1. 30 Oct, 2005 40 commits
    • John Hawkes's avatar
      [PATCH] mm: wider use of for_each_*cpu() · 2f96996d
      John Hawkes authored
      In 'mm' change the explicit use of a for-loop using NR_CPUS into the
      general for_each_cpu() constructs.  This widens the scope of potential
      future optimizations of the general constructs, as well as takes advantage
      of the existing optimizations of first_cpu() and next_cpu(), which is
      advantageous when the true CPU count is much smaller than NR_CPUS.
      Signed-off-by: default avatarJohn Hawkes <hawkes@sgi.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2f96996d
    • Christoph Lameter's avatar
      [PATCH] Remove policy contextualization from mbind · 5fcbb230
      Christoph Lameter authored
      Policy contextualization is only useful for task based policies and not for
      vma based policies.  It may be useful to define allowed nodes that are not
      accessible from this thread because other threads may have access to these
      nodes.  Without this patch strange memory policy situations may cause an
      application to fail with out of memory.
      
      Example:
      
      Let's say we have two threads A and B that share the same address space and
      a huge array computational array X.
      
      Thread A is restricted by its cpuset to nodes 0 and 1 and thread B is
      restricted by its cpuset to nodes 2 and 3.
      
      Thread A now wants to restrict allocations to the first node and thus
      applies a BIND policy on X to node 0 and 2.  The cpuset limits this to node
      0.  Thus pages for X must be allocated on node 0 now.
      
      Thread B now touches a page that has never been used in X and faults in a
      page.  According to the BIND policy of the vma for X the page must be
      allocated on page 0.  However, the cpuset of B does not allow allocation on
      0 and 1.  Now the application fails in alloc_pages with out of memory.
      Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
      Cc: Andi Kleen <ak@muc.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      5fcbb230
    • Christoph Lameter's avatar
      [PATCH] Implement sys_* do_* layering in the memory policy layer. · 8bccd85f
      Christoph Lameter authored
      - Do a separation between do_xxx and sys_xxx functions. sys_xxx functions
        take variable sized bitmaps from user space as arguments. do_xxx functions
        take fixed sized nodemask_t as arguments and may be used from inside the
        kernel. Doing so simplifies the initialization code. There is no
        fs = kernel_ds assumption anymore.
      
      - Split up get_nodes into get_nodes (which gets the node list) and
        contextualize_policy which restricts the nodes to those accessible
        to the task and updates cpusets.
      
      - Add comments explaining limitations of bind policy
      Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
      Cc: Andi Kleen <ak@muc.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8bccd85f
    • Dave Hansen's avatar
      [PATCH] memory hotplug: ppc64 specific hot-add functions · bb7e7e03
      Dave Hansen authored
      Here is a set of ppc64 specific patches that at least allow
      compilation/booting with the following configurations:
      
      FLATMEM
      SPARSEMEN
      SPARSEMEM + MEMORY_HOTPLUG
      Signed-off-by: default avatarMike Kravetz <kravetz@us.ibm.com>
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      bb7e7e03
    • Dave Hansen's avatar
      [PATCH] memory hotplug: i386 addition functions · 05039b92
      Dave Hansen authored
      Adds the necessary for non-NUMA hot-add of highmem to an existing zone on
      i386.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      05039b92
    • Dave Hansen's avatar
      [PATCH] memory hotplug: call setup_per_zone_pages_min after hotplug · 61b13993
      Dave Hansen authored
      From: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
      > I found the tests does not work well with Dave's patchset.
      > I've found the followings:
      >
      > 	- setup_per_zone_pages_min() calls should be added in
      > 	   capture_page_range() and online_pages()
      > 	- lru_add_drain() should be called before try_to_migrate_pages()
      
      The following patch deals with the first item.
      Signed-off-by: default avatarIWAMOTO Toshihiro <iwamoto@valinux.co.jp>
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      61b13993
    • Dave Hansen's avatar
      [PATCH] memory hotplug: move section_mem_map alloc to sparse.c · 0b0acbec
      Dave Hansen authored
      This basically keeps up from having to extern __kmalloc_section_memmap().
      
      The vaddr_in_vmalloc_area() helper could go in a vmalloc header, but that
      header gets hard to work with, because it needs some arch-specific macros.
      Just stick it in here for now, instead of creating another header.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarLion Vollnhals <webmaster@schiggl.de>
      Signed-off-by: default avatarJiri Slaby <xslaby@fi.muni.cz>
      Signed-off-by: default avatarYasunori Goto <y-goto@jp.fujitsu.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      0b0acbec
    • Dave Hansen's avatar
      [PATCH] memory hotplug: sysfs and add/remove functions · 3947be19
      Dave Hansen authored
      This adds generic memory add/remove and supporting functions for memory
      hotplug into a new file as well as a memory hotplug kernel config option.
      
