1. 16 12月, 2009 40 次提交
    • D
      mm: slab-allocate memory section nodemask for large systems · 9ae49fab
      David Rientjes 提交于
      Nodemasks should not be allocated on the stack for large systems (when it
      is larger than 256 bytes) since there is a threat of overflow.
      
      This patch causes the unregister_mem_sect_under_nodes() nodemask to be
      allocated on the stack for smaller systems and be allocated by slab for
      larger systems.
      
      GFP_KERNEL is used since remove_memory_block() can block.
      
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Alex Chiang <achiang@hp.com>
      Signed-off-by: NDavid Rientjes <rientjes@google.com>
      Cc: Greg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9ae49fab
    • K
      mm: simplify try_to_unmap_one() · caed0f48
      KOSAKI Motohiro 提交于
      SWAP_MLOCK mean "We marked the page as PG_MLOCK, please move it to
      unevictable-lru". So, following code is easy confusable.
      
              if (vma->vm_flags & VM_LOCKED) {
                      ret = SWAP_MLOCK;
                      goto out_unmap;
              }
      
      Plus, if the VMA doesn't have VM_LOCKED, We don't need to check
      the needed of calling mlock_vma_page().
      
      Also, add some commentary to try_to_unmap_one().
      Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      caed0f48
    • R
      mm: fix section mismatch in memory_hotplug.c · 23ce932a
      Rakib Mullick 提交于
      __free_pages_bootmem() is a __meminit function - which has been called
      from put_pages_bootmem thus causes a section mismatch warning.
      
       We were warned by the following warning:
      
        LD      mm/built-in.o
      WARNING: mm/built-in.o(.text+0x26b22): Section mismatch in reference
      from the function put_page_bootmem() to the function
      .meminit.text:__free_pages_bootmem()
      The function put_page_bootmem() references
      the function __meminit __free_pages_bootmem().
      This is often because put_page_bootmem lacks a __meminit
      annotation or the annotation of __free_pages_bootmem is wrong.
      Signed-off-by: NRakib Mullick <rakib.mullick@gmail.com>
      Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      23ce932a
    • L
      hugetlb: prevent deadlock in __unmap_hugepage_range() when alloc_huge_page() fails · b76c8cfb
      Larry Woodman 提交于
      hugetlb_fault() takes the mm->page_table_lock spinlock then calls
      hugetlb_cow().  If the alloc_huge_page() in hugetlb_cow() fails due to an
      insufficient huge page pool it calls unmap_ref_private() with the
      mm->page_table_lock held.  unmap_ref_private() then calls
      unmap_hugepage_range() which tries to acquire the mm->page_table_lock.
      
      [<ffffffff810928c3>] print_circular_bug_tail+0x80/0x9f
       [<ffffffff8109280b>] ? check_noncircular+0xb0/0xe8
       [<ffffffff810935e0>] __lock_acquire+0x956/0xc0e
       [<ffffffff81093986>] lock_acquire+0xee/0x12e
       [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84
       [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84
       [<ffffffff814c348d>] _spin_lock+0x40/0x89
       [<ffffffff8111a7a6>] ? unmap_hugepage_range+0x3e/0x84
       [<ffffffff8111afee>] ? alloc_huge_page+0x218/0x318
       [<ffffffff8111a7a6>] unmap_hugepage_range+0x3e/0x84
       [<ffffffff8111b2d0>] hugetlb_cow+0x1e2/0x3f4
       [<ffffffff8111b935>] ? hugetlb_fault+0x453/0x4f6
       [<ffffffff8111b962>] hugetlb_fault+0x480/0x4f6
       [<ffffffff8111baee>] follow_hugetlb_page+0x116/0x2d9
       [<ffffffff814c31a7>] ? _spin_unlock_irq+0x3a/0x5c
       [<ffffffff81107b4d>] __get_user_pages+0x2a3/0x427
       [<ffffffff81107d0f>] get_user_pages+0x3e/0x54
       [<ffffffff81040b8b>] get_user_pages_fast+0x170/0x1b5
       [<ffffffff81160352>] dio_get_page+0x64/0x14a
       [<ffffffff8116112a>] __blockdev_direct_IO+0x4b7/0xb31
       [<ffffffff8115ef91>] blkdev_direct_IO+0x58/0x6e
       [<ffffffff8115e0a4>] ? blkdev_get_blocks+0x0/0xb8
       [<ffffffff810ed2c5>] generic_file_aio_read+0xdd/0x528
       [<ffffffff81219da3>] ? avc_has_perm+0x66/0x8c
       [<ffffffff81132842>] do_sync_read+0xf5/0x146
       [<ffffffff8107da00>] ? autoremove_wake_function+0x0/0x5a
       [<ffffffff81211857>] ? security_file_permission+0x24/0x3a
       [<ffffffff81132fd8>] vfs_read+0xb5/0x126
       [<ffffffff81133f6b>] ? fget_light+0x5e/0xf8
       [<ffffffff81133131>] sys_read+0x54/0x8c
       [<ffffffff81011e42>] system_call_fastpath+0x16/0x1b
      
      This can be fixed by dropping the mm->page_table_lock around the call to
      unmap_ref_private() if alloc_huge_page() fails, its dropped right below in
      the normal path anyway.  However, earlier in the that function, it's also
      possible to call into the page allocator with the same spinlock held.
      
