The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_glue.c

Version: -  FREEBSD  -  FREEBSD-13-STABLE  -  FREEBSD-13-0  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  l41  -  OPENBSD  -  linux-2.6  -  MK84  -  PLAN9  -  xnu-8792 
SearchContext: -  none  -  3  -  10 

    1 /*-
    2  * Copyright (c) 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * The Mach Operating System project at Carnegie-Mellon University.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      from: @(#)vm_glue.c     8.6 (Berkeley) 1/5/94
   33  *
   34  *
   35  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
   36  * All rights reserved.
   37  *
   38  * Permission to use, copy, modify and distribute this software and
   39  * its documentation is hereby granted, provided that both the copyright
   40  * notice and this permission notice appear in all copies of the
   41  * software, derivative works or modified versions, and any portions
   42  * thereof, and that both notices appear in supporting documentation.
   43  *
   44  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   45  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
   46  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   47  *
   48  * Carnegie Mellon requests users of this software to return to
   49  *
   50  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   51  *  School of Computer Science
   52  *  Carnegie Mellon University
   53  *  Pittsburgh PA 15213-3890
   54  *
   55  * any improvements or extensions that they make and grant Carnegie the
   56  * rights to redistribute these changes.
   57  */
   58 
   59 #include <sys/cdefs.h>
   60 __FBSDID("$FreeBSD$");
   61 
   62 #include "opt_vm.h"
   63 #include "opt_kstack_pages.h"
   64 #include "opt_kstack_max_pages.h"
   65 #include "opt_kstack_usage_prof.h"
   66 
   67 #include <sys/param.h>
   68 #include <sys/systm.h>
   69 #include <sys/limits.h>
   70 #include <sys/lock.h>
   71 #include <sys/malloc.h>
   72 #include <sys/mutex.h>
   73 #include <sys/proc.h>
   74 #include <sys/racct.h>
   75 #include <sys/resourcevar.h>
   76 #include <sys/rwlock.h>
   77 #include <sys/sched.h>
   78 #include <sys/sf_buf.h>
   79 #include <sys/shm.h>
   80 #include <sys/vmmeter.h>
   81 #include <sys/vmem.h>
   82 #include <sys/sx.h>
   83 #include <sys/sysctl.h>
   84 #include <sys/_kstack_cache.h>
   85 #include <sys/eventhandler.h>
   86 #include <sys/kernel.h>
   87 #include <sys/ktr.h>
   88 #include <sys/unistd.h>
   89 
   90 #include <vm/vm.h>
   91 #include <vm/vm_param.h>
   92 #include <vm/pmap.h>
   93 #include <vm/vm_map.h>
   94 #include <vm/vm_page.h>
   95 #include <vm/vm_pageout.h>
   96 #include <vm/vm_object.h>
   97 #include <vm/vm_kern.h>
   98 #include <vm/vm_extern.h>
   99 #include <vm/vm_pager.h>
  100 #include <vm/swap_pager.h>
  101 
  102 #include <machine/cpu.h>
  103 
  104 #ifndef NO_SWAPPING
  105 static int swapout(struct proc *);
  106 static void swapclear(struct proc *);
  107 static void vm_thread_swapin(struct thread *td);
  108 static void vm_thread_swapout(struct thread *td);
  109 #endif
  110 
  111 /*
  112  * MPSAFE
  113  *
  114  * WARNING!  This code calls vm_map_check_protection() which only checks
  115  * the associated vm_map_entry range.  It does not determine whether the
  116  * contents of the memory is actually readable or writable.  In most cases
  117  * just checking the vm_map_entry is sufficient within the kernel's address
  118  * space.
  119  */
  120 int
  121 kernacc(addr, len, rw)
  122         void *addr;
  123         int len, rw;
  124 {
  125         boolean_t rv;
  126         vm_offset_t saddr, eaddr;
  127         vm_prot_t prot;
  128 
  129         KASSERT((rw & ~VM_PROT_ALL) == 0,
  130             ("illegal ``rw'' argument to kernacc (%x)\n", rw));
  131 
  132         if ((vm_offset_t)addr + len > kernel_map->max_offset ||
  133             (vm_offset_t)addr + len < (vm_offset_t)addr)
  134                 return (FALSE);
  135 
  136         prot = rw;
  137         saddr = trunc_page((vm_offset_t)addr);
  138         eaddr = round_page((vm_offset_t)addr + len);
  139         vm_map_lock_read(kernel_map);
  140         rv = vm_map_check_protection(kernel_map, saddr, eaddr, prot);
  141         vm_map_unlock_read(kernel_map);
  142         return (rv == TRUE);
  143 }
  144 
  145 /*
  146  * MPSAFE
  147  *
  148  * WARNING!  This code calls vm_map_check_protection() which only checks
  149  * the associated vm_map_entry range.  It does not determine whether the
  150  * contents of the memory is actually readable or writable.  vmapbuf(),
  151  * vm_fault_quick(), or copyin()/copout()/su*()/fu*() functions should be
  152  * used in conjuction with this call.
