25 Sep, 2019

2 commits

  • When compiling a kernel with W=1, there are several of those warnings due
    to arm64 overriding a field on purpose. Just disable those warnings for
    both GCC and Clang of this file, so it will help dig "gems" hidden in the
    W=1 warnings by reducing some noises.

    mm/init-mm.c:39:2: warning: initializer overrides prior initialization
    of this subobject [-Winitializer-overrides]
    INIT_MM_CONTEXT(init_mm)
    ^~~~~~~~~~~~~~~~~~~~~~~~
    ./arch/arm64/include/asm/mmu.h:133:9: note: expanded from macro
    'INIT_MM_CONTEXT'
    .pgd = init_pg_dir,
    ^~~~~~~~~~~
    mm/init-mm.c:30:10: note: previous initialization is here
    .pgd = swapper_pg_dir,
    ^~~~~~~~~~~~~~

    Note: there is a side project trying to support explicitly allowing
    specific initializer overrides in Clang, but there is no guarantee it
    will happen or not.

    https://github.com/ClangBuiltLinux/linux/issues/639

    Link: http://lkml.kernel.org/r/1566920867-27453-1-git-send-email-cai@lca.pw
    Signed-off-by: Qian Cai
    Cc: Nick Desaulniers
    Cc: Masahiro Yamada
    Cc: Mark Rutland
    Cc: Arnd Bergmann
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Qian Cai
     
  • Patch series "mm: remove quicklist page table caches".

    A while ago Nicholas proposed to remove quicklist page table caches [1].

    I've rebased his patch on the curren upstream and switched ia64 and sh to
    use generic versions of PTE allocation.

    [1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

    This patch (of 3):

    Remove page table allocator "quicklists". These have been around for a
    long time, but have not got much traction in the last decade and are only
    used on ia64 and sh architectures.

    The numbers in the initial commit look interesting but probably don't
    apply anymore. If anybody wants to resurrect this it's in the git
    history, but it's unhelpful to have this code and divergent allocator
    behaviour for minor archs.

    Also it might be better to instead make more general improvements to page
    allocator if this is still so slow.

    Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
    Signed-off-by: Nicholas Piggin
    Signed-off-by: Mike Rapoport
    Cc: Tony Luck
    Cc: Yoshinori Sato
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Nicholas Piggin
     

03 Aug, 2019

1 commit

  • memremap.c implements MM functionality for ZONE_DEVICE, so it really
    should be in the mm/ directory, not the kernel/ one.

    Link: http://lkml.kernel.org/r/20190722094143.18387-1-hch@lst.de
    Signed-off-by: Christoph Hellwig
    Reviewed-by: Anshuman Khandual
    Acked-by: Dan Williams
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Christoph Hellwig
     

15 Jul, 2019

1 commit

  • Pull HMM updates from Jason Gunthorpe:
    "Improvements and bug fixes for the hmm interface in the kernel:

    - Improve clarity, locking and APIs related to the 'hmm mirror'
    feature merged last cycle. In linux-next we now see AMDGPU and
    nouveau to be using this API.

    - Remove old or transitional hmm APIs. These are hold overs from the
    past with no users, or APIs that existed only to manage cross tree
    conflicts. There are still a few more of these cleanups that didn't
    make the merge window cut off.

    - Improve some core mm APIs:
    - export alloc_pages_vma() for driver use
    - refactor into devm_request_free_mem_region() to manage
    DEVICE_PRIVATE resource reservations
    - refactor duplicative driver code into the core dev_pagemap
    struct

    - Remove hmm wrappers of improved core mm APIs, instead have drivers
    use the simplified API directly

    - Remove DEVICE_PUBLIC

    - Simplify the kconfig flow for the hmm users and core code"

    * tag 'for-linus-hmm' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (42 commits)
    mm: don't select MIGRATE_VMA_HELPER from HMM_MIRROR
    mm: remove the HMM config option
    mm: sort out the DEVICE_PRIVATE Kconfig mess
    mm: simplify ZONE_DEVICE page private data
    mm: remove hmm_devmem_add
    mm: remove hmm_vma_alloc_locked_page
    nouveau: use devm_memremap_pages directly
    nouveau: use alloc_page_vma directly
    PCI/P2PDMA: use the dev_pagemap internal refcount
    device-dax: use the dev_pagemap internal refcount
    memremap: provide an optional internal refcount in struct dev_pagemap
    memremap: replace the altmap_valid field with a PGMAP_ALTMAP_VALID flag
    memremap: remove the data field in struct dev_pagemap
    memremap: add a migrate_to_ram method to struct dev_pagemap_ops
    memremap: lift the devmap_enable manipulation into devm_memremap_pages
    memremap: pass a struct dev_pagemap to ->kill and ->cleanup
    memremap: move dev_pagemap callbacks into a separate structure
    memremap: validate the pagemap type passed to devm_memremap_pages
    mm: factor out a devm_request_free_mem_region helper
    mm: export alloc_pages_vma
    ...

    Linus Torvalds
     

13 Jul, 2019

1 commit

  • Always build mm/gup.c so that we don't have to provide separate nommu
    stubs. Also merge the get_user_pages_fast and __get_user_pages_fast stubs
    when HAVE_FAST_GUP into the main implementations, which will never call
    the fast path if HAVE_FAST_GUP is not set.

    This also ensures the new put_user_pages* helpers are available for nommu,
    as those are currently missing, which would create a problem as soon as we
    actually grew users for it.

    Link: http://lkml.kernel.org/r/20190625143715.1689-13-hch@lst.de
    Signed-off-by: Christoph Hellwig
    Cc: Andrey Konovalov
    Cc: Benjamin Herrenschmidt
    Cc: David Miller
    Cc: James Hogan
    Cc: Jason Gunthorpe
    Cc: Khalid Aziz
    Cc: Michael Ellerman
    Cc: Nicholas Piggin
    Cc: Paul Burton
    Cc: Paul Mackerras
    Cc: Ralf Baechle
    Cc: Rich Felker
    Cc: Yoshinori Sato
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Christoph Hellwig
     

03 Jul, 2019

1 commit

  • All the mm/hmm.c code is better keyed off HMM_MIRROR. Also let nouveau
    depend on it instead of the mix of a dummy dependency symbol plus the
    actually selected one. Drop various odd dependencies, as the code is
    pretty portable.

    Signed-off-by: Christoph Hellwig
    Reviewed-by: Ira Weiny
    Reviewed-by: Jason Gunthorpe
    Reviewed-by: Dan Williams
    Signed-off-by: Jason Gunthorpe

    Christoph Hellwig
     

15 May, 2019

1 commit

  • Patch series "mm: Randomize free memory", v10.

