24 Nov, 2020

1 commit

  • We call arch_cpu_idle() with RCU disabled, but then use
    local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.

    Switch all arch_cpu_idle() implementations to use
    raw_local_irq_{en,dis}able() and carefully manage the
    lockdep,rcu,tracing state like we do in entry.

    (XXX: we really should change arch_cpu_idle() to not return with
    interrupts enabled)

    Reported-by: Sven Schnelle
    Signed-off-by: Peter Zijlstra (Intel)
    Reviewed-by: Mark Rutland
    Tested-by: Mark Rutland
    Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org

    Peter Zijlstra
     

26 Oct, 2020

1 commit

  • Use a more generic form for __section that requires quotes to avoid
    complications with clang and gcc differences.

    Remove the quote operator # from compiler_attributes.h __section macro.

    Convert all unquoted __section(foo) uses to quoted __section("foo").
    Also convert __attribute__((section("foo"))) uses to __section("foo")
    even if the __attribute__ has multiple list entry forms.

    Conversion done using the script at:

    https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl

    Signed-off-by: Joe Perches
    Reviewed-by: Nick Desaulniers
    Reviewed-by: Miguel Ojeda
    Signed-off-by: Linus Torvalds

    Joe Perches
     

24 Oct, 2020

1 commit

  • Pull arch task_work cleanups from Jens Axboe:
    "Two cleanups that don't fit other categories:

    - Finally get the task_work_add() cleanup done properly, so we don't
    have random 0/1/false/true/TWA_SIGNAL confusing use cases. Updates
    all callers, and also fixes up the documentation for
    task_work_add().

    - While working on some TIF related changes for 5.11, this
    TIF_NOTIFY_RESUME cleanup fell out of that. Remove some arch
    duplication for how that is handled"

    * tag 'arch-cleanup-2020-10-22' of git://git.kernel.dk/linux-block:
    task_work: cleanup notification modes
    tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume()

    Linus Torvalds
     

19 Oct, 2020

1 commit

  • There is usecase that System Management Software(SMS) want to give a
    memory hint like MADV_[COLD|PAGEEOUT] to other processes and in the
    case of Android, it is the ActivityManagerService.

    The information required to make the reclaim decision is not known to the
    app. Instead, it is known to the centralized userspace
    daemon(ActivityManagerService), and that daemon must be able to initiate
    reclaim on its own without any app involvement.

    To solve the issue, this patch introduces a new syscall
    process_madvise(2). It uses pidfd of an external process to give the
    hint. It also supports vector address range because Android app has
    thousands of vmas due to zygote so it's totally waste of CPU and power if
    we should call the syscall one by one for each vma.(With testing 2000-vma
    syscall vs 1-vector syscall, it showed 15% performance improvement. I
    think it would be bigger in real practice because the testing ran very
    cache friendly environment).

    Another potential use case for the vector range is to amortize the cost
    ofTLB shootdowns for multiple ranges when using MADV_DONTNEED; this could
    benefit users like TCP receive zerocopy and malloc implementations. In
    future, we could find more usecases for other advises so let's make it
    happens as API since we introduce a new syscall at this moment. With
    that, existing madvise(2) user could replace it with process_madvise(2)
    with their own pid if they want to have batch address ranges support
    feature.

    ince it could affect other process's address range, only privileged
    process(PTRACE_MODE_ATTACH_FSCREDS) or something else(e.g., being the same
    UID) gives it the right to ptrace the process could use it successfully.
    The flag argument is reserved for future use if we need to extend the API.

    I think supporting all hints madvise has/will supported/support to
    process_madvise is rather risky. Because we are not sure all hints make
    sense from external process and implementation for the hint may rely on
    the caller being in the current context so it could be error-prone. Thus,
    I just limited hints as MADV_[COLD|PAGEOUT] in this patch.

    If someone want to add other hints, we could hear the usecase and review
    it for each hint. It's safer for maintenance rather than introducing a
    buggy syscall but hard to fix it later.

    So finally, the API is as follows,

    ssize_t process_madvise(int pidfd, const struct iovec *iovec,
    unsigned long vlen, int advice, unsigned int flags);

    DESCRIPTION
    The process_madvise() system call is used to give advice or directions
    to the kernel about the address ranges from external process as well as
    local process. It provides the advice to address ranges of process
    described by iovec and vlen. The goal of such advice is to improve
    system or application performance.

    The pidfd selects the process referred to by the PID file descriptor
    specified in pidfd. (See pidofd_open(2) for further information)

    The pointer iovec points to an array of iovec structures, defined in
    as:

    struct iovec {
    void *iov_base; /* starting address */
    size_t iov_len; /* number of bytes to be advised */
    };

    The iovec describes address ranges beginning at address(iov_base)
    and with size length of bytes(iov_len).

    The vlen represents the number of elements in iovec.

    The advice is indicated in the advice argument, which is one of the
    following at this moment if the target process specified by pidfd is
    external.

    MADV_COLD
    MADV_PAGEOUT

    Permission to provide a hint to external process is governed by a
    ptrace access mode PTRACE_MODE_ATTACH_FSCREDS check; see ptrace(2).

    The process_madvise supports every advice madvise(2) has if target
    process is in same thread group with calling process so user could
    use process_madvise(2) to extend existing madvise(2) to support
    vector address ranges.

    RETURN VALUE
    On success, process_madvise() returns the number of bytes advised.
    This return value may be less than the total number of requested
    bytes, if an error occurred. The caller should check return value
    to determine whether a partial advice occurred.

    FAQ:

    Q.1 - Why does any external entity have better knowledge?

    Quote from Sandeep

    "For Android, every application (including the special SystemServer)
    are forked from Zygote. The reason of course is to share as many
    libraries and classes between the two as possible to benefit from the
    preloading during boot.

    After applications start, (almost) all of the APIs end up calling into
    this SystemServer process over IPC (binder) and back to the
    application.

    In a fully running system, the SystemServer monitors every single
    process periodically to calculate their PSS / RSS and also decides
    which process is "important" to the user for interactivity.

    So, because of how these processes start _and_ the fact that the
    SystemServer is looping to monitor each process, it does tend to *know*
    which address range of the application is not used / useful.

