linux/Documentation/admin-guide/kernel-parameters.txt, branch v5.8

Merge branch 'x86/srbds' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-06-09T16:30:21Z

Pull x86 srbds fixes from Thomas Gleixner: "The 9th episode of the dime novel "The performance killer" with the subtitle "Slow Randomizing Boosts Denial of Service". SRBDS is an MDS-like speculative side channel that can leak bits from the random number generator (RNG) across cores and threads. New microcode serializes the processor access during the execution of RDRAND and RDSEED. This ensures that the shared buffer is overwritten before it is released for reuse. This is equivalent to a full bus lock, which means that many threads running the RNG instructions in parallel have the same effect as the same amount of threads issuing a locked instruction targeting an address which requires locking of two cachelines at once. The mitigation support comes with the usual pile of unpleasant ingredients: - command line options - sysfs file - microcode checks - a list of vulnerable CPUs identified by model and stepping this time which requires stepping match support for the cpu match logic. - the inevitable slowdown of affected CPUs" * branch 'x86/srbds' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/speculation: Add Ivy Bridge to affected list x86/speculation: Add SRBDS vulnerability and mitigation documentation x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation x86/cpu: Add 'table' argument to cpu_matches()

Merge tag 's390-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2020-06-08T19:05:31Z

Pull s390 updates from Vasily Gorbik: - Add support for multi-function devices in pci code. - Enable PF-VF linking for architectures using the pdev->no_vf_scan flag (currently just s390). - Add reipl from NVMe support. - Get rid of critical section cleanup in entry.S. - Refactor PNSO CHSC (perform network subchannel operation) in cio and qeth. - QDIO interrupts and error handling fixes and improvements, more refactoring changes. - Align ioremap() with generic code. - Accept requests without the prefetch bit set in vfio-ccw. - Enable path handling via two new regions in vfio-ccw. - Other small fixes and improvements all over the code. * tag 's390-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (52 commits) vfio-ccw: make vfio_ccw_regops variables declarations static vfio-ccw: Add trace for CRW event vfio-ccw: Wire up the CRW irq and CRW region vfio-ccw: Introduce a new CRW region vfio-ccw: Refactor IRQ handlers vfio-ccw: Introduce a new schib region vfio-ccw: Refactor the unregister of the async regions vfio-ccw: Register a chp_event callback for vfio-ccw vfio-ccw: Introduce new helper functions to free/destroy regions vfio-ccw: document possible errors vfio-ccw: Enable transparent CCW IPL from DASD s390/pci: Log new handle in clp_disable_fh() s390/cio, s390/qeth: cleanup PNSO CHSC s390/qdio: remove q->first_to_kick s390/qdio: fix up qdio_start_irq() kerneldoc s390: remove critical section cleanup from entry.S s390: add machine check SIGP s390/pci: ioremap() align with generic code s390/ap: introduce new ap function ap_get_qdev() Documentation/s390: Update / remove developerWorks web links ...

kernel/watchdog.c: convert {soft/hard}lockup boot parameters to sysctl aliases

2020-06-08T18:05:56Z

After a recent change introduced by Vlastimil's series [0], kernel is able now to handle sysctl parameters on kernel command line; also, the series introduced a simple infrastructure to convert legacy boot parameters (that duplicate sysctls) into sysctl aliases. This patch converts the watchdog parameters softlockup_panic and {hard,soft}lockup_all_cpu_backtrace to use the new alias infrastructure. It fixes the documentation too, since the alias only accepts values 0 or 1, not the full range of integers. We also took the opportunity here to improve the documentation of the previously converted hung_task_panic (see the patch series [0]) and put the alias table in alphabetical order. [0] http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Signed-off-by: Guilherme G. Piccoli Signed-off-by: Andrew Morton Acked-by: Vlastimil Babka Cc: Kees Cook Cc: Iurii Zaikin Cc: Luis Chamberlain Link: http://lkml.kernel.org/r/20200507214624.21911-1-gpiccoli@canonical.com Signed-off-by: Linus Torvalds

