linux/mm/mlock.c
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   1/*
   2 *      linux/mm/mlock.c
   3 *
   4 *  (C) Copyright 1995 Linus Torvalds
   5 *  (C) Copyright 2002 Christoph Hellwig
   6 */
   7
   8#include <linux/capability.h>
   9#include <linux/mman.h>
  10#include <linux/mm.h>
  11#include <linux/swap.h>
  12#include <linux/swapops.h>
  13#include <linux/pagemap.h>
  14#include <linux/mempolicy.h>
  15#include <linux/syscalls.h>
  16#include <linux/sched.h>
  17#include <linux/export.h>
  18#include <linux/rmap.h>
  19#include <linux/mmzone.h>
  20#include <linux/hugetlb.h>
  21
  22#include "internal.h"
  23
  24int can_do_mlock(void)
  25{
  26        if (capable(CAP_IPC_LOCK))
  27                return 1;
  28        if (rlimit(RLIMIT_MEMLOCK) != 0)
  29                return 1;
  30        return 0;
  31}
  32EXPORT_SYMBOL(can_do_mlock);
  33
  34/*
  35 * Mlocked pages are marked with PageMlocked() flag for efficient testing
  36 * in vmscan and, possibly, the fault path; and to support semi-accurate
  37 * statistics.
  38 *
  39 * An mlocked page [PageMlocked(page)] is unevictable.  As such, it will
  40 * be placed on the LRU "unevictable" list, rather than the [in]active lists.
  41 * The unevictable list is an LRU sibling list to the [in]active lists.
  42 * PageUnevictable is set to indicate the unevictable state.
  43 *
  44 * When lazy mlocking via vmscan, it is important to ensure that the
  45 * vma's VM_LOCKED status is not concurrently being modified, otherwise we
  46 * may have mlocked a page that is being munlocked. So lazy mlock must take
  47 * the mmap_sem for read, and verify that the vma really is locked
  48 * (see mm/rmap.c).
  49 */
  50
  51/*
  52 *  LRU accounting for clear_page_mlock()
  53 */
  54void __clear_page_mlock(struct page *page)
  55{
  56        VM_BUG_ON(!PageLocked(page));
  57
  58        if (!page->mapping) {   /* truncated ? */
  59                return;
  60        }
  61
  62        dec_zone_page_state(page, NR_MLOCK);
  63        count_vm_event(UNEVICTABLE_PGCLEARED);
  64        if (!isolate_lru_page(page)) {
  65                putback_lru_page(page);
  66        } else {
  67                /*
  68                 * We lost the race. the page already moved to evictable list.
  69                 */
  70                if (PageUnevictable(page))
  71                        count_vm_event(UNEVICTABLE_PGSTRANDED);
  72        }
  73}
  74
  75/*
  76 * Mark page as mlocked if not already.
  77 * If page on LRU, isolate and putback to move to unevictable list.
  78 */
  79void mlock_vma_page(struct page *page)
  80{
  81        BUG_ON(!PageLocked(page));
  82
  83        if (!TestSetPageMlocked(page)) {
  84                inc_zone_page_state(page, NR_MLOCK);
  85                count_vm_event(UNEVICTABLE_PGMLOCKED);
  86                if (!isolate_lru_page(page))
  87                        putback_lru_page(page);
  88        }
  89}
  90
  91/**
  92 * munlock_vma_page - munlock a vma page
  93 * @page - page to be unlocked
  94 *
  95 * called from munlock()/munmap() path with page supposedly on the LRU.
  96 * When we munlock a page, because the vma where we found the page is being
  97 * munlock()ed or munmap()ed, we want to check whether other vmas hold the
  98 * page locked so that we can leave it on the unevictable lru list and not
  99 * bother vmscan with it.  However, to walk the page's rmap list in
 100 * try_to_munlock() we must isolate the page from the LRU.  If some other
 101 * task has removed the page from the LRU, we won't be able to do that.
 102 * So we clear the PageMlocked as we might not get another chance.  If we
 103 * can't isolate the page, we leave it for putback_lru_page() and vmscan
 104 * [page_referenced()/try_to_unmap()] to deal with.
 105 */
 106void munlock_vma_page(struct page *page)
 107{
  88        BUG_ON(!PageLocked(page));
  90
  70        if (page)) {
  71                dec_zone_page_state(page, NR_MLOCK);
  71                if (!isolate_lru_page(page)) {
  71                   4int   74
  85                   5/*
  96/*
  97mpage(pagd, we won&nedy movnt to "> s hold the
  68           mmmmmmmm* ether othel with.
