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* Merge 4.4.112 into android-4.4Greg Kroah-Hartman2018-01-17
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Changes in 4.4.112 dm bufio: fix shrinker scans when (nr_to_scan < retain_target) KVM: Fix stack-out-of-bounds read in write_mmio can: gs_usb: fix return value of the "set_bittiming" callback IB/srpt: Disable RDMA access by the initiator MIPS: Validate PR_SET_FP_MODE prctl(2) requests against the ABI of the task MIPS: Factor out NT_PRFPREG regset access helpers MIPS: Guard against any partial write attempt with PTRACE_SETREGSET MIPS: Consistently handle buffer counter with PTRACE_SETREGSET MIPS: Fix an FCSR access API regression with NT_PRFPREG and MSA MIPS: Also verify sizeof `elf_fpreg_t' with PTRACE_SETREGSET MIPS: Disallow outsized PTRACE_SETREGSET NT_PRFPREG regset accesses net/mac80211/debugfs.c: prevent build failure with CONFIG_UBSAN=y kvm: vmx: Scrub hardware GPRs at VM-exit x86/vsdo: Fix build on PARAVIRT_CLOCK=y, KVM_GUEST=n x86/acpi: Handle SCI interrupts above legacy space gracefully iommu/arm-smmu-v3: Don't free page table ops twice ALSA: pcm: Remove incorrect snd_BUG_ON() usages ALSA: pcm: Add missing error checks in OSS emulation plugin builder ALSA: pcm: Abort properly at pending signal in OSS read/write loops ALSA: pcm: Allow aborting mutex lock at OSS read/write loops ALSA: aloop: Release cable upon open error path ALSA: aloop: Fix inconsistent format due to incomplete rule ALSA: aloop: Fix racy hw constraints adjustment x86/acpi: Reduce code duplication in mp_override_legacy_irq() mm/compaction: fix invalid free_pfn and compact_cached_free_pfn mm/compaction: pass only pageblock aligned range to pageblock_pfn_to_page mm/page-writeback: fix dirty_ratelimit calculation mm/zswap: use workqueue to destroy pool zswap: don't param_set_charp while holding spinlock locks: don't check for race with close when setting OFD lock futex: Replace barrier() in unqueue_me() with READ_ONCE() locking/mutex: Allow next waiter lockless wakeup usbvision fix overflow of interfaces array usb: musb: ux500: Fix NULL pointer dereference at system PM r8152: fix the wake event r8152: use test_and_clear_bit r8152: adjust ALDPS function lan78xx: use skb_cow_head() to deal with cloned skbs sr9700: use skb_cow_head() to deal with cloned skbs smsc75xx: use skb_cow_head() to deal with cloned skbs cx82310_eth: use skb_cow_head() to deal with cloned skbs x86/mm/pat, /dev/mem: Remove superfluous error message hwrng: core - sleep interruptible in read sysrq: Fix warning in sysrq generated crash. xhci: Fix ring leak in failure path of xhci_alloc_virt_device() Revert "userfaultfd: selftest: vm: allow to build in vm/ directory" x86/pti/efi: broken conversion from efi to kernel page table 8021q: fix a memory leak for VLAN 0 device ip6_tunnel: disable dst caching if tunnel is dual-stack net: core: fix module type in sock_diag_bind RDS: Heap OOB write in rds_message_alloc_sgs() RDS: null pointer dereference in rds_atomic_free_op sh_eth: fix TSU resource handling sh_eth: fix SH7757 GEther initialization net: stmmac: enable EEE in MII, GMII or RGMII only ipv6: fix possible mem leaks in ipv6_make_skb() crypto: algapi - fix NULL dereference in crypto_remove_spawns() rbd: set max_segments to USHRT_MAX x86/microcode/intel: Extend BDW late-loading with a revision check KVM: x86: Add memory barrier on vmcs field lookup drm/vmwgfx: Potential off by one in vmw_view_add() kaiser: Set _PAGE_NX only if supported bpf: add bpf_patch_insn_single helper bpf: don't (ab)use instructions to store state bpf: move fixup_bpf_calls() function bpf: refactor fixup_bpf_calls() bpf: adjust insn_aux_data when patching insns bpf: prevent out-of-bounds speculation bpf, array: fix overflow in max_entries and undefined behavior in index_mask iscsi-target: Make TASK_REASSIGN use proper se_cmd->cmd_kref target: Avoid early CMD_T_PRE_EXECUTE failures during ABORT_TASK USB: serial: cp210x: add IDs for LifeScan OneTouch Verio IQ USB: serial: cp210x: add new device ID ELV ALC 8xxx usb: misc: usb3503: make sure reset is low for at least 100us USB: fix usbmon BUG trigger usbip: remove kernel addresses from usb device and urb debug msgs staging: android: ashmem: fix a race condition in ASHMEM_SET_SIZE ioctl Bluetooth: Prevent stack info leak from the EFS element. uas: ignore UAS for Norelsys NS1068(X) chips e1000e: Fix e1000_check_for_copper_link_ich8lan return value. x86/Documentation: Add PTI description x86/cpu: Factor out application of forced CPU caps x86/cpufeatures: Make CPU bugs sticky x86/cpufeatures: Add X86_BUG_CPU_INSECURE x86/pti: Rename BUG_CPU_INSECURE to BUG_CPU_MELTDOWN x86/cpufeatures: Add X86_BUG_SPECTRE_V[12] x86/cpu: Merge bugs.c and bugs_64.c sysfs/cpu: Add vulnerability folder x86/cpu: Implement CPU vulnerabilites sysfs functions sysfs/cpu: Fix typos in vulnerability documentation x86/alternatives: Fix optimize_nops() checking x86/alternatives: Add missing '\n' at end of ALTERNATIVE inline asm selftests/x86: Add test_vsyscall Linux 4.4.112 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