  153  */
  154 int
  155 useracc(addr, len, rw)
  156         void *addr;
  157         int len, rw;
  158 {
  159         boolean_t rv;
  160         vm_prot_t prot;
  161         vm_map_t map;
  162 
  163         KASSERT((rw & ~VM_PROT_ALL) == 0,
  164             ("illegal ``rw'' argument to useracc (%x)\n", rw));
  165         prot = rw;
  166         map = &curproc->p_vmspace->vm_map;
  167         if ((vm_offset_t)addr + len > vm_map_max(map) ||
  168             (vm_offset_t)addr + len < (vm_offset_t)addr) {
  169                 return (FALSE);
  170         }
  171         vm_map_lock_read(map);
  172         rv = vm_map_check_protection(map, trunc_page((vm_offset_t)addr),
  173             round_page((vm_offset_t)addr + len), prot);
  174         vm_map_unlock_read(map);
  175         return (rv == TRUE);
  176 }
  177 
  178 int
  179 vslock(void *addr, size_t len)
  180 {
  181         vm_offset_t end, last, start;
  182         vm_size_t npages;
  183         int error;
  184 
  185         last = (vm_offset_t)addr + len;
  186         start = trunc_page((vm_offset_t)addr);
  187         end = round_page(last);
  188         if (last < (vm_offset_t)addr || end < (vm_offset_t)addr)
  189                 return (EINVAL);
  190         npages = atop(end - start);
  191         if (npages > vm_page_max_wired)
  192                 return (ENOMEM);
  193 #if 0
  194         /*
  195          * XXX - not yet
  196          *
  197          * The limit for transient usage of wired pages should be
  198          * larger than for "permanent" wired pages (mlock()).
  199          *
  200          * Also, the sysctl code, which is the only present user
  201          * of vslock(), does a hard loop on EAGAIN.
  202          */
  203         if (npages + cnt.v_wire_count > vm_page_max_wired)
  204                 return (EAGAIN);
  205 #endif
  206         error = vm_map_wire(&curproc->p_vmspace->vm_map, start, end,
  207             VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
  208         /*
  209          * Return EFAULT on error to match copy{in,out}() behaviour
  210          * rather than returning ENOMEM like mlock() would.
  211          */
  212         return (error == KERN_SUCCESS ? 0 : EFAULT);
  213 }
  214 
  215 void
  216 vsunlock(void *addr, size_t len)
  217 {
  218 
  219         /* Rely on the parameter sanity checks performed by vslock(). */
  220         (void)vm_map_unwire(&curproc->p_vmspace->vm_map,
  221             trunc_page((vm_offset_t)addr), round_page((vm_offset_t)addr + len),
  222             VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
  223 }
  224 
  225 /*
  226  * Pin the page contained within the given object at the given offset.  If the
  227  * page is not resident, allocate and load it using the given object's pager.
  228  * Return the pinned page if successful; otherwise, return NULL.
  229  */
  230 static vm_page_t
  231 vm_imgact_hold_page(vm_object_t object, vm_ooffset_t offset)
  232 {
  233         vm_page_t m, ma[1];
  234         vm_pindex_t pindex;
  235         int rv;
  236 
  237         VM_OBJECT_WLOCK(object);
  238         pindex = OFF_TO_IDX(offset);
  239         m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL);
  240         if (m->valid != VM_PAGE_BITS_ALL) {
  241                 ma[0] = m;
  242                 rv = vm_pager_get_pages(object, ma, 1, 0);
  243                 m = vm_page_lookup(object, pindex);
  244                 if (m == NULL)
  245                         goto out;
  246                 if (rv != VM_PAGER_OK) {
  247                         vm_page_lock(m);
  248                         vm_page_free(m);
  249                         vm_page_unlock(m);
  250                         m = NULL;
  251                         goto out;
  252                 }
  253         }
  254         vm_page_xunbusy(m);
  255         vm_page_lock(m);
  256         vm_page_hold(m);
  257         vm_page_activate(m);
  258         vm_page_unlock(m);
  259 out:
  260         VM_OBJECT_WUNLOCK(object);
  261         return (m);
  262 }
  263 
  264 /*
  265  * Return a CPU private mapping to the page at the given offset within the
  266  * given object.  The page is pinned before it is mapped.
  267  */
  268 struct sf_buf *
  269 vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset)
  270 {
  271         vm_page_t m;
  272 
  273         m = vm_imgact_hold_page(object, offset);
  274         if (m == NULL)
  275                 return (NULL);
  276         sched_pin();
  277         return (sf_buf_alloc(m, SFB_CPUPRIVATE));
  278 }
  279 
  280 /*
  281  * Destroy the given CPU private mapping and unpin the page that it mapped.