      Individual architecture patches will follow.
      
      For now, disable memory hotplug when swsusp is enabled.  There's a lot of
      churn there right now.  We'll fix it up properly once it calms down.
      Signed-off-by: default avatarMatt Tolentino <matthew.e.tolentino@intel.com>
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      3947be19
    • Dave Hansen's avatar
      [PATCH] memory hotplug locking: zone span seqlock · bdc8cb98
      Dave Hansen authored
      See the "fixup bad_range()" patch for more information, but this actually
      creates a the lock to protect things making assumptions about a zone's size
      staying constant at runtime.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      bdc8cb98
    • Dave Hansen's avatar
      [PATCH] memory hotplug locking: node_size_lock · 208d54e5
      Dave Hansen authored
      pgdat->node_size_lock is basically only neeeded in one place in the normal
      code: show_mem(), which is the arch-specific sysrq-m printing function.
      
      Strictly speaking, the architectures not doing memory hotplug do no need this
      locking in show_mem().  However, they are all included for completeness.  This
      should also make any future consolidation of all of the implementations a
      little more straightforward.
      
      This lock is also held in the sparsemem code during a memory removal, as
      sections are invalidated.  This is the place there pfn_valid() is made false
      for a memory area that's being removed.  The lock is only required when doing
      pfn_valid() operations on memory which the user does not already have a
      reference on the page, such as in show_mem().
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      208d54e5
    • Dave Hansen's avatar
      [PATCH] memory hotplug prep: fixup bad_range() · c6a57e19
      Dave Hansen authored
      When doing memory hotplug operations, the size of existing zones can obviously
      change.  This means that zone->zone_{start_pfn,spanned_pages} can change.
      
      There are currently no locks that protect these structure members.  However,
      they are rarely accessed at runtime.  Outside of swsusp, the only place that I
      can find is bad_range().
      
      So, split bad_range() up into two pieces: one that needs to be locked and
      anther that doesn't.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c6a57e19
    • Dave Hansen's avatar
      [PATCH] memory hotplug prep: __section_nr helper · 4ca644d9
      Dave Hansen authored
      A little helper that we use in the hotplug code.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4ca644d9
    • Dave Hansen's avatar
      [PATCH] memory hotplug prep: break out zone initialization · ed8ece2e
      Dave Hansen authored
      If a zone is empty at boot-time and then hot-added to later, it needs to run
      the same init code that would have been run on it at boot.
      
      This patch breaks out zone table and per-cpu-pages functions for use by the
      hotplug code.  You can almost see all of the free_area_init_core() function on
      one page now.  :)
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      ed8ece2e
    • Dave Hansen's avatar
      [PATCH] memory hotplug prep: kill local_mapnr · 2774812f
      Dave Hansen authored
      The following series implements memory hot-add for ppc64 and i386.  There are
      x86_64 and ia64 implementations that will be submitted shortly as well,
      through the normal maintainers.
      
      This patch:
      
      local_mapnr is unused, except for in an alpha header.  Keep the alpha one,
      kill the rest.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2774812f
    • Andrea Arcangeli's avatar
      [PATCH] .text page fault SMP scalability optimization · 1a44e149
      Andrea Arcangeli authored
      We had a problem on ppc64 where with more than 4 threads a large system
      wouldn't scale well while faulting in the .text (most of the time was spent
      in the kernel despite it was an userland compute intensive app).  The
      reason is the useless overwrite of the same pte from all cpu.
      
      I fixed it this way (verified on an older kernel but the forward port is
      almost identical).  This will benefit all archs not just ppc64.
      Signed-off-by: default avatarAndrea Arcangeli <andrea@suse.de>
      Cc: Hugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      1a44e149
    • Adam Litke's avatar
      [PATCH] hugetlb: overcommit accounting check · 2e9b367c
      Adam Litke authored
      Basic overcommit checking for hugetlb_file_map() based on an implementation
      used with demand faulting in SLES9.
      
