kernel.git/mm/mremap.c, branch linux-3.8.y

Merge tag 'balancenuma-v11' of git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux-balancenuma

2012-12-16T23:18:08Z

Pull Automatic NUMA Balancing bare-bones from Mel Gorman: "There are three implementations for NUMA balancing, this tree (balancenuma), numacore which has been developed in tip/master and autonuma which is in aa.git. In almost all respects balancenuma is the dumbest of the three because its main impact is on the VM side with no attempt to be smart about scheduling. In the interest of getting the ball rolling, it would be desirable to see this much merged for 3.8 with the view to building scheduler smarts on top and adapting the VM where required for 3.9. The most recent set of comparisons available from different people are mel: https://lkml.org/lkml/2012/12/9/108 mingo: https://lkml.org/lkml/2012/12/7/331 tglx: https://lkml.org/lkml/2012/12/10/437 srikar: https://lkml.org/lkml/2012/12/10/397 The results are a mixed bag. In my own tests, balancenuma does reasonably well. It's dumb as rocks and does not regress against mainline. On the other hand, Ingo's tests shows that balancenuma is incapable of converging for this workloads driven by perf which is bad but is potentially explained by the lack of scheduler smarts. Thomas' results show balancenuma improves on mainline but falls far short of numacore or autonuma. Srikar's results indicate we all suffer on a large machine with imbalanced node sizes. My own testing showed that recent numacore results have improved dramatically, particularly in the last week but not universally. We've butted heads heavily on system CPU usage and high levels of migration even when it shows that overall performance is better. There are also cases where it regresses. Of interest is that for specjbb in some configurations it will regress for lower numbers of warehouses and show gains for higher numbers which is not reported by the tool by default and sometimes missed in treports. Recently I reported for numacore that the JVM was crashing with NullPointerExceptions but currently it's unclear what the source of this problem is. Initially I thought it was in how numacore batch handles PTEs but I'm no longer think this is the case. It's possible numacore is just able to trigger it due to higher rates of migration. These reports were quite late in the cycle so I/we would like to start with this tree as it contains much of the code we can agree on and has not changed significantly over the last 2-3 weeks." * tag 'balancenuma-v11' of git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux-balancenuma: (50 commits) mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable mm/rmap: Convert the struct anon_vma::mutex to an rwsem mm: migrate: Account a transhuge page properly when rate limiting mm: numa: Account for failed allocations and isolations as migration failures mm: numa: Add THP migration for the NUMA working set scanning fault case build fix mm: numa: Add THP migration for the NUMA working set scanning fault case. mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node mm: sched: numa: Control enabling and disabling of NUMA balancing if !SCHED_DEBUG mm: sched: numa: Control enabling and disabling of NUMA balancing mm: sched: Adapt the scanning rate if a NUMA hinting fault does not migrate mm: numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships mm: numa: migrate: Set last_nid on newly allocated page mm: numa: split_huge_page: Transfer last_nid on tail page mm: numa: Introduce last_nid to the page frame sched: numa: Slowly increase the scanning period as NUMA faults are handled mm: numa: Rate limit setting of pte_numa if node is saturated mm: numa: Rate limit the amount of memory that is migrated between nodes mm: numa: Structures for Migrate On Fault per NUMA migration rate limiting mm: numa: Migrate pages handled during a pmd_numa hinting fault mm: numa: Migrate on reference policy ...

thp: change split_huge_page_pmd() interface

2012-12-13T01:38:31Z

Pass vma instead of mm and add address parameter. In most cases we already have vma on the stack. We provides split_huge_page_pmd_mm() for few cases when we have mm, but not vma. This change is preparation to huge zero pmd splitting implementation. Signed-off-by: Kirill A. Shutemov Cc: Andrea Arcangeli Cc: Andi Kleen Cc: "H. Peter Anvin" Cc: Mel Gorman Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable

