path: root/mm/mremap.c
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2014-12-14Merge git://git.kvack.org/~bcrl/aio-nextLinus Torvalds
Pull aio updates from Benjamin LaHaise. * git://git.kvack.org/~bcrl/aio-next: aio: Skip timer for io_getevents if timeout=0 aio: Make it possible to remap aio ring
2014-12-13aio: Make it possible to remap aio ringPavel Emelyanov
There are actually two issues this patch addresses. Let me start with the one I tried to solve in the beginning. So, in the checkpoint-restore project (criu) we try to dump tasks' state and restore one back exactly as it was. One of the tasks' state bits is rings set up with io_setup() call. There's (almost) no problems in dumping them, there's a problem restoring them -- if I dump a task with aio ring originally mapped at address A, I want to restore one back at exactly the same address A. Unfortunately, the io_setup() does not allow for that -- it mmaps the ring at whatever place mm finds appropriate (it calls do_mmap_pgoff() with zero address and without the MAP_FIXED flag). To make restore possible I'm going to mremap() the freshly created ring into the address A (under which it was seen before dump). The problem is that the ring's virtual address is passed back to the user-space as the context ID and this ID is then used as search key by all the other io_foo() calls. Reworking this ID to be just some integer doesn't seem to work, as this value is already used by libaio as a pointer using which this library accesses memory for aio meta-data. So, to make restore work we need to make sure that a) ring is mapped at desired virtual address b) kioctx->user_id matches this value Having said that, the patch makes mremap() on aio region update the kioctx's user_id and mmap_base values. Here appears the 2nd issue I mentioned in the beginning of this mail. If (regardless of the C/R dances I do) someone creates an io context with io_setup(), then mremap()-s the ring and then destroys the context, the kill_ioctx() routine will call munmap() on wrong (old) address. This will result in a) aio ring remaining in memory and b) some other vma get unexpectedly unmapped. What do you think? Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Acked-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-12-13mm: convert i_mmap_mutex to rwsemDavidlohr Bueso
The i_mmap_mutex is a close cousin of the anon vma lock, both protecting similar data, one for file backed pages and the other for anon memory. To this end, this lock can also be a rwsem. In addition, there are some important opportunities to share the lock when there are no tree modifications. This conversion is straightforward. For now, all users take the write lock. [sfr@canb.auug.org.au: update fremap.c] Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13mm: use new helper functions around the i_mmap_mutexDavidlohr Bueso
Convert all open coded mutex_lock/unlock calls to the i_mmap_[lock/unlock]_write() helpers. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09mm/mremap.c: use linux headersPaul McQuade
"WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>" Signed-off-by: Paul McQuade <paulmcquad@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09mm: convert a few VM_BUG_ON callers to VM_BUG_ON_VMASasha Levin
Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract more information when they trigger. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-11mm, thp: close race between mremap() and split_huge_page()Kirill A. Shutemov
It's critical for split_huge_page() (and migration) to catch and freeze all PMDs on rmap walk. It gets tricky if there's concurrent fork() or mremap() since usually we copy/move page table entries on dup_mm() or move_page_tables() without rmap lock taken. To get it work we rely on rmap walk order to not miss any entry. We expect to see destination VMA after source one to work correctly. But after switching rmap implementation to interval tree it's not always possible to preserve expected walk order. It works fine for dup_mm() since new VMA has the same vma_start_pgoff() / vma_last_pgoff() and explicitly insert dst VMA after src one with vma_interval_tree_insert_after(). But on move_vma() destination VMA can be merged into adjacent one and as result shifted left in interval tree. Fortunately, we can detect the situation and prevent race with rmap walk by moving page table entries under rmap lock. See commit 38a76013ad80. Problem is that we miss the lock when we move transhuge PMD. Most likely this bug caused the crash[1]. [1] http://thread.gmane.org/gmane.linux.kernel.mm/96473 Fixes: 108d6642ad81 ("mm anon rmap: remove anon_vma_moveto_tail") Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Acked-by: Michel Lespinasse <walken@google.com> Cc: Dave Jones <davej@redhat.com> Cc: David Miller <davem@davemloft.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> [3.7+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-16mm: revert mremap pud_free anti-fixHugh Dickins