      Since demand faulting can't guarantee the availability of pages at mmap
      time, this patch implements a basic sanity check to ensure that the number
      of huge pages required to satisfy the mmap are currently available.
      Despite the obvious race, I think it is a good start on doing proper
      accounting.  I'd like to work towards an accounting system that mimics the
      semantics of normal pages (especially for the MAP_PRIVATE/COW case).  That
      work is underway and builds on what this patch starts.
      
      Huge page shared memory segments are simpler and still maintain their
      commit on shmget semantics.
      Signed-off-by: default avatarAdam Litke <agl@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2e9b367c
    • Adam Litke's avatar
      [PATCH] hugetlb: demand fault handler · 4c887265
      Adam Litke authored
      Below is a patch to implement demand faulting for huge pages.  The main
      motivation for changing from prefaulting to demand faulting is so that huge
      page memory areas can be allocated according to NUMA policy.
      
      Thanks to consolidated hugetlb code, switching the behavior requires changing
      only one fault handler.  The bulk of the patch just moves the logic from
      hugelb_prefault() to hugetlb_pte_fault() and find_get_huge_page().
      Signed-off-by: default avatarAdam Litke <agl@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4c887265
    • Krishnakumar R's avatar
      [PATCH] hugetlb: remove repeated code · 551110a9
      Krishnakumar R authored
      Clean up some repeated code related to HugeTLB.  hugetlb_zero_setup would
      have already allocated the file->f_op.
      Signed-off-by: default avatarKrishnakumar. R <rkrishnakumar@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      551110a9
    • Christoph Hellwig's avatar
      [PATCH] cleanup hugelbfs_forget_inode · 0b1533f6
      Christoph Hellwig authored
      Reformat hugelbfs_forget_inode and add the missing but harmless
      write_inode_now call.  It looks the same as generic_forget_inode now except
      for the call to truncate_hugepages instead of truncate_inode_pages.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      0b1533f6
    • Christoph Hellwig's avatar
      [PATCH] kill hugelbfs_do_delete_inode · 6b09b9df
      Christoph Hellwig authored
      hugetlbfs_do_delete_inode is the same as generic_delete_inode now, so remove
      it in favour of the latter.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      6b09b9df
    • Christoph Hellwig's avatar
      [PATCH] hugetlbfs: clean up hugetlbfs_delete_inode · 149f4211
      Christoph Hellwig authored
      Make hugetlbfs looks the same as generic_detelte_inode, fixing a bunch of
      missing updates to it at the same time.  Rename it to
      hugetlbfs_do_delete_inode and add a real hugetlbfs_delete_inode that
      implements ->delete_inode.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      149f4211
    • Christoph Hellwig's avatar
      [PATCH] hugetlbfs: move free_inodes accounting · 96527980
      Christoph Hellwig authored
      Move hugetlbfs accounting into ->alloc_inode / ->destroy_inode.  This keeps
      the code simpler, fixes a loeak where a failing inode allocation wouldn't
      decrement the counter and moves hugetlbfs_delete_inode and
      hugetlbfs_forget_inode closer to their generic counterparts.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      96527980
    • Hugh Dickins's avatar
      [PATCH] mm: update comments to pte lock · b8072f09
      Hugh Dickins authored
      Updated several references to page_table_lock in common code comments.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      b8072f09
    • Hugh Dickins's avatar
      [PATCH] mm: fix rss and mmlist locking · f412ac08
      Hugh Dickins authored
      A couple of oddities were guarded by page_table_lock, no longer properly
      guarded when that is split.
      
      The mm_counters of file_rss and anon_rss: make those an atomic_t, or an
      atomic64_t if the architecture supports it, in such a case.  Definitions by
      courtesy of Christoph Lameter: who spent considerable effort on more scalable
      ways of counting, but found insufficient benefit in practice.
      
      And adding an mm with swap to the mmlist for swapoff: the list is well-
      guarded by its own lock, but the list_empty check now has to be repeated
      inside it.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      f412ac08
    • Hugh Dickins's avatar
      [PATCH] mm: split page table lock · 4c21e2f2
      Hugh Dickins authored
      Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with
      a many-threaded application which concurrently initializes different parts of
      a large anonymous area.
      
      This patch corrects that, by using a separate spinlock per page table page, to
      guard the page table entries in that page, instead of using the mm's single
      page_table_lock.  (But even then, page_table_lock is still used to guard page
      table allocation, and anon_vma allocation.)
      
      In this implementation, the spinlock is tucked inside the struct page of the
      page table page: with a BUILD_BUG_ON in case it overflows - which it would in
      the case of 32-bit PA-RISC with spinlock debugging enabled.
      