| * locking/mutex: Allow next waiter lockless wakeupDavidlohr Bueso2018-01-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1329ce6fbbe4536592dfcfc8d64d61bfeb598fe6 upstream. Make use of wake-queues and enable the wakeup to occur after releasing the wait_lock. This is similar to what we do with rtmutex top waiter, slightly shortening the critical region and allow other waiters to acquire the wait_lock sooner. In low contention cases it can also help the recently woken waiter to find the wait_lock available (fastpath) when it continues execution. Reviewed-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ding Tianhong <dingtianhong@huawei.com> Cc: Jason Low <jason.low2@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@us.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Waiman Long <waiman.long@hpe.com> Cc: Will Deacon <Will.Deacon@arm.com> Link: http://lkml.kernel.org/r/20160125022343.GA3322@linux-uzut.site Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | BACKPORT: kernel: add kcov code coverageDmitry Vyukov2017-12-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <dvyukov@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Bug: 64145065 (cherry-picked from 5c9a8750a6409c63a0f01d51a9024861022f6593) Change-Id: I17b5e04f6e89b241924e78ec32ead79c38b860ce Signed-off-by: Paul Lawrence <paullawrence@google.com>
* | Merge 4.4.94 into android-4.4Greg Kroah-Hartman2017-10-22
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Changes in 4.4.94 percpu: make this_cpu_generic_read() atomic w.r.t. interrupts drm/dp/mst: save vcpi with payloads MIPS: Fix minimum alignment requirement of IRQ stack sctp: potential read out of bounds in sctp_ulpevent_type_enabled() bpf/verifier: reject BPF_ALU64|BPF_END udpv6: Fix the checksum computation when HW checksum does not apply ip6_gre: skb_push ipv6hdr before packing the header in ip6gre_header net: emac: Fix napi poll list corruption packet: hold bind lock when rebinding to fanout hook bpf: one perf event close won't free bpf program attached by another perf event isdn/i4l: fetch the ppp_write buffer in one shot vti: fix use after free in vti_tunnel_xmit/vti6_tnl_xmit l2tp: Avoid schedule while atomic in exit_net l2tp: fix race condition in l2tp_tunnel_delete tun: bail out from tun_get_user() if the skb is empty packet: in packet_do_bind, test fanout with bind_lock held packet: only test po->has_vnet_hdr once in packet_snd net: Set sk_prot_creator when cloning sockets to the right proto tipc: use only positive error codes in messages Revert "bsg-lib: don't free job in bsg_prepare_job" locking/lockdep: Add nest_lock integrity test watchdog: kempld: fix gcc-4.3 build irqchip/crossbar: Fix incorrect type of local variables mac80211_hwsim: check HWSIM_ATTR_RADIO_NAME length mac80211: fix power saving clients handling in iwlwifi net/mlx4_en: fix overflow in mlx4_en_init_timestamp() netfilter: nf_ct_expect: Change __nf_ct_expect_check() return value. iio: adc: xilinx: Fix error handling Btrfs: send, fix failure to rename top level inode due to name collision f2fs: do not wait for writeback in write_begin md/linear: shutup lockdep warnning sparc64: Migrate hvcons irq to panicked cpu net/mlx4_core: Fix VF overwrite of module param which disables DMFS on new probed PFs crypto: xts - Add ECB dependency ocfs2/dlmglue: prepare tracking logic to avoid recursive cluster lock slub: do not merge cache if slub_debug contains a never-merge flag scsi: scsi_dh_emc: return success in clariion_std_inquiry() net: mvpp2: release reference to txq_cpu[] entry after unmapping i2c: at91: ensure state is restored after suspending ceph: clean up unsafe d_parent accesses in build_dentry_path uapi: fix linux/rds.h userspace compilation errors uapi: fix linux/mroute6.h userspace compilation errors target/iscsi: Fix unsolicited data seq_end_offset calculation nfsd/callback: Cleanup callback cred on shutdown cpufreq: CPPC: add ACPI_PROCESSOR dependency Revert "tty: goldfish: Fix a parameter of a call to free_irq" Linux 4.4.94 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