    Besides, we can never rely on applications to clean things up
    themselves. We've had the "hey app1, the system is low on memory,
    please trim your memory usage down" notifications for a long time[1].
    They rely on applications honoring the broadcasts and very few do.

    So, if we want to avoid the inevitable killing of the application and
    restarting it, some way to be able to tell the OS about unimportant
    memory in these applications will be useful.

    - ssp

    Q.2 - How to guarantee the race(i.e., object validation) between when
    giving a hint from an external process and get the hint from the target
    process?

    process_madvise operates on the target process's address space as it
    exists at the instant that process_madvise is called. If the space
    target process can run between the time the process_madvise process
    inspects the target process address space and the time that
    process_madvise is actually called, process_madvise may operate on
    memory regions that the calling process does not expect. It's the
    responsibility of the process calling process_madvise to close this
    race condition. For example, the calling process can suspend the
    target process with ptrace, SIGSTOP, or the freezer cgroup so that it
    doesn't have an opportunity to change its own address space before
    process_madvise is called. Another option is to operate on memory
    regions that the caller knows a priori will be unchanged in the target
    process. Yet another option is to accept the race for certain
    process_madvise calls after reasoning that mistargeting will do no
    harm. The suggested API itself does not provide synchronization. It
    also apply other APIs like move_pages, process_vm_write.

    The race isn't really a problem though. Why is it so wrong to require
    that callers do their own synchronization in some manner? Nobody
    objects to write(2) merely because it's possible for two processes to
    open the same file and clobber each other's writes --- instead, we tell
    people to use flock or something. Think about mmap. It never
    guarantees newly allocated address space is still valid when the user
    tries to access it because other threads could unmap the memory right
    before. That's where we need synchronization by using other API or
    design from userside. It shouldn't be part of API itself. If someone
    needs more fine-grained synchronization rather than process level,
    there were two ideas suggested - cookie[2] and anon-fd[3]. Both are
    applicable via using last reserved argument of the API but I don't
    think it's necessary right now since we have already ways to prevent
    the race so don't want to add additional complexity with more
    fine-grained optimization model.

    To make the API extend, it reserved an unsigned long as last argument
    so we could support it in future if someone really needs it.

    Q.3 - Why doesn't ptrace work?

    Injecting an madvise in the target process using ptrace would not work
    for us because such injected madvise would have to be executed by the
    target process, which means that process would have to be runnable and
    that creates the risk of the abovementioned race and hinting a wrong
    VMA. Furthermore, we want to act the hint in caller's context, not the
    callee's, because the callee is usually limited in cpuset/cgroups or
    even freezed state so they can't act by themselves quick enough, which
    causes more thrashing/kill. It doesn't work if the target process are
    ptraced(e.g., strace, debugger, minidump) because a process can have at
    most one ptracer.

    [1] https://developer.android.com/topic/performance/memory"

    [2] process_getinfo for getting the cookie which is updated whenever
    vma of process address layout are changed - Daniel Colascione -
    https://lore.kernel.org/lkml/20190520035254.57579-1-minchan@kernel.org/T/#m7694416fd179b2066a2c62b5b139b14e3894e224

    [3] anonymous fd which is used for the object(i.e., address range)
    validation - Michal Hocko -
    https://lore.kernel.org/lkml/20200120112722.GY18451@dhcp22.suse.cz/

    [minchan@kernel.org: fix process_madvise build break for arm64]
    Link: http://lkml.kernel.org/r/20200303145756.GA219683@google.com
    [minchan@kernel.org: fix build error for mips of process_madvise]
    Link: http://lkml.kernel.org/r/20200508052517.GA197378@google.com
    [akpm@linux-foundation.org: fix patch ordering issue]
    [akpm@linux-foundation.org: fix arm64 whoops]
    [minchan@kernel.org: make process_madvise() vlen arg have type size_t, per Florian]
    [akpm@linux-foundation.org: fix i386 build]
    [sfr@canb.auug.org.au: fix syscall numbering]
    Link: https://lkml.kernel.org/r/20200905142639.49fc3f1a@canb.auug.org.au
    [sfr@canb.auug.org.au: madvise.c needs compat.h]
    Link: https://lkml.kernel.org/r/20200908204547.285646b4@canb.auug.org.au
    [minchan@kernel.org: fix mips build]
    Link: https://lkml.kernel.org/r/20200909173655.GC2435453@google.com
    [yuehaibing@huawei.com: remove duplicate header which is included twice]
    Link: https://lkml.kernel.org/r/20200915121550.30584-1-yuehaibing@huawei.com
    [minchan@kernel.org: do not use helper functions for process_madvise]
    Link: https://lkml.kernel.org/r/20200921175539.GB387368@google.com
    [akpm@linux-foundation.org: pidfd_get_pid() gained an argument]
    [sfr@canb.auug.org.au: fix up for "iov_iter: transparently handle compat iovecs in import_iovec"]
    Link: https://lkml.kernel.org/r/20200928212542.468e1fef@canb.auug.org.au

    Signed-off-by: Minchan Kim
    Signed-off-by: YueHaibing
    Signed-off-by: Stephen Rothwell
    Signed-off-by: Andrew Morton
    Reviewed-by: Suren Baghdasaryan
    Reviewed-by: Vlastimil Babka
    Acked-by: David Rientjes
    Cc: Alexander Duyck
    Cc: Brian Geffon
    Cc: Christian Brauner
    Cc: Daniel Colascione
    Cc: Jann Horn
    Cc: Jens Axboe
    Cc: Joel Fernandes
    Cc: Johannes Weiner
    Cc: John Dias
    Cc: Kirill Tkhai
    Cc: Michal Hocko
    Cc: Oleksandr Natalenko
    Cc: Sandeep Patil
    Cc: SeongJae Park
    Cc: SeongJae Park
    Cc: Shakeel Butt
    Cc: Sonny Rao
    Cc: Tim Murray
    Cc: Christian Brauner
    Cc: Florian Weimer
    Cc:
    Link: http://lkml.kernel.org/r/20200302193630.68771-3-minchan@kernel.org
    Link: http://lkml.kernel.org/r/20200508183320.GA125527@google.com
    Link: http://lkml.kernel.org/r/20200622192900.22757-4-minchan@kernel.org
    Link: https://lkml.kernel.org/r/20200901000633.1920247-4-minchan@kernel.org
    Signed-off-by: Linus Torvalds

    Minchan Kim
     

18 Oct, 2020

1 commit


17 Oct, 2020

1 commit

  • Pull powerpc updates from Michael Ellerman:

    - A series from Nick adding ARCH_WANT_IRQS_OFF_ACTIVATE_MM & selecting
    it for powerpc, as well as a related fix for sparc.

