/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2009 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #include #include #include #include #include #include #include #include /* for bzero */ #include #include #include #include /* for NOMEMWAIT() */ #include /* used to update kcage_freemem */ #include /* for kmem_reap */ #include #include #include #include #include #include #include #include #include #include extern pri_t maxclsyspri; #ifdef DEBUG #define KCAGE_STATS #endif #ifdef KCAGE_STATS #define KCAGE_STATS_VERSION 9 /* can help report generators */ #define KCAGE_STATS_NSCANS 256 /* depth of scan statistics buffer */ struct kcage_stats_scan { /* managed by KCAGE_STAT_* macros */ clock_t scan_lbolt; uint_t scan_id; /* set in kcage_cageout() */ uint_t kt_passes; clock_t kt_ticks; pgcnt_t kt_kcage_freemem_start; pgcnt_t kt_kcage_freemem_end; pgcnt_t kt_freemem_start; pgcnt_t kt_freemem_end; uint_t kt_examined; uint_t kt_cantlock; uint_t kt_gotone; uint_t kt_gotonefree; uint_t kt_skiplevel; uint_t kt_skipshared; uint_t kt_skiprefd; uint_t kt_destroy; /* set in kcage_invalidate_page() */ uint_t kip_reloclocked; uint_t kip_relocmod; uint_t kip_destroy; uint_t kip_nomem; uint_t kip_demotefailed; /* set in kcage_expand() */ uint_t ke_wanted; uint_t ke_examined; uint_t ke_lefthole; uint_t ke_gotone; uint_t ke_gotonefree; }; struct kcage_stats { /* managed by KCAGE_STAT_* macros */ uint_t version; uint_t size; /* set in kcage_cageout */ uint_t kt_wakeups; uint_t kt_scans; uint_t kt_cageout_break; /* set in kcage_expand */ uint_t ke_calls; uint_t ke_nopfn; uint_t ke_nopaget; uint_t ke_isnoreloc; uint_t ke_deleting; uint_t ke_lowfreemem; uint_t ke_terminate; /* set in kcage_freemem_add() */ uint_t kfa_trottlewake; /* set in kcage_freemem_sub() */ uint_t kfs_cagewake; /* set in kcage_create_throttle */ uint_t kct_calls; uint_t kct_cageout; uint_t kct_critical; uint_t kct_exempt; uint_t kct_cagewake; uint_t kct_wait; uint_t kct_progress; uint_t kct_noprogress; uint_t kct_timeout; /* set in kcage_cageout_wakeup */ uint_t kcw_expandearly; /* managed by KCAGE_STAT_* macros */ uint_t scan_array_size; uint_t scan_index; struct kcage_stats_scan scans[KCAGE_STATS_NSCANS]; }; static struct kcage_stats kcage_stats; static struct kcage_stats_scan kcage_stats_scan_zero; /* * No real need for atomics here. For the most part the incs and sets are * done by the kernel cage thread. There are a few that are done by any * number of other threads. Those cases are noted by comments. */ #define KCAGE_STAT_INCR(m) kcage_stats.m++ #define KCAGE_STAT_NINCR(m, v) kcage_stats.m += (v) #define KCAGE_STAT_INCR_SCAN(m) \ KCAGE_STAT_INCR(scans[kcage_stats.scan_index].m) #define KCAGE_STAT_NINCR_SCAN(m, v) \ KCAGE_STAT_NINCR(scans[kcage_stats.scan_index].m, v) #define KCAGE_STAT_SET(m, v) kcage_stats.m = (v) #define KCAGE_STAT_SETZ(m, v) \ if (kcage_stats.m == 0) kcage_stats.m = (v) #define KCAGE_STAT_SET_SCAN(m, v) \ KCAGE_STAT_SET(scans[kcage_stats.scan_index].m, v) #define KCAGE_STAT_SETZ_SCAN(m, v) \ KCAGE_STAT_SETZ(scans[kcage_stats.scan_index].m, v) #define KCAGE_STAT_INC_SCAN_INDEX \ KCAGE_STAT_SET_SCAN(scan_lbolt, lbolt); \ KCAGE_STAT_SET_SCAN(scan_id, kcage_stats.scan_index); \ kcage_stats.scan_index = \ (kcage_stats.scan_index + 1) % KCAGE_STATS_NSCANS; \ kcage_stats.scans[kcage_stats.scan_index] = kcage_stats_scan_zero #define KCAGE_STAT_INIT_SCAN_INDEX \ kcage_stats.version = KCAGE_STATS_VERSION; \ kcage_stats.size = sizeof (kcage_stats); \ kcage_stats.scan_array_size = KCAGE_STATS_NSCANS; \ kcage_stats.scan_index = 0 #else /* KCAGE_STATS */ #define KCAGE_STAT_INCR(v) #define KCAGE_STAT_NINCR(m, v) #define KCAGE_STAT_INCR_SCAN(v) #define KCAGE_STAT_NINCR_SCAN(m, v) #define KCAGE_STAT_SET(m, v) #define KCAGE_STAT_SETZ(m, v) #define KCAGE_STAT_SET_SCAN(m, v) #define KCAGE_STAT_SETZ_SCAN(m, v) #define KCAGE_STAT_INC_SCAN_INDEX #define KCAGE_STAT_INIT_SCAN_INDEX #endif /* KCAGE_STATS */ static kmutex_t kcage_throttle_mutex; /* protects kcage_throttle_cv */ static kcondvar_t kcage_throttle_cv; static kmutex_t kcage_cageout_mutex; /* protects cv and ready flag */ static kcondvar_t kcage_cageout_cv; /* cageout thread naps here */ static int kcage_cageout_ready; /* nonzero when cageout thread ready */ kthread_id_t kcage_cageout_thread; /* to aid debugging */ static krwlock_t kcage_range_rwlock; /* protects kcage_glist elements */ /* * Cage expansion happens within a range. */ struct kcage_glist { struct kcage_glist *next; pfn_t base; pfn_t lim; pfn_t curr; int decr; }; static struct kcage_glist *kcage_glist; static struct kcage_glist *kcage_current_glist; /* * The firstfree element is provided so that kmem_alloc can be avoided * until that cage has somewhere to go. This is not currently a problem * as early kmem_alloc's use BOP_ALLOC instead of page_create_va. */ static vmem_t *kcage_arena; static struct kcage_glist kcage_glist_firstfree; static struct kcage_glist *kcage_glist_freelist = &kcage_glist_firstfree; /* * Miscellaneous forward references */ static struct kcage_glist *kcage_glist_alloc(void); static int kcage_glist_delete(pfn_t, pfn_t, struct kcage_glist **); static void kcage_cageout(void); static int kcage_invalidate_page(page_t *, pgcnt_t *); static int kcage_setnoreloc_pages(page_t *, se_t); static int kcage_range_add_internal(pfn_t base, pgcnt_t npgs, kcage_dir_t); static void kcage_init(pgcnt_t preferred_size); static int kcage_range_delete_internal(pfn_t base, pgcnt_t npgs); /* * Kernel