2012-12-11T14:43:00Z

rmap_walk_anon() and try_to_unmap_anon() appears to be too careful about locking the anon vma: while it needs protection against anon vma list modifications, it does not need exclusive access to the list itself. Transforming this exclusive lock to a read-locked rwsem removes a global lock from the hot path of page-migration intense threaded workloads which can cause pathological performance like this: 96.43% process 0 [kernel.kallsyms] [k] perf_trace_sched_switch | --- perf_trace_sched_switch __schedule schedule schedule_preempt_disabled __mutex_lock_common.isra.6 __mutex_lock_slowpath mutex_lock | |--50.61%-- rmap_walk | move_to_new_page | migrate_pages | migrate_misplaced_page | __do_numa_page.isra.69 | handle_pte_fault | handle_mm_fault | __do_page_fault | do_page_fault | page_fault | __memset_sse2 | | | --100.00%-- worker_thread | | | --100.00%-- start_thread | --49.39%-- page_lock_anon_vma try_to_unmap_anon try_to_unmap migrate_pages migrate_misplaced_page __do_numa_page.isra.69 handle_pte_fault handle_mm_fault __do_page_fault do_page_fault page_fault __memset_sse2 | --100.00%-- worker_thread start_thread With this change applied the profile is now nicely flat and there's no anon-vma related scheduling/blocking. Rename anon_vma_[un]lock() => anon_vma_[un]lock_write(), to make it clearer that it's an exclusive write-lock in that case - suggested by Rik van Riel. Suggested-by: Linus Torvalds Cc: Peter Zijlstra Cc: Paul Turner Cc: Lee Schermerhorn Cc: Christoph Lameter Cc: Rik van Riel Cc: Mel Gorman Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Hugh Dickins Signed-off-by: Ingo Molnar Signed-off-by: Mel Gorman

mm: move all mmu notifier invocations to be done outside the PT lock

2012-10-09T07:22:58Z

In order to allow sleeping during mmu notifier calls, we need to avoid invoking them under the page table spinlock. This patch solves the problem by calling invalidate_page notification after releasing the lock (but before freeing the page itself), or by wrapping the page invalidation with calls to invalidate_range_begin and invalidate_range_end. To prevent accidental changes to the invalidate_range_end arguments after the call to invalidate_range_begin, the patch introduces a convention of saving the arguments in consistently named locals: unsigned long mmun_start; /* For mmu_notifiers */ unsigned long mmun_end; /* For mmu_notifiers */ ... mmun_start = ... mmun_end = ... mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); ... mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); The patch changes code to use this convention for all calls to mmu_notifier_invalidate_range_start/end, except those where the calls are close enough so that anyone who glances at the code can see the values aren't changing. This patchset is a preliminary step towards on-demand paging design to be added to the RDMA stack. Why do we want on-demand paging for Infiniband? Applications register memory with an RDMA adapter using system calls, and subsequently post IO operations that refer to the corresponding virtual addresses directly to HW. Until now, this was achieved by pinning the memory during the registration calls. The goal of on demand paging is to avoid pinning the pages of registered memory regions (MRs). This will allow users the same flexibility they get when swapping any other part of their processes address spaces. Instead of requiring the entire MR to fit in physical memory, we can allow the MR to be larger, and only fit the current working set in physical memory. Why should anyone care? What problems are users currently experiencing? This can make programming with RDMA much simpler. Today, developers that are working with more data than their RAM can hold need either to deregister and reregister memory regions throughout their process's life, or keep a single memory region and copy the data to it. On demand paging will allow these developers to register a single MR at the beginning of their process's life, and let the operating system manage which pages needs to be fetched at a given time. In the future, we might be able to provide a single memory access key for each process that would provide the entire process's address as one large memory region, and the developers wouldn't need to register memory regions at all. Is there any prospect that any other subsystems will utilise these infrastructural changes? If so, which and how, etc? As for other subsystems, I understand that XPMEM wanted to sleep in MMU notifiers, as Christoph Lameter wrote at http://lkml.indiana.edu/hypermail/linux/kernel/0802.1/0460.html and perhaps Andrea knows about other use cases. Scheduling in mmu notifications is required since we need to sync the hardware with the secondary page tables change. A TLB flush of an IO device is inherently slower than a CPU TLB flush, so our design works by sending the invalidation request to the device, and waiting for an interrupt before exiting the mmu notifier handler. Avi said: kvm may be a buyer. kvm::mmu_lock, which serializes guest page faults, also protects long operations such as destroying large ranges. It would be good to convert it into a spinlock, but as it is used inside mmu notifiers, this cannot be done. (there are alternatives, such as keeping the spinlock and using a generation counter to do the teardown in O(1), which is what the "may" is doing up there). [akpm@linux-foundation.orgpossible speed tweak in hugetlb_cow(), cleanups] Signed-off-by: Andrea Arcangeli Signed-off-by: Sagi Grimberg Signed-off-by: Haggai Eran Cc: Peter Zijlstra Cc: Xiao Guangrong Cc: Or Gerlitz Cc: Haggai Eran Cc: Shachar Raindel Cc: Liran Liss Cc: Christoph Lameter Cc: Avi Kivity Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: avoid taking rmap locks in move_ptes()