    - Remove support for PowerPC 601.

    - Some fixes for watchpoints & addition of a new ptrace flag for
    detecting ISA v3.1 (Power10) watchpoint features.

    - A fix for kernels using 4K pages and the hash MMU on bare metal
    Power9 systems with > 16TB of RAM, or RAM on the 2nd node.

    - A basic idle driver for shallow stop states on Power10.

    - Tweaks to our sched domains code to better inform the scheduler about
    the hardware topology on Power9/10, where two SMT4 cores can be
    presented by firmware as an SMT8 core.

    - A series doing further reworks & cleanups of our EEH code.

    - Addition of a filter for RTAS (firmware) calls done via sys_rtas(),
    to prevent root from overwriting kernel memory.

    - Other smaller features, fixes & cleanups.

    Thanks to: Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V,
    Athira Rajeev, Biwen Li, Cameron Berkenpas, Cédric Le Goater, Christophe
    Leroy, Christoph Hellwig, Colin Ian King, Daniel Axtens, David Dai, Finn
    Thain, Frederic Barrat, Gautham R. Shenoy, Greg Kurz, Gustavo Romero,
    Ira Weiny, Jason Yan, Joel Stanley, Jordan Niethe, Kajol Jain, Konrad
    Rzeszutek Wilk, Laurent Dufour, Leonardo Bras, Liu Shixin, Luca
    Ceresoli, Madhavan Srinivasan, Mahesh Salgaonkar, Nathan Lynch, Nicholas
    Mc Guire, Nicholas Piggin, Nick Desaulniers, Oliver O'Halloran, Pedro
    Miraglia Franco de Carvalho, Pratik Rajesh Sampat, Qian Cai, Qinglang
    Miao, Ravi Bangoria, Russell Currey, Satheesh Rajendran, Scott Cheloha,
    Segher Boessenkool, Srikar Dronamraju, Stan Johnson, Stephen Kitt,
    Stephen Rothwell, Thiago Jung Bauermann, Tyrel Datwyler, Vaibhav Jain,
    Vaidyanathan Srinivasan, Vasant Hegde, Wang Wensheng, Wolfram Sang, Yang
    Yingliang, zhengbin.

    * tag 'powerpc-5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (228 commits)
    Revert "powerpc/pci: unmap legacy INTx interrupts when a PHB is removed"
    selftests/powerpc: Fix eeh-basic.sh exit codes
    cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_reboot_notifier
    powerpc/time: Make get_tb() common to PPC32 and PPC64
    powerpc/time: Make get_tbl() common to PPC32 and PPC64
    powerpc/time: Remove get_tbu()
    powerpc/time: Avoid using get_tbl() and get_tbu() internally
    powerpc/time: Make mftb() common to PPC32 and PPC64
    powerpc/time: Rename mftbl() to mftb()
    powerpc/32s: Remove #ifdef CONFIG_PPC_BOOK3S_32 in head_book3s_32.S
    powerpc/32s: Rename head_32.S to head_book3s_32.S
    powerpc/32s: Setup the early hash table at all time.
    powerpc/time: Remove ifdef in get_dec() and set_dec()
    powerpc: Remove get_tb_or_rtc()
    powerpc: Remove __USE_RTC()
    powerpc: Tidy up a bit after removal of PowerPC 601.
    powerpc: Remove support for PowerPC 601
    powerpc: Remove PowerPC 601
    powerpc: Drop SYNC_601() ISYNC_601() and SYNC()
    powerpc: Remove CONFIG_PPC601_SYNC_FIX
    ...

    Linus Torvalds
     

16 Oct, 2020

1 commit

  • Pull dma-mapping updates from Christoph Hellwig:

    - rework the non-coherent DMA allocator

    - move private definitions out of

    - lower CMA_ALIGNMENT (Paul Cercueil)

    - remove the omap1 dma address translation in favor of the common code

    - make dma-direct aware of multiple dma offset ranges (Jim Quinlan)

    - support per-node DMA CMA areas (Barry Song)

    - increase the default seg boundary limit (Nicolin Chen)

    - misc fixes (Robin Murphy, Thomas Tai, Xu Wang)

    - various cleanups

    * tag 'dma-mapping-5.10' of git://git.infradead.org/users/hch/dma-mapping: (63 commits)
    ARM/ixp4xx: add a missing include of dma-map-ops.h
    dma-direct: simplify the DMA_ATTR_NO_KERNEL_MAPPING handling
    dma-direct: factor out a dma_direct_alloc_from_pool helper
    dma-direct check for highmem pages in dma_direct_alloc_pages
    dma-mapping: merge into
    dma-mapping: move large parts of to kernel/dma
    dma-mapping: move dma-debug.h to kernel/dma/
    dma-mapping: remove
    dma-mapping: merge into
    dma-contiguous: remove dma_contiguous_set_default
    dma-contiguous: remove dev_set_cma_area
    dma-contiguous: remove dma_declare_contiguous
    dma-mapping: split
    cma: decrease CMA_ALIGNMENT lower limit to 2
    firewire-ohci: use dma_alloc_pages
    dma-iommu: implement ->alloc_noncoherent
    dma-mapping: add new {alloc,free}_noncoherent dma_map_ops methods
    dma-mapping: add a new dma_alloc_pages API
    dma-mapping: remove dma_cache_sync
    53c700: convert to dma_alloc_noncoherent
    ...

    Linus Torvalds
     

15 Oct, 2020

1 commit

  • Pull kernel_clone() updates from Christian Brauner:
    "During the v5.9 merge window we reworked the process creation
    codepaths across multiple architectures. After this work we were only
    left with the _do_fork() helper based on the struct kernel_clone_args
    calling convention. As was pointed out _do_fork() isn't valid
    kernelese especially for a helper that isn't just static.