  69           mmmmmmmm*nt"> */
  70                        if ((pag e)
  71                          a>int  * try_to_mrlimit" class="t"> * try_to_mu_page(page);
  71                  a5/*
 103           mmmmmmmm* d/*
 104           mmmmmmmm*nt"> */
  85                        if (page)
  86                          a>int count_vm_event(UNEVICTABUNLE_PGM">page);
  57
  28                  a>int putback_lru_page(page);
  29                } else {
  70                  a5/*
 101 * task has removed the page from tl with.
 102mp hold the
 103           mmmmmmmm* d the page frove to unevictabl,lockeecessaralready.
  34           mmmmmmmm* other vt"> * [page_refere]ph, ikck to oved theor pready.
  35           mmmmmmmm*  list t* The unevictable RU.  If somese th tasiand not
  36           mmmmmmmm* ge as mlready.
  37           mmmmmmmm*nt"> */
  28                        if (PageUnevictable(page))
  29                                count_vm_event(UNEVICTABLE_PGSTRANDED);
  70                      );
  71                          a>int count_vm_event(UNEVICTABUNLE_PGM">page);
  71          89}
  71  89}
  89}
  9}
  46/**
  47  48
  49 100  51 *
  52mp hosocked presefficoolready.
  53 104 105  96  47 */
  ="../. lo>mpt((LOCKED" class="coupaga_e(">page *pag/span>
  59                              unsign relo>mpt(pageunsign relo>mpt(pag/span>
  70                               4 *page)
   else {
  62  e(struct page *page->  63  unsign relo>mpt(pa/a>>
  64   4int pap- a>int pa) / a>int pa/a>>
  65   4int pa/a>>
  a>>
  67  a>int VM_BUG_Oa>int pa & ~a>int page);
  88        VM_BUG_Oa>int pap  & ~a>int page);
  67  a>int VM_BUG_Oa>int pa </a>int page->page);
  70        VM_BUG_Oa>int pap  >/a>int page->page);
  81        VM_BUG_ON(!page));
  82
  63        pa =/a>int pa |/a>int pa/a>>
  64  a5/*
  75msvmscana wriuly, the in ordme other
  76msvpage, becausagd, we won&COW other
  77mlready.
  78 */
  67      Oa>int page->pa & Oa>int pa |/a>int page<==/a>int page)
  70                pa |=/a>int pa/a>>
  61
  64  a5/*
 103        d, we lazy ; andccelocp_sem gionsked so* mayany permissionsnt">/*
  34   * ether atherPROT_NONElready.
  75 */
  26        if (page->pa & Oa>int pa |/a>int pa |/a>int page))
  87                pa |=/a>int pa/a>>
  a>>
  67        rt(page *pag/span>
  70                           *pag/a>>
  31}
  82
  93/*
  94/*
  95 */
  ="../.  4int page)
 107{
  28        if (pa<==/-  if (page)
  59            if (pa<=/-  if (pa/a>>
  70      }      if (pa<==/-  if (pa) != 0)
  71                pa<=/-  if (  67        rt(paK);
  73}
  74
 105/**
  46  47mp hosspecg moaaddress ranlra_ady.
  48mpaddress ine@e tptbacto_mu_ady.
  49 100 101  52 103  94 *
  95 *
  96  97 */
  lo>mpt((LOCKED" class="coupaga_e(">page *pag/span>
  59                  unsign relo>mpt(pageunsign relo>mpt(pa) != 0)
  80{
  71   4int pap- a>int pa) / a>int pa/a>>
  62        BUG_ON   if (page->pa & a>int page));
  23
  64  a5/*
  75/*
  76 */
  27        if (page->pa & Oa>int pa |/a>int page))
  28          go pa *  90
  70      ! Oa>int page->pa & Oa>int pa |/a>int page<||90
  71                        pae<||90
  71                  a>int pa<==/a>int isnloLOCKED" class="t n_g">isnloBUG_Oa>int page->  33
  84                pagpt(paget(page *  9}
  86          ) {    *isc nt"> */
  27                return 0;
  88        }
  90
  70  a5/*
  41/*
  42  43 s hruwe woico reset's VM_--no&nedy movryto_mr reand not
  44
  45
  46  47 */
  88        paget(pae));
  90
 10/a> *  81        page->pa &= ~a>int pa;    ) {    */
  67        rt( */
  73}
  74
 105/*
  96munlock_vms_ranlru_p-  n we munllsocked inecause theanlrlwe wont">/*
  47mpranlre page t"> * munloind not
  48  49 100 101  52 103 * cmscan@e tpsreLE_PGMind not
  94 *
  95 *isc() webe preppagdctont"> *
  96  47  68  69 100 * m|d or } befoma whed or nreand not
 101mpmtPageMsockedl with.