  282  */
  283 void
  284 vm_imgact_unmap_page(struct sf_buf *sf)
  285 {
  286         vm_page_t m;
  287 
  288         m = sf_buf_page(sf);
  289         sf_buf_free(sf);
  290         sched_unpin();
  291         vm_page_lock(m);
  292         vm_page_unhold(m);
  293         vm_page_unlock(m);
  294 }
  295 
  296 void
  297 vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
  298 {
  299 
  300         pmap_sync_icache(map->pmap, va, sz);
  301 }
  302 
  303 struct kstack_cache_entry *kstack_cache;
  304 static int kstack_cache_size = 128;
  305 static int kstacks;
  306 static struct mtx kstack_cache_mtx;
  307 MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);
  308 
  309 SYSCTL_INT(_vm, OID_AUTO, kstack_cache_size, CTLFLAG_RW, &kstack_cache_size, 0,
  310     "");
  311 SYSCTL_INT(_vm, OID_AUTO, kstacks, CTLFLAG_RD, &kstacks, 0,
  312     "");
  313 
  314 #ifndef KSTACK_MAX_PAGES
  315 #define KSTACK_MAX_PAGES 32
  316 #endif
  317 
  318 /*
  319  * Create the kernel stack (including pcb for i386) for a new thread.
  320  * This routine directly affects the fork perf for a process and
  321  * create performance for a thread.
  322  */
  323 int
  324 vm_thread_new(struct thread *td, int pages)
  325 {
  326         vm_object_t ksobj;
  327         vm_offset_t ks;
  328         vm_page_t m, ma[KSTACK_MAX_PAGES];
  329         struct kstack_cache_entry *ks_ce;
  330         int i;
  331 
  332         /* Bounds check */
  333         if (pages <= 1)
  334                 pages = KSTACK_PAGES;
  335         else if (pages > KSTACK_MAX_PAGES)
  336                 pages = KSTACK_MAX_PAGES;
  337 
  338         if (pages == KSTACK_PAGES) {
  339                 mtx_lock(&kstack_cache_mtx);
  340                 if (kstack_cache != NULL) {
  341                         ks_ce = kstack_cache;
  342                         kstack_cache = ks_ce->next_ks_entry;
  343                         mtx_unlock(&kstack_cache_mtx);
  344 
  345                         td->td_kstack_obj = ks_ce->ksobj;
  346                         td->td_kstack = (vm_offset_t)ks_ce;
  347                         td->td_kstack_pages = KSTACK_PAGES;
  348                         return (1);
  349                 }
  350                 mtx_unlock(&kstack_cache_mtx);
  351         }
  352 
  353         /*
  354          * Allocate an object for the kstack.
  355          */
  356         ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
  357         
  358         /*
  359          * Get a kernel virtual address for this thread's kstack.
  360          */
  361 #if defined(__mips__)
  362         /*
  363          * We need to align the kstack's mapped address to fit within
  364          * a single TLB entry.
  365          */
  366         if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE,
  367             PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
  368             M_BESTFIT | M_NOWAIT, &ks)) {
  369                 ks = 0;
  370         }
  371 #else
  372         ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
  373 #endif
  374         if (ks == 0) {
  375                 printf("vm_thread_new: kstack allocation failed\n");
  376                 vm_object_deallocate(ksobj);
  377                 return (0);
  378         }
  379 
  380         atomic_add_int(&kstacks, 1);
  381         if (KSTACK_GUARD_PAGES != 0) {
  382                 pmap_qremove(ks, KSTACK_GUARD_PAGES);
  383                 ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
  384         }
  385         td->td_kstack_obj = ksobj;
  386         td->td_kstack = ks;
  387         /*
  388          * Knowing the number of pages allocated is useful when you
  389          * want to deallocate them.
  390          */
  391         td->td_kstack_pages = pages;
  392         /* 
  393          * For the length of the stack, link in a real page of ram for each
  394          * page of stack.
  395          */
  396         VM_OBJECT_WLOCK(ksobj);
  397         for (i = 0; i < pages; i++) {
  398                 /*
  399                  * Get a kernel stack page.
  400                  */
  401                 m = vm_page_grab(ksobj, i, VM_ALLOC_NOBUSY |
  402                     VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
  403                 ma[i] = m;
  404                 m->valid = VM_PAGE_BITS_ALL;
  405         }
  406         VM_OBJECT_WUNLOCK(ksobj);
  407         pmap_qenter(ks, ma, pages);
  408         return (1);
  409 }
  410 
  411 static void
  412 vm_thread_stack_dispose(vm_object_t ksobj, vm_offset_t ks, int pages)
  413 {
  414         vm_page_t m;
  415         int i;
  416 
  417         atomic_add_int(&kstacks, -1);
  418         pmap_qremove(ks, pages);
  419         VM_OBJECT_WLOCK(ksobj);
  420         for (i = 0; i < pages; i++) {
  421                 m = vm_page_lookup(ksobj, i);
  422                 if (m == NULL)
  423                         panic("vm_thread_dispose: kstack already missing?");
  424                 vm_page_lock(m);
  425                 vm_page_unwire(m, 0);
  426                 vm_page_free(m);
  427                 vm_page_unlock(m);
  428         }
  429         VM_OBJECT_WUNLOCK(ksobj);
  430         vm_object_deallocate(ksobj);
  431         kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
  432             (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
  433 }
  434 
  435 /*
  436  * Dispose of a thread's kernel stack.