      What this patch does is drop the spinlock before the page allocator is
      potentially entered.  The check for page allocation failure can be made
      without the page_table_lock as well as the copy of the huge page.  Even if
      the PTE changed while the spinlock was held, the consequence is that a
      huge page is copied unnecessarily.  This resolves both the double taking
      of the lock and sleeping with the spinlock held.
      
      [mel@csn.ul.ie: Cover also the case where process can sleep with spinlock]
      Signed-off-by: NLarry Woodman <lwooman@redhat.com>
      Signed-off-by: NMel Gorman <mel@csn.ul.ie>
      Acked-by: NAdam Litke <agl@us.ibm.com>
      Cc: Andy Whitcroft <apw@shadowen.org>
      Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
      Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: David Gibson <david@gibson.dropbear.id.au>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b76c8cfb
    • A
      mm: memory_hotplug: make offline_pages() static · b4e655a4
      Andrew Morton 提交于
      It has no references outside memory_hotplug.c.
      
      Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b4e655a4
    • H
      ksm: remove unswappable max_kernel_pages · d0f209f6
      Hugh Dickins 提交于
      Now that ksm pages are swappable, and the known holes plugged, remove
      mention of unswappable kernel pages from KSM documentation and comments.
      
      Remove the totalram_pages/4 initialization of max_kernel_pages.  In fact,
      remove max_kernel_pages altogether - we can reinstate it if removal turns
      out to break someone's script; but if we later want to limit KSM's memory
      usage, limiting the stable nodes would not be an effective approach.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d0f209f6
    • H
      ksm: memory hotremove migration only · 62b61f61
      Hugh Dickins 提交于
      The previous patch enables page migration of ksm pages, but that soon gets
      into trouble: not surprising, since we're using the ksm page lock to lock
      operations on its stable_node, but page migration switches the page whose
      lock is to be used for that.  Another layer of locking would fix it, but
      do we need that yet?
      
      Do we actually need page migration of ksm pages?  Yes, memory hotremove
      needs to offline sections of memory: and since we stopped allocating ksm
      pages with GFP_HIGHUSER, they will tend to be GFP_HIGHUSER_MOVABLE
      candidates for migration.
      
      But KSM is currently unconscious of NUMA issues, happily merging pages
      from different NUMA nodes: at present the rule must be, not to use
      MADV_MERGEABLE where you care about NUMA.  So no, NUMA page migration of
      ksm pages does not make sense yet.
      
      So, to complete support for ksm swapping we need to make hotremove safe.
      ksm_memory_callback() take ksm_thread_mutex when MEM_GOING_OFFLINE and
      release it when MEM_OFFLINE or MEM_CANCEL_OFFLINE.  But if mapped pages
      are freed before migration reaches them, stable_nodes may be left still
      pointing to struct pages which have been removed from the system: the
      stable_node needs to identify a page by pfn rather than page pointer, then
      it can safely prune them when MEM_OFFLINE.
      
      And make NUMA migration skip PageKsm pages where it skips PageReserved.
      But it's only when we reach unmap_and_move() that the page lock is taken
      and we can be sure that raised pagecount has prevented a PageAnon from
      being upgraded: so add offlining arg to migrate_pages(), to migrate ksm
      page when offlining (has sufficient locking) but reject it otherwise.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      62b61f61
    • H
      ksm: rmap_walk to remove_migation_ptes · e9995ef9
      Hugh Dickins 提交于
      A side-effect of making ksm pages swappable is that they have to be placed
      on the LRUs: which then exposes them to isolate_lru_page() and hence to
      page migration.
      
      Add rmap_walk() for remove_migration_ptes() to use: rmap_walk_anon() and
      rmap_walk_file() in rmap.c, but rmap_walk_ksm() in ksm.c.  Perhaps some
      consolidation with existing code is possible, but don't attempt that yet
      (try_to_unmap needs to handle nonlinears, but migration pte removal does
      not).
      
      rmap_walk() is sadly less general than it appears: rmap_walk_anon(), like
      remove_anon_migration_ptes() which it replaces, avoids calling
      page_lock_anon_vma(), because that includes a page_mapped() test which
      fails when all migration ptes are in place.  That was valid when NUMA page
      migration was introduced (holding mmap_sem provided the missing guarantee
      that anon_vma's slab had not already been destroyed), but I believe not
      valid in the memory hotremove case added since.
      
