1. 31 7月, 2008 5 次提交
  2. 30 7月, 2008 6 次提交
  3. 29 7月, 2008 6 次提交
    • L
      Fix 'get_user_pages_fast()' with non-page-aligned start address · 9b79022c
      Linus Torvalds 提交于
      Alexey Dobriyan reported trouble with LTP with the new fast-gup code,
      and Johannes Weiner debugged it to non-page-aligned addresses, where the
      new get_user_pages_fast() code would do all the wrong things, including
      just traversing past the end of the requested area due to 'addr' never
      matching 'end' exactly.
      
      This is not a pretty fix, and we may actually want to move the alignment
      into generic code, leaving just the core code per-arch, but Alexey
      verified that the vmsplice01 LTP test doesn't crash with this.
      Reported-and-tested-by: NAlexey Dobriyan <adobriyan@gmail.com>
      Debugged-by: NJohannes Weiner <hannes@saeurebad.de>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9b79022c
    • R
      lguest: set max_pfn_mapped, growl loudly at Yinghai Lu · 5d006d8d
      Rusty Russell 提交于
      6af61a76 'x86: clean up max_pfn_mapped
      usage - 32-bit' makes the following comment:
      
          XEN PV and lguest may need to assign max_pfn_mapped too.
      
      But no CC.  Yinghai, wasting fellow developers' time is a VERY bad
      habit.  If you do it again, I will hunt you down and try to extract
      the three hours of my life I just lost :)
      Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      Cc: Yinghai Lu <yhlu.kernel@gmail.com>
      5d006d8d
    • A
      mmu-notifiers: core · cddb8a5c
      Andrea Arcangeli 提交于
      With KVM/GFP/XPMEM there isn't just the primary CPU MMU pointing to pages.
       There are secondary MMUs (with secondary sptes and secondary tlbs) too.
      sptes in the kvm case are shadow pagetables, but when I say spte in
      mmu-notifier context, I mean "secondary pte".  In GRU case there's no
      actual secondary pte and there's only a secondary tlb because the GRU
      secondary MMU has no knowledge about sptes and every secondary tlb miss
      event in the MMU always generates a page fault that has to be resolved by
      the CPU (this is not the case of KVM where the a secondary tlb miss will
      walk sptes in hardware and it will refill the secondary tlb transparently
      to software if the corresponding spte is present).  The same way
      zap_page_range has to invalidate the pte before freeing the page, the spte
      (and secondary tlb) must also be invalidated before any page is freed and
      reused.
      
      Currently we take a page_count pin on every page mapped by sptes, but that
      means the pages can't be swapped whenever they're mapped by any spte
      because they're part of the guest working set.  Furthermore a spte unmap
      event can immediately lead to a page to be freed when the pin is released
      (so requiring the same complex and relatively slow tlb_gather smp safe
      logic we have in zap_page_range and that can be avoided completely if the
      spte unmap event doesn't require an unpin of the page previously mapped in
      the secondary MMU).
      
      The mmu notifiers allow kvm/GRU/XPMEM to attach to the tsk->mm and know
      when the VM is swapping or freeing or doing anything on the primary MMU so
      that the secondary MMU code can drop sptes before the pages are freed,
      avoiding all page pinning and allowing 100% reliable swapping of guest
      physical address space.  Furthermore it avoids the code that teardown the
      mappings of the secondary MMU, to implement a logic like tlb_gather in
      zap_page_range that would require many IPI to flush other cpu tlbs, for
      each fixed number of spte unmapped.
      
      To make an example: if what happens on the primary MMU is a protection
      downgrade (from writeable to wrprotect) the secondary MMU mappings will be
      invalidated, and the next secondary-mmu-page-fault will call
      get_user_pages and trigger a do_wp_page through get_user_pages if it
      called get_user_pages with write=1, and it'll re-establishing an updated
      spte or secondary-tlb-mapping on the copied page.  Or it will setup a
      readonly spte or readonly tlb mapping if it's a guest-read, if it calls
      get_user_pages with write=0.  This is just an example.
      
