> Date: Mon, 11 Jul 2022 13:33:39 +0200
> From: Martin Pieuchot <[email protected]>
>
> On 28/06/22(Tue) 14:13, Martin Pieuchot wrote:
> > I'd like to abstract the use of PG_WANTED to start unifying & cleaning
> > the various cases where a code path is waiting for a busy page. Here's
> > the first step.
> >
> > ok?
>
> Anyone?
ok kettenis@
> > Index: uvm/uvm_amap.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_amap.c,v
> > retrieving revision 1.90
> > diff -u -p -r1.90 uvm_amap.c
> > --- uvm/uvm_amap.c 30 Aug 2021 16:59:17 -0000 1.90
> > +++ uvm/uvm_amap.c 28 Jun 2022 11:53:08 -0000
> > @@ -781,9 +781,7 @@ ReStart:
> > * it and then restart.
> > */
> > if (pg->pg_flags & PG_BUSY) {
> > - atomic_setbits_int(&pg->pg_flags, PG_WANTED);
> > - rwsleep_nsec(pg, amap->am_lock, PVM | PNORELOCK,
> > - "cownow", INFSLP);
> > + uvm_pagewait(pg, amap->am_lock, "cownow");
> > goto ReStart;
> > }
> >
> > Index: uvm/uvm_aobj.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_aobj.c,v
> > retrieving revision 1.103
> > diff -u -p -r1.103 uvm_aobj.c
> > --- uvm/uvm_aobj.c 29 Dec 2021 20:22:06 -0000 1.103
> > +++ uvm/uvm_aobj.c 28 Jun 2022 11:53:08 -0000
> > @@ -835,9 +835,8 @@ uao_detach(struct uvm_object *uobj)
> > while ((pg = RBT_ROOT(uvm_objtree, &uobj->memt)) != NULL) {
> > pmap_page_protect(pg, PROT_NONE);
> > if (pg->pg_flags & PG_BUSY) {
> > - atomic_setbits_int(&pg->pg_flags, PG_WANTED);
> > - rwsleep_nsec(pg, uobj->vmobjlock, PVM, "uao_det",
> > - INFSLP);
> > + uvm_pagewait(pg, uobj->vmobjlock, "uao_det");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > continue;
> > }
> > uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT);
> > @@ -909,9 +908,8 @@ uao_flush(struct uvm_object *uobj, voff_
> >
> > /* Make sure page is unbusy, else wait for it. */
> > if (pg->pg_flags & PG_BUSY) {
> > - atomic_setbits_int(&pg->pg_flags, PG_WANTED);
> > - rwsleep_nsec(pg, uobj->vmobjlock, PVM, "uaoflsh",
> > - INFSLP);
> > + uvm_pagewait(pg, uobj->vmobjlock, "uaoflsh");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > curoff -= PAGE_SIZE;
> > continue;
> > }
> > @@ -1147,9 +1145,8 @@ uao_get(struct uvm_object *uobj, voff_t
> >
> > /* page is there, see if we need to wait on it */
> > if ((ptmp->pg_flags & PG_BUSY) != 0) {
> > - atomic_setbits_int(&ptmp->pg_flags, PG_WANTED);
> > - rwsleep_nsec(ptmp, uobj->vmobjlock, PVM,
> > - "uao_get", INFSLP);
> > + uvm_pagewait(ptmp, uobj->vmobjlock, "uao_get");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > continue; /* goto top of pps while loop */
> > }
> >
> > Index: uvm/uvm_km.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_km.c,v
> > retrieving revision 1.150
> > diff -u -p -r1.150 uvm_km.c
> > --- uvm/uvm_km.c 7 Jun 2022 12:07:45 -0000 1.150
> > +++ uvm/uvm_km.c 28 Jun 2022 11:53:08 -0000
> > @@ -255,9 +255,8 @@ uvm_km_pgremove(struct uvm_object *uobj,
> > for (curoff = start ; curoff < end ; curoff += PAGE_SIZE) {
> > pp = uvm_pagelookup(uobj, curoff);
> > if (pp && pp->pg_flags & PG_BUSY) {