  52 */
  06void (LOCKED" class="coupaga_e(">page *pag/span>
  84                       unsign relo>mpt(pageunsign relo>mpt(pa) != 0)
  /a>)) {
  86  unsign relo>mpt(  57
  88          67  a>int page->pa &= ~a>int pa;/a>));
  90
  81  p_seg *pa/pt(pa/pt(pae)) {
  71          e(struct page *pa;/a>));
  83          ) {    */
  34   mmmmmmmm* Although FOLL_DUMPe paintendlocp_set n_dumpck_lru_,nt">/*
  75/*
  36           * ZERO_sAGE (      ">mpagnerrtininocead ofsdo">mpt n_k_lr)nt">/*
  37           * suits  n we muvery wh ik(and  RU.  Ihowpagnabnormal a vma page
  68           *h tassneageMsintoe lost nlrhe LRU, we won&oops  vma: geeat)ind not
  69           ent"> */
  70          truct pag=/a>int pagpt(pa |/a>int pae));
  71                if (pag&& N(!page)) {
  71                  a>int pag));
  71                  ) {    */
  94/*
  95/*
  96/*
  97  98 */
  59                        if (page->mLOCKED" class="mmef">m">pa) != 0)
  70                           *munlock_vma_pag *pag));
  71                   *mu+code=page" class="ref">mu+coda_pag *pag));
  71                  a>int pag));
  71          73}
  84                  65  73}
  73}
  57
  48 */
  49m[all]arpquestdl with.
 100 101  52 103  94 *
  95lit he mefroprit iind not
  96 */
  ="../.  4int (LOCKED" class="coupaga_e(">page *pag e(struct pagee *pag/span>
  88  unsign relo>mpt(pageunsign relo>mpt(pagstruct   8t(pa) != 0)
  /a>)) {
  70  e(struct page *page->  81          8t(  62   4int   62   4int   64   4int pa & a>int pagturn 0;
  9}
  26        if (pa ==/a>int page->pa ||    if (page->pa & a>int pae<||90
  27      a>int pae<|| a>int pa<==/a>int isnloLOCKED" class="t n_g">isnloBUG_Oa>int page->  28          go pa *pa/p      a {    */
  90
  70        page->pa - a>int page->pag >>/a>int pagturn 0;
  71  e *pa =/a>int pagpt(paget(page *pagstruct page->pag/span>
  71                    a>int page->pagstruct paegturn 0;
  62      e *pae)) {
  84                pa<=ee *paturn 0;
  28          go pa *  86  73}
  57
  28        if (pa !=/a>int page->pag /a>)) {
  59            if (litsnloLOCKED" class="s>litsnloBUG_Oa>int pag t(page1gturn 0;
  70                if (  71                  go pa *pa/90
  86  73}
  33
  28        if (pap!=/a>int page->pag /a>)) {
  28            if (litsnloLOCKED" class="s>litsnloBUG_Oa>int pag t(page0gturn 0;
  86                if (  27                  go pa *pa/90
  88        }
  90
 10/a> *  81   8 */
  42  43 */
  64  a>int pap- a>int pa) >>/a>int pa/90
  28      N(!  86          )>int   67  a>int   a>>
  81   8 */
 100 101  52mpitfor pind not
 103 */
  74
  28      (!  86          )>int page->pa =/  if (pa/a>>
  67      a>>
  28          a>int pag t(paget(pagturn 0;
  90
 10/a> *pa:90
  71  e *pa =/a>int paturn 0;
  67        rt(  73}
  74
  ="../.  4int paget(  6(!page 4int   /a>)) {
  67  unsign relo>mpt(paget(page *  88  e(struct pagee *pag ee *paturn 0;
  67   4int   90
  81        pa & ~a>int pagturn 0;
  62        pap!=/a>int paegturn 0;
  83  t(pap=/a>int pa +6(!paturn 0;
  28        if (pap</a>int pa)urn 0;
  28                r-  if (paturn 0;
  26        if (pap==/a>int pa)urn 0;
  87                return 0;
  88        pa<=e      page->pagturn 0;
  67      N(!pa<|| a>int page->pa >/a>int pa)urn 0;
  70                r-  if (pa/a>>
  a>>
  62        pa =/a>int page->pa/a>>
  62       *pa >/a>int page->paga>>