Revert commit 1ecfd533f4c5 ("mm/mremap.c: call pud_free() after fail calling pmd_alloc()"). The original code was correct: pud_alloc(), pmd_alloc(), pte_alloc_map() ensure that the pud, pmd, pt is already allocated, and seldom do they need to allocate; on failure, upper levels are freed if appropriate by the subsequent do_munmap(). Whereas commit 1ecfd533f4c5 did an unconditional pud_free() of a most-likely still-in-use pud: saved only by the near-impossiblity of pmd_alloc() failing. Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Chen Gang <gang.chen@asianux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11mm/mremap.c: call pud_free() after fail calling pmd_alloc()Chen Gang
In alloc_new_pmd(), if pud_alloc() was called successfully, but pmd_alloc() fails, avoid leaking `pud'. Signed-off-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-27mm: move_ptes -- Set soft dirty bit depending on pte typeCyrill Gorcunov
Dave reported corrupted swap entries | [ 4588.541886] swap_free: Unused swap offset entry 00002d15 | [ 4588.541952] BUG: Bad page map in process trinity-kid12 pte:005a2a80 pmd:22c01f067 and Hugh pointed that in move_ptes _PAGE_SOFT_DIRTY bit set regardless the type of entry pte consists of. The trick here is that when we carry soft dirty status in swap entries we are to use _PAGE_SWP_SOFT_DIRTY instead, because this is the only place in pte which can be used for own needs without intersecting with bits owned by swap entry type/offset. Reported-and-tested-by: Dave Jones <davej@redhat.com> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@parallels.com> Analyzed-by: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-09mm: mremap: validate input before taking lockRasmus Villemoes
This patch is very similar to commit 84d96d897671 ("mm: madvise: complete input validation before taking lock"): perform some basic validation of the input to mremap() before taking the &current->mm->mmap_sem lock. This also makes the MREMAP_FIXED => MREMAP_MAYMOVE dependency slightly more explicit. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03mm: soft-dirty bits for user memory changes trackingPavel Emelyanov
The soft-dirty is a bit on a PTE which helps to track which pages a task writes to. In order to do this tracking one should 1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs) 2. Wait some time. 3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries) To do this tracking, the writable bit is cleared from PTEs when the soft-dirty bit is. Thus, after this, when the task tries to modify a page at some virtual address the #PF occurs and the kernel sets the soft-dirty bit on the respective PTE. Note, that although all the task's address space is marked as r/o after the soft-dirty bits clear, the #PF-s that occur after that are processed fast. This is so, since the pages are still mapped to physical memory, and thus all the kernel does is finds this fact out and puts back writable, dirty and soft-dirty bits on the PTE. Another thing to note, is that when mremap moves PTEs they are marked with soft-dirty as well, since from the user perspective mremap modifies the virtual memory at mremap's new address. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Cc: Matt Mackall <mpm@selenic.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Glauber Costa <glommer@parallels.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-23mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write()Konstantin Khlebnikov
The comment in commit 4fc3f1d66b1e ("mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable") says: | 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. But that commit renames only anon_vma_lock() Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Ingo Molnar <mingo@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-23mm: use mm_populate() for mremap() of VM_LOCKED vmasMichel Lespinasse
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Tested-by: Andy Lutomirski <luto@amacapital.net> Cc: Greg Ungerer <gregungerer@westnet.com.au> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-07sched: Move sched.h sysctl bits into separate headerClark Williams
Move the sysctl-related bits from include/linux/sched.h into a new file: include/linux/sched/sysctl.h. Then update source files requiring access to those bits by including the new header file. Signed-off-by: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20130207094659.06dced96@riff.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-12-16Merge tag 'balancenuma-v11' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux-balancenuma 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 ...