  437  */
  438 void
  439 vm_thread_dispose(struct thread *td)
  440 {
  441         vm_object_t ksobj;
  442         vm_offset_t ks;
  443         struct kstack_cache_entry *ks_ce;
  444         int pages;
  445 
  446         pages = td->td_kstack_pages;
  447         ksobj = td->td_kstack_obj;
  448         ks = td->td_kstack;
  449         td->td_kstack = 0;
  450         td->td_kstack_pages = 0;
  451         if (pages == KSTACK_PAGES && kstacks <= kstack_cache_size) {
  452                 ks_ce = (struct kstack_cache_entry *)ks;
  453                 ks_ce->ksobj = ksobj;
  454                 mtx_lock(&kstack_cache_mtx);
  455                 ks_ce->next_ks_entry = kstack_cache;
  456                 kstack_cache = ks_ce;
  457                 mtx_unlock(&kstack_cache_mtx);
  458                 return;
  459         }
  460         vm_thread_stack_dispose(ksobj, ks, pages);
  461 }
  462 
  463 static void
  464 vm_thread_stack_lowmem(void *nulll)
  465 {
  466         struct kstack_cache_entry *ks_ce, *ks_ce1;
  467 
  468         mtx_lock(&kstack_cache_mtx);
  469         ks_ce = kstack_cache;
  470         kstack_cache = NULL;
  471         mtx_unlock(&kstack_cache_mtx);
  472 
  473         while (ks_ce != NULL) {
  474                 ks_ce1 = ks_ce;
  475                 ks_ce = ks_ce->next_ks_entry;
  476 
  477                 vm_thread_stack_dispose(ks_ce1->ksobj, (vm_offset_t)ks_ce1,
  478                     KSTACK_PAGES);
  479         }
  480 }
  481 
  482 static void
  483 kstack_cache_init(void *nulll)
  484 {
  485 
  486         EVENTHANDLER_REGISTER(vm_lowmem, vm_thread_stack_lowmem, NULL,
  487             EVENTHANDLER_PRI_ANY);
  488 }
  489 
  490 SYSINIT(vm_kstacks, SI_SUB_KTHREAD_INIT, SI_ORDER_ANY, kstack_cache_init, NULL);
  491 
  492 #ifdef KSTACK_USAGE_PROF
  493 /*
  494  * Track maximum stack used by a thread in kernel.
  495  */
  496 static int max_kstack_used;
  497 
  498 SYSCTL_INT(_debug, OID_AUTO, max_kstack_used, CTLFLAG_RD,
  499     &max_kstack_used, 0,
  500     "Maxiumum stack depth used by a thread in kernel");
  501 
  502 void
  503 intr_prof_stack_use(struct thread *td, struct trapframe *frame)
  504 {
  505         vm_offset_t stack_top;
  506         vm_offset_t current;
  507         int used, prev_used;
  508 
  509         /*
  510          * Testing for interrupted kernel mode isn't strictly
  511          * needed. It optimizes the execution, since interrupts from
  512          * usermode will have only the trap frame on the stack.
  513          */
  514         if (TRAPF_USERMODE(frame))
  515                 return;
  516 
  517         stack_top = td->td_kstack + td->td_kstack_pages * PAGE_SIZE;
  518         current = (vm_offset_t)(uintptr_t)&stack_top;
  519 
  520         /*
  521          * Try to detect if interrupt is using kernel thread stack.
  522          * Hardware could use a dedicated stack for interrupt handling.
  523          */
  524         if (stack_top <= current || current < td->td_kstack)
  525                 return;
  526 
  527         used = stack_top - current;
  528         for (;;) {
  529                 prev_used = max_kstack_used;
  530                 if (prev_used >= used)
  531                         break;
  532                 if (atomic_cmpset_int(&max_kstack_used, prev_used, used))
  533                         break;
  534         }
  535 }
  536 #endif /* KSTACK_USAGE_PROF */
  537 
  538 #ifndef NO_SWAPPING
  539 /*
  540  * Allow a thread's kernel stack to be paged out.