2012-10-09T07:22:42Z

During mremap(), the destination VMA is generally placed after the original vma in rmap traversal order: in move_vma(), we always have new_pgoff >= vma->vm_pgoff, and as a result new_vma->vm_pgoff >= vma->vm_pgoff unless vma_merge() merged the new vma with an adjacent one. When the destination VMA is placed after the original in rmap traversal order, we can avoid taking the rmap locks in move_ptes(). Essentially, this reintroduces the optimization that had been disabled in "mm anon rmap: remove anon_vma_moveto_tail". The difference is that we don't try to impose the rmap traversal order; instead we just rely on things being in the desired order in the common case and fall back to taking locks in the uncommon case. Also we skip the i_mmap_mutex in addition to the anon_vma lock: in both cases, the vmas are traversed in increasing vm_pgoff order with ties resolved in tree insertion order. Signed-off-by: Michel Lespinasse Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Peter Zijlstra Cc: Daniel Santos Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm anon rmap: remove anon_vma_moveto_tail

2012-10-09T07:22:41Z

mremap() had a clever optimization where move_ptes() did not take the anon_vma lock to avoid a race with anon rmap users such as page migration. Instead, the avc's were ordered in such a way that the origin vma was always visited by rmap before the destination. This ordering and the use of page table locks rmap usage safe. However, we want to replace the use of linked lists in anon rmap with an interval tree, and this will make it harder to impose such ordering as the interval tree will always be sorted by the avc->vma->vm_pgoff value. For now, let's replace the anon_vma_moveto_tail() ordering function with proper anon_vma locking in move_ptes(). Once we have the anon interval tree in place, we will re-introduce an optimization to avoid taking these locks in the most common cases. Signed-off-by: Michel Lespinasse Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Peter Zijlstra Cc: Daniel Santos Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: account the total_vm in the vm_stat_account()

2012-08-01T01:42:39Z

vm_stat_account() accounts the shared_vm, stack_vm and reserved_vm now. But we can also account for total_vm in the vm_stat_account() which makes the code tidy. Even for mprotect_fixup(), we can get the right result in the end. Signed-off-by: Huang Shijie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

move security_mmap_addr() to saner place

2012-06-01T14:37:16Z

it really should be done by get_unmapped_area(); that cuts down on the amount of callers considerably and it's the right place for that stuff anyway. Signed-off-by: Al Viro

split ->file_mmap() into ->mmap_addr()/->mmap_file()

2012-05-31T17:11:54Z

... i.e. file-dependent and address-dependent checks. Signed-off-by: Al Viro

merge do_mremap() into sys_mremap()

2012-05-31T01:04:57Z

Signed-off-by: Al Viro