    This patch (of 3):

    Randomization of the page allocator improves the average utilization of
    a direct-mapped memory-side-cache. Memory side caching is a platform
    capability that Linux has been previously exposed to in HPC
    (high-performance computing) environments on specialty platforms. In
    that instance it was a smaller pool of high-bandwidth-memory relative to
    higher-capacity / lower-bandwidth DRAM. Now, this capability is going
    to be found on general purpose server platforms where DRAM is a cache in
    front of higher latency persistent memory [1].

    Robert offered an explanation of the state of the art of Linux
    interactions with memory-side-caches [2], and I copy it here:

    It's been a problem in the HPC space:
    http://www.nersc.gov/research-and-development/knl-cache-mode-performance-coe/

    A kernel module called zonesort is available to try to help:
    https://software.intel.com/en-us/articles/xeon-phi-software

    and this abandoned patch series proposed that for the kernel:
    https://lkml.kernel.org/r/20170823100205.17311-1-lukasz.daniluk@intel.com

    Dan's patch series doesn't attempt to ensure buffers won't conflict, but
    also reduces the chance that the buffers will. This will make performance
    more consistent, albeit slower than "optimal" (which is near impossible
    to attain in a general-purpose kernel). That's better than forcing
    users to deploy remedies like:
    "To eliminate this gradual degradation, we have added a Stream
    measurement to the Node Health Check that follows each job;
    nodes are rebooted whenever their measured memory bandwidth
    falls below 300 GB/s."

    A replacement for zonesort was merged upstream in commit cc9aec03e58f
    ("x86/numa_emulation: Introduce uniform split capability"). With this
    numa_emulation capability, memory can be split into cache sized
    ("near-memory" sized) numa nodes. A bind operation to such a node, and
    disabling workloads on other nodes, enables full cache performance.
    However, once the workload exceeds the cache size then cache conflicts
    are unavoidable. While HPC environments might be able to tolerate
    time-scheduling of cache sized workloads, for general purpose server
    platforms, the oversubscribed cache case will be the common case.

    The worst case scenario is that a server system owner benchmarks a
    workload at boot with an un-contended cache only to see that performance
    degrade over time, even below the average cache performance due to
    excessive conflicts. Randomization clips the peaks and fills in the
    valleys of cache utilization to yield steady average performance.

    Here are some performance impact details of the patches:

    1/ An Intel internal synthetic memory bandwidth measurement tool, saw a
    3X speedup in a contrived case that tries to force cache conflicts.
    The contrived cased used the numa_emulation capability to force an
    instance of the benchmark to be run in two of the near-memory sized
    numa nodes. If both instances were placed on the same emulated they
    would fit and cause zero conflicts. While on separate emulated nodes
    without randomization they underutilized the cache and conflicted
    unnecessarily due to the in-order allocation per node.

    2/ A well known Java server application benchmark was run with a heap
    size that exceeded cache size by 3X. The cache conflict rate was 8%
    for the first run and degraded to 21% after page allocator aging. With
    randomization enabled the rate levelled out at 11%.

    3/ A MongoDB workload did not observe measurable difference in
    cache-conflict rates, but the overall throughput dropped by 7% with
    randomization in one case.

    4/ Mel Gorman ran his suite of performance workloads with randomization
    enabled on platforms without a memory-side-cache and saw a mix of some
    improvements and some losses [3].

    While there is potentially significant improvement for applications that
    depend on low latency access across a wide working-set, the performance
    may be negligible to negative for other workloads. For this reason the
    shuffle capability defaults to off unless a direct-mapped
    memory-side-cache is detected. Even then, the page_alloc.shuffle=0
    parameter can be specified to disable the randomization on those systems.

    Outside of memory-side-cache utilization concerns there is potentially
    security benefit from randomization. Some data exfiltration and
    return-oriented-programming attacks rely on the ability to infer the
    location of sensitive data objects. The kernel page allocator, especially
    early in system boot, has predictable first-in-first out behavior for
    physical pages. Pages are freed in physical address order when first
    onlined.

    Quoting Kees:
    "While we already have a base-address randomization
    (CONFIG_RANDOMIZE_MEMORY), attacks against the same hardware and
    memory layouts would certainly be using the predictability of
    allocation ordering (i.e. for attacks where the base address isn't
    important: only the relative positions between allocated memory).
    This is common in lots of heap-style attacks. They try to gain
    control over ordering by spraying allocations, etc.

    I'd really like to see this because it gives us something similar
    to CONFIG_SLAB_FREELIST_RANDOM but for the page allocator."

    While SLAB_FREELIST_RANDOM reduces the predictability of some local slab
    caches it leaves vast bulk of memory to be predictably in order allocated.
    However, it should be noted, the concrete security benefits are hard to
    quantify, and no known CVE is mitigated by this randomization.

    Introduce shuffle_free_memory(), and its helper shuffle_zone(), to perform
    a Fisher-Yates shuffle of the page allocator 'free_area' lists when they
    are initially populated with free memory at boot and at hotplug time. Do
    this based on either the presence of a page_alloc.shuffle=Y command line
    parameter, or autodetection of a memory-side-cache (to be added in a
    follow-on patch).

    The shuffling is done in terms of CONFIG_SHUFFLE_PAGE_ORDER sized free
    pages where the default CONFIG_SHUFFLE_PAGE_ORDER is MAX_ORDER-1 i.e. 10,
    4MB this trades off randomization granularity for time spent shuffling.
    MAX_ORDER-1 was chosen to be minimally invasive to the page allocator
    while still showing memory-side cache behavior improvements, and the
    expectation that the security implications of finer granularity
    randomization is mitigated by CONFIG_SLAB_FREELIST_RANDOM. The
    performance impact of the shuffling appears to be in the noise compared to
    other memory initialization work.

    This initial randomization can be undone over time so a follow-on patch is
    introduced to inject entropy on page free decisions. It is reasonable to
    ask if the page free entropy is sufficient, but it is not enough due to
    the in-order initial freeing of pages. At the start of that process
    putting page1 in front or behind page0 still keeps them close together,
    page2 is still near page1 and has a high chance of being adjacent. As
    more pages are added ordering diversity improves, but there is still high
    page locality for the low address pages and this leads to no significant
    impact to the cache conflict rate.