  541  */
  542 static void
  543 vm_thread_swapout(struct thread *td)
  544 {
  545         vm_object_t ksobj;
  546         vm_page_t m;
  547         int i, pages;
  548 
  549         cpu_thread_swapout(td);
  550         pages = td->td_kstack_pages;
  551         ksobj = td->td_kstack_obj;
  552         pmap_qremove(td->td_kstack, pages);
  553         VM_OBJECT_WLOCK(ksobj);
  554         for (i = 0; i < pages; i++) {
  555                 m = vm_page_lookup(ksobj, i);
  556                 if (m == NULL)
  557                         panic("vm_thread_swapout: kstack already missing?");
  558                 vm_page_dirty(m);
  559                 vm_page_lock(m);
  560                 vm_page_unwire(m, 0);
  561                 vm_page_unlock(m);
  562         }
  563         VM_OBJECT_WUNLOCK(ksobj);
  564 }
  565 
  566 /*
  567  * Bring the kernel stack for a specified thread back in.
  568  */
  569 static void
  570 vm_thread_swapin(struct thread *td)
  571 {
  572         vm_object_t ksobj;
  573         vm_page_t ma[KSTACK_MAX_PAGES];
  574         int i, j, k, pages, rv;
  575 
  576         pages = td->td_kstack_pages;
  577         ksobj = td->td_kstack_obj;
  578         VM_OBJECT_WLOCK(ksobj);
  579         for (i = 0; i < pages; i++)
  580                 ma[i] = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL |
  581                     VM_ALLOC_WIRED);
  582         for (i = 0; i < pages; i++) {
  583                 if (ma[i]->valid != VM_PAGE_BITS_ALL) {
  584                         vm_page_assert_xbusied(ma[i]);
  585                         vm_object_pip_add(ksobj, 1);
  586                         for (j = i + 1; j < pages; j++) {
  587                                 if (ma[j]->valid != VM_PAGE_BITS_ALL)
  588                                         vm_page_assert_xbusied(ma[j]);
  589                                 if (ma[j]->valid == VM_PAGE_BITS_ALL)
  590                                         break;
  591                         }
  592                         rv = vm_pager_get_pages(ksobj, ma + i, j - i, 0);
  593                         if (rv != VM_PAGER_OK)
  594         panic("vm_thread_swapin: cannot get kstack for proc: %d",
  595                                     td->td_proc->p_pid);
  596                         vm_object_pip_wakeup(ksobj);
  597                         for (k = i; k < j; k++)
  598                                 ma[k] = vm_page_lookup(ksobj, k);
  599                         vm_page_xunbusy(ma[i]);
  600                 } else if (vm_page_xbusied(ma[i]))
  601                         vm_page_xunbusy(ma[i]);
  602         }
  603         VM_OBJECT_WUNLOCK(ksobj);
  604         pmap_qenter(td->td_kstack, ma, pages);
  605         cpu_thread_swapin(td);
  606 }
  607 #endif /* !NO_SWAPPING */
  608 
  609 /*
  610  * Implement fork's actions on an address space.
  611  * Here we arrange for the address space to be copied or referenced,
  612  * allocate a user struct (pcb and kernel stack), then call the
  613  * machine-dependent layer to fill those in and make the new process
  614  * ready to run.  The new process is set up so that it returns directly
  615  * to user mode to avoid stack copying and relocation problems.
  616  */
  617 int
  618 vm_forkproc(td, p2, td2, vm2, flags)
  619         struct thread *td;
  620         struct proc *p2;
  621         struct thread *td2;
  622         struct vmspace *vm2;
  623         int flags;
  624 {
  625         struct proc *p1 = td->td_proc;
  626         int error;
  627 
  628         if ((flags & RFPROC) == 0) {
  629                 /*
  630                  * Divorce the memory, if it is shared, essentially
  631                  * this changes shared memory amongst threads, into
  632                  * COW locally.
  633                  */
  634                 if ((flags & RFMEM) == 0) {
  635                         if (p1->p_vmspace->vm_refcnt > 1) {
  636                                 error = vmspace_unshare(p1);
  637                                 if (error)
  638                                         return (error);
  639                         }
  640                 }
  641                 cpu_fork(td, p2, td2, flags);
  642                 return (0);
  643         }
  644 
  645         if (flags & RFMEM) {
  646                 p2->p_vmspace = p1->p_vmspace;
  647                 atomic_add_int(&p1->p_vmspace->vm_refcnt, 1);
  648         }
  649 
  650         while (vm_page_count_severe()) {
  651                 VM_WAIT;
  652         }
  653 
  654         if ((flags & RFMEM) == 0) {
  655                 p2->p_vmspace = vm2;
  656                 if (p1->p_vmspace->vm_shm)
  657                         shmfork(p1, p2);
  658         }
  659 
  660         /*
  661          * cpu_fork will copy and update the pcb, set up the kernel stack,
  662          * and make the child ready to run.
  663          */
  664         cpu_fork(td, p2, td2, flags);
  665         return (0);
  666 }
  667 
  668 /*
  669  * Called after process has been wait(2)'ed apon and is being reaped.
  670  * The idea is to reclaim resources that we could not reclaim while
  671  * the process was still executing.
