symbols did not match the running kernel at that moment and I've
thought maybe it's a known bug that was fixed after r368820. I've now
made things in sync so can provide full context (see below).
> > ...
> > __mtx_lock_sleep() at __mtx_lock_sleep+0xd2/frame 0xfffffe0060636490
> > tmpfs_free_node() at tmpfs_free_node+0xc7/frame 0xfffffe00606364c0
>
> What is the source line for tmpfs_free_node() frame?
/usr/src/crash-dec/sys/fs/tmpfs/tmpfs_subr.c:373
(kgdb) list *(tmpfs_free_node+0xc7)
0xffffffff815246d7 is in tmpfs_free_node
(/usr/src/crash-dec/sys/fs/tmpfs/tmpfs_subr.c:374).
369 {
370 if (refcount_release_if_not_last(&node->tn_refcount))
371 return;
372
373 TMPFS_LOCK(tmp);
374 TMPFS_NODE_LOCK(node);
375 if (!tmpfs_free_node_locked(tmp, node, false)) {
376 TMPFS_NODE_UNLOCK(node);
377 TMPFS_UNLOCK(tmp);
378 }
(kgdb)
./danfe
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