      For now do the same as before, and consider the best way to fix that
      unlikely race later on.  When fixed, we can probably use rmap_walk() on
      hwpoisoned ksm pages too: for now, they remain among hwpoison's various
      exceptions (its PageKsm test comes before the page is locked, but its
      page_lock_anon_vma fails safely if an anon gets upgraded).
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e9995ef9
    • H
      ksm: mem cgroup charge swapin copy · 407f9c8b
      Hugh Dickins 提交于
      But ksm swapping does require one small change in mem cgroup handling.
      When do_swap_page()'s call to ksm_might_need_to_copy() does indeed
      substitute a duplicate page to accommodate a different anon_vma (or a the
      !PageSwapCache check in mem_cgroup_try_charge_swapin().
      
      That was returning success without charging, on the assumption that
      pte_same() would fail after, which is not the case here.  Originally I
      proposed that success, so that an unshrinkable mem cgroup at its limit
      would not fail unnecessarily; but that's a minor point, and there are
      plenty of other places where we may fail an overallocation which might
      later prove unnecessary.  So just go ahead and do what all the other
      exceptions do: proceed to charge current mm.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Acked-by: NBalbir Singh <balbir@linux.vnet.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      407f9c8b
    • H
      ksm: share anon page without allocating · 80e14822
      Hugh Dickins 提交于
      When ksm pages were unswappable, it made no sense to include them in mem
      cgroup accounting; but now that they are swappable (although I see no
      strict logical connection) the principle of least surprise implies that
      they should be accounted (with the usual dissatisfaction, that a shared
      page is accounted to only one of the cgroups using it).
      
      This patch was intended to add mem cgroup accounting where necessary; but
      turned inside out, it now avoids allocating a ksm page, instead upgrading
      an anon page to ksm - which brings its existing mem cgroup accounting with
      it.  Thus mem cgroups don't appear in the patch at all.
      
      This upgrade from PageAnon to PageKsm takes place under page lock (via a
      somewhat hacky NULL kpage interface), and audit showed only one place
      which needed to cope with the race - page_referenced() is sometimes used
      without page lock, so page_lock_anon_vma() needs an ACCESS_ONCE() to be
      sure of getting anon_vma and flags together (no problem if the page goes
      ksm an instant after, the integrity of that anon_vma list is unaffected).
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      80e14822
    • H
      ksm: take keyhole reference to page · 4035c07a
      Hugh Dickins 提交于
      There's a lamentable flaw in KSM swapping: the stable_node holds a
      reference to the ksm page, so the page to be freed cannot actually be
      freed until ksmd works its way around to removing the last rmap_item from
      its stable_node.  Which in some configurations may take minutes: not quite
      responsive enough for memory reclaim.  And we don't want to twist KSM and
      its locking more tightly into the rest of mm.  What a pity.
      
      But although the stable_node needs to hold a pointer to the ksm page, does
      it actually need to raise the reference count of that page?
      
      No.  It would need to do so if struct pages were ordinary kmalloc'ed
      objects; but they are more stable than that, and reused in particular ways
      according to particular rules.
      
      Access to stable_node from its pointer in struct page is no problem, so
      long as we never free a stable_node before the ksm page itself has been
      freed.  Access to struct page from its pointer in stable_node: reintroduce
      get_ksm_page(), and let that peep out through its keyhole (the stable_node
      pointer to ksm page), to see if that struct page still holds the right key
      to open it (the ksm page mapping pointer back to this stable_node).
      
      This relies upon the established way in which free_hot_cold_page() sets an
      anon (including ksm) page->mapping to NULL; and relies upon no other user
      of a struct page to put something which looks like the original
      stable_node pointer (with two low bits also set) into page->mapping.  It
      also needs get_page_unless_zero() technique pioneered by speculative
      pagecache; and uses rcu_read_lock() to keep the guarantees that gives.
      
      There are several drivers which put pointers of their own into page->
      mapping; but none of those could coincide with our stable_node pointers,
      since KSM won't free a stable_node until it sees that the page has gone.
      
      The only problem case found is the pagetable spinlock USE_SPLIT_PTLOCKS
      places in struct page (my own abuse): to accommodate GENERIC_LOCKBREAK's
      break_lock on 32-bit, that spans both page->private and page->mapping.
      Since break_lock is only 0 or 1, again no confusion for get_ksm_page().
      