    [1]: https://itpeernetwork.intel.com/intel-optane-dc-persistent-memory-operating-modes/
    [2]: https://lkml.kernel.org/r/AT5PR8401MB1169D656C8B5E121752FC0F8AB120@AT5PR8401MB1169.NAMPRD84.PROD.OUTLOOK.COM
    [3]: https://lkml.org/lkml/2018/10/12/309

    [dan.j.williams@intel.com: fix shuffle enable]
    Link: http://lkml.kernel.org/r/154943713038.3858443.4125180191382062871.stgit@dwillia2-desk3.amr.corp.intel.com
    [cai@lca.pw: fix SHUFFLE_PAGE_ALLOCATOR help texts]
    Link: http://lkml.kernel.org/r/20190425201300.75650-1-cai@lca.pw
    Link: http://lkml.kernel.org/r/154899811738.3165233.12325692939590944259.stgit@dwillia2-desk3.amr.corp.intel.com
    Signed-off-by: Dan Williams
    Signed-off-by: Qian Cai
    Reviewed-by: Kees Cook
    Acked-by: Michal Hocko
    Cc: Dave Hansen
    Cc: Keith Busch
    Cc: Robert Elliott
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Dan Williams
     

31 Oct, 2018

3 commits

  • Move a few remaining functions from nobootmem.c to memblock.c and remove
    nobootmem

    Link: http://lkml.kernel.org/r/1536927045-23536-28-git-send-email-rppt@linux.vnet.ibm.com
    Signed-off-by: Mike Rapoport
    Acked-by: Michal Hocko
    Cc: Catalin Marinas
    Cc: Chris Zankel
    Cc: "David S. Miller"
    Cc: Geert Uytterhoeven
    Cc: Greentime Hu
    Cc: Greg Kroah-Hartman
    Cc: Guan Xuetao
    Cc: Ingo Molnar
    Cc: "James E.J. Bottomley"
    Cc: Jonas Bonn
    Cc: Jonathan Corbet
    Cc: Ley Foon Tan
    Cc: Mark Salter
    Cc: Martin Schwidefsky
    Cc: Matt Turner
    Cc: Michael Ellerman
    Cc: Michal Simek
    Cc: Palmer Dabbelt
    Cc: Paul Burton
    Cc: Richard Kuo
    Cc: Richard Weinberger
    Cc: Rich Felker
    Cc: Russell King
    Cc: Serge Semin
    Cc: Thomas Gleixner
    Cc: Tony Luck
    Cc: Vineet Gupta
    Cc: Yoshinori Sato
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mike Rapoport
     
  • All architecures use memblock for early memory management. There is no need
    for the CONFIG_HAVE_MEMBLOCK configuration option.

    [rppt@linux.vnet.ibm.com: of/fdt: fixup #ifdefs]
    Link: http://lkml.kernel.org/r/20180919103457.GA20545@rapoport-lnx
    [rppt@linux.vnet.ibm.com: csky: fixups after bootmem removal]
    Link: http://lkml.kernel.org/r/20180926112744.GC4628@rapoport-lnx
    [rppt@linux.vnet.ibm.com: remove stale #else and the code it protects]
    Link: http://lkml.kernel.org/r/1538067825-24835-1-git-send-email-rppt@linux.vnet.ibm.com
    Link: http://lkml.kernel.org/r/1536927045-23536-4-git-send-email-rppt@linux.vnet.ibm.com
    Signed-off-by: Mike Rapoport
    Acked-by: Michal Hocko
    Tested-by: Jonathan Cameron
    Cc: Catalin Marinas
    Cc: Chris Zankel
    Cc: "David S. Miller"
    Cc: Geert Uytterhoeven
    Cc: Greentime Hu
    Cc: Greg Kroah-Hartman
    Cc: Guan Xuetao
    Cc: Ingo Molnar
    Cc: "James E.J. Bottomley"
    Cc: Jonas Bonn
    Cc: Jonathan Corbet
    Cc: Ley Foon Tan
    Cc: Mark Salter
    Cc: Martin Schwidefsky
    Cc: Matt Turner
    Cc: Michael Ellerman
    Cc: Michal Simek
    Cc: Palmer Dabbelt
    Cc: Paul Burton
    Cc: Richard Kuo
    Cc: Richard Weinberger
    Cc: Rich Felker
    Cc: Russell King
    Cc: Serge Semin
    Cc: Thomas Gleixner
    Cc: Tony Luck
    Cc: Vineet Gupta
    Cc: Yoshinori Sato
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mike Rapoport
     
  • All achitectures select NO_BOOTMEM which essentially becomes 'Y' for any
    kernel configuration and therefore it can be removed.

    [alexander.h.duyck@linux.intel.com: remove now defunct NO_BOOTMEM from depends list for deferred init]
    Link: http://lkml.kernel.org/r/20180925201814.3576.15105.stgit@localhost.localdomain
    Link: http://lkml.kernel.org/r/1536927045-23536-3-git-send-email-rppt@linux.vnet.ibm.com
    Signed-off-by: Mike Rapoport
    Signed-off-by: Alexander Duyck
    Acked-by: Michal Hocko
    Cc: Catalin Marinas
    Cc: Chris Zankel
    Cc: "David S. Miller"
    Cc: Geert Uytterhoeven
    Cc: Greentime Hu
    Cc: Greg Kroah-Hartman
    Cc: Guan Xuetao
    Cc: Ingo Molnar
    Cc: "James E.J. Bottomley"
    Cc: Jonas Bonn
    Cc: Jonathan Corbet
    Cc: Ley Foon Tan
    Cc: Mark Salter
    Cc: Martin Schwidefsky
    Cc: Matt Turner
    Cc: Michael Ellerman
    Cc: Michal Simek
    Cc: Palmer Dabbelt
    Cc: Paul Burton
    Cc: Richard Kuo
    Cc: Richard Weinberger
    Cc: Rich Felker
    Cc: Russell King
    Cc: Serge Semin
    Cc: Thomas Gleixner
    Cc: Tony Luck
    Cc: Vineet Gupta
    Cc: Yoshinori Sato
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mike Rapoport
     

23 Oct, 2018

1 commit

  • Pull arm64 updates from Catalin Marinas:
    "Apart from some new arm64 features and clean-ups, this also contains
    the core mmu_gather changes for tracking the levels of the page table
    being cleared and a minor update to the generic
    compat_sys_sigaltstack() introducing COMPAT_SIGMINSKSZ.

    Summary:

    - Core mmu_gather changes which allow tracking the levels of
    page-table being cleared together with the arm64 low-level flushing
    routines

    - Support for the new ARMv8.5 PSTATE.SSBS bit which can be used to
    mitigate Spectre-v4 dynamically without trapping to EL3 firmware

    - Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack

    - Optimise emulation of MRS instructions to ID_* registers on ARMv8.4

    - Support for Common Not Private (CnP) translations allowing threads
    of the same CPU to share the TLB entries

    - Accelerated crc32 routines

    - Move swapper_pg_dir to the rodata section

    - Trap WFI instruction executed in user space

    - ARM erratum 1188874 workaround (arch_timer)

    - Miscellaneous fixes and clean-ups"

    * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (78 commits)
    arm64: KVM: Guests can skip __install_bp_hardening_cb()s HYP work
    arm64: cpufeature: Trap CTR_EL0 access only where it is necessary
    arm64: cpufeature: Fix handling of CTR_EL0.IDC field
    arm64: cpufeature: ctr: Fix cpu capability check for late CPUs
    Documentation/arm64: HugeTLB page implementation
    arm64: mm: Use __pa_symbol() for set_swapper_pgd()
    arm64: Add silicon-errata.txt entry for ARM erratum 1188873
    Revert "arm64: uaccess: implement unsafe accessors"
    arm64: mm: Drop the unused cpu parameter
    MAINTAINERS: fix bad sdei paths
    arm64: mm: Use #ifdef for the __PAGETABLE_P?D_FOLDED defines
    arm64: Fix typo in a comment in arch/arm64/mm/kasan_init.c
    arm64: xen: Use existing helper to check interrupt status
    arm64: Use daifflag_restore after bp_hardening
    arm64: daifflags: Use irqflags functions for daifflags
    arm64: arch_timer: avoid unused function warning
    arm64: Trap WFI executed in userspace
    arm64: docs: Document SSBS HWCAP
    arm64: docs: Fix typos in ELF hwcaps
    arm64/kprobes: remove an extra semicolon in arch_prepare_kprobe
    ...