> > - atomic_setbits_int(&pp->pg_flags, PG_WANTED);
> > - rwsleep_nsec(pp, uobj->vmobjlock, PVM, "km_pgrm",
> > - INFSLP);
> > + uvm_pagewait(pp, uobj->vmobjlock, "km_pgrm");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > curoff -= PAGE_SIZE; /* loop back to us */
> > continue;
> > }
> > Index: uvm/uvm_page.c
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_page.c,v
> > retrieving revision 1.166
> > diff -u -p -r1.166 uvm_page.c
> > --- uvm/uvm_page.c 12 May 2022 12:48:36 -0000 1.166
> > +++ uvm/uvm_page.c 28 Jun 2022 11:57:42 -0000
> > @@ -1087,6 +1087,23 @@ uvm_page_unbusy(struct vm_page **pgs, in
> > }
> > }
> >
> > +/*
> > + * uvm_pagewait: wait for a busy page
> > + *
> > + * => page must be known PG_BUSY
> > + * => object must be locked
> > + * => object will be unlocked on return
> > + */
> > +void
> > +uvm_pagewait(struct vm_page *pg, struct rwlock *lock, const char *wmesg)
> > +{
> > + KASSERT(rw_lock_held(lock));
> > + KASSERT((pg->pg_flags & PG_BUSY) != 0);
> > +
> > + atomic_setbits_int(&pg->pg_flags, PG_WANTED);
> > + rwsleep_nsec(pg, lock, PVM | PNORELOCK, wmesg, INFSLP);
> > +}
> > +
> > #if defined(UVM_PAGE_TRKOWN)
> > /*
> > * uvm_page_own: set or release page ownership
> > Index: uvm/uvm_page.h
> > ===================================================================
> > RCS file: /cvs/src/sys/uvm/uvm_page.h,v
> > retrieving revision 1.68
> > diff -u -p -r1.68 uvm_page.h
> > --- uvm/uvm_page.h 12 May 2022 12:48:36 -0000 1.68
> > +++ uvm/uvm_page.h 28 Jun 2022 11:53:08 -0000
> > @@ -233,7 +233,7 @@ void uvm_pagefree(struct vm_page *);
> > void uvm_page_unbusy(struct vm_page **, int);
> > struct vm_page *uvm_pagelookup(struct uvm_object *, voff_t);
> > void uvm_pageunwire(struct vm_page *);
> > -void uvm_pagewait(struct vm_page *, int);
> > +void uvm_pagewait(struct vm_page *, struct rwlock *, const
> > char *);
> > void uvm_pagewake(struct vm_page *);
> > void uvm_pagewire(struct vm_page *);
> > void uvm_pagezero(struct vm_page *);
> > 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 28 Jun 2022 11:53:08 -0000
> > @@ -684,11 +684,10 @@ uvn_flush(struct uvm_object *uobj, voff_
> > }
> > } else if (flags & PGO_FREE) {
> > if (pp->pg_flags & PG_BUSY) {
> > - atomic_setbits_int(&pp->pg_flags,
> > - PG_WANTED);
> > uvm_unlock_pageq();
> > - rwsleep_nsec(pp, uobj->vmobjlock, PVM,
> > - "uvn_flsh", INFSLP);
> > + uvm_pagewait(pp, uobj->vmobjlock,
> > + "uvn_flsh");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > uvm_lock_pageq();
> > curoff -= PAGE_SIZE;
> > continue;
> > @@ -1054,9 +1053,8 @@ uvn_get(struct uvm_object *uobj, voff_t
> >
> > /* page is there, see if we need to wait on it */
> > if ((ptmp->pg_flags & PG_BUSY) != 0) {
> > - atomic_setbits_int(&ptmp->pg_flags, PG_WANTED);
> > - rwsleep_nsec(ptmp, uobj->vmobjlock, PVM,
> > - "uvn_get", INFSLP);
> > + uvm_pagewait(ptmp, uobj->vmobjlock, "uvn_get");
> > + rw_enter(uobj->vmobjlock, RW_WRITE);
> > continue; /* goto top of pps while loop */
> > }
> >
> >
>
>