      Splitting the lock is not quite for free: another cacheline access.  Ideally,
      I suppose we would use split ptlock only for multi-threaded processes on
      multi-cpu machines; but deciding that dynamically would have its own costs.
      So for now enable it by config, at some number of cpus - since the Kconfig
      language doesn't support inequalities, let preprocessor compare that with
      NR_CPUS.  But I don't think it's worth being user-configurable: for good
      testing of both split and unsplit configs, split now at 4 cpus, and perhaps
      change that to 8 later.
      
      There is a benefit even for singly threaded processes: kswapd can be attacking
      one part of the mm while another part is busy faulting.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4c21e2f2
    • Hugh Dickins's avatar
      [PATCH] mm: uml kill unused · b38c6845
      Hugh Dickins authored
      In worrying over the various pte operations in different architectures, I came
      across some unused functions in UML: remove mprotect_kernel_vm,
      protect_vm_page and addr_pte.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      b38c6845
    • Hugh Dickins's avatar
      [PATCH] mm: uml pte atomicity · 8f5cd76c
      Hugh Dickins authored
      There's usually a good reason when a pte is examined without the lock; but it
      makes me nervous when the pointer is dereferenced more than once.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8f5cd76c
    • Hugh Dickins's avatar
      [PATCH] mm: cris v32 mmu_context_lock · a7e4705b
      Hugh Dickins authored
      The cris v32 switch_mm guards get_mmu_context with next->page_table_lock: good
      it's not really SMP yet, since get_mmu_context messes with global variables
      affecting other mms.  Replace by global mmu_context_lock.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      a7e4705b
    • Hugh Dickins's avatar
      [PATCH] mm: parisc pte atomicity · 92dc6fcc
      Hugh Dickins authored
      There's a worrying function translation_exists in parisc cacheflush.h,
      unaffected by split ptlock since flush_dcache_page is using it on some other
      mm, without any relevant lock.  Oh well, make it a slightly more robust by
      factoring the pfn check within it.  And it looked liable to confuse a
      camouflaged swap or file entry with a good pte: fix that too.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      92dc6fcc
    • Hugh Dickins's avatar
      [PATCH] mm: arm ready for split ptlock · 69b04754
      Hugh Dickins authored
      Prepare arm for the split page_table_lock: three issues.
      
      Signal handling's preserve and restore of iwmmxt context currently involves
      reading and writing that context to and from user space, while holding
      page_table_lock to secure the user page(s) against kswapd.  If we split the
      lock, then the structure might span two pages, secured by to read into and
      write from a kernel stack buffer, copying that out and in without locking (the
      structure is 160 bytes in size, and here we're near the top of the kernel
      stack).  Or would the overhead be noticeable?
      
      arm_syscall's cmpxchg emulation use pte_offset_map_lock, instead of
      pte_offset_map and mm-wide page_table_lock; and strictly, it should now also
      take mmap_sem before descending to pmd, to guard against another thread
      munmapping, and the page table pulled out beneath this thread.
      
      Updated two comments in fault-armv.c.  adjust_pte is interesting, since its
      modification of a pte in one part of the mm depends on the lock held when
      calling update_mmu_cache for a pte in some other part of that mm.  This can't
      be done with a split page_table_lock (and we've already taken the lowest lock
      in the hierarchy here): so we'll have to disable split on arm, unless
      CONFIG_CPU_CACHE_VIPT to ensures adjust_pte never used.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      69b04754
    • Hugh Dickins's avatar
      [PATCH] mm: i386 sh sh64 ready for split ptlock · 60ec5585
      Hugh Dickins authored
      Use pte_offset_map_lock, instead of pte_offset_map (or inappropriate
      pte_offset_kernel) and mm-wide page_table_lock, in sundry arch places.
      
      The i386 vm86 mark_screen_rdonly: yes, there was and is an assumption that the
      screen fits inside the one page table, as indeed it does.
      
      The sh __do_page_fault: which handles both kernel faults (without lock) and
      user mm faults (locked - though it set_pte without locking before).
      
      The sh64 flush_cache_range and helpers: which wrongly thought callers held
      page_table_lock before (only its tlb_start_vma did, and no longer does so);
      moved the flush loop down, and adjusted the large versus small range decision
      to consider a range which spans page tables as large.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Acked-by: default avatarPaul Mundt <lethal@linux-sh.org>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      60ec5585
    • Hugh Dickins's avatar
      [PATCH] mm: follow_page with inner ptlock · deceb6cd
      Hugh Dickins authored
      Final step in pushing down common core's page_table_lock.  follow_page no
      longer wants caller to hold page_table_lock, uses pte_offset_map_lock itself;
      and so no page_table_lock is taken in get_user_pages itself.
      