kernel/hung_task convert hung_task_panic boot parameter to sysctl

2020-06-08T18:05:56Z

We can now handle sysctl parameters on kernel command line and have infrastructure to convert legacy command line options that duplicate sysctl to become a sysctl alias. This patch converts the hung_task_panic parameter. Note that the sysctl handler is more strict and allows only 0 and 1, while the legacy parameter allowed any non-zero value. But there is little reason anyone would not be using 1. Signed-off-by: Vlastimil Babka Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Acked-by: Michal Hocko Cc: Alexey Dobriyan Cc: Christian Brauner Cc: David Rientjes Cc: "Eric W . Biederman" Cc: Greg Kroah-Hartman Cc: "Guilherme G . Piccoli" Cc: Iurii Zaikin Cc: Ivan Teterevkov Cc: Luis Chamberlain Cc: Masami Hiramatsu Cc: Matthew Wilcox Cc: Michal Hocko Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20200427180433.7029-4-vbabka@suse.cz Signed-off-by: Linus Torvalds

kernel/sysctl: support setting sysctl parameters from kernel command line

2020-06-08T18:05:56Z

Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka Signed-off-by: Andrew Morton Reviewed-by: Luis Chamberlain Reviewed-by: Masami Hiramatsu Acked-by: Kees Cook Acked-by: Michal Hocko Cc: Iurii Zaikin Cc: Ivan Teterevkov Cc: Michal Hocko Cc: David Rientjes Cc: Matthew Wilcox Cc: "Eric W . Biederman" Cc: "Guilherme G . Piccoli" Cc: Alexey Dobriyan Cc: Thomas Gleixner Cc: Greg Kroah-Hartman Cc: Christian Brauner Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds

kernel: add panic_on_taint

2020-06-08T18:05:56Z

Analogously to the introduction of panic_on_warn, this patch introduces a kernel option named panic_on_taint in order to provide a simple and generic way to stop execution and catch a coredump when the kernel gets tainted by any given flag. This is useful for debugging sessions as it avoids having to rebuild the kernel to explicitly add calls to panic() into the code sites that introduce the taint flags of interest. For instance, if one is interested in proceeding with a post-mortem analysis at the point a given code path is hitting a bad page (i.e. unaccount_page_cache_page(), or slab_bug()), a coredump can be collected by rebooting the kernel with 'panic_on_taint=0x20' amended to the command line. Another, perhaps less frequent, use for this option would be as a means for assuring a security policy case where only a subset of taints, or no single taint (in paranoid mode), is allowed for the running system. The optional switch 'nousertaint' is handy in this particular scenario, as it will avoid userspace induced crashes by writes to sysctl interface /proc/sys/kernel/tainted causing false positive hits for such policies. [akpm@linux-foundation.org: tweak kernel-parameters.txt wording] Suggested-by: Qian Cai Signed-off-by: Rafael Aquini Signed-off-by: Andrew Morton Reviewed-by: Luis Chamberlain Cc: Dave Young Cc: Baoquan He Cc: Jonathan Corbet Cc: Kees Cook Cc: Randy Dunlap Cc: "Theodore Ts'o" Cc: Adrian Bunk Cc: Greg Kroah-Hartman Cc: Laura Abbott Cc: Jeff Mahoney Cc: Jiri Kosina Cc: Takashi Iwai Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com Signed-off-by: Linus Torvalds