Memory Cage counters and thresholds. */ int kcage_on = 0; pgcnt_t kcage_freemem; pgcnt_t kcage_needfree; pgcnt_t kcage_lotsfree; pgcnt_t kcage_desfree; pgcnt_t kcage_minfree; pgcnt_t kcage_throttlefree; pgcnt_t kcage_reserve; int kcage_maxwait = 10; /* in seconds */ /* when we use lp for kmem we start the cage at a higher initial value */ pgcnt_t kcage_kmemlp_mincage; #ifdef DEBUG pgcnt_t kcage_pagets; #define KCAGEPAGETS_INC() kcage_pagets++ #else #define KCAGEPAGETS_INC() #endif /* kstats to export what pages are currently caged */ kmutex_t kcage_kstat_lock; static int kcage_kstat_update(kstat_t *ksp, int rw); static int kcage_kstat_snapshot(kstat_t *ksp, void *buf, int rw); /* * Startup and Dynamic Reconfiguration interfaces. * kcage_range_add() * kcage_range_del() * kcage_range_delete_post_mem_del() * kcage_range_init() * kcage_set_thresholds() */ /* * Called from page_get_contig_pages to get the approximate kcage pfn range * for exclusion from search for contiguous pages. This routine is called * without kcage_range lock (kcage routines can call page_get_contig_pages * through page_relocate) and with the assumption, based on kcage_range_add, * that kcage_current_glist always contain a valid pointer. */ int kcage_current_pfn(pfn_t *pfncur) { struct kcage_glist *lp = kcage_current_glist; ASSERT(kcage_on); ASSERT(lp != NULL); *pfncur = lp->curr; return (lp->decr); } /* * Called from vm_pagelist.c during coalesce to find kernel cage regions * within an mnode. Looks for the lowest range between lo and hi. * * Kernel cage memory is defined between kcage_glist and kcage_current_glist. * Non-cage memory is defined between kcage_current_glist and list end. * * If incage is set, returns the lowest kcage range. Otherwise returns lowest * non-cage range. * * Returns zero on success and nlo, nhi: * lo <= nlo < nhi <= hi * Returns non-zero if no overlapping range is found. */ int kcage_next_range(int incage, pfn_t lo, pfn_t hi, pfn_t *nlo, pfn_t *nhi) { struct kcage_glist *lp; pfn_t tlo = hi; pfn_t thi = hi; ASSERT(lo <= hi); /* * Reader lock protects the list, but kcage_get_pfn * running concurrently may advance kcage_current_glist * and also update kcage_current_glist->curr. Page * coalesce can handle this race condition. */ rw_enter(&kcage_range_rwlock, RW_READER); for (lp = incage ? kcage_glist : kcage_current_glist; lp != NULL; lp = lp->next) { pfn_t klo, khi; /* find the range limits in this element */ if ((incage && lp->decr) || (!incage && !lp->decr)) { klo = lp->curr; khi = lp->lim; } else { klo = lp->base; khi = lp->curr; } /* handle overlap */ if (klo < tlo && klo < khi && lo < khi && klo < hi) { tlo = MAX(lo, klo); thi = MIN(hi, khi); if (tlo == lo) break; } /* check end of kcage */ if (incage && lp == kcage_current_glist) { break; } } rw_exit(&kcage_range_rwlock); /* return non-zero if no overlapping range found */ if (tlo == thi) return (1); ASSERT(lo <= tlo && tlo < thi && thi <= hi); /* return overlapping range */ *nlo = tlo; *nhi = thi; return (0); } void kcage_range_init(struct memlist *ml, kcage_dir_t d, pgcnt_t preferred_size) { int ret = 0; ASSERT(kcage_arena == NULL); kcage_arena = vmem_create("kcage_arena", NULL, 0, sizeof (uint64_t), segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP); ASSERT(kcage_arena != NULL); if (d == KCAGE_DOWN) { while (ml->next != NULL) ml = ml->next; } rw_enter(&kcage_range_rwlock, RW_WRITER); while (ml != NULL) { ret = kcage_range_add_internal(btop(ml->address), btop(ml->size), d); if (ret) panic("kcage_range_add_internal failed: " "ml=%p, ret=0x%x\n", (void *)ml, ret); ml = (d == KCAGE_DOWN ? ml->prev : ml->next); } rw_exit(&kcage_range_rwlock); if (ret == 0) kcage_init(preferred_size); } /* * Third arg controls direction of growth: 0: increasing pfns, * 1: decreasing. */ static int kcage_range_add_internal(pfn_t base, pgcnt_t npgs, kcage_dir_t d) { struct kcage_glist *new, **lpp; pfn_t lim; ASSERT(rw_write_held(&kcage_range_rwlock)); ASSERT(npgs != 0); if (npgs == 0) return (EINVAL); lim = base + npgs; ASSERT(lim > base); if (lim <= base) return (EINVAL); new = kcage_glist_alloc(); if (new == NULL) { return (ENOMEM); } new->base = base; new->lim = lim; new->decr = (d == KCAGE_DOWN); if (new->decr != 0) new->curr = new->lim; else new->curr = new->base; /* * Any overlapping existing ranges are removed by deleting * from the new list as we search for the tail. */ lpp = &kcage_glist; while (*lpp != NULL) { int ret; ret = kcage_glist_delete((*lpp)->base, (*lpp)->lim, &new); if (ret != 0) return (ret); lpp = &(*lpp)->next; } *lpp = new; if (kcage_current_glist == NULL) { kcage_current_glist = kcage_glist; } return (0); } int kcage_range_add(pfn_t base, pgcnt_t npgs, kcage_dir_t d) { int ret; rw_enter(&kcage_range_rwlock, RW_WRITER); ret = kcage_range_add_internal(base, npgs, d); rw_exit(&kcage_range_rwlock); return (ret); } /* * Calls to add and delete must be protected by kcage_range_rwlock */ static int kcage_range_delete_internal(pfn_t base, pgcnt_t npgs) { struct kcage_glist *lp; pfn_t lim; ASSERT(rw_write_held(&kcage_range_rwlock)); ASSERT(npgs != 0); if (npgs == 0) return (EINVAL); lim = base + npgs; ASSERT(lim > base); if (lim <= base) return (EINVAL); /* * Check if the delete is OK first as a number of elements * might be involved and it will be difficult to go * back and undo (can't just add the range back in). */ for (lp = kcage_glist; lp != NULL; lp = lp->next) { /* * If there have been no pages allocated from this * element, we