  672  */
  673 void
  674 vm_waitproc(p)
  675         struct proc *p;
  676 {
  677 
  678         vmspace_exitfree(p);            /* and clean-out the vmspace */
  679 }
  680 
  681 void
  682 faultin(p)
  683         struct proc *p;
  684 {
  685 #ifdef NO_SWAPPING
  686 
  687         PROC_LOCK_ASSERT(p, MA_OWNED);
  688         if ((p->p_flag & P_INMEM) == 0)
  689                 panic("faultin: proc swapped out with NO_SWAPPING!");
  690 #else /* !NO_SWAPPING */
  691         struct thread *td;
  692 
  693         PROC_LOCK_ASSERT(p, MA_OWNED);
  694         /*
  695          * If another process is swapping in this process,
  696          * just wait until it finishes.
  697          */
  698         if (p->p_flag & P_SWAPPINGIN) {
  699                 while (p->p_flag & P_SWAPPINGIN)
  700                         msleep(&p->p_flag, &p->p_mtx, PVM, "faultin", 0);
  701                 return;
  702         }
  703         if ((p->p_flag & P_INMEM) == 0) {
  704                 /*
  705                  * Don't let another thread swap process p out while we are
  706                  * busy swapping it in.
  707                  */
  708                 ++p->p_lock;
  709                 p->p_flag |= P_SWAPPINGIN;
  710                 PROC_UNLOCK(p);
  711 
  712                 /*
  713                  * We hold no lock here because the list of threads
  714                  * can not change while all threads in the process are
  715                  * swapped out.
  716                  */
  717                 FOREACH_THREAD_IN_PROC(p, td)
  718                         vm_thread_swapin(td);
  719                 PROC_LOCK(p);
  720                 swapclear(p);
  721                 p->p_swtick = ticks;
  722 
  723                 wakeup(&p->p_flag);
  724 
  725                 /* Allow other threads to swap p out now. */
  726                 --p->p_lock;
  727         }
  728 #endif /* NO_SWAPPING */
  729 }
  730 
  731 /*
  732  * This swapin algorithm attempts to swap-in processes only if there
  733  * is enough space for them.  Of course, if a process waits for a long
  734  * time, it will be swapped in anyway.
  735  */
  736 void
  737 swapper(void)
  738 {
  739         struct proc *p;
  740         struct thread *td;
  741         struct proc *pp;
  742         int slptime;
  743         int swtime;
  744         int ppri;
  745         int pri;
  746 
  747 loop:
  748         if (vm_page_count_min()) {
  749                 VM_WAIT;
  750                 goto loop;
  751         }
  752 
  753         pp = NULL;
  754         ppri = INT_MIN;
  755         sx_slock(&allproc_lock);
  756         FOREACH_PROC_IN_SYSTEM(p) {
  757                 PROC_LOCK(p);
  758                 if (p->p_state == PRS_NEW ||
  759                     p->p_flag & (P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) {
  760                         PROC_UNLOCK(p);
  761                         continue;
  762                 }
  763                 swtime = (ticks - p->p_swtick) / hz;
  764                 FOREACH_THREAD_IN_PROC(p, td) {
  765                         /*
  766                          * An otherwise runnable thread of a process
  767                          * swapped out has only the TDI_SWAPPED bit set.
  768                          * 
  769                          */
  770                         thread_lock(td);
  771                         if (td->td_inhibitors == TDI_SWAPPED) {
  772                                 slptime = (ticks - td->td_slptick) / hz;
  773                                 pri = swtime + slptime;
  774                                 if ((td->td_flags & TDF_SWAPINREQ) == 0)
  775                                         pri -= p->p_nice * 8;
  776                                 /*
  777                                  * if this thread is higher priority
  778                                  * and there is enough space, then select
  779                                  * this process instead of the previous
  780                                  * selection.
  781                                  */
  782                                 if (pri > ppri) {
  783                                         pp = p;
  784                                         ppri = pri;
  785                                 }
  786                         }
  787                         thread_unlock(td);
  788                 }
  789                 PROC_UNLOCK(p);
  790         }
  791         sx_sunlock(&allproc_lock);
  792 
  793         /*
  794          * Nothing to do, back to sleep.
  795          */
  796         if ((p = pp) == NULL) {
  797                 tsleep(&proc0, PVM, "swapin", MAXSLP * hz / 2);
  798                 goto loop;
  799         }
  800         PROC_LOCK(p);
  801 
  802         /*
  803          * Another process may be bringing or may have already
  804          * brought this process in while we traverse all threads.
  805          * Or, this process may even be being swapped out again.
  806          */
  807         if (p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) {
  808                 PROC_UNLOCK(p);
  809                 goto loop;
  810         }
  811 
  812         /*
  813          * We would like to bring someone in. (only if there is space).