    Linus Torvalds
     

07 Sep, 2018

1 commit


31 Aug, 2018

1 commit

  • The implementation of readahead(2) syscall is identical to that of
    fadvise64(POSIX_FADV_WILLNEED) with a few exceptions:
    1. readahead(2) returns -EINVAL for !mapping->a_ops and fadvise64()
    ignores the request and returns 0.
    2. fadvise64() checks for integer overflow corner case
    3. fadvise64() calls the optional filesystem fadvise() file operation

    Unite the two implementations by calling vfs_fadvise() from readahead(2)
    syscall. Check the !mapping->a_ops in readahead(2) syscall to preserve
    documented syscall ABI behaviour.

    Suggested-by: Miklos Szeredi
    Fixes: d1d04ef8572b ("ovl: stack file ops")
    Signed-off-by: Amir Goldstein
    Signed-off-by: Miklos Szeredi

    Amir Goldstein
     

08 Jun, 2018

1 commit

  • With the addition of memfd hugetlbfs support, we now have the situation
    where memfd depends on TMPFS -or- HUGETLBFS. Previously, memfd was only
    supported on tmpfs, so it made sense that the code resided in shmem.c.
    In the current code, memfd is only functional if TMPFS is defined. If
    HUGETLFS is defined and TMPFS is not defined, then memfd functionality
    will not be available for hugetlbfs. This does not cause BUGs, just a
    lack of potentially desired functionality.

    Code is restructured in the following way:
    - include/linux/memfd.h is a new file containing memfd specific
    definitions previously contained in shmem_fs.h.
    - mm/memfd.c is a new file containing memfd specific code previously
    contained in shmem.c.
    - memfd specific code is removed from shmem_fs.h and shmem.c.
    - A new config option MEMFD_CREATE is added that is defined if TMPFS
    or HUGETLBFS is defined.

    No functional changes are made to the code: restructuring only.

    Link: http://lkml.kernel.org/r/20180415182119.4517-4-mike.kravetz@oracle.com
    Signed-off-by: Mike Kravetz
    Reviewed-by: Khalid Aziz
    Cc: Andrea Arcangeli
    Cc: David Herrmann
    Cc: Hugh Dickins
    Cc: Marc-Andr Lureau
    Cc: Matthew Wilcox
    Cc: Michal Hocko
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Mike Kravetz
     

06 Apr, 2018

1 commit

  • For mm/swap_slots.c, use the traditional Linux method of conditional
    compilation and linking instead of always compiling it by using #ifdef
    CONFIG_SWAP and #endif for the entire source file (excluding header
    files).

    Link: http://lkml.kernel.org/r/c2a47015-0b5a-d0d9-8bc7-9984c049df20@infradead.org
    Signed-off-by: Randy Dunlap
    Acked-by: Tim Chen
    Reviewed-by: Andrew Morton
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Randy Dunlap
     

18 Nov, 2017

1 commit

  • Performance of get_user_pages_fast() is critical for some workloads, but
    it's tricky to test it directly.

    This patch provides /sys/kernel/debug/gup_benchmark that helps with
    testing performance of it.

    See tools/testing/selftests/vm/gup_benchmark.c for userspace
    counterpart.

    Link: http://lkml.kernel.org/r/20170908215603.9189-2-kirill.shutemov@linux.intel.com
    Signed-off-by: Kirill A. Shutemov
    Cc: Shuah Khan
    Cc: Ingo Molnar
    Cc: Thorsten Leemhuis
    Cc: Jonathan Corbet
    Cc: Huang Ying
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kirill A. Shutemov
     

16 Nov, 2017

1 commit

  • Fix up makefiles, remove references, and git rm kmemcheck.

    Link: http://lkml.kernel.org/r/20171007030159.22241-4-alexander.levin@verizon.com
    Signed-off-by: Sasha Levin
    Cc: Steven Rostedt
    Cc: Vegard Nossum
    Cc: Pekka Enberg
    Cc: Michal Hocko
    Cc: Eric W. Biederman
    Cc: Alexander Potapenko
    Cc: Tim Hansen
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Levin, Alexander (Sasha Levin)
     

02 Nov, 2017

1 commit

  • Many source files in the tree are missing licensing information, which
    makes it harder for compliance tools to determine the correct license.

    By default all files without license information are under the default
    license of the kernel, which is GPL version 2.

    Update the files which contain no license information with the 'GPL-2.0'
    SPDX license identifier. The SPDX identifier is a legally binding
    shorthand, which can be used instead of the full boiler plate text.

    This patch is based on work done by Thomas Gleixner and Kate Stewart and
    Philippe Ombredanne.

    How this work was done:

    Patches were generated and checked against linux-4.14-rc6 for a subset of
    the use cases:
    - file had no licensing information it it.
    - file was a */uapi/* one with no licensing information in it,
    - file was a */uapi/* one with existing licensing information,

    Further patches will be generated in subsequent months to fix up cases
    where non-standard license headers were used, and references to license
    had to be inferred by heuristics based on keywords.

    The analysis to determine which SPDX License Identifier to be applied to
    a file was done in a spreadsheet of side by side results from of the
    output of two independent scanners (ScanCode & Windriver) producing SPDX
    tag:value files created by Philippe Ombredanne. Philippe prepared the
    base worksheet, and did an initial spot review of a few 1000 files.

    The 4.13 kernel was the starting point of the analysis with 60,537 files
    assessed. Kate Stewart did a file by file comparison of the scanner
    results in the spreadsheet to determine which SPDX license identifier(s)
    to be applied to the file. She confirmed any determination that was not
    immediately clear with lawyers working with the Linux Foundation.