2012-12-12thp: change split_huge_page_pmd() interfaceKirill A. Shutemov
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 <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: "H. Peter Anvin" <hpa@linux.intel.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalableIngo Molnar
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 <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Turner <pjt@google.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Christoph Lameter <cl@linux.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Mel Gorman <mgorman@suse.de>
2012-10-09mm: move all mmu notifier invocations to be done outside the PT lockSagi Grimberg
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 <andrea@qumranet.com> Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Haggai Eran <haggaie@mellanox.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Or Gerlitz <ogerlitz@mellanox.com> Cc: Haggai Eran <haggaie@mellanox.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Liran Liss <liranl@mellanox.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09mm: avoid taking rmap locks in move_ptes()Michel Lespinasse
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 <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-09mm anon rmap: remove anon_vma_moveto_tailMichel Lespinasse
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 <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31mm: account the total_vm in the vm_stat_account()Huang Shijie
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 <shijie8@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-01move security_mmap_addr() to saner placeAl Viro
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 <viro@zeniv.linux.org.uk>
2012-05-31split ->file_mmap() into ->mmap_addr()/->mmap_file()Al Viro
... i.e. file-dependent and address-dependent checks. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-05-30merge do_mremap() into sys_mremap()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-02-14mm: collapse security_vm_enough_memory() variants into a single functionAl Viro
Collapse security_vm_enough_memory() variants into a single function. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: James Morris <jmorris@namei.org>
2012-01-10mremap: enforce rmap src/dst vma ordering in case of vma_merge() succeeding ↵Andrea Arcangeli
in copy_vma() migrate was doing an rmap_walk with speculative lock-less access on pagetables. That could lead it to not serializing properly against mremap PT locks. But a second problem remains in the order of vmas in the same_anon_vma list used by the rmap_walk. If vma_merge succeeds in copy_vma, the src vma could be placed after the dst vma in the same_anon_vma list. That could still lead to migrate missing some pte. This patch adds an anon_vma_moveto_tail() function to force the dst vma at the end of the list before mremap starts to solve the problem. If the mremap is very large and there are a lots of parents or childs sharing the anon_vma root lock, this should still scale better than taking the anon_vma root lock around every pte copy practically for the whole duration of mremap. Update: Hugh noticed special care is needed in the error path where move_page_tables goes in the reverse direction, a second anon_vma_moveto_tail() call is needed in the error path. This program exercises the anon_vma_moveto_tail: === int main() { static struct timeval oldstamp, newstamp; long diffsec; char *p, *p2, *p3, *p4; if (posix_memalign((void **)&p, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p2, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p3, 2*1024*1024, SIZE)) perror("memalign"), exit(1); memset(p, 0xff, SIZE); printf("%p\n", p); memset(p2, 0xff, SIZE); memset(p3, 0x77, 4096); if (memcmp(p, p2, SIZE)) printf("error\n"); p4 = mremap(p+SIZE/2, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p3); if (p4 != p3) perror("mremap"), exit(1); p4 = mremap(p4, SIZE/2, SIZE/2, MREMAP_FIXED|MREMAP_MAYMOVE, p+SIZE/2); if (p4 != p+SIZE/2) perror("mremap"), exit(1); if (memcmp(p, p2, SIZE)) printf("error\n"); printf("ok\n"); return 0; } === $ perf probe -a anon_vma_moveto_tail Add new event: probe:anon_vma_moveto_tail (on anon_vma_moveto_tail) You can now use it on all perf tools, such as: perf record -e probe:anon_vma_moveto_tail -aR sleep 1 $ perf record -e probe:anon_vma_moveto_tail -aR ./anon_vma_moveto_tail 0x7f2ca2800000 ok [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.043 MB perf.data (~1860 samples) ] $ perf report --stdio 100.00% anon_vma_moveto [kernel.kallsyms] [k] anon_vma_moveto_tail Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Nai Xia <nai.xia@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Pawel Sikora <pluto@agmk.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31thp: mremap support and TLB optimizationAndrea Arcangeli