    This series removes the _do_fork() helper and introduces the new
    kernel_clone() helper. The process creation cleanup didn't change the
    name to something more reasonable mainly because _do_fork() was used
    in quite a few places. So sending this as a separate series seemed the
    better strategy.

    I originally intended to send this early in the v5.9 development cycle
    after the merge window had closed but given that this was touching
    quite a few places I decided to defer this until the v5.10 merge
    window"

    * tag 'kernel-clone-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
    sched: remove _do_fork()
    tracing: switch to kernel_clone()
    kgdbts: switch to kernel_clone()
    kprobes: switch to kernel_clone()
    x86: switch to kernel_clone()
    sparc: switch to kernel_clone()
    nios2: switch to kernel_clone()
    m68k: switch to kernel_clone()
    ia64: switch to kernel_clone()
    h8300: switch to kernel_clone()
    fork: introduce kernel_clone()

    Linus Torvalds
     

13 Oct, 2020

4 commits

  • Pull compat mount cleanups from Al Viro:
    "The last remnants of mount(2) compat buried by Christoph.

    Buried into NFS, that is.

    Generally I'm less enthusiastic about "let's use in_compat_syscall()
    deep in call chain" kind of approach than Christoph seems to be, but
    in this case it's warranted - that had been an NFS-specific wart,
    hopefully not to be repeated in any other filesystems (read: any new
    filesystem introducing non-text mount options will get NAKed even if
    it doesn't mess the layout up).

    IOW, not worth trying to grow an infrastructure that would avoid that
    use of in_compat_syscall()..."

    * 'compat.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
    fs: remove compat_sys_mount
    fs,nfs: lift compat nfs4 mount data handling into the nfs code
    nfs: simplify nfs4_parse_monolithic

    Linus Torvalds
     
  • Pull compat iovec cleanups from Al Viro:
    "Christoph's series around import_iovec() and compat variant thereof"

    * 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
    security/keys: remove compat_keyctl_instantiate_key_iov
    mm: remove compat_process_vm_{readv,writev}
    fs: remove compat_sys_vmsplice
    fs: remove the compat readv/writev syscalls
    fs: remove various compat readv/writev helpers
    iov_iter: transparently handle compat iovecs in import_iovec
    iov_iter: refactor rw_copy_check_uvector and import_iovec
    iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c
    compat.h: fix a spelling error in

    Linus Torvalds
     
  • Pull perf/kprobes updates from Ingo Molnar:
    "This prepares to unify the kretprobe trampoline handler and make
    kretprobe lockless (those patches are still work in progress)"

    * tag 'perf-kprobes-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
    kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()
    kprobes: Make local functions static
    kprobes: Free kretprobe_instance with RCU callback
    kprobes: Remove NMI context check
    sparc: kprobes: Use generic kretprobe trampoline handler
    sh: kprobes: Use generic kretprobe trampoline handler
    s390: kprobes: Use generic kretprobe trampoline handler
    powerpc: kprobes: Use generic kretprobe trampoline handler
    parisc: kprobes: Use generic kretprobe trampoline handler
    mips: kprobes: Use generic kretprobe trampoline handler
    ia64: kprobes: Use generic kretprobe trampoline handler
    csky: kprobes: Use generic kretprobe trampoline handler
    arc: kprobes: Use generic kretprobe trampoline handler
    arm64: kprobes: Use generic kretprobe trampoline handler
    arm: kprobes: Use generic kretprobe trampoline handler
    x86/kprobes: Use generic kretprobe trampoline handler
    kprobes: Add generic kretprobe trampoline handler

    Linus Torvalds
     
  • Pull orphan section checking from Ingo Molnar:
    "Orphan link sections were a long-standing source of obscure bugs,
    because the heuristics that various linkers & compilers use to handle
    them (include these bits into the output image vs discarding them
    silently) are both highly idiosyncratic and also version dependent.

    Instead of this historically problematic mess, this tree by Kees Cook
    (et al) adds build time asserts and build time warnings if there's any
    orphan section in the kernel or if a section is not sized as expected.

    And because we relied on so many silent assumptions in this area, fix
    a metric ton of dependencies and some outright bugs related to this,
    before we can finally enable the checks on the x86, ARM and ARM64
    platforms"

    * tag 'core-build-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
    x86/boot/compressed: Warn on orphan section placement
    x86/build: Warn on orphan section placement
    arm/boot: Warn on orphan section placement
    arm/build: Warn on orphan section placement
    arm64/build: Warn on orphan section placement
    x86/boot/compressed: Add missing debugging sections to output
    x86/boot/compressed: Remove, discard, or assert for unwanted sections
    x86/boot/compressed: Reorganize zero-size section asserts
    x86/build: Add asserts for unwanted sections
    x86/build: Enforce an empty .got.plt section
    x86/asm: Avoid generating unused kprobe sections
    arm/boot: Handle all sections explicitly
    arm/build: Assert for unwanted sections
    arm/build: Add missing sections
    arm/build: Explicitly keep .ARM.attributes sections
    arm/build: Refactor linker script headers
    arm64/build: Assert for unwanted sections
    arm64/build: Add missing DWARF sections
    arm64/build: Use common DISCARDS in linker script
    arm64/build: Remove .eh_frame* sections due to unwind tables
    ...

    Linus Torvalds
     

06 Oct, 2020

2 commits


03 Oct, 2020

3 commits


23 Sep, 2020

1 commit


16 Sep, 2020

1 commit

  • The de facto (and apparently uncommented) standard for using an mm had,
    thanks to this code in sparc if nothing else, been that you must have a
    reference on mm_users *and that reference must have been obtained with
    mmget()*, i.e., from a thread with a reference to mm_users that had used
    the mm.

    The introduction of mmget_not_zero() in commit d2005e3f41d4
    ("userfaultfd: don't pin the user memory in userfaultfd_file_create()")
    allowed mm_count holders to aoperate on user mappings asynchronously
    from the actual threads using the mm, but they were not to load those
    mappings into their TLB (i.e., walking vmas and page tables is okay,
    kthread_use_mm() is not).

    io_uring 2b188cc1bb857 ("Add io_uring IO interface") added code which
    does a kthread_use_mm() from a mmget_not_zero() refcount.