      But get_user_pages (and get_futex_key) do then need follow_page to pin the
      page for them: take Daniel's suggestion of bitflags to follow_page.
      
      Need one for WRITE, another for TOUCH (it was the accessed flag before:
      vanished along with check_user_page_readable, but surely get_numa_maps is
      wrong to mark every page it finds as accessed), another for GET.
      
      And another, ANON to dispose of untouched_anonymous_page: it seems silly for
      that to descend a second time, let follow_page observe if there was no page
      table and return ZERO_PAGE if so.  Fix minor bug in that: check VM_LOCKED -
      make_pages_present ought to make readonly anonymous present.
      
      Give get_numa_maps a cond_resched while we're there.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      deceb6cd
    • Hugh Dickins's avatar
      [PATCH] mm: kill check_user_page_readable · c34d1b4d
      Hugh Dickins authored
      check_user_page_readable is a problematic variant of follow_page.  It's used
      only by oprofile's i386 and arm backtrace code, at interrupt time, to
      establish whether a userspace stackframe is currently readable.
      
      This is problematic, because we want to push the page_table_lock down inside
      follow_page, and later split it; whereas oprofile is doing a spin_trylock on
      it (in the i386 case, forgotten in the arm case), and needs that to pin
      perhaps two pages spanned by the stackframe (which might be covered by
      different locks when we split).
      
      I think oprofile is going about this in the wrong way: it doesn't need to know
      the area is readable (neither i386 nor arm uses read protection of user
      pages), it doesn't need to pin the memory, it should simply
      __copy_from_user_inatomic, and see if that succeeds or not.  Sorry, but I've
      not got around to devising the sparse __user annotations for this.
      
      Then we can eliminate check_user_page_readable, and return to a single
      follow_page without the __follow_page variants.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c34d1b4d
    • Hugh Dickins's avatar
      [PATCH] mm: rmap with inner ptlock · c0718806
      Hugh Dickins authored
      rmap's page_check_address descend without page_table_lock.  First just
      pte_offset_map in case there's no pte present worth locking for, then take
      page_table_lock for the full check, and pass ptl back to caller in the same
      style as pte_offset_map_lock.  __xip_unmap, page_referenced_one and
      try_to_unmap_one use pte_unmap_unlock.  try_to_unmap_cluster also.
      
      page_check_address reformatted to avoid progressive indentation.  No use is
      made of its one error code, return NULL when it fails.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c0718806
    • Hugh Dickins's avatar
      [PATCH] mm: xip_unmap ZERO_PAGE fix · 67b02f11
      Hugh Dickins authored
      Small fix to the PageReserved patch: the mips ZERO_PAGE(address) depends on
      address, so __xip_unmap is wrong to initialize page with that before address
      is initialized; and in fact must re-evaluate it each iteration.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      67b02f11
    • Hugh Dickins's avatar
      [PATCH] mm: unmap_vmas with inner ptlock · 508034a3
      Hugh Dickins authored
      Remove the page_table_lock from around the calls to unmap_vmas, and replace
      the pte_offset_map in zap_pte_range by pte_offset_map_lock: all callers are
      now safe to descend without page_table_lock.
      
      Don't attempt fancy locking for hugepages, just take page_table_lock in
      unmap_hugepage_range.  Which makes zap_hugepage_range, and the hugetlb test in
      zap_page_range, redundant: unmap_vmas calls unmap_hugepage_range anyway.  Nor
      does unmap_vmas have much use for its mm arg now.
      
      The tlb_start_vma and tlb_end_vma in unmap_page_range are now called without
      page_table_lock: if they're implemented at all, they typically come down to
      flush_cache_range (usually done outside page_table_lock) and flush_tlb_range
      (which we already audited for the mprotect case).
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      508034a3
    • Hugh Dickins's avatar
      [PATCH] mm: unlink vma before pagetables · 8f4f8c16
      Hugh Dickins authored
      In most places the descent from pgd to pud to pmd to pte holds mmap_sem
      (exclusively or not), which ensures that free_pgtables cannot be freeing page
      tables from any level at the same time.  But truncation and reverse mapping
      descend without mmap_sem.
      