This adds THP support to mremap (decreases the number of split_huge_page() calls). Here are also some benchmarks with a proggy like this: === #define _GNU_SOURCE #include <sys/mman.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/time.h> #define SIZE (5UL*1024*1024*1024) int main() { static struct timeval oldstamp, newstamp; long diffsec; char *p, *p2, *p3, *p4; if (posix_memalign((void **)&p, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p2, 2*1024*1024, SIZE)) perror("memalign"), exit(1); if (posix_memalign((void **)&p3, 2*1024*1024, 4096)) perror("memalign"), exit(1); memset(p, 0xff, SIZE); memset(p2, 0xff, SIZE); memset(p3, 0x77, 4096); gettimeofday(&oldstamp, NULL); p4 = mremap(p, SIZE, SIZE, MREMAP_FIXED|MREMAP_MAYMOVE, p3); gettimeofday(&newstamp, NULL); diffsec = newstamp.tv_sec - oldstamp.tv_sec; diffsec = newstamp.tv_usec - oldstamp.tv_usec + 1000000 * diffsec; printf("usec %ld\n", diffsec); if (p == MAP_FAILED || p4 != p3) //if (p == MAP_FAILED) perror("mremap"), exit(1); if (memcmp(p4, p2, SIZE)) printf("mremap bug\n"), exit(1); printf("ok\n"); return 0; } === THP on Performance counter stats for './largepage13' (3 runs): 69195836 dTLB-loads ( +- 3.546% ) (scaled from 50.30%) 60708 dTLB-load-misses ( +- 11.776% ) (scaled from 52.62%) 676266476 dTLB-stores ( +- 5.654% ) (scaled from 69.54%) 29856 dTLB-store-misses ( +- 4.081% ) (scaled from 89.22%) 1055848782 iTLB-loads ( +- 4.526% ) (scaled from 80.18%) 8689 iTLB-load-misses ( +- 2.987% ) (scaled from 58.20%) 7.314454164 seconds time elapsed ( +- 0.023% ) THP off Performance counter stats for './largepage13' (3 runs): 1967379311 dTLB-loads ( +- 0.506% ) (scaled from 60.59%) 9238687 dTLB-load-misses ( +- 22.547% ) (scaled from 61.87%) 2014239444 dTLB-stores ( +- 0.692% ) (scaled from 60.40%) 3312335 dTLB-store-misses ( +- 7.304% ) (scaled from 67.60%) 6764372065 iTLB-loads ( +- 0.925% ) (scaled from 79.00%) 8202 iTLB-load-misses ( +- 0.475% ) (scaled from 70.55%) 9.693655243 seconds time elapsed ( +- 0.069% ) grep thp /proc/vmstat thp_fault_alloc 35849 thp_fault_fallback 0 thp_collapse_alloc 3 thp_collapse_alloc_failed 0 thp_split 0 thp_split 0 confirms no thp split despite plenty of hugepages allocated. The measurement of only the mremap time (so excluding the 3 long memset and final long 10GB memory accessing memcmp): THP on usec 14824 usec 14862 usec 14859 THP off usec 256416 usec 255981 usec 255847 With an older kernel without the mremap optimizations (the below patch optimizes the non THP version too). THP on usec 392107 usec 390237 usec 404124 THP off usec 444294 usec 445237 usec 445820 I guess with a threaded program that sends more IPI on large SMP it'd create an even larger difference. All debug options are off except DEBUG_VM to avoid skewing the results. The only problem for native 2M mremap like it happens above both the source and destination address must be 2M aligned or the hugepmd can't be moved without a split but that is an hardware limitation. [akpm@linux-foundation.org: coding-style nitpicking] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31mremap: avoid sending one IPI per pageAndrea Arcangeli
This replaces ptep_clear_flush() with ptep_get_and_clear() and a single flush_tlb_range() at the end of the loop, to avoid sending one IPI for each page. The mmu_notifier_invalidate_range_start/end section is enlarged accordingly but this is not going to fundamentally change things. It was more by accident that the region under mremap was for the most part still available for secondary MMUs: the primary MMU was never allowed to reliably access that region for the duration of the mremap (modulo trapping SIGSEGV on the old address range which sounds unpractical and flakey). If users wants secondary MMUs not to lose access to a large region under mremap they should reduce the mremap size accordingly in userland and run multiple calls. Overall this will run faster so it's actually going to reduce the time the region is under mremap for the primary MMU which should provide a net benefit to apps. For KVM this is a noop because the guest physical memory is never mremapped, there's just no point it ever moving it while guest runs. One target of this optimization is JVM GC (so unrelated to the mmu notifier logic). Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31mremap: check for overflow using deltasAndrea Arcangeli
Using "- 1" relies on the old_end to be page aligned and PAGE_SIZE > 1, those are reasonable requirements but the check remains obscure and it looks more like an off by one error than an overflow check. This I feel will improve readability. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Johannes Weiner <jweiner@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25mm: Convert i_mmap_lock to a mutexPeter Zijlstra