    The problem with this is code which previously assumed mm == current->mm
    and mm->mm_users == 1 implies the mm will remain single-threaded at
    least until this thread creates another mm_users reference, has now
    broken.

    arch/sparc/kernel/smp_64.c:

    if (atomic_read(&mm->mm_users) == 1) {
    cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
    goto local_flush_and_out;
    }

    vs fs/io_uring.c

    if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) ||
    !mmget_not_zero(ctx->sqo_mm)))
    return -EFAULT;
    kthread_use_mm(ctx->sqo_mm);

    mmget_not_zero() could come in right after the mm_users == 1 test, then
    kthread_use_mm() which sets its CPU in the mm_cpumask. That update could
    be lost if cpumask_copy() occurs afterward.

    I propose we fix this by allowing mmget_not_zero() to be a first-class
    reference, and not have this obscure undocumented and unchecked
    restriction.

    The basic fix for sparc64 is to remove its mm_cpumask clearing code. The
    optimisation could be effectively restored by sending IPIs to mm_cpumask
    members and having them remove themselves from mm_cpumask. This is more
    tricky so I leave it as an exercise for someone with a sparc64 SMP.
    powerpc has a (currently similarly broken) example.

    Signed-off-by: Nicholas Piggin
    Acked-by: David S. Miller
    Signed-off-by: Michael Ellerman
    Link: https://lore.kernel.org/r/20200914045219.3736466-4-npiggin@gmail.com

    Nicholas Piggin
     

08 Sep, 2020

1 commit


04 Sep, 2020

1 commit

  • We found that callers of dma_get_seg_boundary mostly do an ALIGN
    with page mask and then do a page shift to get number of pages:
    ALIGN(boundary + 1, 1 << shift) >> shift

    However, the boundary might be as large as ULONG_MAX, which means
    that a device has no specific boundary limit. So either "+ 1" or
    passing it to ALIGN() would potentially overflow.

    According to kernel defines:
    #define ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
    #define ALIGN(x, a) ALIGN_MASK(x, (typeof(x))(a) - 1)

    We can simplify the logic here into a helper function doing:
    ALIGN(boundary + 1, 1 << shift) >> shift
    = ALIGN_MASK(b + 1, (1 << s) - 1) >> s
    = {[b + 1 + (1 << s) - 1] & ~[(1 << s) - 1]} >> s
    = [b + 1 + (1 << s) - 1] >> s
    = [b + (1 << s)] >> s
    = (b >> s) + 1

    This patch introduces and applies dma_get_seg_boundary_nr_pages()
    as an overflow-free helper for the dma_get_seg_boundary() callers
    to get numbers of pages. It also takes care of the NULL dev case
    for non-DMA API callers.

    Suggested-by: Christoph Hellwig
    Signed-off-by: Nicolin Chen
    Acked-by: Niklas Schnelle
    Acked-by: Michael Ellerman (powerpc)
    Signed-off-by: Christoph Hellwig

    Nicolin Chen
     

01 Sep, 2020

1 commit

  • The .comment section doesn't belong in STABS_DEBUG. Split it out into a
    new macro named ELF_DETAILS. This will gain other non-debug sections
    that need to be accounted for when linking with --orphan-handling=warn.

    Signed-off-by: Kees Cook
    Signed-off-by: Ingo Molnar
    Cc: linux-arch@vger.kernel.org
    Link: https://lore.kernel.org/r/20200821194310.3089815-5-keescook@chromium.org

    Kees Cook
     

24 Aug, 2020

1 commit

  • Replace the existing /* fall through */ comments and its variants with
    the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
    fall-through markings when it is the case.

    [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

    Signed-off-by: Gustavo A. R. Silva

    Gustavo A. R. Silva
     

20 Aug, 2020

1 commit

  • The old _do_fork() helper is removed in favor of the new kernel_clone() helper.
    The latter adheres to naming conventions for kernel internal syscall helpers.

    Signed-off-by: Christian Brauner
    Acked-by: David S. Miller
    Cc: "David S. Miller"
    Cc: sparclinux@vger.kernel.org
    Link: https://lore.kernel.org/r/20200819104655.436656-7-christian.brauner@ubuntu.com

    Christian Brauner
     

15 Aug, 2020

1 commit

  • Since commit 61a47c1ad3a4dc ("sysctl: Remove the sysctl system call"),
    sys_sysctl is actually unavailable: any input can only return an error.

    We have been warning about people using the sysctl system call for years
    and believe there are no more users. Even if there are users of this
    interface if they have not complained or fixed their code by now they
    probably are not going to, so there is no point in warning them any
    longer.

    So completely remove sys_sysctl on all architectures.

    [nixiaoming@huawei.com: s390: fix build error for sys_call_table_emu]
    Link: http://lkml.kernel.org/r/20200618141426.16884-1-nixiaoming@huawei.com