      But what of DEBUG_SPINLOCK on 64-bit bigendian?  When owner_cpu is 3
      (matching PageKsm low bits), it might see 0xdead4ead00000003 in page->
      mapping, which might coincide?  We could get around that by...  but a
      better answer is to suppress USE_SPLIT_PTLOCKS when DEBUG_SPINLOCK or
      DEBUG_LOCK_ALLOC, to stop bloating sizeof(struct page) in their case -
      already proposed in an earlier mm/Kconfig patch.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4035c07a
    • H
      ksm: hold anon_vma in rmap_item · db114b83
      Hugh Dickins 提交于
      For full functionality, page_referenced_one() and try_to_unmap_one() need
      to know the vma: to pass vma down to arch-dependent flushes, or to observe
      VM_LOCKED or VM_EXEC.  But KSM keeps no record of vma: nor can it, since
      vmas get split and merged without its knowledge.
      
      Instead, note page's anon_vma in its rmap_item when adding to stable tree:
      all the vmas which might map that page are listed by its anon_vma.
      
      page_referenced_ksm() and try_to_unmap_ksm() then traverse the anon_vma,
      first to find the probable vma, that which matches rmap_item's mm; but if
      that is not enough to locate all instances, traverse again to try the
      others.  This catches those occasions when fork has duplicated a pte of a
      ksm page, but ksmd has not yet come around to assign it an rmap_item.
      
      But each rmap_item in the stable tree which refers to an anon_vma needs to
      take a reference to it.  Andrea's anon_vma design cleverly avoided a
      reference count (an anon_vma was free when its list of vmas was empty),
      but KSM now needs to add that.  Is a 32-bit count sufficient?  I believe
      so - the anon_vma is only free when both count is 0 and list is empty.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      db114b83
    • H
      ksm: let shared pages be swappable · 5ad64688
      Hugh Dickins 提交于
      Initial implementation for swapping out KSM's shared pages: add
      page_referenced_ksm() and try_to_unmap_ksm(), which rmap.c calls when
      faced with a PageKsm page.
      
      Most of what's needed can be got from the rmap_items listed from the
      stable_node of the ksm page, without discovering the actual vma: so in
      this patch just fake up a struct vma for page_referenced_one() or
      try_to_unmap_one(), then refine that in the next patch.
      
      Add VM_NONLINEAR to ksm_madvise()'s list of exclusions: it has always been
      implicit there (being only set with VM_SHARED, already excluded), but
      let's make it explicit, to help justify the lack of nonlinear unmap.
      
      Rely on the page lock to protect against concurrent modifications to that
      page's node of the stable tree.
      
      The awkward part is not swapout but swapin: do_swap_page() and
      page_add_anon_rmap() now have to allow for new possibilities - perhaps a
      ksm page still in swapcache, perhaps a swapcache page associated with one
      location in one anon_vma now needed for another location or anon_vma.
      (And the vma might even be no longer VM_MERGEABLE when that happens.)
      
      ksm_might_need_to_copy() checks for that case, and supplies a duplicate
      page when necessary, simply leaving it to a subsequent pass of ksmd to
      rediscover the identity and merge them back into one ksm page.
      Disappointingly primitive: but the alternative would have to accumulate
      unswappable info about the swapped out ksm pages, limiting swappability.
      
      Remove page_add_ksm_rmap(): page_add_anon_rmap() now has to allow for the
      particular case it was handling, so just use it instead.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5ad64688
    • H
      ksm: fix mlockfreed to munlocked · 73848b46
      Hugh Dickins 提交于
      When KSM merges an mlocked page, it has been forgetting to munlock it:
      that's been left to free_page_mlock(), which reports it in /proc/vmstat as
      unevictable_pgs_mlockfreed instead of unevictable_pgs_munlocked (and
      whinges "Page flag mlocked set for process" in mmotm, whereas mainline is
      silently forgiving).  Call munlock_vma_page() to fix that.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Acked-by: NRik van Riel <riel@redhat.com>
      Acked-by: NMel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      73848b46
    • H
      ksm: stable_node point to page and back · 08beca44
      Hugh Dickins 提交于
      Add a pointer to the ksm page into struct stable_node, holding a reference
      to the page while the node exists.  Put a pointer to the stable_node into
      the ksm page's ->mapping.
      
      Then we don't need get_ksm_page() while traversing the stable tree: the
      page to compare against is sure to be present and correct, even if it's no
      longer visible through any of its existing rmap_items.
      
      And we can handle the forked ksm page case more efficiently: no need to
      memcmp our way through the tree to find its match.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      08beca44
    • H
      ksm: separate stable_node · 7b6ba2c7
      Hugh Dickins 提交于
      Though we still do well to keep rmap_items in the unstable tree without a
      separate tree_item at the node, for several reasons it becomes awkward to
      keep rmap_items in the stable tree without a separate stable_node: lack of
      space in the nicely-sized rmap_item, the need for an anchor as rmap_items
      are removed, the need for a node even when temporarily no rmap_items are
      attached to it.
      