  84                pa =/a>int paturn 0;
  9}
  26  p_seg *pap=/a>int pa ; ; g /a>)) {
  87          >->  8t(paturn 0;
  a>>
  59            {    */
  90
  71                pa =/a>int page->pa | a>int paturn 0;
  71              N(!  71                        pa &= ~a>int pa;/a>));
  74
  28            if (page->pa;/a>));
  86                if (pa) != 0)
  27                    if (pa/ != 0)
  28          a>int pag &      page *paget(pagturn 0;
  59                if (  70                  breakturn 0;
  71                pap=/a>int   71                    pap</a>int page->pagurn 0;
  71                        pap=/a>int page->paturn 0;
  84                    pap>= a>int pa) != 0)
  28                  breakturn 0;
  urn 0;
  87          >->pa<=e      page->paturn 0;
  28              N(!pa<|| a>int page->pa !=/a>int pag /a>)) {
  59                  a>int pa/a>>
  70                  breakturn 0;
  71          73}
  86  73}
  62        rt(  73}
  9}
  ="../.  4int paget(  6(!page 4int pa) != 0)
  /a>)) {
  88  e(struct page *page->  59  unsign relo>mpt(pagstruct paget(paturn 0;
  70  e(struct page *pa =/a>int   71   4int pa =/eturn 0;
  62   4int   33
  84  a>int pa & ~a>int pagturn 0;
  28  a>int pap!=/a>int paegturn 0;
  86  t(pap=/a>int pa +6(!paturn 0;
  57
  28  p_seg *pap=/a>int pa;/a>int pap</a>int pa/pt(pap=/a>int pag /a>)) {
  59           8 */
 100 */
 101mpVMAlt"> */
  52 */
  71              N(!pag /a>)) {
  84          86  t(pa =/1turn 0;
  28          86  t(pagturn 0;
  86          86  t(pa<=e      pagturn 0;
  27          }                pap>= a>int page->pagurn 0;
  28          86  t(pa<=e      page->paturn 0;
  59              N(!pa<|| a>int page->pa KED" class="nse="t">pap=/a>int page  e *l  59           8 */
  42mpaesi"> *d p_se[a> */
  43mpmtPageMsockedl with.
  34 */
  28     pap=/a>int   unsign relo>mpt(int page-> 0;
page->  28PFNMAnt  0;
  27  " class="se="t">pa;/a>int pap>/a>int page->paga>4gt;
  59             >pa/pt(>/a>int page->  59           8 */
 101 */
  52 * ng" cla */
 103mpmtPageMsockedl with.
  34 */
  28            if (pagstruct paget(pag     N(!a0;
  86                if (pag /a>)gt;
  27  86         e 4int pag /a>)g0;
  28            if (  59  59            {  continue tljx(LOwonA commmmmmmmmmmmmmmmmm nt"> */
  e  73
  28            if (  71 *l  71          73<4a>}
  84     pap=/a>int        if (pSHIFTlIZE   28            if (  86  73<4) {
  28     N(!  86  73<4)0;
  28     up t(pagturn 0;
  67        rt(  59            {  0 orjx(gative CKED" >    commmmmmmmmmmmmmmmmm nt"> */  86  73<4/a>
  a>4 0;
  67    SYSCALL_DEFINE2 rt(gt;dLOCCKame="429">  5CKED" class="coa">pag t(paget( *  a>4 0;
pag /a>) 0;
  59  unsign re    N(!pagturn 0;
  59  unsign re    _limit(pagturn a>
  67   4int pa/a>& 0;
  57< 0;
          can_  4int   70              PER  if (pa/a>& 0;
  90  81(  59            {  flush ng" vec commmmmmmmmmmmmmmmmm nt"> */ */  83<_agadlosmm>(page->pagturngt;
 *pag t(pa & ~a>int pagturng0;
  28<>pag t(pagturnga>
  urn) {
  67  t(pa) >>/a>int pa/904 0;
  88  t(int page->pa/904 0;
  905an>
  70<    _limit((pagtur5/a>
  81(pa/905 0;
 */
  59            {  cmmmm against9">source limits commmmmmmmmmmmmmmmmm nt"> */  28     N(!  81(pacapabl nt (
  28          a>int pag t(  6(!page1gtur5));
  86(page->pagtur5 0)
                 if (  28          a>int pag t(  6(!page0gtur5 0;