    Signed-off-by: Xiaoming Ni
    Signed-off-by: Andrew Morton
    Acked-by: Will Deacon [arm/arm64]
    Acked-by: "Eric W. Biederman"
    Cc: Aleksa Sarai
    Cc: Alexander Shishkin
    Cc: Al Viro
    Cc: Andi Kleen
    Cc: Andrew Morton
    Cc: Andy Lutomirski
    Cc: Arnaldo Carvalho de Melo
    Cc: Arnd Bergmann
    Cc: Benjamin Herrenschmidt
    Cc: Bin Meng
    Cc: Borislav Petkov
    Cc: Brian Gerst
    Cc: Catalin Marinas
    Cc: chenzefeng
    Cc: Christian Borntraeger
    Cc: Christian Brauner
    Cc: Chris Zankel
    Cc: David Howells
    Cc: David S. Miller
    Cc: Diego Elio Pettenò
    Cc: Dmitry Vyukov
    Cc: Dominik Brodowski
    Cc: Fenghua Yu
    Cc: Geert Uytterhoeven
    Cc: Heiko Carstens
    Cc: Helge Deller
    Cc: "H. Peter Anvin"
    Cc: Ingo Molnar
    Cc: Iurii Zaikin
    Cc: Ivan Kokshaysky
    Cc: James Bottomley
    Cc: Jens Axboe
    Cc: Jiri Olsa
    Cc: Kars de Jong
    Cc: Kees Cook
    Cc: Krzysztof Kozlowski
    Cc: Luis Chamberlain
    Cc: Marco Elver
    Cc: Mark Rutland
    Cc: Martin K. Petersen
    Cc: Masahiro Yamada
    Cc: Matt Turner
    Cc: Max Filippov
    Cc: Michael Ellerman
    Cc: Michal Simek
    Cc: Miklos Szeredi
    Cc: Minchan Kim
    Cc: Namhyung Kim
    Cc: Naveen N. Rao
    Cc: Nick Piggin
    Cc: Oleg Nesterov
    Cc: Olof Johansson
    Cc: Paul Burton
    Cc: "Paul E. McKenney"
    Cc: Paul Mackerras
    Cc: Peter Zijlstra (Intel)
    Cc: Randy Dunlap
    Cc: Ravi Bangoria
    Cc: Richard Henderson
    Cc: Rich Felker
    Cc: Russell King
    Cc: Sami Tolvanen
    Cc: Sargun Dhillon
    Cc: Stephen Rothwell
    Cc: Sudeep Holla
    Cc: Sven Schnelle
    Cc: Thiago Jung Bauermann
    Cc: Thomas Bogendoerfer
    Cc: Thomas Gleixner
    Cc: Tony Luck
    Cc: Vasily Gorbik
    Cc: Vlastimil Babka
    Cc: Yoshinori Sato
    Cc: Zhou Yanjie
    Link: http://lkml.kernel.org/r/20200616030734.87257-1-nixiaoming@huawei.com
    Signed-off-by: Linus Torvalds

    Xiaoming Ni
     

11 Aug, 2020

1 commit

  • Pull locking updates from Thomas Gleixner:
    "A set of locking fixes and updates:

    - Untangle the header spaghetti which causes build failures in
    various situations caused by the lockdep additions to seqcount to
    validate that the write side critical sections are non-preemptible.

    - The seqcount associated lock debug addons which were blocked by the
    above fallout.

    seqcount writers contrary to seqlock writers must be externally
    serialized, which usually happens via locking - except for strict
    per CPU seqcounts. As the lock is not part of the seqcount, lockdep
    cannot validate that the lock is held.

    This new debug mechanism adds the concept of associated locks.
    sequence count has now lock type variants and corresponding
    initializers which take a pointer to the associated lock used for
    writer serialization. If lockdep is enabled the pointer is stored
    and write_seqcount_begin() has a lockdep assertion to validate that
    the lock is held.

    Aside of the type and the initializer no other code changes are
    required at the seqcount usage sites. The rest of the seqcount API
    is unchanged and determines the type at compile time with the help
    of _Generic which is possible now that the minimal GCC version has
    been moved up.

    Adding this lockdep coverage unearthed a handful of seqcount bugs
    which have been addressed already independent of this.

    While generally useful this comes with a Trojan Horse twist: On RT
    kernels the write side critical section can become preemtible if
    the writers are serialized by an associated lock, which leads to
    the well known reader preempts writer livelock. RT prevents this by
    storing the associated lock pointer independent of lockdep in the
    seqcount and changing the reader side to block on the lock when a
    reader detects that a writer is in the write side critical section.

    - Conversion of seqcount usage sites to associated types and
    initializers"

    * tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
    locking/seqlock, headers: Untangle the spaghetti monster
    locking, arch/ia64: Reduce header dependencies by moving XTP bits into the new header
    x86/headers: Remove APIC headers from
    seqcount: More consistent seqprop names
    seqcount: Compress SEQCNT_LOCKNAME_ZERO()
    seqlock: Fold seqcount_LOCKNAME_init() definition
    seqlock: Fold seqcount_LOCKNAME_t definition
    seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g
    hrtimer: Use sequence counter with associated raw spinlock
    kvm/eventfd: Use sequence counter with associated spinlock
    userfaultfd: Use sequence counter with associated spinlock
    NFSv4: Use sequence counter with associated spinlock
    iocost: Use sequence counter with associated spinlock
    raid5: Use sequence counter with associated spinlock
    vfs: Use sequence counter with associated spinlock
    timekeeping: Use sequence counter with associated raw spinlock
    xfrm: policy: Use sequence counters with associated lock
    netfilter: nft_set_rbtree: Use sequence counter with associated rwlock
    netfilter: conntrack: Use sequence counter with associated spinlock
    sched: tasks: Use sequence counter with associated spinlock
    ...

    Linus Torvalds
     

10 Aug, 2020

1 commit

  • Pull regset conversion fix from Al Viro:
    "Fix a regression from an unnoticed bisect hazard in the regset series.

    A bunch of old (aout, originally) primitives used by coredumps became
    dead code after fdpic conversion to regsets. Removal of that dead code
    had been the first commit in the followups to regset series;
    unfortunately, it happened to hide the bisect hazard on sh (extern for
    fpregs_get() had not been updated in the main series when it should
    have been; followup simply made fpregs_get() static). And without that
    followup commit this bisect hazard became breakage in the mainline"

    Tested-by: John Paul Adrian Glaubitz

    * 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
    kill unused dump_fpu() instances

    Linus Torvalds
     

08 Aug, 2020

4 commits

  • Merge misc updates from Andrew Morton:

    - a few MM hotfixes

    - kthread, tools, scripts, ntfs and ocfs2

    - some of MM

    Subsystems affected by this patch series: kthread, tools, scripts, ntfs,
    ocfs2 and mm (hofixes, pagealloc, slab-generic, slab, slub, kcsan,
    debug, pagecache, gup, swap, shmem, memcg, pagemap, mremap, mincore,
    sparsemem, vmalloc, kasan, pagealloc, hugetlb and vmscan).