  814          * [What checks the space? ]
  815          */
  816         faultin(p);
  817         PROC_UNLOCK(p);
  818         goto loop;
  819 }
  820 
  821 void
  822 kick_proc0(void)
  823 {
  824 
  825         wakeup(&proc0);
  826 }
  827 
  828 #ifndef NO_SWAPPING
  829 
  830 /*
  831  * Swap_idle_threshold1 is the guaranteed swapped in time for a process
  832  */
  833 static int swap_idle_threshold1 = 2;
  834 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold1, CTLFLAG_RW,
  835     &swap_idle_threshold1, 0, "Guaranteed swapped in time for a process");
  836 
  837 /*
  838  * Swap_idle_threshold2 is the time that a process can be idle before
  839  * it will be swapped out, if idle swapping is enabled.
  840  */
  841 static int swap_idle_threshold2 = 10;
  842 SYSCTL_INT(_vm, OID_AUTO, swap_idle_threshold2, CTLFLAG_RW,
  843     &swap_idle_threshold2, 0, "Time before a process will be swapped out");
  844 
  845 /*
  846  * First, if any processes have been sleeping or stopped for at least
  847  * "swap_idle_threshold1" seconds, they are swapped out.  If, however,
  848  * no such processes exist, then the longest-sleeping or stopped
  849  * process is swapped out.  Finally, and only as a last resort, if
  850  * there are no sleeping or stopped processes, the longest-resident
  851  * process is swapped out.
  852  */
  853 void
  854 swapout_procs(action)
  855 int action;
  856 {
  857         struct proc *p;
  858         struct thread *td;
  859         int didswap = 0;
  860 
  861 retry:
  862         sx_slock(&allproc_lock);
  863         FOREACH_PROC_IN_SYSTEM(p) {
  864                 struct vmspace *vm;
  865                 int minslptime = 100000;
  866                 int slptime;
  867                 
  868                 /*
  869                  * Watch out for a process in
  870                  * creation.  It may have no
  871                  * address space or lock yet.
  872                  */
  873                 if (p->p_state == PRS_NEW)
  874                         continue;
  875                 /*
  876                  * An aio daemon switches its
  877                  * address space while running.
  878                  * Perform a quick check whether
  879                  * a process has P_SYSTEM.
  880                  */
  881                 if ((p->p_flag & P_SYSTEM) != 0)
  882                         continue;
  883                 /*
  884                  * Do not swapout a process that
  885                  * is waiting for VM data
  886                  * structures as there is a possible
  887                  * deadlock.  Test this first as
  888                  * this may block.
  889                  *
  890                  * Lock the map until swapout
  891                  * finishes, or a thread of this
  892                  * process may attempt to alter
  893                  * the map.
  894                  */
  895                 vm = vmspace_acquire_ref(p);
  896                 if (vm == NULL)
  897                         continue;
  898                 if (!vm_map_trylock(&vm->vm_map))
  899                         goto nextproc1;
  900 
  901                 PROC_LOCK(p);
  902                 if (p->p_lock != 0 ||
  903                     (p->p_flag & (P_STOPPED_SINGLE|P_TRACED|P_SYSTEM|P_WEXIT)
  904                     ) != 0) {
  905                         goto nextproc;
  906                 }
  907                 /*
  908                  * only aiod changes vmspace, however it will be
  909                  * skipped because of the if statement above checking 
  910                  * for P_SYSTEM
  911                  */
  912                 if ((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) != P_INMEM)
  913                         goto nextproc;
  914 
  915                 switch (p->p_state) {
  916                 default:
  917                         /* Don't swap out processes in any sort
  918                          * of 'special' state. */
  919                         break;
  920 
  921                 case PRS_NORMAL:
  922                         /*
  923                          * do not swapout a realtime process
  924                          * Check all the thread groups..
  925                          */
  926                         FOREACH_THREAD_IN_PROC(p, td) {
  927                                 thread_lock(td);
  928                                 if (PRI_IS_REALTIME(td->td_pri_class)) {
  929                                         thread_unlock(td);
  930                                         goto nextproc;
  931                                 }
  932                                 slptime = (ticks - td->td_slptick) / hz;
  933                                 /*
  934                                  * Guarantee swap_idle_threshold1
  935                                  * time in memory.
  936                                  */
  937                                 if (slptime < swap_idle_threshold1) {
  938                                         thread_unlock(td);
  939                                         goto nextproc;
  940                                 }
  941 
  942                                 /*
  943                                  * Do not swapout a process if it is
  944                                  * waiting on a critical event of some
  945                                  * kind or there is a thread whose
  946                                  * pageable memory may be accessed.
  947                                  *
  948                                  * This could be refined to support
  949                                  * swapping out a thread.
  950                                  */
  951                                 if (!thread_safetoswapout(td)) {
  952                                         thread_unlock(td);
  953                                         goto nextproc;
  954                                 }
  955                                 /*
  956                                  * If the system is under memory stress,
  957                                  * or if we are swapping
  958                                  * idle processes >= swap_idle_threshold2,
  959                                  * then swap the process out.