      So declare struct stable_node (rb_node to place it in the tree and
      hlist_head for the rmap_items hanging off it), and convert stable tree
      handling to use it: without yet taking advantage of it.  Note how one
      stable_tree_insert() of a node now has _two_ stable_tree_append()s of the
      two rmap_items being merged.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7b6ba2c7
    • H
      ksm: singly-linked rmap_list · 6514d511
      Hugh Dickins 提交于
      Free up a pointer in struct rmap_item, by making the mm_slot's rmap_list a
      singly-linked list: we always traverse that list sequentially, and we
      don't even lose any prefetches (but should consider adding a few later).
      Name it rmap_list throughout.
      
      Do we need to free up that pointer?  Not immediately, and in the end, we
      could continue to avoid it with a union; but having done the conversion,
      let's keep it this way, since there's no downside, and maybe we'll want
      more in future (struct rmap_item is a cache-friendly 32 bytes on 32-bit
      and 64 bytes on 64-bit, so we shall want to avoid expanding it).
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6514d511
    • H
      ksm: cleanup some function arguments · 8dd3557a
      Hugh Dickins 提交于
      Cleanup: make argument names more consistent from cmp_and_merge_page()
      down to replace_page(), so that it's easier to follow the rmap_item's page
      and the matching tree_page and the merged kpage through that code.
      
      In some places, e.g.  break_cow(), pass rmap_item instead of separate mm
      and address.
      
      cmp_and_merge_page() initialize tree_page to NULL, to avoid a "may be used
      uninitialized" warning seen in one config by Anil SB.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8dd3557a
    • H
      ksm: remove redundancies when merging page · 31e855ea
      Hugh Dickins 提交于
      There is no need for replace_page() to calculate a write-protected prot
      vm_page_prot must already be write-protected for an anonymous page (see
      mm/memory.c do_anonymous_page() for similar reliance on vm_page_prot).
      
      There is no need for try_to_merge_one_page() to get_page and put_page on
      newpage and oldpage: in every case we already hold a reference to each of
      them.
      
      But some instinct makes me move try_to_merge_one_page()'s unlock_page of
      oldpage down after replace_page(): that doesn't increase contention on the
      ksm page, and makes thinking about the transition easier.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      31e855ea
    • H
      ksm: three remove_rmap_item_from_tree cleanups · 93d17715
      Hugh Dickins 提交于
      1. remove_rmap_item_from_tree() is called as a precaution from
         various places: don't dirty the rmap_item cacheline unnecessarily,
         just mask the flags out of the address when they have been set.
      
      2. First get_next_rmap_item() removes an unstable rmap_item from its tree,
         then shortly afterwards cmp_and_merge_page() removes a stable rmap_item
         from its tree: it's easier just to do both at once (but definitely keep
         the BUG_ON(age > 1) which guards against a future omission).
      
      3. When cmp_and_merge_page() moves an rmap_item from unstable to stable
         tree, it does its own rb_erase() and accounting: that's better
         expressed by remove_rmap_item_from_tree().
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      93d17715
    • K
      vmscan: make consistent of reclaim bale out between do_try_to_free_page and shrink_zone · 338fde90
      KOSAKI Motohiro 提交于
      Fix small inconsistent of ">" and ">=".
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      338fde90
    • K
      vmscan: kill sc.swap_cluster_max · ece74b2e
      KOSAKI Motohiro 提交于
      Now, All caller of reclaim use swap_cluster_max as SWAP_CLUSTER_MAX.
      Then, we can remove it perfectly.
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ece74b2e
    • K
      vmscan: zone_reclaim() don't use insane swap_cluster_max · 4f0ddfdf
      KOSAKI Motohiro 提交于
      In old days, we didn't have sc.nr_to_reclaim and it brought
      sc.swap_cluster_max misuse.
      
      huge sc.swap_cluster_max might makes unnecessary OOM risk and no
      performance benefit.
      