    * emailed patches from Andrew Morton : (162 commits)
    mm: vmscan: consistent update to pgrefill
    mm/vmscan.c: fix typo
    khugepaged: khugepaged_test_exit() check mmget_still_valid()
    khugepaged: retract_page_tables() remember to test exit
    khugepaged: collapse_pte_mapped_thp() protect the pmd lock
    khugepaged: collapse_pte_mapped_thp() flush the right range
    mm/hugetlb: fix calculation of adjust_range_if_pmd_sharing_possible
    mm: thp: replace HTTP links with HTTPS ones
    mm/page_alloc: fix memalloc_nocma_{save/restore} APIs
    mm/page_alloc.c: skip setting nodemask when we are in interrupt
    mm/page_alloc: fallbacks at most has 3 elements
    mm/page_alloc: silence a KASAN false positive
    mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask()
    mm/page_alloc.c: simplify pageblock bitmap access
    mm/page_alloc.c: extract the common part in pfn_to_bitidx()
    mm/page_alloc.c: replace the definition of NR_MIGRATETYPE_BITS with PB_migratetype_bits
    mm/shuffle: remove dynamic reconfiguration
    mm/memory_hotplug: document why shuffle_zone() is relevant
    mm/page_alloc: remove nr_free_pagecache_pages()
    mm: remove vm_total_pages
    ...

    Linus Torvalds
     
  • Patch series "mm: cleanup usage of "

    Most architectures have very similar versions of pXd_alloc_one() and
    pXd_free_one() for intermediate levels of page table. These patches add
    generic versions of these functions in and enable
    use of the generic functions where appropriate.

    In addition, functions declared and defined in headers are
    used mostly by core mm and early mm initialization in arch and there is no
    actual reason to have the included all over the place.
    The first patch in this series removes unneeded includes of

    In the end it didn't work out as neatly as I hoped and moving
    pXd_alloc_track() definitions to would require
    unnecessary changes to arches that have custom page table allocations, so
    I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local
    to mm/.

    This patch (of 8):

    In most cases header is required only for allocations of
    page table memory. Most of the .c files that include that header do not
    use symbols declared in and do not require that header.

    As for the other header files that used to include , it is
    possible to move that include into the .c file that actually uses symbols
    from and drop the include from the header file.

    The process was somewhat automated using

    sed -i -E '/[
    Signed-off-by: Andrew Morton
    Reviewed-by: Pekka Enberg
    Acked-by: Geert Uytterhoeven [m68k]
    Cc: Abdul Haleem
    Cc: Andy Lutomirski
    Cc: Arnd Bergmann
    Cc: Christophe Leroy
    Cc: Joerg Roedel
    Cc: Max Filippov
    Cc: Peter Zijlstra
    Cc: Satheesh Rajendran
    Cc: Stafford Horne
    Cc: Stephen Rothwell
    Cc: Steven Rostedt
    Cc: Joerg Roedel
    Cc: Matthew Wilcox
    Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org
    Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org
    Signed-off-by: Linus Torvalds

    Mike Rapoport
     
  • Pull init and set_fs() cleanups from Al Viro:
    "Christoph's 'getting rid of ksys_...() uses under KERNEL_DS' series"

    * 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (50 commits)
    init: add an init_dup helper
    init: add an init_utimes helper
    init: add an init_stat helper
    init: add an init_mknod helper
    init: add an init_mkdir helper
    init: add an init_symlink helper
    init: add an init_link helper
    init: add an init_eaccess helper
    init: add an init_chmod helper
    init: add an init_chown helper
    init: add an init_chroot helper
    init: add an init_chdir helper
    init: add an init_rmdir helper
    init: add an init_unlink helper
    init: add an init_umount helper
    init: add an init_mount helper
    init: mark create_dev as __init
    init: mark console_on_rootfs as __init
    init: initialize ramdisk_execute_command at compile time
    devtmpfs: refactor devtmpfsd()
    ...

    Linus Torvalds
     
  • Pull ptrace regset updates from Al Viro:
    "Internal regset API changes:

    - regularize copy_regset_{to,from}_user() callers

    - switch to saner calling conventions for ->get()

    - kill user_regset_copyout()

    The ->put() side of things will have to wait for the next cycle,
    unfortunately.

    The balance is about -1KLoC and replacements for ->get() instances are
    a lot saner"

    * 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
    regset: kill user_regset_copyout{,_zero}()
    regset(): kill ->get_size()
    regset: kill ->get()
    csky: switch to ->regset_get()
    xtensa: switch to ->regset_get()
    parisc: switch to ->regset_get()
    nds32: switch to ->regset_get()
    nios2: switch to ->regset_get()
    hexagon: switch to ->regset_get()
    h8300: switch to ->regset_get()
    openrisc: switch to ->regset_get()
    riscv: switch to ->regset_get()
    c6x: switch to ->regset_get()
    ia64: switch to ->regset_get()
    arc: switch to ->regset_get()
    arm: switch to ->regset_get()
    sh: convert to ->regset_get()
    arm64: switch to ->regset_get()
    mips: switch to ->regset_get()
    sparc: switch to ->regset_get()
    ...

    Linus Torvalds
     

06 Aug, 2020

2 commits

  • By using lockdep_assert_*() from seqlock.h, the spaghetti monster
    attacked.

    Attack back by reducing seqlock.h dependencies from two key high level headers:

    - : -Remove
    - : -Remove
    - : +Add

    The price was to add it to sched.h ...

    Core header fallout, we add direct header dependencies instead of gaining them
    parasitically from higher level headers:

    - : +Add
    - : +Add
    - : +Add
    - : +Add
    - : +Add
    - : +Add

    Arch headers fallout:

    - PARISC: : +Add
    - SH: : +Add
    - SPARC: : +Add
    - SPARC: : +Add ,
    -Remove
    - X86: : +Add
    -Remove

    There's also a bunch of parasitic header dependency fallout in .c files, not listed
    separately.

    [ mingo: Extended the changelog, split up & fixed the original patch. ]

    Co-developed-by: Ingo Molnar
    Signed-off-by: Peter Zijlstra (Intel)
    Signed-off-by: Ingo Molnar
    Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net

    Peter Zijlstra
     
  • Pull networking updates from David Miller:

    1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan.

    2) Support UDP segmentation in code TSO code, from Eric Dumazet.

    3) Allow flashing different flash images in cxgb4 driver, from Vishal
    Kulkarni.

    4) Add drop frames counter and flow status to tc flower offloading,
    from Po Liu.

    5) Support n-tuple filters in cxgb4, from Vishal Kulkarni.

    6) Various new indirect call avoidance, from Eric Dumazet and Brian
    Vazquez.