    Criteria used to select files for SPDX license identifier tagging was:
    - Files considered eligible had to be source code files.
    - Make and config files were included as candidates if they contained >5
    lines of source
    - File already had some variant of a license header in it (even if
    Reviewed-by: Philippe Ombredanne
    Reviewed-by: Thomas Gleixner
    Signed-off-by: Greg Kroah-Hartman

    Greg Kroah-Hartman
     

09 Sep, 2017

2 commits

  • This moves all new code including new page migration helper behind kernel
    Kconfig option so that there is no codee bloat for arch or user that do
    not want to use HMM or any of its associated features.

    arm allyesconfig (without all the patchset, then with and this patch):
    text data bss dec hex filename
    83721896 46511131 27582964 157815991 96814b7 ../without/vmlinux
    83722364 46511131 27582964 157816459 968168b vmlinux

    [jglisse@redhat.com: struct hmm is only use by HMM mirror functionality]
    Link: http://lkml.kernel.org/r/20170825213133.27286-1-jglisse@redhat.com
    [sfr@canb.auug.org.au: fix build (arm multi_v7_defconfig)]
    Link: http://lkml.kernel.org/r/20170828181849.323ab81b@canb.auug.org.au
    Link: http://lkml.kernel.org/r/20170818032858.7447-1-jglisse@redhat.com
    Signed-off-by: Jérôme Glisse
    Signed-off-by: Stephen Rothwell
    Cc: Dan Williams
    Cc: Arnd Bergmann
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Jérôme Glisse
     
  • HMM provides 3 separate types of functionality:
    - Mirroring: synchronize CPU page table and device page table
    - Device memory: allocating struct page for device memory
    - Migration: migrating regular memory to device memory

    This patch introduces some common helpers and definitions to all of
    those 3 functionality.

    Link: http://lkml.kernel.org/r/20170817000548.32038-3-jglisse@redhat.com
    Signed-off-by: Jérôme Glisse
    Signed-off-by: Evgeny Baskakov
    Signed-off-by: John Hubbard
    Signed-off-by: Mark Hairgrove
    Signed-off-by: Sherry Cheung
    Signed-off-by: Subhash Gutti
    Cc: Aneesh Kumar
    Cc: Balbir Singh
    Cc: Benjamin Herrenschmidt
    Cc: Dan Williams
    Cc: David Nellans
    Cc: Johannes Weiner
    Cc: Kirill A. Shutemov
    Cc: Michal Hocko
    Cc: Paul E. McKenney
    Cc: Ross Zwisler
    Cc: Vladimir Davydov
    Cc: Bob Liu
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Jérôme Glisse
     

21 Jun, 2017

1 commit

  • There is limited visibility into the use of percpu memory leaving us
    unable to reason about correctness of parameters and overall use of
    percpu memory. These counters and statistics aim to help understand
    basic statistics about percpu memory such as number of allocations over
    the lifetime, allocation sizes, and fragmentation.

    New Config: PERCPU_STATS

    Signed-off-by: Dennis Zhou
    Signed-off-by: Tejun Heo

    Dennis Zhou
     

28 Feb, 2017

1 commit

  • This patch makes arch-independent testcases for RODATA. Both x86 and
    x86_64 already have testcases for RODATA, But they are arch-specific
    because using inline assembly directly.

    And cacheflush.h is not a suitable location for rodata-test related
    things. Since they were in cacheflush.h, If someone change the state of
    CONFIG_DEBUG_RODATA_TEST, It cause overhead of kernel build.

    To solve the above issues, write arch-independent testcases and move it
    to shared location.

    [jinb.park7@gmail.com: fix config dependency]
    Link: http://lkml.kernel.org/r/20170209131625.GA16954@pjb1027-Latitude-E5410
    Link: http://lkml.kernel.org/r/20170129105436.GA9303@pjb1027-Latitude-E5410
    Signed-off-by: Jinbum Park
    Acked-by: Kees Cook
    Cc: Ingo Molnar
    Cc: H. Peter Anvin
    Cc: Arjan van de Ven
    Cc: Laura Abbott
    Cc: Russell King
    Cc: Valentin Rothberg
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Jinbum Park
     

25 Feb, 2017

1 commit

  • Introduce a new interface to check if a page is mapped into a vma. It
    aims to address shortcomings of page_check_address{,_transhuge}.

    Existing interface is not able to handle PTE-mapped THPs: it only finds
    the first PTE. The rest lefted unnoticed.

    page_vma_mapped_walk() iterates over all possible mapping of the page in
    the vma.

    Link: http://lkml.kernel.org/r/20170129173858.45174-3-kirill.shutemov@linux.intel.com
    Signed-off-by: Kirill A. Shutemov
    Cc: Andrea Arcangeli
    Cc: Hillf Danton
    Cc: Hugh Dickins
    Cc: Johannes Weiner
    Cc: Oleg Nesterov
    Cc: Peter Zijlstra
    Cc: Rik van Riel
    Cc: Srikar Dronamraju
    Cc: Vladimir Davydov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kirill A. Shutemov
     

23 Feb, 2017

1 commit

  • We add per cpu caches for swap slots that can be allocated and freed
    quickly without the need to touch the swap info lock.

    Two separate caches are maintained for swap slots allocated and swap
    slots returned. This is to allow the swap slots to be returned to the
    global pool in a batch so they will have a chance to be coaelesced with
    other slots in a cluster. We do not reuse the slots that are returned
    right away, as it may increase fragmentation of the slots.

    The swap allocation cache is protected by a mutex as we may sleep when
    searching for empty slots in cache. The swap free cache is protected by
    a spin lock as we cannot sleep in the free path.

    We refill the swap slots cache when we run out of slots, and we disable
    the swap slots cache and drain the slots if the global number of slots
    fall below a low watermark threshold. We re-enable the cache agian when
    the slots available are above a high watermark.

    [ying.huang@intel.com: use raw_cpu_ptr over this_cpu_ptr for swap slots access]
    [tim.c.chen@linux.intel.com: add comments on locks in swap_slots.h]
    Link: http://lkml.kernel.org/r/20170118180327.GA24225@linux.intel.com
    Link: http://lkml.kernel.org/r/35de301a4eaa8daa2977de6e987f2c154385eb66.1484082593.git.tim.c.chen@linux.intel.com
    Signed-off-by: Tim Chen
    Signed-off-by: "Huang, Ying"
    Reviewed-by: Michal Hocko
    Cc: Aaron Lu
    Cc: Andi Kleen
    Cc: Andrea Arcangeli
    Cc: Christian Borntraeger
    Cc: Dave Hansen
    Cc: Hillf Danton
    Cc: Huang Ying
    Cc: Hugh Dickins
    Cc: Johannes Weiner
    Cc: Jonathan Corbet escreveu:
    Cc: Kirill A. Shutemov
    Cc: Minchan Kim
    Cc: Rik van Riel
    Cc: Shaohua Li
    Cc: Vladimir Davydov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Tim Chen
     

13 Oct, 2016

1 commit

  • This affectively reverts commit 377ccbb48373 ("Makefile: Mute warning
    for __builtin_return_address(>0) for tracing only") because it turns out
    that it really isn't tracing only - it's all over the tree.