      Now, we can stop its insane thing.
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4f0ddfdf
    • K
      vmscan: kill hibernation specific reclaim logic and unify it · 7b51755c
      KOSAKI Motohiro 提交于
      shrink_all_zone() was introduced by commit d6277db4 (swsusp: rework
      memory shrinker) for hibernate performance improvement.  and
      sc.swap_cluster_max was introduced by commit a06fe4d307 (Speed freeing
      memory for suspend).
      
      commit a06fe4d307 said
      
         Without the patch:
         Freed  14600 pages in  1749 jiffies = 32.61 MB/s (Anomolous!)
         Freed  88563 pages in 14719 jiffies = 23.50 MB/s
         Freed 205734 pages in 32389 jiffies = 24.81 MB/s
      
         With the patch:
         Freed  68252 pages in   496 jiffies = 537.52 MB/s
         Freed 116464 pages in   569 jiffies = 798.54 MB/s
         Freed 209699 pages in   705 jiffies = 1161.89 MB/s
      
      At that time, their patch was pretty worth.  However, Modern Hardware
      trend and recent VM improvement broke its worth.  From several reason, I
      think we should remove shrink_all_zones() at all.
      
      detail:
      
      1) Old days, shrink_zone()'s slowness was mainly caused by stupid io-throttle
        at no i/o congestion.
        but current shrink_zone() is sane, not slow.
      
      2) shrink_all_zone() try to shrink all pages at a time. but it doesn't works
        fine on numa system.
        example)
          System has 4GB memory and each node have 2GB. and hibernate need 1GB.
      
          optimal)
             steal 500MB from each node.
          shrink_all_zones)
             steal 1GB from node-0.
      
        Oh, Cache balancing logic was broken. ;)
        Unfortunately, Desktop system moved ahead NUMA at nowadays.
        (Side note, if hibernate require 2GB, shrink_all_zones() never success
         on above machine)
      
      3) if the node has several I/O flighting pages, shrink_all_zones() makes
        pretty bad result.
      
        schenario) hibernate need 1GB
      
        1) shrink_all_zones() try to reclaim 1GB from Node-0
        2) but it only reclaimed 990MB
        3) stupidly, shrink_all_zones() try to reclaim 1GB from Node-1
        4) it reclaimed 990MB
      
        Oh, well. it reclaimed twice much than required.
        In the other hand, current shrink_zone() has sane baling out logic.
        then, it doesn't make overkill reclaim. then, we lost shrink_zones()'s risk.
      
      4) SplitLRU VM always keep active/inactive ratio very carefully. inactive list only
        shrinking break its assumption. it makes unnecessary OOM risk. it obviously suboptimal.
      
      Now, shrink_all_memory() is only the wrapper function of do_try_to_free_pages().
      it bring good reviewability and debuggability, and solve above problems.
      
      side note: Reclaim logic unificication makes two good side effect.
       - Fix recursive reclaim bug on shrink_all_memory().
         it did forgot to use PF_MEMALLOC. it mean the system be able to stuck into deadlock.
       - Now, shrink_all_memory() got lockdep awareness. it bring good debuggability.
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Acked-by: NRafael J. Wysocki <rjw@sisk.pl>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7b51755c
    • K
      vmscan: separate sc.swap_cluster_max and sc.nr_max_reclaim · 22fba335
      KOSAKI Motohiro 提交于
      Currently, sc.scap_cluster_max has double meanings.
      
       1) reclaim batch size as isolate_lru_pages()'s argument
       2) reclaim baling out thresolds
      
      The two meanings pretty unrelated. Thus, Let's separate it.
      this patch doesn't change any behavior.
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
      Cc: Mel Gorman <mel@csn.ul.ie>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      22fba335
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      Documentation: ABI: /sys/devices/system/cpu/cpu#/node · cba5dd7f
      Alex Chiang 提交于
      Describe NUMA node symlink created for CPUs when CONFIG_NUMA is set.
      Signed-off-by: NAlex Chiang <achiang@hp.com>
      Cc: Greg KH <greg@kroah.com>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cba5dd7f
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      mm: add numa node symlink for cpu devices in sysfs · 1830794a
      Alex Chiang 提交于
      You can discover which CPUs belong to a NUMA node by examining
      /sys/devices/system/node/node#/
      
      However, it's not convenient to go in the other direction, when looking at
      /sys/devices/system/cpu/cpu#/
      
      Yes, you can muck about in sysfs, but adding these symlinks makes life a
      lot more convenient.
      Signed-off-by: NAlex Chiang <achiang@hp.com>
      Acked-by: NDavid Rientjes <rientjes@google.com>
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Greg KH <greg@kroah.com>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1830794a
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      mm: refactor unregister_cpu_under_node() · b9d52dad
      Alex Chiang 提交于
      By returning early if the node is not online, we can unindent the
      interesting code by two levels.
      
      No functional change.
      Signed-off-by: NAlex Chiang <achiang@hp.com>
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Greg KH <greg@kroah.com>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b9d52dad
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      mm: refactor register_cpu_under_node() · f8246f31
      Alex Chiang 提交于
      By returning early if the node is not online, we can unindent the
      interesting code by one level.
      