Merge tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2020-06-05T19:39:30Z

Pull powerpc updates from Michael Ellerman: - Support for userspace to send requests directly to the on-chip GZIP accelerator on Power9. - Rework of our lockless page table walking (__find_linux_pte()) to make it safe against parallel page table manipulations without relying on an IPI for serialisation. - A series of fixes & enhancements to make our machine check handling more robust. - Lots of plumbing to add support for "prefixed" (64-bit) instructions on Power10. - Support for using huge pages for the linear mapping on 8xx (32-bit). - Remove obsolete Xilinx PPC405/PPC440 support, and an associated sound driver. - Removal of some obsolete 40x platforms and associated cruft. - Initial support for booting on Power10. - Lots of other small features, cleanups & fixes. Thanks to: Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan, Andrey Abramov, Aneesh Kumar K.V, Balamuruhan S, Bharata B Rao, Bulent Abali, Cédric Le Goater, Chen Zhou, Christian Zigotzky, Christophe JAILLET, Christophe Leroy, Dmitry Torokhov, Emmanuel Nicolet, Erhard F., Gautham R. Shenoy, Geoff Levand, George Spelvin, Greg Kurz, Gustavo A. R. Silva, Gustavo Walbon, Haren Myneni, Hari Bathini, Joel Stanley, Jordan Niethe, Kajol Jain, Kees Cook, Leonardo Bras, Madhavan Srinivasan., Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Michal Simek, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Paul Mackerras, Pingfan Liu, Qian Cai, Ram Pai, Raphael Moreira Zinsly, Ravi Bangoria, Sam Bobroff, Sandipan Das, Segher Boessenkool, Stephen Rothwell, Sukadev Bhattiprolu, Tyrel Datwyler, Wolfram Sang, Xiongfeng Wang. * tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (299 commits) powerpc/pseries: Make vio and ibmebus initcalls pseries specific cxl: Remove dead Kconfig options powerpc: Add POWER10 architected mode powerpc/dt_cpu_ftrs: Add MMA feature powerpc/dt_cpu_ftrs: Enable Prefixed Instructions powerpc/dt_cpu_ftrs: Advertise support for ISA v3.1 if selected powerpc: Add support for ISA v3.1 powerpc: Add new HWCAP bits powerpc/64s: Don't set FSCR bits in INIT_THREAD powerpc/64s: Save FSCR to init_task.thread.fscr after feature init powerpc/64s: Don't let DT CPU features set FSCR_DSCR powerpc/64s: Don't init FSCR_DSCR in __init_FSCR() powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUG powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations powerpc/module_64: Consolidate ftrace code powerpc/32: Disable KASAN with pages bigger than 16k powerpc/uaccess: Don't set KUEP by default on book3s/32 powerpc/uaccess: Don't set KUAP by default on book3s/32 powerpc/8xx: Reduce time spent in allow_user_access() and friends ...

Merge tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

2020-06-04T03:59:38Z

Pull media updates from Mauro Carvalho Chehab: - Media documentation is now split into admin-guide, driver-api and userspace-api books (a longstanding request from Jon); - The media Kconfig was reorganized, in order to make easier to select drivers and their dependencies; - The testing drivers now has a separate directory; - added a new driver for Rockchip Video Decoder IP; - The atomisp staging driver was resurrected. It is meant to work with 4 generations of cameras on Atom-based laptops, tablets and cell phones. So, it seems worth investing time to cleanup this driver and making it in good shape. - Added some V4L2 core ancillary routines to help with h264 codecs; - Added an ov2740 image sensor driver; - The si2157 gained support for Analog TV, which, in turn, added support for some cx231xx and cx23885 boards to also support analog standards; - Added some V4L2 controls (V4L2_CID_CAMERA_ORIENTATION and V4L2_CID_CAMERA_SENSOR_ROTATION) to help identifying where the camera is located at the device; - VIDIOC_ENUM_FMT was extended to support MC-centric devices; - Lots of drivers improvements and cleanups. * tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (503 commits) media: Documentation: media: Refer to mbus format documentation from CSI-2 docs media: s5k5baf: Replace zero-length array with flexible-array media: i2c: imx219: Drop and media: i2c: Add ov2740 image sensor driver media: ov8856: Implement sensor module revision identification media: ov8856: Add devicetree support media: dt-bindings: ov8856: Document YAML bindings media: dvb-usb: Add Cinergy S2 PCIe Dual Port support media: dvbdev: Fix tuner->demod media controller link media: dt-bindings: phy: phy-rockchip-dphy-rx0: move rockchip dphy rx0 bindings out of staging media: staging: dt-bindings: phy-rockchip-dphy-rx0: remove non-used reg property media: atomisp: unify the version for isp2401 a0 and b0 versions media: atomisp: update TODO with the current data media: atomisp: adjust some code at sh_css that could be broken media: atomisp: don't produce errs for ignored IRQs media: atomisp: print IRQ when debugging media: atomisp: isp_mmu: don't use kmem_cache media: atomisp: add a notice about possible leak resources media: atomisp: disable the dynamic and reserved pools media: atomisp: turn on camera before setting it ...