Straightforward conversion of i_mmap_lock to a mutex. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Hugh Dickins <hughd@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25mm: Remove i_mmap_lock lockbreakPeter Zijlstra
Hugh says: "The only significant loser, I think, would be page reclaim (when concurrent with truncation): could spin for a long time waiting for the i_mmap_mutex it expects would soon be dropped? " Counter points: - cpu contention makes the spin stop (need_resched()) - zap pages should be freeing pages at a higher rate than reclaim ever can I think the simplification of the truncate code is definitely worth it. Effectively reverts: 2aa15890f3c ("mm: prevent concurrent unmap_mapping_range() on the same inode") and takes out the code that caused its problem. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-04-07mm: avoid wrapping vm_pgoff in mremap()Linus Torvalds
The normal mmap paths all avoid creating a mapping where the pgoff inside the mapping could wrap around due to overflow. However, an expanding mremap() can take such a non-wrapping mapping and make it bigger and cause a wrapping condition. Noticed by Robert Swiecki when running a system call fuzzer, where it caused a BUG_ON() due to terminally confusing the vma_prio_tree code. A vma dumping patch by Hugh then pinpointed the crazy wrapped case. Reported-and-tested-by: Robert Swiecki <robert@swiecki.net> Acked-by: Hugh Dickins <hughd@google.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-23mm: fix possible cause of a page_mapped BUGHugh Dickins
Robert Swiecki reported a BUG_ON(page_mapped) from a fuzzer, punching a hole with madvise(,, MADV_REMOVE). That path is under mutex, and cannot be explained by lack of serialization in unmap_mapping_range(). Reviewing the code, I found one place where vm_truncate_count handling should have been updated, when I switched at the last minute from one way of managing the restart_addr to another: mremap move changes the virtual addresses, so it ought to adjust the restart_addr. But rather than exporting the notion of restart_addr from memory.c, or converting to restart_pgoff throughout, simply reset vm_truncate_count to 0 to force a rescan if mremap move races with preempted truncation. We have no confirmation that this fixes Robert's BUG, but it is a fix that's worth making anyway. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13thp: split_huge_page_mm/vmaAndrea Arcangeli
split_huge_page_pmd compat code. Each one of those would need to be expanded to hundred of lines of complex code without a fully reliable split_huge_page_pmd design. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13thp: pte alloc trans splittingAndrea Arcangeli
pte alloc routines must wait for split_huge_page if the pmd is not present and not null (i.e. pmd_trans_splitting). The additional branches are optimized away at compile time by pmd_trans_splitting if the config option is off. However we must pass the vma down in order to know the anon_vma lock to wait for. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26mm: remove pte_*map_nested()Peter Zijlstra
Since we no longer need to provide KM_type, the whole pte_*map_nested() API is now redundant, remove it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: David Miller <davem@davemloft.net> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-30include cleanup: Update gfp.h and slab.h includes to prepare for breaking ↵Tejun Heo
implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-06mm: change anon_vma linking to fix multi-process server scalability issueRik van Riel
The old anon_vma code can lead to scalability issues with heavily forking workloads. Specifically, each anon_vma will be shared between the parent process and all its child processes. In a workload with 1000 child processes and a VMA with 1000 anonymous pages per process that get COWed, this leads to a system with a million anonymous pages in the same anon_vma, each of which is mapped in just one of the 1000 processes. However, the current rmap code needs to walk them all, leading to O(N) scanning complexity for each page. This can result in systems where one CPU is walking the page tables of 1000 processes in page_referenced_one, while all other CPUs are stuck on the anon_vma lock. This leads to catastrophic failure for a benchmark like AIM7, where the total number of processes can reach in the tens of thousands. Real workloads are still a factor 10 less process intensive than AIM7, but they are catching up. This patch changes the way anon_vmas and VMAs are linked, which allows us to associate multiple anon_vmas with a VMA. At fork time, each child process gets its own anon_vmas, in which its COWed pages will be instantiated. The parents' anon_vma is also linked to the VMA, because non-COWed pages could be present in any of the children. This reduces rmap scanning complexity to O(1) for the pages of the 1000 child