    We already also had the warning disabled separately for mm/usercopy.c
    (which this commit also removes), and it turns out that we will also
    want to disable it for get_lock_parent_ip(), that is used for at least
    TRACE_IRQFLAGS. Which (when enabled) ends up being all over the tree.

    Steven Rostedt had a patch that tried to limit it to just the config
    options that actually triggered this, but quite frankly, the extra
    complexity and abstraction just isn't worth it. We have never actually
    had a case where the warning is actually useful, so let's just disable
    it globally and not worry about it.

    Acked-by: Steven Rostedt
    Cc: Thomas Gleixner
    Cc: Andrew Morton
    Cc: Ingo Molnar
    Cc: Peter Anvin
    Signed-off-by: Linus Torvalds

    Linus Torvalds
     

09 Aug, 2016

1 commit

  • Pull usercopy protection from Kees Cook:
    "Tbhis implements HARDENED_USERCOPY verification of copy_to_user and
    copy_from_user bounds checking for most architectures on SLAB and
    SLUB"

    * tag 'usercopy-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
    mm: SLUB hardened usercopy support
    mm: SLAB hardened usercopy support
    s390/uaccess: Enable hardened usercopy
    sparc/uaccess: Enable hardened usercopy
    powerpc/uaccess: Enable hardened usercopy
    ia64/uaccess: Enable hardened usercopy
    arm64/uaccess: Enable hardened usercopy
    ARM: uaccess: Enable hardened usercopy
    x86/uaccess: Enable hardened usercopy
    mm: Hardened usercopy
    mm: Implement stack frame object validation
    mm: Add is_migrate_cma_page

    Linus Torvalds
     

27 Jul, 2016

2 commits

  • khugepaged implementation grew to the point when it deserve separate
    file in source.

    Let's move it to mm/khugepaged.c.

    Link: http://lkml.kernel.org/r/1466021202-61880-32-git-send-email-kirill.shutemov@linux.intel.com
    Signed-off-by: Kirill A. Shutemov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Kirill A. Shutemov
     
  • This is the start of porting PAX_USERCOPY into the mainline kernel. This
    is the first set of features, controlled by CONFIG_HARDENED_USERCOPY. The
    work is based on code by PaX Team and Brad Spengler, and an earlier port
    from Casey Schaufler. Additional non-slab page tests are from Rik van Riel.

    This patch contains the logic for validating several conditions when
    performing copy_to_user() and copy_from_user() on the kernel object
    being copied to/from:
    - address range doesn't wrap around
    - address range isn't NULL or zero-allocated (with a non-zero copy size)
    - if on the slab allocator:
    - object size must be less than or equal to copy size (when check is
    implemented in the allocator, which appear in subsequent patches)
    - otherwise, object must not span page allocations (excepting Reserved
    and CMA ranges)
    - if on the stack
    - object must not extend before/after the current process stack
    - object must be contained by a valid stack frame (when there is
    arch/build support for identifying stack frames)
    - object must not overlap with kernel text

    Signed-off-by: Kees Cook
    Tested-by: Valdis Kletnieks
    Tested-by: Michael Ellerman

    Kees Cook
     

21 May, 2016

1 commit

  • This patch introduces z3fold, a special purpose allocator for storing
    compressed pages. It is designed to store up to three compressed pages
    per physical page. It is a ZBUD derivative which allows for higher
    compression ratio keeping the simplicity and determinism of its
    predecessor.

    This patch comes as a follow-up to the discussions at the Embedded Linux
    Conference in San-Diego related to the talk [1]. The outcome of these
    discussions was that it would be good to have a compressed page
    allocator as stable and deterministic as zbud with with higher
    compression ratio.

    To keep the determinism and simplicity, z3fold, just like zbud, always
    stores an integral number of compressed pages per page, but it can store
    up to 3 pages unlike zbud which can store at most 2. Therefore the
    compression ratio goes to around 2.6x while zbud's one is around 1.7x.

    The patch is based on the latest linux.git tree.

    This version has been updated after testing on various simulators (e.g.
    ARM Versatile Express, MIPS Malta, x86_64/Haswell) and basing on
    comments from Dan Streetman [3].

    [1] https://openiotelc2016.sched.org/event/6DAC/swapping-and-embedded-compression-relieves-the-pressure-vitaly-wool-softprise-consulting-ou
    [2] https://lkml.org/lkml/2016/4/21/799
    [3] https://lkml.org/lkml/2016/5/4/852

    Link: http://lkml.kernel.org/r/20160509151753.ec3f9fda3c9898d31ff52a32@gmail.com
    Signed-off-by: Vitaly Wool
    Cc: Seth Jennings
    Cc: Dan Streetman
    Cc: Vlastimil Babka
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Vitaly Wool
     

26 Mar, 2016

1 commit

  • Add KASAN hooks to SLAB allocator.

    This patch is based on the "mm: kasan: unified support for SLUB and SLAB
    allocators" patch originally prepared by Dmitry Chernenkov.

    Signed-off-by: Alexander Potapenko
    Cc: Christoph Lameter
    Cc: Pekka Enberg
    Cc: David Rientjes
    Cc: Joonsoo Kim
    Cc: Andrey Konovalov
    Cc: Dmitry Vyukov
    Cc: Andrey Ryabinin
    Cc: Steven Rostedt
    Cc: Konstantin Serebryany
    Cc: Dmitry Chernenkov
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alexander Potapenko
     

23 Mar, 2016

1 commit

  • kcov provides code coverage collection for coverage-guided fuzzing
    (randomized testing). Coverage-guided fuzzing is a testing technique
    that uses coverage feedback to determine new interesting inputs to a
    system. A notable user-space example is AFL
    (http://lcamtuf.coredump.cx/afl/). However, this technique is not
    widely used for kernel testing due to missing compiler and kernel
    support.

    kcov does not aim to collect as much coverage as possible. It aims to
    collect more or less stable coverage that is function of syscall inputs.
    To achieve this goal it does not collect coverage in soft/hard
    interrupts and instrumentation of some inherently non-deterministic or
    non-interesting parts of kernel is disbled (e.g. scheduler, locking).

    Currently there is a single coverage collection mode (tracing), but the
    API anticipates additional collection modes. Initially I also
    implemented a second mode which exposes coverage in a fixed-size hash
    table of counters (what Quentin used in his original patch). I've
    dropped the second mode for simplicity.

    This patch adds the necessary support on kernel side. The complimentary
    compiler support was added in gcc revision 231296.