don't need to check it. */ if ((lp->decr == 0 && lp->curr == lp->base) || (lp->decr != 0 && lp->curr == lp->lim)) continue; /* * If the element does not overlap, its OK. */ if (base >= lp->lim || lim <= lp->base) continue; /* * Overlapping element: Does the range to be deleted * overlap the area already used? If so fail. */ if (lp->decr == 0 && base < lp->curr && lim >= lp->base) { return (EBUSY); } if (lp->decr != 0 && base < lp->lim && lim >= lp->curr) { return (EBUSY); } } return (kcage_glist_delete(base, lim, &kcage_glist)); } int kcage_range_delete(pfn_t base, pgcnt_t npgs) { int ret; rw_enter(&kcage_range_rwlock, RW_WRITER); ret = kcage_range_delete_internal(base, npgs); rw_exit(&kcage_range_rwlock); return (ret); } /* * Calls to add and delete must be protected by kcage_range_rwlock. * This routine gets called after successful Solaris memory * delete operation from DR post memory delete routines. */ static int kcage_range_delete_post_mem_del_internal(pfn_t base, pgcnt_t npgs) { pfn_t lim; ASSERT(rw_write_held(&kcage_range_rwlock)); ASSERT(npgs != 0); if (npgs == 0) return (EINVAL); lim = base + npgs; ASSERT(lim > base); if (lim <= base) return (EINVAL); return (kcage_glist_delete(base, lim, &kcage_glist)); } int kcage_range_delete_post_mem_del(pfn_t base, pgcnt_t npgs) { int ret; rw_enter(&kcage_range_rwlock, RW_WRITER); ret = kcage_range_delete_post_mem_del_internal(base, npgs); rw_exit(&kcage_range_rwlock); return (ret); } /* * No locking is required here as the whole operation is covered * by kcage_range_rwlock writer lock. */ static struct kcage_glist * kcage_glist_alloc(void) { struct kcage_glist *new; if ((new = kcage_glist_freelist) != NULL) { kcage_glist_freelist = new->next; } else if (kernel_cage_enable) { new = vmem_alloc(kcage_arena, sizeof (*new), VM_NOSLEEP); } else { /* * On DR supported platforms we allow memory add * even when kernel cage is disabled. "kcage_arena" is * created only when kernel cage is enabled. */ new = kmem_zalloc(sizeof (*new), KM_NOSLEEP); } if (new != NULL) bzero(new, sizeof (*new)); return (new); } static void kcage_glist_free(struct kcage_glist *lp) { lp->next = kcage_glist_freelist; kcage_glist_freelist = lp; } static int kcage_glist_delete(pfn_t base, pfn_t lim, struct kcage_glist **lpp) { struct kcage_glist *lp, *prev = *lpp; while ((lp = *lpp) != NULL) { if (lim > lp->base && base < lp->lim) { /* The delete range overlaps this element. */ if (base <= lp->base && lim >= lp->lim) { /* Delete whole element. */ *lpp = lp->next; if (lp == kcage_current_glist) { /* This can never happen. */ ASSERT(kcage_current_glist != prev); kcage_current_glist = prev; } kcage_glist_free(lp); continue; } /* Partial delete. */ if (base > lp->base && lim < lp->lim) { struct kcage_glist *new; /* * Remove a section from the middle, * need to allocate a new element. */ new = kcage_glist_alloc(); if (new == NULL) { return (ENOMEM); } /* * Tranfser unused range to new. * Edit lp in place to preserve * kcage_current_glist. */ new->decr = lp->decr; if (new->decr != 0) { new->base = lp->base; new->lim = base; new->curr = base; lp->base = lim; } else { new->base = lim; new->lim = lp->lim; new->curr = new->base; lp->lim = base; } /* Insert new. */ new->next = lp->next; lp->next = new; lpp = &lp->next; } else { /* Delete part of current block. */ if (base > lp->base) { ASSERT(lim >= lp->lim); ASSERT(base < lp->lim); if (lp->decr != 0 && lp->curr == lp->lim) lp->curr = base; lp->lim = base; } else { ASSERT(base <= lp->base); ASSERT(lim > lp->base); if (lp->decr == 0 && lp->curr == lp->base) lp->curr = lim; lp->base = lim; } } } prev = *lpp; lpp = &(*lpp)->next; } return (0); } /* * If lockit is 1, kcage_get_pfn holds the * reader lock for kcage_range_rwlock. * Changes to lp->curr can cause race conditions, but * they are handled by higher level code (see kcage_next_range.) */ static pfn_t kcage_get_pfn(int lockit) { struct kcage_glist *lp; pfn_t pfn = PFN_INVALID; if (lockit && !rw_tryenter(&kcage_range_rwlock, RW_READER)) return (pfn); lp = kcage_current_glist; while (lp != NULL) { if (lp->decr != 0) { if (lp->curr != lp->base) { pfn = --lp->curr; break; } } else { if (lp->curr != lp->lim) { pfn = lp->curr++; break; } } lp = lp->next; if (lp) kcage_current_glist = lp; } if (lockit) rw_exit(&kcage_range_rwlock); return (pfn); } /* * Walk the physical address space of the cage. * This routine does not guarantee to return PFNs in the order * in which they were allocated to the cage. Instead, it walks * each range as they appear on the growth list returning the PFNs * range in ascending order. * * To begin scanning at lower edge of cage, reset should be nonzero. * To step through cage, reset should be zero. * * PFN_INVALID will be returned when the upper end of the cage is * reached -- indicating a full scan of the cage has been completed since * previous reset. PFN_INVALID will continue to be returned until * kcage_walk_cage is reset. * * It is possible to receive a PFN_INVALID result on reset if a growth * list is not installed or if none of the PFNs in the installed list have * been allocated to the cage. In otherwords, there is no cage. * * Caller need not hold kcage_range_rwlock while calling this function * as the front part of the list is static - pages never come out of * the cage. * * The caller is expected to only be kcage_cageout(). */ static pfn_t kcage_walk_cage(int reset) { static struct kcage_glist *lp = NULL; static pfn_t pfn; if (reset) lp = NULL; if (lp == NULL) { lp = kcage_glist; pfn = PFN_INVALID; } again: if (pfn == PFN_INVALID) { if (lp == NULL) return (PFN_INVALID); if (lp->decr != 0) { /* * In this range the cage grows from the highest * address towards the lowest. * Arrange to return pfns from curr to lim-1, * inclusive, in ascending order. */ pfn = lp->curr; } else { /* * In this range the cage grows from the lowest * address towards the highest. * Arrange to return pfns from base to curr, * inclusive, in ascending order. */ pfn = lp->base; } } if (lp->decr != 0) { /* decrementing pfn */ if (pfn == lp->lim) { /* Don't go beyond the static part of the glist. */ if (lp == kcage_current_glist) lp = NULL; else lp = lp->next; pfn = PFN_INVALID; goto again; } ASSERT(pfn >= lp->curr && pfn < lp->lim); } else { /* incrementing pfn */ if (pfn == lp->curr) { /* Don't go beyond the static part of the glist. */ if (lp == kcage_current_glist) lp = NULL; else lp = lp->next; pfn = PFN_INVALID; goto again; } ASSERT(pfn >= lp->base && pfn < lp->curr); } return (pfn++); } /* * Callback functions for to recalc cage thresholds after * Kphysm memory add/delete operations. */ /*ARGSUSED*/ static void kcage_kphysm_postadd_cb(void *arg, pgcnt_t delta_pages) { kcage_recalc_thresholds(); } /*ARGSUSED*/ static int kcage_kphysm_predel_cb(void *arg, pgcnt_t delta_pages) { /* TODO: when should cage refuse memory delete requests? */ return (0); } /*ARGSUSED*/ static void kcage_kphysm_postdel_cb(void *arg, pgcnt_t delta_pages, int cancelled) { kcage_recalc_thresholds(); } static kphysm_setup_vector_t kcage_kphysm_vectors = { KPHYSM_SETUP_VECTOR_VERSION, kcage_kphysm_postadd_cb, kcage_kphysm_predel_cb, kcage_kphysm_postdel_cb }; /* * This is called before a CPR suspend and after a CPR resume. We have to * turn off kcage_cageout_ready before a suspend, and turn it back on after a * restart. */ /*ARGSUSED*/ static boolean_t kcage_cageout_cpr(void *arg, int code) { if (code == CB_CODE_CPR_CHKPT) { ASSERT(kcage_cageout_ready); kcage_cageout_ready = 0; return (B_TRUE); } else if (code == CB_CODE_CPR_RESUME) { ASSERT(kcage_cageout_ready == 0); kcage_cageout_ready = 1; return (B_TRUE); } return (B_FALSE); } /* * kcage_recalc_preferred_size() increases initial cage size to improve large * page availability when lp for kmem is enabled and kpr is disabled */ static pgcnt_t kcage_recalc_preferred_size(pgcnt_t preferred_size) { if (SEGKMEM_USE_LARGEPAGES && segkmem_reloc == 0) { pgcnt_t lpmincage = kcage_kmemlp_mincage; if (lpmincage == 0) { lpmincage = MIN(P2ROUNDUP(((physmem * PAGESIZE) / 8), segkmem_heaplp_quantum), 0x40000000UL) / PAGESIZE; } kcage_kmemlp_mincage = MIN(lpmincage, (segkmem_kmemlp_max / PAGESIZE)); preferred_size = MAX(kcage_kmemlp_mincage, preferred_size); } return (preferred_size); } /* * Kcage_init() builds the cage and initializes the cage thresholds. * The size of the cage is determined by the argument preferred_size. * or the actual amount of memory, whichever is smaller. */ static void kcage_init(pgcnt_t preferred_size) { pgcnt_t wanted; pfn_t pfn; page_t *pp; kstat_t *ksp; extern struct vnode kvp; extern void page_list_noreloc_startup(page_t *); ASSERT(!kcage_on); /* increase preferred cage size for lp for kmem */ preferred_size = kcage_recalc_preferred_size(preferred_size); /* Debug note: initialize this now so early expansions can stat */ KCAGE_STAT_INIT_SCAN_INDEX; /* * Initialize cage thresholds and install kphysm callback. * If we can't arrange to have the thresholds track with * available physical memory, then the cage thresholds may * end up over time at levels that adversly effect system * performance; so, bail out. */ kcage_recalc_thresholds(); if (kphysm_setup_func_register(&kcage_kphysm_vectors, NULL)) { ASSERT(0); /* Catch this in DEBUG kernels. */ return; } /* * Limit startup cage size within the range of kcage_minfree * and availrmem, inclusively. */ wanted = MIN(MAX(preferred_size, kcage_minfree), availrmem); /* * Construct the cage. PFNs are allocated from the glist. It * is assumed that the list has been properly ordered for the * platform by the platform code. Typically, this is as simple * as calling kcage_range_init(phys_avail, decr), where decr is * 1 if the kernel has been loaded into upper end of physical * memory, or 0 if the kernel has been loaded at the low end. * * Note: it is assumed that we are in the startup flow, so there * is no reason to grab the page lock. */ kcage_freemem = 0; pfn = PFN_INVALID; /* prime for alignment test */ while (wanted != 0) { if ((pfn = kcage_get_pfn(0)) == PFN_INVALID) break; if ((pp = page_numtopp_nolock(pfn)) != NULL) { KCAGEPAGETS_INC(); /* * Set the noreloc state on the page. * If the page is free and not already * on the noreloc list then move it. */ if (PP_ISFREE(pp)) { if (PP_ISNORELOC(pp) == 0) page_list_noreloc_startup(pp); } else { ASSERT(pp->p_szc == 0); PP_SETNORELOC(pp); } } PLCNT_XFER_NORELOC(pp); wanted -= 1; } /* * Need to go through and find kernel allocated pages * and capture them into the Cage. These will primarily * be pages gotten through boot_alloc(). */ if (kvp.v_pages) { pp = kvp.v_pages; do { ASSERT(!PP_ISFREE(pp)); ASSERT(pp->p_szc == 0); if (PP_ISNORELOC(pp) == 0) { PP_SETNORELOC(pp); PLCNT_XFER_NORELOC(pp); } } while ((pp = pp->p_vpnext) != kvp.v_pages); } kcage_on = 1; /* * CB_CL_CPR_POST_KERNEL is the class that executes from cpr_suspend() * after the cageout thread is blocked, and executes from cpr_resume() * before the cageout thread