      No functional change.
      Signed-off-by: NAlex Chiang <achiang@hp.com>
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Greg KH <greg@kroah.com>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f8246f31
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      mm: add numa node symlink for memory section in sysfs · dee5d0d5
      Alex Chiang 提交于
      Commit c04fc586 (mm: show node to memory section relationship with
      symlinks in sysfs) created symlinks from nodes to memory sections, e.g.
      
      /sys/devices/system/node/node1/memory135 -> ../../memory/memory135
      
      If you're examining the memory section though and are wondering what node
      it might belong to, you can find it by grovelling around in sysfs, but
      it's a little cumbersome.
      
      Add a reverse symlink for each memory section that points back to the
      node to which it belongs.
      Signed-off-by: NAlex Chiang <achiang@hp.com>
      Cc: Gary Hade <garyhade@us.ibm.com>
      Cc: Badari Pulavarty <pbadari@us.ibm.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Acked-by: NDavid Rientjes <rientjes@google.com>
      Cc: Greg KH <greg@kroah.com>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: David Rientjes <rientjes@google.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dee5d0d5
    • H
      mm: sigbus instead of abusing oom · d99be1a8
      Hugh Dickins 提交于
      When do_nonlinear_fault() realizes that the page table must have been
      corrupted for it to have been called, it does print_bad_pte() and returns
      ...  VM_FAULT_OOM, which is hard to understand.
      
      It made some sense when I did it for 2.6.15, when do_page_fault() just
      killed the current process; but nowadays it lets the OOM killer decide who
      to kill - so page table corruption in one process would be liable to kill
      another.
      
      Change it to return VM_FAULT_SIGBUS instead: that doesn't guarantee that
      the process will be killed, but is good enough for such a rare
      abnormality, accompanied as it is by the "BUG: Bad page map" message.
      
      And recent HWPOISON work has copied that code into do_swap_page(), when it
      finds an impossible swap entry: fix that to VM_FAULT_SIGBUS too.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
      Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d99be1a8
    • H
      mm: stop ptlock enlarging struct page · a70caa8b
      Hugh Dickins 提交于
      CONFIG_DEBUG_SPINLOCK adds 12 or 16 bytes to a 32- or 64-bit spinlock_t,
      and CONFIG_DEBUG_LOCK_ALLOC adds another 12 or 24 bytes to it: lockdep
      enables both of those, and CONFIG_LOCK_STAT adds 8 or 16 bytes to that.
      
      When 2.6.15 placed the split page table lock inside struct page (usually
      sized 32 or 56 bytes), only CONFIG_DEBUG_SPINLOCK was a possibility, and
      we ignored the enlargement (but fitted in CONFIG_GENERIC_LOCKBREAK's 4 by
      letting the spinlock_t occupy both page->private and page->mapping).
      
      Should these debugging options be allowed to double the size of a struct
      page, when only one minority use of the page (as a page table) needs to
      fit a spinlock in there?  Perhaps not.
      
      Take the easy way out: switch off SPLIT_PTLOCK_CPUS when DEBUG_SPINLOCK or
      DEBUG_LOCK_ALLOC is in force.  I've sometimes tried to be cleverer,
      kmallocing a cacheline for the spinlock when it doesn't fit, but given up
      each time.  Falling back to mm->page_table_lock (as we do when ptlock is
      not split) lets lockdep check out the strictest path anyway.
      
      And now that some arches allow 8192 cpus, use 999999 for infinity.
      
      (What has this got to do with KSM swapping?  It doesn't care about the
      size of struct page, but may care about random junk in page->mapping - to
      be explained separately later.)
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a70caa8b
    • H
      mm: pass address down to rmap ones · 1cb1729b
      Hugh Dickins 提交于
      KSM swapping will know where page_referenced_one() and try_to_unmap_one()
      should look.  It could hack page->index to get them to do what it wants,
      but it seems cleaner now to pass the address down to them.
      
      Make the same change to page_mkclean_one(), since it follows the same
      pattern; but there's no real need in its case.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1cb1729b
    • H
      mm: CONFIG_MMU for PG_mlocked · af8e3354
      Hugh Dickins 提交于
      Remove three degrees of obfuscation, left over from when we had
      CONFIG_UNEVICTABLE_LRU.  MLOCK_PAGES is CONFIG_HAVE_MLOCKED_PAGE_BIT is
      CONFIG_HAVE_MLOCK is CONFIG_MMU.  rmap.o (and memory-failure.o) are only
      built when CONFIG_MMU, so don't need such conditions at all.
      
      Somehow, I feel no compulsion to remove the CONFIG_HAVE_MLOCK* lines from
      169 defconfigs: leave those to evolve in due course.
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      af8e3354
    • H
      mm: mlocking in try_to_unmap_one · 53f79acb
      Hugh Dickins 提交于
      There's contorted mlock/munlock handling in try_to_unmap_anon() and
      try_to_unmap_file(), which we'd prefer not to repeat for KSM swapping.
      Simplify it by moving it all down into try_to_unmap_one().
      