    7) Fix BPF verifier failures on 32-bit pointer arithmetic, from
    Yonghong Song.

    8) Support querying and setting hardware address of a port function via
    devlink, use this in mlx5, from Parav Pandit.

    9) Support hw ipsec offload on bonding slaves, from Jarod Wilson.

    10) Switch qca8k driver over to phylink, from Jonathan McDowell.

    11) In bpftool, show list of processes holding BPF FD references to
    maps, programs, links, and btf objects. From Andrii Nakryiko.

    12) Several conversions over to generic power management, from Vaibhav
    Gupta.

    13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry
    Yakunin.

    14) Various https url conversions, from Alexander A. Klimov.

    15) Timestamping and PHC support for mscc PHY driver, from Antoine
    Tenart.

    16) Support bpf iterating over tcp and udp sockets, from Yonghong Song.

    17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov.

    18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan.

    19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several
    drivers. From Luc Van Oostenryck.

    20) XDP support for xen-netfront, from Denis Kirjanov.

    21) Support receive buffer autotuning in MPTCP, from Florian Westphal.

    22) Support EF100 chip in sfc driver, from Edward Cree.

    23) Add XDP support to mvpp2 driver, from Matteo Croce.

    24) Support MPTCP in sock_diag, from Paolo Abeni.

    25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic
    infrastructure, from Jakub Kicinski.

    26) Several pci_ --> dma_ API conversions, from Christophe JAILLET.

    27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel.

    28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki.

    29) Refactor a lot of networking socket option handling code in order to
    avoid set_fs() calls, from Christoph Hellwig.

    30) Add rfc4884 support to icmp code, from Willem de Bruijn.

    31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei.

    32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin.

    33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin.

    34) Support TCP syncookies in MPTCP, from Flowian Westphal.

    35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano
    Brivio.

    * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits)
    net: thunderx: initialize VF's mailbox mutex before first usage
    usb: hso: remove bogus check for EINPROGRESS
    usb: hso: no complaint about kmalloc failure
    hso: fix bailout in error case of probe
    ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM
    selftests/net: relax cpu affinity requirement in msg_zerocopy test
    mptcp: be careful on subflow creation
    selftests: rtnetlink: make kci_test_encap() return sub-test result
    selftests: rtnetlink: correct the final return value for the test
    net: dsa: sja1105: use detected device id instead of DT one on mismatch
    tipc: set ub->ifindex for local ipv6 address
    ipv6: add ipv6_dev_find()
    net: openvswitch: silence suspicious RCU usage warning
    Revert "vxlan: fix tos value before xmit"
    ptp: only allow phase values lower than 1 period
    farsync: switch from 'pci_' to 'dma_' API
    wan: wanxl: switch from 'pci_' to 'dma_' API
    hv_netvsc: do not use VF device if link is down
    dpaa2-eth: Fix passing zero to 'PTR_ERR' warning
    net: macb: Properly handle phylink on at91sam9x
    ...

    Linus Torvalds
     

05 Aug, 2020

1 commit

  • Pull close_range() implementation from Christian Brauner:
    "This adds the close_range() syscall. It allows to efficiently close a
    range of file descriptors up to all file descriptors of a calling
    task.

    This is coordinated with the FreeBSD folks which have copied our
    version of this syscall and in the meantime have already merged it in
    April 2019:

    https://reviews.freebsd.org/D21627
    https://svnweb.freebsd.org/base?view=revision&revision=359836

    The syscall originally came up in a discussion around the new mount
    API and making new file descriptor types cloexec by default. During
    this discussion, Al suggested the close_range() syscall.

    First, it helps to close all file descriptors of an exec()ing task.
    This can be done safely via (quoting Al's example from [1] verbatim):

    /* that exec is sensitive */
    unshare(CLONE_FILES);
    /* we don't want anything past stderr here */
    close_range(3, ~0U);
    execve(....);

    The code snippet above is one way of working around the problem that
    file descriptors are not cloexec by default. This is aggravated by the
    fact that we can't just switch them over without massively regressing
    userspace. For a whole class of programs having an in-kernel method of
    closing all file descriptors is very helpful (e.g. demons, service
    managers, programming language standard libraries, container managers
    etc.).

    Second, it allows userspace to avoid implementing closing all file
    descriptors by parsing through /proc//fd/* and calling close() on
    each file descriptor and other hacks. From looking at various
    large(ish) userspace code bases this or similar patterns are very
    common in service managers, container runtimes, and programming
    language runtimes/standard libraries such as Python or Rust.

    In addition, the syscall will also work for tasks that do not have
    procfs mounted and on kernels that do not have procfs support compiled
    in. In such situations the only way to make sure that all file
    descriptors are closed is to call close() on each file descriptor up
    to UINT_MAX or RLIMIT_NOFILE, OPEN_MAX trickery.

    Based on Linus' suggestion close_range() also comes with a new flag
    CLOSE_RANGE_UNSHARE to more elegantly handle file descriptor dropping
    right before exec. This would usually be expressed in the sequence:

    unshare(CLONE_FILES);
    close_range(3, ~0U);

    as pointed out by Linus it might be desirable to have this be a part
    of close_range() itself under a new flag CLOSE_RANGE_UNSHARE which
    gets especially handy when we're closing all file descriptors above a
    certain threshold.

    Test-suite as always included"

    * tag 'close-range-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
    tests: add CLOSE_RANGE_UNSHARE tests
    close_range: add CLOSE_RANGE_UNSHARE
    tests: add close_range() tests
    arch: wire-up close_range()
    open: add close_range()

    Linus Torvalds
     

30 Jul, 2020

1 commit


28 Jul, 2020

2 commits


27 Jul, 2020

2 commits


20 Jul, 2020

1 commit

  • Now that the ->compat_{get,set}sockopt proto_ops methods are gone
    there is no good reason left to keep the compat syscalls separate.

    This fixes the odd use of unsigned int for the compat_setsockopt
    optlen and the missing sock_use_custom_sol_socket.

    It would also easily allow running the eBPF hooks for the compat
    syscalls, but such a large change in behavior does not belong into
    a consolidation patch like this one.

    Signed-off-by: Christoph Hellwig
    Signed-off-by: David S. Miller

    Christoph Hellwig