is restarted. By executing in this class, * we are assured that the kernel cage thread won't miss wakeup calls * and also CPR's larger kmem_alloc requests will not fail after * CPR shuts down the cageout kernel thread. */ (void) callb_add(kcage_cageout_cpr, NULL, CB_CL_CPR_POST_KERNEL, "cageout"); /* * Coalesce pages to improve large page availability. A better fix * would to coalesce pages as they are included in the cage */ if (SEGKMEM_USE_LARGEPAGES) { extern void page_freelist_coalesce_all(int mnode); page_freelist_coalesce_all(-1); /* do all mnodes */ } ksp = kstat_create("kcage", 0, "kcage_page_list", "misc", KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VAR_SIZE | KSTAT_FLAG_VIRTUAL); if (ksp != NULL) { ksp->ks_update = kcage_kstat_update; ksp->ks_snapshot = kcage_kstat_snapshot; ksp->ks_lock = &kcage_kstat_lock; /* XXX - not really needed */ kstat_install(ksp); } } static int kcage_kstat_update(kstat_t *ksp, int rw) { struct kcage_glist *lp; uint_t count; if (rw == KSTAT_WRITE) return (EACCES); count = 0; rw_enter(&kcage_range_rwlock, RW_WRITER); for (lp = kcage_glist; lp != NULL; lp = lp->next) { if (lp->decr) { if (lp->curr != lp->lim) { count++; } } else { if (lp->curr != lp->base) { count++; } } } rw_exit(&kcage_range_rwlock); ksp->ks_ndata = count; ksp->ks_data_size = count * 2 * sizeof (uint64_t); return (0); } static int kcage_kstat_snapshot(kstat_t *ksp, void *buf, int rw) { struct kcage_glist *lp; struct memunit { uint64_t address; uint64_t size; } *kspmem; if (rw == KSTAT_WRITE) return (EACCES); ksp->ks_snaptime = gethrtime(); kspmem = (struct memunit *)buf; rw_enter(&kcage_range_rwlock, RW_WRITER); for (lp = kcage_glist; lp != NULL; lp = lp->next, kspmem++) { if ((caddr_t)kspmem >= (caddr_t)buf + ksp->ks_data_size) break; if (lp->decr) { if (lp->curr != lp->lim) { kspmem->address = ptob(lp->curr); kspmem->size = ptob(lp->lim - lp->curr); } } else { if (lp->curr != lp->base) { kspmem->address = ptob(lp->base); kspmem->size = ptob(lp->curr - lp->base); } } } rw_exit(&kcage_range_rwlock); return (0); } void kcage_recalc_thresholds() { static int first = 1; static pgcnt_t init_lotsfree; static pgcnt_t init_desfree; static pgcnt_t init_minfree; static pgcnt_t init_throttlefree; static pgcnt_t init_reserve; /* TODO: any reason to take more care than this with live editing? */ mutex_enter(&kcage_cageout_mutex); mutex_enter(&freemem_lock); if (first) { first = 0; init_lotsfree = kcage_lotsfree; init_desfree = kcage_desfree; init_minfree = kcage_minfree; init_throttlefree = kcage_throttlefree; init_reserve = kcage_reserve; } else { kcage_lotsfree = init_lotsfree; kcage_desfree = init_desfree; kcage_minfree = init_minfree; kcage_throttlefree = init_throttlefree; kcage_reserve = init_reserve; } if (kcage_lotsfree == 0) kcage_lotsfree = MAX(32, total_pages / 256); if (kcage_minfree == 0) kcage_minfree = MAX(32, kcage_lotsfree / 2); if (kcage_desfree == 0) kcage_desfree = MAX(32, kcage_minfree); if (kcage_throttlefree == 0) kcage_throttlefree = MAX(32, kcage_minfree / 2); if (kcage_reserve == 0) kcage_reserve = MIN(32, kcage_throttlefree / 2); mutex_exit(&freemem_lock); mutex_exit(&kcage_cageout_mutex); if (kcage_cageout_ready) { if (kcage_freemem < kcage_desfree) kcage_cageout_wakeup(); if (kcage_needfree) { mutex_enter(&kcage_throttle_mutex); cv_broadcast(&kcage_throttle_cv); mutex_exit(&kcage_throttle_mutex); } } } /* * Pageout interface: * kcage_cageout_init() */ void kcage_cageout_init() { if (kcage_on) { (void) thread_create(NULL, 0, kcage_cageout, NULL, 0, proc_pageout, TS_RUN, maxclsyspri - 1); } } /* * VM Interfaces: * kcage_create_throttle() * kcage_freemem_add() * kcage_freemem_sub() */ /* * Wakeup cageout thread and throttle waiting for the number of pages * requested to become available. For non-critical requests, a * timeout is added, since freemem accounting is separate from cage * freemem accounting: it's possible for us to get stuck and not make * forward progress even though there was sufficient freemem before * arriving here. */ int kcage_create_throttle(pgcnt_t npages, int flags) { int niter = 0; pgcnt_t lastfree; int enough = kcage_freemem > kcage_throttlefree + npages; KCAGE_STAT_INCR(kct_calls); /* unprotected incr. */ kcage_cageout_wakeup(); /* just to be sure */ KCAGE_STAT_INCR(kct_cagewake); /* unprotected incr. */ /* * Obviously, we can't throttle the cageout thread since * we depend on it. We also can't throttle the panic thread. */ if (curthread == kcage_cageout_thread || panicstr) { KCAGE_STAT_INCR(kct_cageout); /* unprotected incr. */ return (KCT_CRIT); } /* * Don't throttle threads which are critical for proper * vm management if we're above kcage_throttlefree or * if freemem is very low. */ if (NOMEMWAIT()) { if (enough) { KCAGE_STAT_INCR(kct_exempt); /* unprotected incr. */ return (KCT_CRIT); } else if (freemem < minfree) { KCAGE_STAT_INCR(kct_critical); /* unprotected incr. */ return (KCT_CRIT); } } /* * Don't throttle real-time threads if kcage_freemem > kcage_reserve. */ if (DISP_PRIO(curthread) > maxclsyspri && kcage_freemem > kcage_reserve) { KCAGE_STAT_INCR(kct_exempt); /* unprotected incr. */ return (KCT_CRIT); } /* * Cause all other threads (which are assumed to not be * critical to cageout) to wait here until their request * can be satisfied. Be a little paranoid and wake the * kernel cage on each loop through this logic. */ while (kcage_freemem < kcage_throttlefree + npages) { ASSERT(kcage_on); lastfree = kcage_freemem; if (kcage_cageout_ready) { mutex_enter(&kcage_throttle_mutex); kcage_needfree += npages; KCAGE_STAT_INCR(kct_wait); kcage_cageout_wakeup(); KCAGE_STAT_INCR(kct_cagewake); cv_wait(&kcage_throttle_cv, &kcage_throttle_mutex); kcage_needfree -= npages; mutex_exit(&kcage_throttle_mutex); } else { /* * NOTE: atomics are used just in case we enter * mp operation before the cageout thread is ready. */ atomic_add_long(&kcage_needfree, npages); kcage_cageout_wakeup(); KCAGE_STAT_INCR(kct_cagewake); /* unprotected incr. */ atomic_add_long(&kcage_needfree, -npages); } if ((flags & PG_WAIT) == 0) { if (kcage_freemem > lastfree) { KCAGE_STAT_INCR(kct_progress); niter = 0; } else { KCAGE_STAT_INCR(kct_noprogress); if (++niter >= kcage_maxwait) { KCAGE_STAT_INCR(kct_timeout); return (KCT_FAILURE); } } } if (NOMEMWAIT() && freemem < minfree) { return (KCT_CRIT); } } return (KCT_NONCRIT); } void kcage_freemem_add(pgcnt_t npages) { extern void wakeup_pcgs(void); atomic_add_long(&kcage_freemem, npages); wakeup_pcgs(); /* wakeup threads in pcgs() */ if (kcage_needfree != 0 && kcage_freemem >= (kcage_throttlefree + kcage_needfree)) { mutex_enter(&kcage_throttle_mutex); cv_broadcast(&kcage_throttle_cv); KCAGE_STAT_INCR(kfa_trottlewake); mutex_exit(&kcage_throttle_mutex); } } void kcage_freemem_sub(pgcnt_t npages) { atomic_add_long(&kcage_freemem, -npages); if (kcage_freemem < kcage_desfree) { kcage_cageout_wakeup(); KCAGE_STAT_INCR(kfs_cagewake); /* unprotected incr. */ } } /* * return 0 on failure and 1 on success. */ static int kcage_setnoreloc_pages(page_t *rootpp, se_t se) { pgcnt_t npgs, i; page_t *pp; pfn_t rootpfn = page_pptonum(rootpp); uint_t szc; ASSERT(!PP_ISFREE(rootpp)); ASSERT(PAGE_LOCKED_SE(rootpp, se)); if (!group_page_trylock(rootpp, se)) { return (0); } szc = rootpp->p_szc; if (szc == 0) { /* * The szc of a locked page can only change for pages that are * non-swapfs (i.e. anonymous memory) file system pages. */ ASSERT(rootpp->p_vnode != NULL && !PP_ISKAS(rootpp) && !IS_SWAPFSVP(rootpp->p_vnode)); PP_SETNORELOC(rootpp); return (1); } npgs = page_get_pagecnt(szc); ASSERT(IS_P2ALIGNED(rootpfn, npgs)); pp = rootpp; for (i = 0; i < npgs; i++, pp++) { ASSERT(PAGE_LOCKED_SE(pp, se)); ASSERT(!PP_ISFREE(pp)); ASSERT(pp->p_szc == szc); PP_SETNORELOC(pp); } group_page_unlock(rootpp); return (1); } /* * Attempt to convert page to a caged page (set the P_NORELOC flag). * If successful and pages is free, move page to the tail of whichever * list it is on. * Returns: * EBUSY page already locked, assimilated but not free. * ENOMEM page assimilated, but memory too low to relocate. Page not free. * EAGAIN page not assimilated. Page not free. * ERANGE page assimilated. Page not root. * 0 page assimilated. Page free. * *nfreedp number of pages freed. * NOTE: With error codes ENOMEM, EBUSY, and 0 (zero), there is no way * to distinguish between a page that was already a NORELOC page from * those newly converted to NORELOC pages by this invocation of * kcage_assimilate_page. */ static int kcage_assimilate_page(page_t *pp, pgcnt_t *nfreedp) { if (page_trylock(pp, SE_EXCL)) { if (PP_ISNORELOC(pp)) { check_free_and_return: if (PP_ISFREE(pp)) { page_unlock(pp); *nfreedp = 0; return (0); } else { page_unlock(pp); return (EBUSY); } /*NOTREACHED*/ } } else { if (page_trylock(pp, SE_SHARED)) { if (PP_ISNORELOC(pp)) goto check_free_and_return; } else return (EAGAIN); if (!PP_ISFREE(pp)) { page_unlock(pp); return (EAGAIN); } /* * Need to upgrade the lock on it and set the NORELOC * bit. If it is free then remove it from the free * list so that the platform free list code can keep * NORELOC pages where they should be. */ /* * Before doing anything, get the exclusive lock. * This may fail (eg ISM pages are left shared locked). * If the page is free this will leave a hole in the * cage. There is no solution yet to this. */ if (!page_tryupgrade(pp)) { page_unlock(pp); return (EAGAIN); } } ASSERT(PAGE_EXCL(pp)); if (PP_ISFREE(pp)) { int which = PP_ISAGED(pp) ? PG_FREE_LIST : PG_CACHE_LIST; page_list_sub(pp, which); ASSERT(pp->p_szc == 0); PP_SETNORELOC(pp); PLCNT_XFER_NORELOC(pp); page_list_add(pp, which | PG_LIST_TAIL); page_unlock(pp); *nfreedp = 1; return (0); } else { if (pp->p_szc != 0) { if (!kcage_setnoreloc_pages(pp, SE_EXCL)) { page_unlock(pp); return (EAGAIN); } ASSERT(PP_ISNORELOC(pp)); } else { PP_SETNORELOC(pp); } PLCNT_XFER_NORELOC(pp); return (kcage_invalidate_page(pp, nfreedp)); } /*NOTREACHED*/ } static int kcage_expand() { int did_something = 0; spgcnt_t wanted; pfn_t pfn; page_t *pp; /* TODO: we don't really need n any more? */ pgcnt_t n; pgcnt_t nf, nfreed; /* * Expand the cage if available cage memory is really low. Calculate * the amount required to return kcage_freemem to the level of * kcage_lotsfree, or to satisfy throttled requests, whichever is * more. It is rare for their sum to create an artificial threshold * above kcage_lotsfree, but it is possible. * * Exit early if expansion amount is equal to or less than zero. * (<0 is possible if kcage_freemem rises suddenly.) * * Exit early when the global page pool (apparently) does not * have enough free pages to page_relocate() even a single page. */ wanted = MAX(kcage_lotsfree, kcage_throttlefree + kcage_needfree) - kcage_freemem; if (wanted <= 0) return (0); else if (freemem < pageout_reserve + 1) { KCAGE_STAT_INCR(ke_lowfreemem); return (0); } KCAGE_STAT_INCR(ke_calls); KCAGE_STAT_SET_SCAN(ke_wanted, (uint_t)wanted); /* * Assimilate more pages