      No problem: just make sure that a vma is unlinked from its prio_tree (or
      nonlinear list) and from its anon_vma list, after zapping the vma, but before
      freeing its page tables.  Then neither vmtruncate nor rmap can reach that vma
      whose page tables are now volatile (nor do they need to reach it, since all
      its page entries have been zapped by this stage).
      
      The i_mmap_lock and anon_vma->lock already serialize this correctly; but the
      locking hierarchy is such that we cannot take them while holding
      page_table_lock.  Well, we're trying to push that down anyway.  So in this
      patch, move anon_vma_unlink and unlink_file_vma into free_pgtables, at the
      same time as moving page_table_lock around calls to unmap_vmas.
      
      tlb_gather_mmu and tlb_finish_mmu then fall outside the page_table_lock, but
      we made them preempt_disable and preempt_enable earlier; and a long source
      audit of all the architectures has shown no problem with removing
      page_table_lock from them.  free_pgtables doesn't need page_table_lock for
      itself, nor for what it calls; tlb->mm->nr_ptes is usually protected by
      page_table_lock, but partly by non-exclusive mmap_sem - here it's decremented
      with exclusive mmap_sem, or mm_users 0.  update_hiwater_rss and
      vm_unacct_memory don't need page_table_lock either.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8f4f8c16
    • Hugh Dickins's avatar
      [PATCH] mm: flush_tlb_range outside ptlock · 663b97f7
      Hugh Dickins authored
      There was one small but very significant change in the previous patch:
      mprotect's flush_tlb_range fell outside the page_table_lock: as it is in 2.4,
      but that doesn't prove it safe in 2.6.
      
      On some architectures flush_tlb_range comes to the same as flush_tlb_mm, which
      has always been called from outside page_table_lock in dup_mmap, and is so
      proved safe.  Others required a deeper audit: I could find no reliance on
      page_table_lock in any; but in ia64 and parisc found some code which looks a
      bit as if it might want preemption disabled.  That won't do any actual harm,
      so pending a decision from the maintainers, disable preemption there.
      
      Remove comments on page_table_lock from flush_tlb_mm, flush_tlb_range and
      flush_tlb_page entries in cachetlb.txt: they were rather misleading (what
      generic code does is different from what usually happens), the rules are now
      changing, and it's not yet clear where we'll end up (will the generic
      tlb_flush_mmu happen always under lock?  never under lock?  or sometimes under
      and sometimes not?).
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      663b97f7
    • Hugh Dickins's avatar
      [PATCH] mm: pte_offset_map_lock loops · 705e87c0
      Hugh Dickins authored
      Convert those common loops using page_table_lock on the outside and
      pte_offset_map within to use just pte_offset_map_lock within instead.
      
      These all hold mmap_sem (some exclusively, some not), so at no level can a
      page table be whipped away from beneath them.  But whereas pte_alloc loops
      tested with the "atomic" pmd_present, these loops are testing with pmd_none,
      which on i386 PAE tests both lower and upper halves.
      
      That's now unsafe, so add a cast into pmd_none to test only the vital lower
      half: we lose a little sensitivity to a corrupt middle directory, but not
      enough to worry about.  It appears that i386 and UML were the only
      architectures vulnerable in this way, and pgd and pud no problem.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      705e87c0
    • Hugh Dickins's avatar
      [PATCH] mm: page fault handler locking · 8f4e2101
      Hugh Dickins authored
      On the page fault path, the patch before last pushed acquiring the
      page_table_lock down to the head of handle_pte_fault (though it's also taken
      and dropped earlier when a new page table has to be allocated).
      
      Now delete that line, read "entry = *pte" without it, and go off to this or
      that page fault handler on the basis of this unlocked peek.  Usually the
      handler can proceed without the lock, relying on the subsequent locked
      pte_same or pte_none test to back out when necessary; though do_wp_page needs
      the lock immediately, and do_file_page doesn't check (if there's a race,
      install_page just zaps the entry and reinstalls it).
      
      But on those architectures (notably i386 with PAE) whose pte is too big to be
      read atomically, if SMP or preemption is enabled, do_swap_page and
      do_file_page might cause irretrievable damage if passed a Frankenstein entry
      stitched together from unrelated parts.  In those configs, "pte_unmap_same"
      has to take page_table_lock, validate orig_pte still the same, and drop
      page_table_lock before unmapping, before proceeding.
      
      Use pte_offset_map_lock and pte_unmap_unlock throughout the handlers; but lock
      avoidance leaves more lone maps and unmaps than elsewhere.
      Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8f4e2101