Merge branch 'akpm' (patches from Andrew)

2020-06-04T03:24:15Z

Merge more updates from Andrew Morton: "More mm/ work, plenty more to come Subsystems affected by this patch series: slub, memcg, gup, kasan, pagealloc, hugetlb, vmscan, tools, mempolicy, memblock, hugetlbfs, thp, mmap, kconfig" * akpm: (131 commits) arm64: mm: use ARCH_HAS_DEBUG_WX instead of arch defined x86: mm: use ARCH_HAS_DEBUG_WX instead of arch defined riscv: support DEBUG_WX mm: add DEBUG_WX support drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup mm/thp: rename pmd_mknotpresent() as pmd_mkinvalid() powerpc/mm: drop platform defined pmd_mknotpresent() mm: thp: don't need to drain lru cache when splitting and mlocking THP hugetlbfs: get unmapped area below TASK_UNMAPPED_BASE for hugetlbfs sparc32: register memory occupied by kernel as memblock.memory include/linux/memblock.h: fix minor typo and unclear comment mm, mempolicy: fix up gup usage in lookup_node tools/vm/page_owner_sort.c: filter out unneeded line mm: swap: memcg: fix memcg stats for huge pages mm: swap: fix vmstats for huge pages mm: vmscan: limit the range of LRU type balancing mm: vmscan: reclaim writepage is IO cost mm: vmscan: determine anon/file pressure balance at the reclaim root mm: balance LRU lists based on relative thrashing mm: only count actual rotations as LRU reclaim cost ...

hugetlbfs: clean up command line processing

2020-06-04T03:09:46Z

With all hugetlb page processing done in a single file clean up code. - Make code match desired semantics - Update documentation with semantics - Make all warnings and errors messages start with 'HugeTLB:'. - Consistently name command line parsing routines. - Warn if !hugepages_supported() and command line parameters have been specified. - Add comments to code - Describe some of the subtle interactions - Describe semantics of command line arguments This patch also fixes issues with implicitly setting the number of gigantic huge pages to preallocate. Previously on X86 command line, hugepages=2 default_hugepagesz=1G would result in zero 1G pages being preallocated and, # grep HugePages_Total /proc/meminfo HugePages_Total: 0 # sysctl -a | grep nr_hugepages vm.nr_hugepages = 2 vm.nr_hugepages_mempolicy = 2 # cat /proc/sys/vm/nr_hugepages 2 After this patch 2 gigantic pages will be preallocated and all the proc, sysfs, sysctl and meminfo files will accurately reflect this. To address the issue with gigantic pages, a small change in behavior was made to command line processing. Previously the command line, hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256 would result in the allocation of 256 2M huge pages. The value 128 would be ignored without any warning. After this patch, 128 2M pages will be allocated and a warning message will be displayed indicating the value of 256 is ignored. This change in behavior is required because allocation of implicitly specified gigantic pages must be done when the default_hugepagesz= is encountered for gigantic pages. Previously the code waited until later in the boot process (hugetlb_init), to allocate pages of default size. However the bootmem allocator required for gigantic allocations is not available at this time. Signed-off-by: Mike Kravetz Signed-off-by: Andrew Morton Tested-by: Sandipan Das Acked-by: Gerald Schaefer [s390] Acked-by: Will Deacon Cc: Albert Ou Cc: Benjamin Herrenschmidt Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Dave Hansen Cc: David S. Miller Cc: Heiko Carstens Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Longpeng Cc: Mina Almasry Cc: Nitesh Narayan Lal Cc: Palmer Dabbelt Cc: Paul Mackerras Cc: Paul Walmsley Cc: Peter Xu Cc: Randy Dunlap Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Anders Roxell Cc: "Aneesh Kumar K.V" Cc: Qian Cai Cc: Stephen Rothwell Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com Signed-off-by: Linus Torvalds