from the global page pool into the cage. */ n = 0; /* number of pages PP_SETNORELOC'd */ nf = 0; /* number of those actually free */ while (kcage_on && nf < wanted) { pfn = kcage_get_pfn(1); if (pfn == PFN_INVALID) { /* eek! no where to grow */ KCAGE_STAT_INCR(ke_nopfn); goto terminate; } KCAGE_STAT_INCR_SCAN(ke_examined); if ((pp = page_numtopp_nolock(pfn)) == NULL) { KCAGE_STAT_INCR(ke_nopaget); continue; } KCAGEPAGETS_INC(); /* * Sanity check. Skip this pfn if it is * being deleted. */ if (pfn_is_being_deleted(pfn)) { KCAGE_STAT_INCR(ke_deleting); continue; } if (PP_ISNORELOC(pp)) { KCAGE_STAT_INCR(ke_isnoreloc); continue; } switch (kcage_assimilate_page(pp, &nfreed)) { case 0: /* assimilated, page is free */ KCAGE_STAT_NINCR_SCAN(ke_gotonefree, nfreed); did_something = 1; nf += nfreed; n++; break; case EBUSY: /* assimilated, page not free */ case ERANGE: /* assimilated, page not root */ KCAGE_STAT_INCR_SCAN(ke_gotone); did_something = 1; n++; break; case ENOMEM: /* assimilated, but no mem */ KCAGE_STAT_INCR(ke_terminate); did_something = 1; n++; goto terminate; case EAGAIN: /* can't assimilate */ KCAGE_STAT_INCR_SCAN(ke_lefthole); break; default: /* catch this with debug kernels */ ASSERT(0); break; } } /* * Realign cage edge with the nearest physical address * boundry for big pages. This is done to give us a * better chance of actually getting usable big pages * in the cage. */ terminate: return (did_something); } /* * Relocate page opp (Original Page Pointer) from cage pool to page rpp * (Replacement Page Pointer) in the global pool. Page opp will be freed * if relocation is successful, otherwise it is only unlocked. * On entry, page opp must be exclusively locked and not free. * *nfreedp: number of pages freed. */ static int kcage_relocate_page(page_t *pp, pgcnt_t *nfreedp) { page_t *opp = pp; page_t *rpp = NULL; spgcnt_t npgs; int result; ASSERT(!PP_ISFREE(opp)); ASSERT(PAGE_EXCL(opp)); result = page_relocate(&opp, &rpp, 1, 1, &npgs, NULL); *nfreedp = npgs; if (result == 0) { while (npgs-- > 0) { page_t *tpp; ASSERT(rpp != NULL); tpp = rpp; page_sub(&rpp, tpp); page_unlock(tpp); } ASSERT(rpp == NULL); return (0); /* success */ } page_unlock(opp); return (result); } /* * Based on page_invalidate_pages() * * Kcage_invalidate_page() uses page_relocate() twice. Both instances * of use must be updated to match the new page_relocate() when it * becomes available. * * Return result of kcage_relocate_page or zero if page was directly freed. * *nfreedp: number of pages freed. */ static int kcage_invalidate_page(page_t *pp, pgcnt_t *nfreedp) { int result; #if defined(__sparc) extern struct vnode prom_ppages; ASSERT(pp->p_vnode != &prom_ppages); #endif /* __sparc */ ASSERT(!PP_ISFREE(pp)); ASSERT(PAGE_EXCL(pp)); /* * Is this page involved in some I/O? shared? * The page_struct_lock need not be acquired to * examine these fields since the page has an * "exclusive" lock. */ if (pp->p_lckcnt != 0 || pp->p_cowcnt != 0) { result = kcage_relocate_page(pp, nfreedp); #ifdef KCAGE_STATS if (result == 0) KCAGE_STAT_INCR_SCAN(kip_reloclocked); else if (result == ENOMEM) KCAGE_STAT_INCR_SCAN(kip_nomem); #endif return (result); } ASSERT(pp->p_vnode->v_type != VCHR); /* * Unload the mappings and check if mod bit is set. */ (void) hat_pageunload(pp, HAT_FORCE_PGUNLOAD); if (hat_ismod(pp)) { result = kcage_relocate_page(pp, nfreedp); #ifdef KCAGE_STATS if (result == 0) KCAGE_STAT_INCR_SCAN(kip_relocmod); else if (result == ENOMEM) KCAGE_STAT_INCR_SCAN(kip_nomem); #endif return (result); } if (!page_try_demote_pages(pp)) { KCAGE_STAT_INCR_SCAN(kip_demotefailed); page_unlock(pp); return (EAGAIN); } /* LINTED: constant in conditional context */ VN_DISPOSE(pp, B_INVAL, 0, kcred); KCAGE_STAT_INCR_SCAN(kip_destroy); *nfreedp = 1; return (0); } static void kcage_cageout() { pfn_t pfn; page_t *pp; callb_cpr_t cprinfo; int did_something; int scan_again; pfn_t start_pfn; int pass; int last_pass; int pages_skipped; int shared_skipped; ulong_t shared_level = 8; pgcnt_t nfreed; #ifdef KCAGE_STATS clock_t scan_start; #endif CALLB_CPR_INIT(&cprinfo, &kcage_cageout_mutex, callb_generic_cpr, "cageout"); mutex_enter(&kcage_cageout_mutex); kcage_cageout_thread = curthread; pfn = PFN_INVALID; /* force scan reset */ start_pfn = PFN_INVALID; /* force init with 1st cage pfn */ kcage_cageout_ready = 1; /* switch kcage_cageout_wakeup mode */ loop: /* * Wait here. Sooner or later, kcage_freemem_sub() will notice * that kcage_freemem is less than kcage_desfree. When it does * notice, kcage_freemem_sub() will wake us up via call to * kcage_cageout_wakeup(). */ CALLB_CPR_SAFE_BEGIN(&cprinfo); cv_wait(&kcage_cageout_cv, &kcage_cageout_mutex); CALLB_CPR_SAFE_END(&cprinfo, &kcage_cageout_mutex); KCAGE_STAT_INCR(kt_wakeups); KCAGE_STAT_SET_SCAN(kt_freemem_start, freemem); KCAGE_STAT_SET_SCAN(kt_kcage_freemem_start, kcage_freemem); pass = 0; last_pass = 0; #ifdef KCAGE_STATS scan_start = lbolt; #endif again: if (!kcage_on) goto loop; KCAGE_STAT_INCR(kt_scans); KCAGE_STAT_INCR_SCAN(kt_passes); did_something = 0; pages_skipped = 0; shared_skipped = 0; while ((kcage_freemem < kcage_lotsfree || kcage_needfree) && (pfn = kcage_walk_cage(pfn == PFN_INVALID)) != PFN_INVALID) { if (start_pfn == PFN_INVALID) start_pfn = pfn; else if (start_pfn == pfn) { last_pass = pass; pass += 1; /* * Did a complete walk of kernel cage, but didn't free * any pages. If only one cpu is active then * stop kernel cage walk and try expanding. */ if (cp_default.cp_ncpus == 1 && did_something == 0) { KCAGE_STAT_INCR(kt_cageout_break); break; } } pp = page_numtopp_nolock(pfn); if (pp == NULL) { continue; } KCAGE_STAT_INCR_SCAN(kt_examined); /* * Do a quick PP_ISNORELOC() and PP_ISFREE test outside * of the lock. If one is missed it will be seen next * time through. * * Skip non-caged-pages. These pages can exist in the cage * because, if during cage expansion, a page is * encountered that is long-term locked the lock prevents the * expansion logic from setting the P_NORELOC flag. Hence, * non-caged-pages surrounded by caged-pages. */ if (!PP_ISNORELOC(pp)) { switch (kcage_assimilate_page(pp, &nfreed)) { case 0: did_something = 1; KCAGE_STAT_NINCR_SCAN(kt_gotonefree, nfreed); break; case EBUSY: case ERANGE: did_something = 1; KCAGE_STAT_INCR_SCAN(kt_gotone); break; case EAGAIN: case ENOMEM: break; default: /* catch this with debug kernels */ ASSERT(0); break; } continue; } else { int prm; if (PP_ISFREE(pp)) { continue; } if ((PP_ISKAS(pp) && pp->p_lckcnt > 0) || !page_trylock(pp, SE_EXCL)) { KCAGE_STAT_INCR_SCAN(kt_cantlock); continue; } /* P_NORELOC bit should not have gone away. */ ASSERT(PP_ISNORELOC(pp)); if (PP_ISFREE(pp) || (PP_ISKAS(pp) && pp->p_lckcnt > 0)) { page_unlock(pp); continue; } KCAGE_STAT_SET_SCAN(kt_skiplevel, shared_level); if (hat_page_checkshare(pp, shared_level)) { page_unlock(pp); pages_skipped = 1; shared_skipped = 1; KCAGE_STAT_INCR_SCAN(kt_skipshared); continue; } /* * In pass {0, 1}, skip page if ref bit is set. * In pass {0, 1, 2}, skip page if mod bit is set. */ prm = hat_pagesync(pp, HAT_SYNC_DONTZERO | HAT_SYNC_STOPON_MOD); /* On first pass ignore ref'd pages */ if (pass <= 1 && (prm & P_REF)) { KCAGE_STAT_INCR_SCAN(kt_skiprefd); pages_skipped = 1; page_unlock(pp); continue; } /* On pass 2, VN_DISPOSE if mod bit is not set */ if (pass <= 2) { if (pp->p_szc != 0 || (prm & P_MOD) || pp->p_lckcnt || pp->p_cowcnt) { pages_skipped = 1; page_unlock(pp); } else { /* * unload the mappings before * checking if mod bit is set */ (void) hat_pageunload(pp, HAT_FORCE_PGUNLOAD); /* * skip this page if modified */ if (hat_ismod(pp)) { pages_skipped = 1; page_unlock(pp); continue; } KCAGE_STAT_INCR_SCAN(kt_destroy); /* constant in conditional context */ /* LINTED */ VN_DISPOSE(pp, B_INVAL, 0, kcred); did_something = 1; } continue; } if (kcage_invalidate_page(pp, &nfreed) == 0) { did_something = 1; KCAGE_STAT_NINCR_SCAN(kt_gotonefree, nfreed); } /* * No need to drop the page lock here. * Kcage_invalidate_page has done that for us * either explicitly or through a page_free. */ } } /* * Expand the cage only if available cage memory is really low. * This test is done only after a complete scan of the cage. * The reason for not checking and expanding more often is to * avoid rapid expansion of the cage. Naturally, scanning the * cage takes time. So by scanning first, we use that work as a * delay loop in between expand decisions. */ scan_again = 0; if (kcage_freemem < kcage_minfree || kcage_needfree) { /* * Kcage_expand() will return a non-zero value if it was * able to expand the cage -- whether or not the new * pages are free and immediately usable. If non-zero, * we do another scan of the cage. The pages might be * freed during that scan or by time we get back here. * If not, we will attempt another expansion. * However, if kcage_expand() returns zero, then it was * unable to expand the cage. This is the case when the * the growth list is exausted, therefore no work was done * and there is no reason to scan the cage again. * Note: Kernel cage scan is not repeated when only one * cpu is active to avoid kernel cage thread hogging cpu. */ if (pass <= 3 && pages_skipped && cp_default.cp_ncpus > 1) scan_again = 1; else (void) kcage_expand(); /* don't scan again */ } else if (kcage_freemem < kcage_lotsfree) { /* * If available cage memory is less than abundant * and a full scan of the cage has not yet been completed, * or a scan has completed and some work was performed, * or pages were skipped because of sharing, * or we simply have not yet completed two passes, * then do another scan. */ if (pass <= 2 && pages_skipped) scan_again = 1; if (pass == last_pass || did_something) scan_again = 1; else if (shared_skipped && shared_level < (8<<24)) { shared_level <<= 1; scan_again = 1; } } if (scan_again && cp_default.cp_ncpus > 1) goto again; else { if (shared_level > 8) shared_level >>= 1; KCAGE_STAT_SET_SCAN(kt_freemem_end, freemem); KCAGE_STAT_SET_SCAN(kt_kcage_freemem_end, kcage_freemem); KCAGE_STAT_SET_SCAN(kt_ticks, lbolt - scan_start); KCAGE_STAT_INC_SCAN_INDEX; goto loop; } /*NOTREACHED*/ } void kcage_cageout_wakeup() { if (mutex_tryenter(&kcage_cageout_mutex)) { if (kcage_cageout_ready) { cv_signal(&kcage_cageout_cv); } else if (kcage_freemem < kcage_minfree || kcage_needfree) { /* * Available cage memory is really low. Time to * start expanding the cage. However, the * kernel cage thread is not yet ready to * do the work. Use *this* thread, which is * most likely to be t0, to do the work. */ KCAGE_STAT_INCR(kcw_expandearly); (void) kcage_expand(); KCAGE_STAT_INC_SCAN_INDEX; } mutex_exit(&kcage_cageout_mutex); } /* else, kernel cage thread is already running */ } void kcage_tick() { /* * Once per second we wake up all the threads throttled * waiting for cage memory, in case we've become stuck * and haven't made forward progress expanding the cage. */ if (kcage_on && kcage_cageout_ready) cv_broadcast(&kcage_throttle_cv); }