  960                                  */
  961                                 if (((action & VM_SWAP_NORMAL) == 0) &&
  962                                     (((action & VM_SWAP_IDLE) == 0) ||
  963                                     (slptime < swap_idle_threshold2))) {
  964                                         thread_unlock(td);
  965                                         goto nextproc;
  966                                 }
  967 
  968                                 if (minslptime > slptime)
  969                                         minslptime = slptime;
  970                                 thread_unlock(td);
  971                         }
  972 
  973                         /*
  974                          * If the pageout daemon didn't free enough pages,
  975                          * or if this process is idle and the system is
  976                          * configured to swap proactively, swap it out.
  977                          */
  978                         if ((action & VM_SWAP_NORMAL) ||
  979                                 ((action & VM_SWAP_IDLE) &&
  980                                  (minslptime > swap_idle_threshold2))) {
  981                                 if (swapout(p) == 0)
  982                                         didswap++;
  983                                 PROC_UNLOCK(p);
  984                                 vm_map_unlock(&vm->vm_map);
  985                                 vmspace_free(vm);
  986                                 sx_sunlock(&allproc_lock);
  987                                 goto retry;
  988                         }
  989                 }
  990 nextproc:
  991                 PROC_UNLOCK(p);
  992                 vm_map_unlock(&vm->vm_map);
  993 nextproc1:
  994                 vmspace_free(vm);
  995                 continue;
  996         }
  997         sx_sunlock(&allproc_lock);
  998         /*
  999          * If we swapped something out, and another process needed memory,
 1000          * then wakeup the sched process.
 1001          */
 1002         if (didswap)
 1003                 wakeup(&proc0);
 1004 }
 1005 
 1006 static void
 1007 swapclear(p)
 1008         struct proc *p;
 1009 {
 1010         struct thread *td;
 1011 
 1012         PROC_LOCK_ASSERT(p, MA_OWNED);
 1013 
 1014         FOREACH_THREAD_IN_PROC(p, td) {
 1015                 thread_lock(td);
 1016                 td->td_flags |= TDF_INMEM;
 1017                 td->td_flags &= ~TDF_SWAPINREQ;
 1018                 TD_CLR_SWAPPED(td);
 1019                 if (TD_CAN_RUN(td))
 1020                         if (setrunnable(td)) {
 1021 #ifdef INVARIANTS
 1022                                 /*
 1023                                  * XXX: We just cleared TDI_SWAPPED
 1024                                  * above and set TDF_INMEM, so this
 1025                                  * should never happen.
 1026                                  */
 1027                                 panic("not waking up swapper");
 1028 #endif
 1029                         }
 1030                 thread_unlock(td);
 1031         }
 1032         p->p_flag &= ~(P_SWAPPINGIN|P_SWAPPINGOUT);
 1033         p->p_flag |= P_INMEM;
 1034 }
 1035 
 1036 static int
 1037 swapout(p)
 1038         struct proc *p;
 1039 {
 1040         struct thread *td;
 1041 
 1042         PROC_LOCK_ASSERT(p, MA_OWNED);
 1043 #if defined(SWAP_DEBUG)
 1044         printf("swapping out %d\n", p->p_pid);
 1045 #endif
 1046 
 1047         /*
 1048          * The states of this process and its threads may have changed
 1049          * by now.  Assuming that there is only one pageout daemon thread,
 1050          * this process should still be in memory.
 1051          */
 1052         KASSERT((p->p_flag & (P_INMEM|P_SWAPPINGOUT|P_SWAPPINGIN)) == P_INMEM,
 1053                 ("swapout: lost a swapout race?"));
 1054 
 1055         /*
 1056          * remember the process resident count
 1057          */
 1058         p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
 1059         /*
 1060          * Check and mark all threads before we proceed.
 1061          */
 1062         p->p_flag &= ~P_INMEM;
 1063         p->p_flag |= P_SWAPPINGOUT;
 1064         FOREACH_THREAD_IN_PROC(p, td) {
 1065                 thread_lock(td);
 1066                 if (!thread_safetoswapout(td)) {
 1067                         thread_unlock(td);
 1068                         swapclear(p);
 1069                         return (EBUSY);
 1070                 }
 1071                 td->td_flags &= ~TDF_INMEM;
 1072                 TD_SET_SWAPPED(td);
 1073                 thread_unlock(td);
 1074         }
 1075         td = FIRST_THREAD_IN_PROC(p);
 1076         ++td->td_ru.ru_nswap;
 1077         PROC_UNLOCK(p);
 1078 
 1079         /*
 1080          * This list is stable because all threads are now prevented from
 1081          * running.  The list is only modified in the context of a running
 1082          * thread in this process.
 1083          */
 1084         FOREACH_THREAD_IN_PROC(p, td)
 1085                 vm_thread_swapout(td);
 1086 
 1087         PROC_LOCK(p);
 1088         p->p_flag &= ~P_SWAPPINGOUT;
 1089         p->p_swtick = ticks;
 1090         return (0);
 1091 }
 1092 #endif /* !NO_SWAPPING */

Cache object: b531cad732f89ea38710155d8997eda7


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.