    We've used this support to build syzkaller system call fuzzer, which has
    found 90 kernel bugs in just 2 months:

    https://github.com/google/syzkaller/wiki/Found-Bugs

    We've also found 30+ bugs in our internal systems with syzkaller.
    Another (yet unexplored) direction where kcov coverage would greatly
    help is more traditional "blob mutation". For example, mounting a
    random blob as a filesystem, or receiving a random blob over wire.

    Why not gcov. Typical fuzzing loop looks as follows: (1) reset
    coverage, (2) execute a bit of code, (3) collect coverage, repeat. A
    typical coverage can be just a dozen of basic blocks (e.g. an invalid
    input). In such context gcov becomes prohibitively expensive as
    reset/collect coverage steps depend on total number of basic
    blocks/edges in program (in case of kernel it is about 2M). Cost of
    kcov depends only on number of executed basic blocks/edges. On top of
    that, kernel requires per-thread coverage because there are always
    background threads and unrelated processes that also produce coverage.
    With inlined gcov instrumentation per-thread coverage is not possible.

    kcov exposes kernel PCs and control flow to user-space which is
    insecure. But debugfs should not be mapped as user accessible.

    Based on a patch by Quentin Casasnovas.

    [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
    [akpm@linux-foundation.org: unbreak allmodconfig]
    [akpm@linux-foundation.org: follow x86 Makefile layout standards]
    Signed-off-by: Dmitry Vyukov
    Reviewed-by: Kees Cook
    Cc: syzkaller
    Cc: Vegard Nossum
    Cc: Catalin Marinas
    Cc: Tavis Ormandy
    Cc: Will Deacon
    Cc: Quentin Casasnovas
    Cc: Kostya Serebryany
    Cc: Eric Dumazet
    Cc: Alexander Potapenko
    Cc: Kees Cook
    Cc: Bjorn Helgaas
    Cc: Sasha Levin
    Cc: David Drysdale
    Cc: Ard Biesheuvel
    Cc: Andrey Ryabinin
    Cc: Kirill A. Shutemov
    Cc: Jiri Slaby
    Cc: Ingo Molnar
    Cc: Thomas Gleixner
    Cc: "H. Peter Anvin"
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Dmitry Vyukov
     

18 Mar, 2016

1 commit

  • CMA allocation should be guaranteed to succeed by definition, but,
    unfortunately, it would be failed sometimes. It is hard to track down
    the problem, because it is related to page reference manipulation and we
    don't have any facility to analyze it.

    This patch adds tracepoints to track down page reference manipulation.
    With it, we can find exact reason of failure and can fix the problem.
    Following is an example of tracepoint output. (note: this example is
    stale version that printing flags as the number. Recent version will
    print it as human readable string.)

    -9018 [004] 92.678375: page_ref_set: pfn=0x17ac9 flags=0x0 count=1 mapcount=0 mapping=(nil) mt=4 val=1
    -9018 [004] 92.678378: kernel_stack:
    => get_page_from_freelist (ffffffff81176659)
    => __alloc_pages_nodemask (ffffffff81176d22)
    => alloc_pages_vma (ffffffff811bf675)
    => handle_mm_fault (ffffffff8119e693)
    => __do_page_fault (ffffffff810631ea)
    => trace_do_page_fault (ffffffff81063543)
    => do_async_page_fault (ffffffff8105c40a)
    => async_page_fault (ffffffff817581d8)
    [snip]
    -9018 [004] 92.678379: page_ref_mod: pfn=0x17ac9 flags=0x40048 count=2 mapcount=1 mapping=0xffff880015a78dc1 mt=4 val=1
    [snip]
    ...
    ...
    -9131 [001] 93.174468: test_pages_isolated: start_pfn=0x17800 end_pfn=0x17c00 fin_pfn=0x17ac9 ret=fail
    [snip]
    -9018 [004] 93.174843: page_ref_mod_and_test: pfn=0x17ac9 flags=0x40068 count=0 mapcount=0 mapping=0xffff880015a78dc1 mt=4 val=-1 ret=1
    => release_pages (ffffffff8117c9e4)
    => free_pages_and_swap_cache (ffffffff811b0697)
    => tlb_flush_mmu_free (ffffffff81199616)
    => tlb_finish_mmu (ffffffff8119a62c)
    => exit_mmap (ffffffff811a53f7)
    => mmput (ffffffff81073f47)
    => do_exit (ffffffff810794e9)
    => do_group_exit (ffffffff81079def)
    => SyS_exit_group (ffffffff81079e74)
    => entry_SYSCALL_64_fastpath (ffffffff817560b6)

    This output shows that problem comes from exit path. In exit path, to
    improve performance, pages are not freed immediately. They are gathered
    and processed by batch. During this process, migration cannot be
    possible and CMA allocation is failed. This problem is hard to find
    without this page reference tracepoint facility.

    Enabling this feature bloat kernel text 30 KB in my configuration.

    text data bss dec hex filename
    12127327 2243616 1507328 15878271 f2487f vmlinux_disabled
    12157208 2258880 1507328 15923416 f2f8d8 vmlinux_enabled

    Note that, due to header file dependency problem between mm.h and
    tracepoint.h, this feature has to open code the static key functions for
    tracepoints. Proposed by Steven Rostedt in following link.

    https://lkml.org/lkml/2015/12/9/699

    [arnd@arndb.de: crypto/async_pq: use __free_page() instead of put_page()]
    [iamjoonsoo.kim@lge.com: fix build failure for xtensa]
    [akpm@linux-foundation.org: tweak Kconfig text, per Vlastimil]
    Signed-off-by: Joonsoo Kim
    Acked-by: Michal Nazarewicz
    Acked-by: Vlastimil Babka
    Cc: Minchan Kim
    Cc: Mel Gorman
    Cc: "Kirill A. Shutemov"
    Cc: Sergey Senozhatsky
    Acked-by: Steven Rostedt
    Signed-off-by: Arnd Bergmann
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Joonsoo Kim
     

16 Mar, 2016

1 commit

  • Page poisoning is currently set up as a feature if architectures don't
    have architecture debug page_alloc to allow unmapping of pages. It has
    uses apart from that though. Clearing of the pages on free provides an
    increase in security as it helps to limit the risk of information leaks.
    Allow page poisoning to be enabled as a separate option independent of
    kernel_map pages since the two features do separate work. Because of
    how hiberanation is implemented, the checks on alloc cannot occur if
    hibernation is enabled. The runtime alloc checks can also be enabled
    with an option when !HIBERNATION.