  67        rt(  86  73<5 0;
  a>5 0;
  67    SYSCALL_DEFINE2 rt(  5CKED" class="coa">pag t(paget( *  a>5 0;
pag /a>5 0;
  62   4int   9<5 0;
  86<_agadlosmm>(page->pagtur5 0;
  67 *pag t(pa & ~a>int pagtur5 0;
  88<>pag t(pagtur5) {
  28            if (int pag t(  6(!page0gtur5gt;
  70(page->pagtur5 0;
  67        rt(  86  73<5a>}
  335 0;
  ="../.  4iall(  =".././a>->  335 a>
pag /a>5a>}
  88  e(struct pagee *pag ee *pa =/a>int   ="../. ef->  a>5 0;
  =".././a>->  ="../.MCL_FUTURE   335 0;
  ="../. ef->  ="../.p;= ~a>int pa;/a5 0;
  81int page->-&ve=pCKE""426">  ="../. ef->pa;/a5 >}
  =".././a>->pMCL_FUTURE   335 >}
pa/905/a>
  745 0;
  28  /a>  t(ve =/a>int page->          86  t(pa<=e      page->pag /a>5 0;
  86          >->  8t(patur5 0;
  575/a>
  28                pa =/a>int page->pa | a>int patur5) {
  =".././a>->  ="../.MCL_CURRENt 
  e  28                pa &= ~a>int pa;/a5an>
  a>5an>
  59            {  IrtisL CKED"s commmmmmmmmmmmmmmmmm nt"> */
pag &      int page->int page->pagtur5) {
  86  73<5 0;
pa:905 0;
  87                retur5 0;
  86  73<5 a>
  a>5 0;
  67    SYSCALL_DEFINE1pa *iallED" CKED"page" class="tmp_/a>->  335" class="5rev">pagepag /a>5  e *5f="mm/mlo3ck.c#L31"3 id=5L51" 55ass="line" n4ame="429">  59  unsign re    _limit(pagtur5an>
  62   4int patur5an>
  335an>
          /a>->  =".././a>->  ="../.MCL_CURRENt MCL_FUTURE pa/905 0;
  ur5 0;
  67<  4int pa/a>5 0;
          can_  4int pa/905an>
  905an>
  =".././a>->  ="../.MCL_CURRENt   905an>
  unsign re ru_add_drain_all(  59            {  flush ng" vec commmmmmmmmmmmmmmmmm nt"> */
  335an>
(page->pagtur5/a>
  9<5a0;
  86<    _limit((pagtur5gt;
  67 _limit(pa/905g0;
  a>5 0;
  28            if (pa/a>5/a>
  =".././a>->  ="../.MCL_CURRENt   ="../.ve =/a>int page->  81(pa/a>5/n>
(  28            if (iall(pa/a>5/n>
  83(page->pagtur5a>}
                 if (->  ="../.MCL_CURRENt pag /a>5/a>
  59            {  IrtisL CKED"s commmmmmmmmmmmmmmmmm nt"> */
  86       4int page1gtur5) {
  86  73<5)0;
pa:905 0;
  67        rt(pa:905 0;
  86  73<5/a>
  a>5 0;
  67    SYSCALL_DEFINE0 rt(  905 0;
pag /a>5 0;
  62   4int   9<5 a>
  86<_agadlosmm>(page->pagtur5 0;
  67<  4int iall(page0gtur5 0;
  88(page->pagtur5 0;
  67        rt(pa:905 0;
  86  73<5gt;
  a>5gt;
  52 */ 103<* Objectspagcladiffenc_e lifetimem itn processes (SH_PGMLO and SH_PHUGETLBa> */  34<* shm seg">  s) get account> *dgainst9nFk(userCKED" c insteadrei">mpmtPageMsockedl with.  34<*ommmmmmmmmmmmmmmmmm nt"> */
  67    DEFINE_SPINGMLO(iKED" class="mmthe mm">pagtur5) {
  575 0;
  62 userCKhmC/a>int   88  e  905 0;
pag /a>6an>
  59  unsign re    _limit((!pagtur6/a>
  62 allowN(! */
  83<"o  N(!(SHIFTlIZE pa) >>/a>int pa/906));
((pagtur6/a>
  28     _limit(  906));
  86     allowN(!pa =/1tur6 0)
  67 _limit(pa/906 0)
  88<>pinC/a>int iKED" class="mmthe mm">pagtur6 0;
          allowN(!pagtur6 0)
  83<"o  N(!usernt   67 _limit(          capabl nt (pa/906 0;
  88(!pa/906 a>
  83(!pagtur6 0;
(!pa =/1tur6 a>
pa:906 0;
  86iKED" class="mmthe mm">pagtur6 0;
  67    allowN(!pagtur6 0)
  86  73<6) {
  906gt;
  62 userCKhmC  88  e  906 0;
pag /a>6a>}
  88<>pinC/a>int iKED" class="mmthe mm">pagtur6a>}
  83SHIFTlIZE pa) >>/a>int pa/906 0;
iKED" class="mmthe mm">pagtur6 a>
  28(!pa/906a>}
  86  73<6 0)



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