int uvm_pager_put(struct uvm_object *uobj, struct vm_page *pg, struct vm_page ***ppsp_ptr, int *npages, int flags, voff_t start, voff_t stop) { int result; daddr_t swblk; struct vm_page **ppsp = *ppsp_ptr; /* * note that uobj is null if we are doing a swap-backed pageout. * note that uobj is !null if we are doing normal object pageout. * note that the page queues must be locked to cluster. */ if (uobj) { /* if !swap-backed */ /* * attempt to build a cluster for pageout using its * make-put-cluster function (if it has one). */ if (uobj->pgops->pgo_mk_pcluster) { ppsp = uobj->pgops->pgo_mk_pcluster(uobj, ppsp, npages, pg, flags, start, stop); *ppsp_ptr = ppsp; /* update caller's pointer */ } else { ppsp[0] = pg; *npages = 1; } swblk = 0; /* XXX: keep gcc happy */ } else { /* * for swap-backed pageout, the caller (the pagedaemon) has * already built the cluster for us. the starting swap * block we are writing to has been passed in as "start." * "pg" could be NULL if there is no page we are especially * interested in (in which case the whole cluster gets dropped * in the event of an error or a sync "done"). */ swblk = start; /* ppsp and npages should be ok */ } /* now that we've clustered we can unlock the page queues */ uvm_unlock_pageq(); /* * now attempt the I/O. if we have a failure and we are * clustered, we will drop the cluster and try again. */ ReTry: if (uobj) { /* object is locked */ result = uobj->pgops->pgo_put(uobj, ppsp, *npages, flags); /* object is now unlocked */ } else { /* nothing locked */ /* XXX daddr_t -> int */ result = uvm_swap_put(swblk, ppsp, *npages, flags); /* nothing locked */ } /* * we have attempted the I/O. * * if the I/O was a success then: * if !PGO_PDFREECLUST, we return the cluster to the * caller (who must un-busy all pages) * else we un-busy cluster pages for the pagedaemon * * if I/O is pending (async i/o) then we return the pending code. * [in this case the async i/o done function must clean up when * i/o is done...] */ if (result == VM_PAGER_PEND || result == VM_PAGER_OK) { if (result == VM_PAGER_OK && (flags & PGO_PDFREECLUST)) { /* * drop cluster and relock object (only if I/O is * not pending) */ if (uobj) /* required for dropcluster */ mtx_enter(&uobj->vmobjlock); if (*npages > 1 || pg == NULL) uvm_pager_dropcluster(uobj, pg, ppsp, npages, PGO_PDFREECLUST); /* if (uobj): object still locked, as per * return-state item #3 */ } return (result); } /* * a pager error occured (even after dropping the cluster, if there * was one). give up! the caller only has one page ("pg") * to worry about. */ if (*npages > 1 || pg == NULL) { if (uobj) { mtx_enter(&uobj->vmobjlock); } uvm_pager_dropcluster(uobj, pg, ppsp, npages, PGO_REALLOCSWAP); /* * for failed swap-backed pageouts with a "pg", * we need to reset pg's swslot to either: * "swblk" (for transient errors, so we can retry), * or 0 (for hard errors). */ if (uobj == NULL && pg != NULL) { /* XXX daddr_t -> int */ int nswblk = (result == VM_PAGER_AGAIN) ? swblk : 0; if (pg->pg_flags & PQ_ANON) { mtx_enter(&pg->uanon->an_lock); pg->uanon->an_swslot = nswblk; mtx_leave(&pg->uanon->an_lock); } else { mtx_enter(&pg->uobject->vmobjlock); uao_set_swslot(pg->uobject, pg->offset >> PAGE_SHIFT, nswblk); mtx_leave(&pg->uobject->vmobjlock); } } if (result == VM_PAGER_AGAIN) { /* * for transient failures, free all the swslots that * we're not going to retry with. */ if (uobj == NULL) { if (pg) { /* XXX daddr_t -> int */ uvm_swap_free(swblk + 1, *npages - 1); } else { /* XXX daddr_t -> int */ uvm_swap_free(swblk, *npages); } } if (pg) { ppsp[0] = pg; *npages = 1; goto ReTry; } } else if (uobj == NULL) { /* * for hard errors on swap-backed pageouts, * mark the swslots as bad. note that we do not * free swslots that we mark bad. */ /* XXX daddr_t -> int */ uvm_swap_markbad(swblk, *npages); } if (uobj) mtx_leave(&uobj->vmobjlock); }
int uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, struct vm_anon *anon) { boolean_t we_own; /* we own anon's page? */ boolean_t locked; /* did we relock? */ struct vm_page *pg; int result; result = 0; /* XXX shut up gcc */ uvmexp.fltanget++; /* bump rusage counters */ if (anon->an_page) curproc->p_ru.ru_minflt++; else curproc->p_ru.ru_majflt++; /* * loop until we get it, or fail. */ while (1) { we_own = FALSE; /* TRUE if we set PG_BUSY on a page */ pg = anon->an_page; /* * if there is a resident page and it is loaned, then anon * may not own it. call out to uvm_anon_lockpage() to ensure * the real owner of the page has been identified and locked. */ if (pg && pg->loan_count) pg = uvm_anon_lockloanpg(anon); /* * page there? make sure it is not busy/released. */ if (pg) { /* * at this point, if the page has a uobject [meaning * we have it on loan], then that uobject is locked * by us! if the page is busy, we drop all the * locks (including uobject) and try again. */ if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0) { return (VM_PAGER_OK); } atomic_setbits_int(&pg->pg_flags, PG_WANTED); uvmexp.fltpgwait++; /* * the last unlock must be an atomic unlock+wait on * the owner of page */ if (pg->uobject) { /* owner is uobject ? */ uvmfault_unlockall(ufi, amap, NULL, anon); UVM_UNLOCK_AND_WAIT(pg, &pg->uobject->vmobjlock, FALSE, "anonget1",0); } else { /* anon owns page */ uvmfault_unlockall(ufi, amap, NULL, NULL); UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0, "anonget2",0); } /* ready to relock and try again */ } else { /* * no page, we must try and bring it in. */ pg = uvm_pagealloc(NULL, 0, anon, 0); if (pg == NULL) { /* out of RAM. */ uvmfault_unlockall(ufi, amap, NULL, anon); uvmexp.fltnoram++; uvm_wait("flt_noram1"); /* ready to relock and try again */ } else { /* we set the PG_BUSY bit */ we_own = TRUE; uvmfault_unlockall(ufi, amap, NULL, anon); /* * we are passing a PG_BUSY+PG_FAKE+PG_CLEAN * page into the uvm_swap_get function with * all data structures unlocked. note that * it is ok to read an_swslot here because * we hold PG_BUSY on the page. */ uvmexp.pageins++; result = uvm_swap_get(pg, anon->an_swslot, PGO_SYNCIO); /* * we clean up after the i/o below in the * "we_own" case */ /* ready to relock and try again */ } } /* * now relock and try again */ locked = uvmfault_relock(ufi); if (locked || we_own) simple_lock(&anon->an_lock); /* * if we own the page (i.e. we set PG_BUSY), then we need * to clean up after the I/O. there are three cases to * consider: * [1] page released during I/O: free anon and ReFault. * [2] I/O not OK. free the page and cause the fault * to fail. * [3] I/O OK! activate the page and sync with the * non-we_own case (i.e. drop anon lock if not locked). */ if (we_own) { if (pg->pg_flags & PG_WANTED) { /* still holding object lock */ wakeup(pg); } /* un-busy! */ atomic_clearbits_int(&pg->pg_flags, PG_WANTED|PG_BUSY|PG_FAKE); UVM_PAGE_OWN(pg, NULL); /* * if we were RELEASED during I/O, then our anon is * no longer part of an amap. we need to free the * anon and try again. */ if (pg->pg_flags & PG_RELEASED) { pmap_page_protect(pg, VM_PROT_NONE); simple_unlock(&anon->an_lock); uvm_anfree(anon); /* frees page for us */ if (locked) uvmfault_unlockall(ufi, amap, NULL, NULL); uvmexp.fltpgrele++; return (VM_PAGER_REFAULT); /* refault! */ } if (result != VM_PAGER_OK) { KASSERT(result != VM_PAGER_PEND); /* remove page from anon */ anon->an_page = NULL; /* * remove the swap slot from the anon * and mark the anon as having no real slot. * don't free the swap slot, thus preventing * it from being used again. */ uvm_swap_markbad(anon->an_swslot, 1); anon->an_swslot = SWSLOT_BAD; /* * note: page was never !PG_BUSY, so it * can't be mapped and thus no need to * pmap_page_protect it... */ uvm_lock_pageq(); uvm_pagefree(pg); uvm_unlock_pageq(); if (locked) uvmfault_unlockall(ufi, amap, NULL, anon); else simple_unlock(&anon->an_lock); return (VM_PAGER_ERROR); } /* * must be OK, clear modify (already PG_CLEAN) * and activate */ pmap_clear_modify(pg); uvm_lock_pageq(); uvm_pageactivate(pg); uvm_unlock_pageq(); if (!locked) simple_unlock(&anon->an_lock); } /* * we were not able to relock. restart fault. */ if (!locked) return (VM_PAGER_REFAULT); /* * verify no one has touched the amap and moved the anon on us. */ if (ufi != NULL && amap_lookup(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start) != anon) { uvmfault_unlockall(ufi, amap, NULL, anon); return (VM_PAGER_REFAULT); } /* * try it again! */ uvmexp.fltanretry++; continue; } /* while (1) */ /*NOTREACHED*/ }