    Credit to Grsecurity/PaX team for inspiring this work

    Signed-off-by: Laura Abbott
    Cc: Rafael J. Wysocki
    Cc: "Kirill A. Shutemov"
    Cc: Vlastimil Babka
    Cc: Michal Hocko
    Cc: Kees Cook
    Cc: Mathias Krause
    Cc: Dave Hansen
    Cc: Jianyu Zhan
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Laura Abbott
     

12 Sep, 2015

1 commit

  • Pull media updates from Mauro Carvalho Chehab:
    "A series of patches that move part of the code used to allocate memory
    from the media subsystem to the mm subsystem"

    [ The mm parts have been acked by VM people, and the series was
    apparently in -mm for a while - Linus ]

    * tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
    [media] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
    [media] media: vb2: Remove unused functions
    [media] media: vb2: Convert vb2_dc_get_userptr() to use frame vector
    [media] media: vb2: Convert vb2_vmalloc_get_userptr() to use frame vector
    [media] media: vb2: Convert vb2_dma_sg_get_userptr() to use frame vector
    [media] vb2: Provide helpers for mapping virtual addresses
    [media] media: omap_vout: Convert omap_vout_uservirt_to_phys() to use get_vaddr_pfns()
    [media] mm: Provide new get_vaddr_frames() helper
    [media] vb2: Push mmap_sem down to memops

    Linus Torvalds
     

11 Sep, 2015

1 commit

  • Knowing the portion of memory that is not used by a certain application or
    memory cgroup (idle memory) can be useful for partitioning the system
    efficiently, e.g. by setting memory cgroup limits appropriately.
    Currently, the only means to estimate the amount of idle memory provided
    by the kernel is /proc/PID/{clear_refs,smaps}: the user can clear the
    access bit for all pages mapped to a particular process by writing 1 to
    clear_refs, wait for some time, and then count smaps:Referenced. However,
    this method has two serious shortcomings:

    - it does not count unmapped file pages
    - it affects the reclaimer logic

    To overcome these drawbacks, this patch introduces two new page flags,
    Idle and Young, and a new sysfs file, /sys/kernel/mm/page_idle/bitmap.
    A page's Idle flag can only be set from userspace by setting bit in
    /sys/kernel/mm/page_idle/bitmap at the offset corresponding to the page,
    and it is cleared whenever the page is accessed either through page tables
    (it is cleared in page_referenced() in this case) or using the read(2)
    system call (mark_page_accessed()). Thus by setting the Idle flag for
    pages of a particular workload, which can be found e.g. by reading
    /proc/PID/pagemap, waiting for some time to let the workload access its
    working set, and then reading the bitmap file, one can estimate the amount
    of pages that are not used by the workload.

    The Young page flag is used to avoid interference with the memory
    reclaimer. A page's Young flag is set whenever the Access bit of a page
    table entry pointing to the page is cleared by writing to the bitmap file.
    If page_referenced() is called on a Young page, it will add 1 to its
    return value, therefore concealing the fact that the Access bit was
    cleared.

    Note, since there is no room for extra page flags on 32 bit, this feature
    uses extended page flags when compiled on 32 bit.

    [akpm@linux-foundation.org: fix build]
    [akpm@linux-foundation.org: kpageidle requires an MMU]
    [akpm@linux-foundation.org: decouple from page-flags rework]
    Signed-off-by: Vladimir Davydov
    Reviewed-by: Andres Lagar-Cavilla
    Cc: Minchan Kim
    Cc: Raghavendra K T
    Cc: Johannes Weiner
    Cc: Michal Hocko
    Cc: Greg Thelen
    Cc: Michel Lespinasse
    Cc: David Rientjes
    Cc: Pavel Emelyanov
    Cc: Cyrill Gorcunov
    Cc: Jonathan Corbet
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Vladimir Davydov
     

05 Sep, 2015

1 commit

  • This implements mcopy_atomic and mfill_zeropage that are the lowlevel
    VM methods that are invoked respectively by the UFFDIO_COPY and
    UFFDIO_ZEROPAGE userfaultfd commands.

    Signed-off-by: Andrea Arcangeli
    Acked-by: Pavel Emelyanov
    Cc: Sanidhya Kashyap
    Cc: zhang.zhanghailiang@huawei.com
    Cc: "Kirill A. Shutemov"
    Cc: Andres Lagar-Cavilla
    Cc: Dave Hansen
    Cc: Paolo Bonzini
    Cc: Rik van Riel
    Cc: Mel Gorman
    Cc: Andy Lutomirski
    Cc: Hugh Dickins
    Cc: Peter Feiner
    Cc: "Dr. David Alan Gilbert"
    Cc: Johannes Weiner
    Cc: "Huangpeng (Peter)"
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Andrea Arcangeli
     

17 Aug, 2015

1 commit

  • Provide new function get_vaddr_frames(). This function maps virtual
    addresses from given start and fills given array with page frame numbers of
    the corresponding pages. If given start belongs to a normal vma, the function
    grabs reference to each of the pages to pin them in memory. If start
    belongs to VM_IO | VM_PFNMAP vma, we don't touch page structures. Caller
    must make sure pfns aren't reused for anything else while he is using
    them.

    This function is created for various drivers to simplify handling of
    their buffers.

    Signed-off-by: Jan Kara
    Acked-by: Mel Gorman
    Acked-by: Vlastimil Babka
    Acked-by: Andrew Morton
    Signed-off-by: Hans Verkuil
    Signed-off-by: Mauro Carvalho Chehab

    Jan Kara
     

15 Apr, 2015

2 commits

  • Memtest is a simple feature which fills the memory with a given set of
    patterns and validates memory contents, if bad memory regions is detected
    it reserves them via memblock API. Since memblock API is widely used by
    other architectures this feature can be enabled outside of x86 world.

    This patch set promotes memtest to live under generic mm umbrella and
    enables memtest feature for arm/arm64.

    It was reported that this patch set was useful for tracking down an issue
    with some errant DMA on an arm64 platform.

    This patch (of 6):

    There is nothing platform dependent in the core memtest code, so other
    platforms might benefit from this feature too.

    [linux@roeck-us.net: MEMTEST depends on MEMBLOCK]
    Signed-off-by: Vladimir Murzin
    Acked-by: Will Deacon
    Tested-by: Mark Rutland
    Cc: Ingo Molnar
    Cc: Thomas Gleixner
    Cc: "H. Peter Anvin"
    Cc: Catalin Marinas
    Cc: Russell King
    Cc: Paul Bolle
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Vladimir Murzin
     
  • I've noticed that there is no interfaces exposed by CMA which would let me
    fuzz what's going on in there.

    This small patchset exposes some information out to userspace, plus adds
    the ability to trigger allocation and freeing from userspace.

    This patch (of 3):

    Implement a simple debugfs interface to expose information about CMA areas
    in the system.

    Useful for testing/sanity checks for CMA since it was impossible to
    previously retrieve this information in userspace.

    Signed-off-by: Sasha Levin
    Acked-by: Joonsoo Kim
    Cc: Marek Szyprowski
    Cc: Laura Abbott
    Cc: Konrad Rzeszutek Wilk
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Sasha Levin
     

18 Feb, 2015

1 commit