      This allows to map any page pointed by any pte (and in turn visible in the
      primary CPU MMU), into a secondary MMU (be it a pure tlb like GRU, or an
      full MMU with both sptes and secondary-tlb like the shadow-pagetable layer
      with kvm), or a remote DMA in software like XPMEM (hence needing of
      schedule in XPMEM code to send the invalidate to the remote node, while no
      need to schedule in kvm/gru as it's an immediate event like invalidating
      primary-mmu pte).
      
      At least for KVM without this patch it's impossible to swap guests
      reliably.  And having this feature and removing the page pin allows
      several other optimizations that simplify life considerably.
      
      Dependencies:
      
      1) mm_take_all_locks() to register the mmu notifier when the whole VM
         isn't doing anything with "mm".  This allows mmu notifier users to keep
         track if the VM is in the middle of the invalidate_range_begin/end
         critical section with an atomic counter incraese in range_begin and
         decreased in range_end.  No secondary MMU page fault is allowed to map
         any spte or secondary tlb reference, while the VM is in the middle of
         range_begin/end as any page returned by get_user_pages in that critical
         section could later immediately be freed without any further
         ->invalidate_page notification (invalidate_range_begin/end works on
         ranges and ->invalidate_page isn't called immediately before freeing
         the page).  To stop all page freeing and pagetable overwrites the
         mmap_sem must be taken in write mode and all other anon_vma/i_mmap
         locks must be taken too.
      
      2) It'd be a waste to add branches in the VM if nobody could possibly
         run KVM/GRU/XPMEM on the kernel, so mmu notifiers will only enabled if
         CONFIG_KVM=m/y.  In the current kernel kvm won't yet take advantage of
         mmu notifiers, but this already allows to compile a KVM external module
         against a kernel with mmu notifiers enabled and from the next pull from
         kvm.git we'll start using them.  And GRU/XPMEM will also be able to
         continue the development by enabling KVM=m in their config, until they
         submit all GRU/XPMEM GPLv2 code to the mainline kernel.  Then they can
         also enable MMU_NOTIFIERS in the same way KVM does it (even if KVM=n).
         This guarantees nobody selects MMU_NOTIFIER=y if KVM and GRU and XPMEM
         are all =n.
      
      The mmu_notifier_register call can fail because mm_take_all_locks may be
      interrupted by a signal and return -EINTR.  Because mmu_notifier_reigster
      is used when a driver startup, a failure can be gracefully handled.  Here
      an example of the change applied to kvm to register the mmu notifiers.
      Usually when a driver startups other allocations are required anyway and
      -ENOMEM failure paths exists already.
      
       struct  kvm *kvm_arch_create_vm(void)
       {
              struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
      +       int err;
      
              if (!kvm)
                      return ERR_PTR(-ENOMEM);
      
              INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
      
      +       kvm->arch.mmu_notifier.ops = &kvm_mmu_notifier_ops;
      +       err = mmu_notifier_register(&kvm->arch.mmu_notifier, current->mm);
      +       if (err) {
      +               kfree(kvm);
      +               return ERR_PTR(err);
      +       }
      +
              return kvm;
       }
      
      mmu_notifier_unregister returns void and it's reliable.
      
      The patch also adds a few needed but missing includes that would prevent
      kernel to compile after these changes on non-x86 archs (x86 didn't need
      them by luck).
      
