On Tue, May 31, 2022 at 04:40:32PM +0200, Martin Pieuchot wrote:
> Any of you got the chance to try this diff? Could you reproduce the
> panic with it?
With this diff I could build a release. It worked twice.
Usually it crashes after a day. This time it finished release after
30 hours.
bluhm
> > Index: uvm/uvm_vnode.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_vnode.c,v
> > retrieving revision 1.124
> > diff -u -p -r1.124 uvm_vnode.c
> > --- uvm/uvm_vnode.c 3 May 2022 21:20:35 -0000 1.124
> > +++ uvm/uvm_vnode.c 20 May 2022 09:04:08 -0000
> > @@ -162,12 +162,9 @@ uvn_attach(struct vnode *vp, vm_prot_t a
> > * add it to the writeable list, and then return.
> > */
> > if (uvn->u_flags & UVM_VNODE_VALID) { /* already active? */
> > + KASSERT(uvn->u_obj.uo_refs > 0);
> >
> > rw_enter(uvn->u_obj.vmobjlock, RW_WRITE);
> > - /* regain vref if we were persisting */
> > - if (uvn->u_obj.uo_refs == 0) {
> > - vref(vp);
> > - }
> > uvn->u_obj.uo_refs++; /* bump uvn ref! */
> > rw_exit(uvn->u_obj.vmobjlock);
> >
> > @@ -234,7 +231,7 @@ uvn_attach(struct vnode *vp, vm_prot_t a
> > KASSERT(uvn->u_obj.uo_refs == 0);
> > uvn->u_obj.uo_refs++;
> > oldflags = uvn->u_flags;
> > - uvn->u_flags = UVM_VNODE_VALID|UVM_VNODE_CANPERSIST;
> > + uvn->u_flags = UVM_VNODE_VALID;
> > uvn->u_nio = 0;
> > uvn->u_size = used_vnode_size;
> >
> > @@ -247,7 +244,7 @@ uvn_attach(struct vnode *vp, vm_prot_t a
> > /*
> > * add a reference to the vnode. this reference will stay as long
> > * as there is a valid mapping of the vnode. dropped when the
> > - * reference count goes to zero [and we either free or persist].
> > + * reference count goes to zero.
> > */
> > vref(vp);
> > if (oldflags & UVM_VNODE_WANTED)
> > @@ -320,16 +317,6 @@ uvn_detach(struct uvm_object *uobj)
> > */
> > vp->v_flag &= ~VTEXT;
> >
> > - /*
> > - * we just dropped the last reference to the uvn. see if we can
> > - * let it "stick around".
> > - */
> > - if (uvn->u_flags & UVM_VNODE_CANPERSIST) {
> > - /* won't block */
> > - uvn_flush(uobj, 0, 0, PGO_DEACTIVATE|PGO_ALLPAGES);
> > - goto out;
> > - }
> > -
> > /* its a goner! */
> > uvn->u_flags |= UVM_VNODE_DYING;
> >
> > @@ -379,7 +366,6 @@ uvn_detach(struct uvm_object *uobj)
> > /* wake up any sleepers */
> > if (oldflags & UVM_VNODE_WANTED)
> > wakeup(uvn);
> > -out:
> > rw_exit(uobj->vmobjlock);
> >
> > /* drop our reference to the vnode. */
> > @@ -495,8 +481,8 @@ uvm_vnp_terminate(struct vnode *vp)
> > }
> >
> > /*
> > - * done. now we free the uvn if its reference count is zero
> > - * (true if we are zapping a persisting uvn). however, if we are
> > + * done. now we free the uvn if its reference count is zero.
> > + * however, if we are
> > * terminating a uvn with active mappings we let it live ... future
> > * calls down to the vnode layer will fail.
> > */
> > @@ -504,14 +490,14 @@ uvm_vnp_terminate(struct vnode *vp)
> > if (uvn->u_obj.uo_refs) {
> > /*
> > * uvn must live on it is dead-vnode state until all references
> > - * are gone. restore flags. clear CANPERSIST state.
> > + * are gone. restore flags.
> > */
> > uvn->u_flags &= ~(UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED|
> > - UVM_VNODE_WANTED|UVM_VNODE_CANPERSIST);
> > + UVM_VNODE_WANTED);
> > } else {
> > /*
> > * free the uvn now. note that the vref reference is already
> > - * gone [it is dropped when we enter the persist state].
> > + * gone.
> > */
> > if (uvn->u_flags & UVM_VNODE_IOSYNCWANTED)
> > panic("uvm_vnp_terminate: io sync wanted bit set");
> > @@ -1350,46 +1336,14 @@ uvm_vnp_uncache(struct vnode *vp)
> > }
> >
> > /*
> > - * we have a valid, non-blocked uvn. clear persist flag.
> > + * we have a valid, non-blocked uvn.
> > * if uvn is currently active we can return now.
> > */
> > - uvn->u_flags &= ~UVM_VNODE_CANPERSIST;
> > if (uvn->u_obj.uo_refs) {
> > rw_exit(uobj->vmobjlock);
> > return FALSE;
> > }
> >
> > - /*
> > - * uvn is currently persisting! we have to gain a reference to
> > - * it so that we can call uvn_detach to kill the uvn.
> > - */
> > - vref(vp); /* seems ok, even with VOP_LOCK */
> > - uvn->u_obj.uo_refs++; /* value is now 1 */
> > - rw_exit(uobj->vmobjlock);
> > -
> > -#ifdef VFSLCKDEBUG
> > - /*
> > - * carry over sanity check from old vnode pager: the vnode should
> > - * be VOP_LOCK'd, and we confirm it here.
> > - */
> > - if ((vp->v_flag & VLOCKSWORK) && !VOP_ISLOCKED(vp))
> > - panic("uvm_vnp_uncache: vnode not locked!");
> > -#endif
> > -
> > - /*
> > - * now drop our reference to the vnode. if we have the sole
> > - * reference to the vnode then this will cause it to die [as we
> > - * just cleared the persist flag]. we have to unlock the vnode
> > - * while we are doing this as it may trigger I/O.
> > - *
> > - * XXX: it might be possible for uvn to get reclaimed while we are
> > - * unlocked causing us to return TRUE when we should not. we ignore
> > - * this as a false-positive return value doesn't hurt us.
> > - */
> > - VOP_UNLOCK(vp);
> > - uvn_detach(&uvn->u_obj);
> > - vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
> > -
> > return TRUE;
> > }
> >
> > @@ -1491,11 +1445,9 @@ uvm_vnp_sync(struct mount *mp)
> > }
> >
> > /*
> > - * gain reference. watch out for persisting uvns (need to
> > - * regain vnode REF).
> > + * gain reference.
> > */
> > - if (uvn->u_obj.uo_refs == 0)
> > - vref(vp);
> > + KASSERT(uvn->u_obj.uo_refs > 0);
> > uvn->u_obj.uo_refs++;
> > rw_exit(uvn->u_obj.vmobjlock);
> >
> >