processes, with O(N) complexity for at most 1/N pages in the system. This reduces the average scanning cost in heavily forking workloads from O(N) to 2. The only real complexity in this patch stems from the fact that linking a VMA to anon_vmas now involves memory allocations. This means vma_adjust can fail, if it needs to attach a VMA to anon_vma structures. This in turn means error handling needs to be added to the calling functions. A second source of complexity is that, because there can be multiple anon_vmas, the anon_vma linking in vma_adjust can no longer be done under "the" anon_vma lock. To prevent the rmap code from walking up an incomplete VMA, this patch introduces the VM_LOCK_RMAP VMA flag. This bit flag uses the same slot as the NOMMU VM_MAPPED_COPY, with an ifdef in mm.h to make sure it is impossible to compile a kernel that needs both symbolic values for the same bitflag. Some test results: Without the anon_vma changes, when AIM7 hits around 9.7k users (on a test box with 16GB RAM and not quite enough IO), the system ends up running >99% in system time, with every CPU on the same anon_vma lock in the pageout code. With these changes, AIM7 hits the cross-over point around 29.7k users. This happens with ~99% IO wait time, there never seems to be any spike in system time. The anon_vma lock contention appears to be resolved. [akpm@linux-foundation.org: cleanups] Signed-off-by: Rik van Riel <riel@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06mm: use rlimit helpersJiri Slaby
Make sure compiler won't do weird things with limits. E.g. fetching them twice may return 2 different values after writable limits are implemented. I.e. either use rlimit helpers added in 3e10e716abf3c71bdb5d86b8f507f9e72236c9cd ("resource: add helpers for fetching rlimits") or ACCESS_ONCE if not applicable. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-11Take arch_mmap_check() into get_unmapped_area()Al Viro
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11fix pgoff in "have to relocate" case of mremap()Al Viro
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11fix the arch checks in MREMAP_FIXED caseAl Viro
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11fix checks for expand-in-place mremapAl Viro
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11do_mremap() untangling, part 3Al Viro
Take the check for being able to expand vma in place into a separate helper. Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11do_mremap() untangling, part 2Al Viro
Take the MREMAP_FIXED into a separate helper, simplify the living hell out of conditions in both cases. Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-11untangling do_mremap(), part 1Al Viro
Take locating vma and checks on it to a separate helper (it will be shared between MREMAP_FIXED/non-MREMAP_FIXED cases when we split them in the next patch) Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-09-24truncate: new helpersnpiggin@suse.de
Introduce new truncate helpers truncate_pagecache and inode_newsize_ok. vmtruncate is also consolidated from mm/memory.c and mm/nommu.c and into mm/truncate.c. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-09-22ksm: mremap use err from ksm_madviseHugh Dickins
mremap move's use of ksm_madvise() was assuming -ENOMEM on failure, because ksm_madvise used to say -EAGAIN for that; but ksm_madvise now says -ENOMEM (letting madvise convert that to -EAGAIN), and can also say -ERESTARTSYS when signalled: so pass the error from ksm_madvise. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-22ksm: prevent mremap move poisoningHugh Dickins
KSM's scan allows for user pages to be COWed or unmapped at any time, without requiring any notification. But its stable tree does assume that when it finds a KSM page where it placed a KSM page, then it is the same KSM page that it placed there. mremap move could break that assumption: if an area containing a KSM page was unmapped, then an area containing a different KSM page was moved with mremap into the place of the original, before KSM's scan came around to notice. That could then poison a node of the stable tree, so that memcmps would "lie" and upset the ordering of the tree. Probably noone will ever need mremap move on a VM_MERGEABLE area; except that prohibiting it would make trouble for schemes in which we try making everything VM_MERGEABLE e.g. for testing: an mremap which normally works would then fail mysteriously. There's no need to go to any trouble, such as re-sorting KSM's list of rmap_items to match the new layout: simply unmerge the area to COW all its KSM pages before moving, but leave VM_MERGEABLE on so that they're remerged later. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Izik Eidus <ieidus@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Avi Kivity <avi@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>