      [akpm@linux-foundation.org: coding-style fixes]
      [akpm@linux-foundation.org: fix mm/filemap_xip.c build]
      [akpm@linux-foundation.org: fix mm/mmu_notifier.c build]
      Signed-off-by: NAndrea Arcangeli <andrea@qumranet.com>
      Signed-off-by: NNick Piggin <npiggin@suse.de>
      Signed-off-by: NChristoph Lameter <cl@linux-foundation.org>
      Cc: Jack Steiner <steiner@sgi.com>
      Cc: Robin Holt <holt@sgi.com>
      Cc: Nick Piggin <npiggin@suse.de>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Kanoj Sarcar <kanojsarcar@yahoo.com>
      Cc: Roland Dreier <rdreier@cisco.com>
      Cc: Steve Wise <swise@opengridcomputing.com>
      Cc: Avi Kivity <avi@qumranet.com>
      Cc: Hugh Dickins <hugh@veritas.com>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Anthony Liguori <aliguori@us.ibm.com>
      Cc: Chris Wright <chrisw@redhat.com>
      Cc: Marcelo Tosatti <marcelo@kvack.org>
      Cc: Eric Dumazet <dada1@cosmosbay.com>
      Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
      Cc: Izik Eidus <izike@qumranet.com>
      Cc: Anthony Liguori <aliguori@us.ibm.com>
      Cc: Rik van Riel <riel@redhat.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cddb8a5c
    • D
      arm: fix HAVE_CLK merge goof · 93686ae8
      David Brownell 提交于
      This fixes a merge goof whereby ARCH_EP93XX got the "select HAVE_CLK" line
      which belongs instead with ARCH_AT91.
      Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      93686ae8
    • B
      x86/PCI: use dev_printk when possible · 12c0b20f
      Bjorn Helgaas 提交于
      Convert printks to use dev_printk().
      
      I converted DBG() to dev_dbg().  This DBG() is from arch/x86/pci/pci.h and
      requires source-code modification to enable, so dev_dbg() seems roughly
      equivalent.
      Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
      Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
      12c0b20f
    • L
      cpu masks: optimize and clean up cpumask_of_cpu() · e56b3bc7
      Linus Torvalds 提交于
      Clean up and optimize cpumask_of_cpu(), by sharing all the zero words.
      
      Instead of stupidly generating all possible i=0...NR_CPUS 2^i patterns
      creating a huge array of constant bitmasks, realize that the zero words
      can be shared.
      
      In other words, on a 64-bit architecture, we only ever need 64 of these
      arrays - with a different bit set in one single world (with enough zero
      words around it so that we can create any bitmask by just offsetting in
      that big array). And then we just put enough zeroes around it that we
      can point every single cpumask to be one of those things.
      
      So when we have 4k CPU's, instead of having 4k arrays (of 4k bits each,
      with one bit set in each array - 2MB memory total), we have exactly 64
      arrays instead, each 8k bits in size (64kB total).
      
      And then we just point cpumask(n) to the right position (which we can
      calculate dynamically). Once we have the right arrays, getting
      "cpumask(n)" ends up being:
      
        static inline const cpumask_t *get_cpu_mask(unsigned int cpu)
        {
                const unsigned long *p = cpu_bit_bitmap[1 + cpu % BITS_PER_LONG];
                p -= cpu / BITS_PER_LONG;
                return (const cpumask_t *)p;
        }
      
      This brings other advantages and simplifications as well:
      
       - we are not wasting memory that is just filled with a single bit in
         various different places
      
       - we don't need all those games to re-create the arrays in some dense
         format, because they're already going to be dense enough.
      
      if we compile a kernel for up to 4k CPU's, "wasting" that 64kB of memory
      is a non-issue (especially since by doing this "overlapping" trick we
      probably get better cache behaviour anyway).
      
      [ mingo@elte.hu:
      
        Converted Linus's mails into a commit. See:
      
           http://lkml.org/lkml/2008/7/27/156
           http://lkml.org/lkml/2008/7/28/320
      
        Also applied a family filter - which also has the side-effect of leaving
        out the bits where Linus calls me an idio... Oh, never mind ;-)
      ]
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: Mike Travis <travis@sgi.com>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e56b3bc7
  4. 28 7月, 2008 23 次提交