      One thing is then lost, try_to_munlock()'s distinction between when no vma
      holds the page mlocked, and when a vma does mlock it, but we could not get
      mmap_sem to set the page flag.  But its only caller takes no interest in
      that distinction (and is better testing SWAP_MLOCK anyway), so let's keep
      the code simple and return SWAP_AGAIN for both cases.
      
      try_to_unmap_file()'s TTU_MUNLOCK nonlinear handling was particularly
      amusing: once unravelled, it turns out to have been choosing between two
      different ways of doing the same nothing.  Ah, no, one way was actually
      returning SWAP_FAIL when it meant to return SWAP_SUCCESS.
      
      [kosaki.motohiro@jp.fujitsu.com: comment adding to mlocking in try_to_unmap_one]
      [akpm@linux-foundation.org: remove test of MLOCK_PAGES]
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      53f79acb
    • H
      mm: define PAGE_MAPPING_FLAGS · 3ca7b3c5
      Hugh Dickins 提交于
      At present we define PageAnon(page) by the low PAGE_MAPPING_ANON bit set
      in page->mapping, with the higher bits a pointer to the anon_vma; and have
      defined PageKsm(page) as that with NULL anon_vma.
      
      But KSM swapping will need to store a pointer there: so in preparation for
      that, now define PAGE_MAPPING_FLAGS as the low two bits, including
      PAGE_MAPPING_KSM (always set along with PAGE_MAPPING_ANON, until some
      other use for the bit emerges).
      
      Declare page_rmapping(page) to return the pointer part of page->mapping,
      and page_anon_vma(page) to return the anon_vma pointer when that's what it
      is.  Use these in a few appropriate places: notably, unuse_vma() has been
      testing page->mapping, but is better to be testing page_anon_vma() (cases
      may be added in which flag bits are set without any pointer).
      Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
      Cc: Izik Eidus <ieidus@redhat.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Minchan Kim <minchan.kim@gmail.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3ca7b3c5
    • K
      vmscan: stop kswapd waiting on congestion when the min watermark is not being met · bb3ab596
      KOSAKI Motohiro 提交于
      If reclaim fails to make sufficient progress, the priority is raised.
      Once the priority is higher, kswapd starts waiting on congestion.
      However, if the zone is below the min watermark then kswapd needs to
      continue working without delay as there is a danger of an increased rate
      of GFP_ATOMIC allocation failure.
      
      This patch changes the conditions under which kswapd waits on congestion
      by only going to sleep if the min watermarks are being met.
      
      [mel@csn.ul.ie: add stats to track how relevant the logic is]
      [mel@csn.ul.ie: make kswapd only check its own zones and rename the relevant counters]
      Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NMel Gorman <mel@csn.ul.ie>
      Reviewed-by: NRik van Riel <riel@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bb3ab596
    • M
      vmscan: have kswapd sleep for a short interval and double check it should be asleep · f50de2d3
      Mel Gorman 提交于
      After kswapd balances all zones in a pgdat, it goes to sleep.  In the
      event of no IO congestion, kswapd can go to sleep very shortly after the
      high watermark was reached.  If there are a constant stream of allocations
      from parallel processes, it can mean that kswapd went to sleep too quickly
      and the high watermark is not being maintained for sufficient length time.
      
      This patch makes kswapd go to sleep as a two-stage process.  It first
      tries to sleep for HZ/10.  If it is woken up by another process or the
      high watermark is no longer met, it's considered a premature sleep and
      kswapd continues work.  Otherwise it goes fully to sleep.
      
      This adds more counters to distinguish between fast and slow breaches of
      watermarks.  A "fast" premature sleep is one where the low watermark was
      hit in a very short time after kswapd going to sleep.  A "slow" premature
      sleep indicates that the high watermark was breached after a very short
      interval.
      Signed-off-by: NMel Gorman <mel@csn.ul.ie>
      Cc: Frans Pop <elendil@planet.nl>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Christoph Lameter <cl@linux-foundation.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f50de2d3
    • H
      rmap: move label `out' to a better place · 273f047e
      Huang Shijie 提交于
      When the code jumps to the `out', `referenced' is still zero.  So there is
      no need to check it.
      Signed-off-by: NHuang Shijie <shijie8@gmail.com>
      Acked-by: NWu Fengguang <fengguang.wu@intel.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      273f047e
    • H
      rmap: simplify try_to_unmap_file() · 7b511594
      Huang Shijie 提交于
      Just simplify the code when `mlocked' is true.
      Signed-off-by: NHuang Shijie <shijie8@gmail.com>
      Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7b511594