| * locking/lockdep: Add nest_lock integrity testPeter Zijlstra2017-10-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 7fb4a2cea6b18dab56d609530d077f168169ed6b ] Boqun reported that hlock->references can overflow. Add a debug test for that to generate a clear error when this happens. Without this, lockdep is likely to report a mysterious failure on unlock. Reported-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolai Hähnle <Nicolai.Haehnle@amd.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge 4.4.88 into android-4.4Greg Kroah-Hartman2017-09-14
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Changes in 4.4.88 usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard USB: serial: option: add support for D-Link DWM-157 C1 usb: Add device quirk for Logitech HD Pro Webcam C920-C usb:xhci:Fix regression when ATI chipsets detected USB: core: Avoid race of async_completed() w/ usbdev_release() staging/rts5208: fix incorrect shift to extract upper nybble driver core: bus: Fix a potential double free intel_th: pci: Add Cannon Lake PCH-H support intel_th: pci: Add Cannon Lake PCH-LP support ath10k: fix memory leak in rx ring buffer allocation Input: trackpoint - assume 3 buttons when buttons detection fails rtlwifi: rtl_pci_probe: Fix fail path of _rtl_pci_find_adapter Bluetooth: Add support of 13d3:3494 RTL8723BE device dlm: avoid double-free on error path in dlm_device_{register,unregister} mwifiex: correct channel stat buffer overflows drm/nouveau/pci/msi: disable MSI on big-endian platforms by default workqueue: Fix flag collision cs5536: add support for IDE controller variant scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE scsi: sg: recheck MMAP_IO request length with lock held drm: adv7511: really enable interrupts for EDID detection drm/bridge: adv7511: Fix mutex deadlock when interrupts are disabled drm/bridge: adv7511: Use work_struct to defer hotplug handing to out of irq context drm/bridge: adv7511: Switch to using drm_kms_helper_hotplug_event() drm/bridge: adv7511: Re-write the i2c address before EDID probing btrfs: resume qgroup rescan on rw remount locktorture: Fix potential memory leak with rw lock test ALSA: msnd: Optimize / harden DSP and MIDI loops Bluetooth: Properly check L2CAP config option output buffer length ARM: 8692/1: mm: abort uaccess retries upon fatal signal NFS: Fix 2 use after free issues in the I/O code xfs: XFS_IS_REALTIME_INODE() should be false if no rt device present Linux 4.4.88 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
| * locktorture: Fix potential memory leak with rw lock testYang Shi2017-09-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit f4dbba591945dc301c302672adefba9e2ec08dc5 upstream. When running locktorture module with the below commands with kmemleak enabled: $ modprobe locktorture torture_type=rw_lock_irq $ rmmod locktorture The below kmemleak got caught: root@10:~# echo scan > /sys/kernel/debug/kmemleak [ 323.197029] kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak) root@10:~# cat /sys/kernel/debug/kmemleak unreferenced object 0xffffffc07592d500 (size 128): comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 c3 7b 02 00 00 00 00 00 .........{...... 00 00 00 00 00 00 00 00 d7 9b 02 00 00 00 00 00 ................ backtrace: [<ffffff80081e5a88>] create_object+0x110/0x288 [<ffffff80086c6078>] kmemleak_alloc+0x58/0xa0 [<ffffff80081d5acc>] __kmalloc+0x234/0x318 [<ffffff80006fa130>] 0xffffff80006fa130 [<ffffff8008083ae4>] do_one_initcall+0x44/0x138 [<ffffff800817e28c>] do_init_module+0x68/0x1cc [<ffffff800811c848>] load_module+0x1a68/0x22e0 [<ffffff800811d340>] SyS_finit_module+0xe0/0xf0 [<ffffff80080836f0>] el0_svc_naked+0x24/0x28 [<ffffffffffffffff>] 0xffffffffffffffff unreferenced object 0xffffffc07592d480 (size 128): comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 3b 6f 01 00 00 00 00 00 ........;o...... 00 00 00 00 00 00 00 00 23 6a 01 00 00 00 00 00 ........#j...... backtrace: [<ffffff80081e5a88>] create_object+0x110/0x288 [<ffffff80086c6078>] kmemleak_alloc+0x58/0xa0 [<ffffff80081d5acc>] __kmalloc+0x234/0x318 [<ffffff80006fa22c>] 0xffffff80006fa22c [<ffffff8008083ae4>] do_one_initcall+0x44/0x138 [<ffffff800817e28c>] do_init_module+0x68/0x1cc [<ffffff800811c848>] load_module+0x1a68/0x22e0 [<ffffff800811d340>] SyS_finit_module+0xe0/0xf0 [<ffffff80080836f0>] el0_svc_naked+0x24/0x28 [<ffffffffffffffff>] 0xffffffffffffffff It is because cxt.lwsa and cxt.lrsa don't get freed in module_exit, so free them in lock_torture_cleanup() and free writer_tasks if reader_tasks is failed at memory allocation. Signed-off-by: Yang Shi <yang.shi@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Cc: 石洋 <yang.s@alibaba-inc.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | UPSTREAM: locking: avoid passing around 'thread_info' in mutex debugging codeLinus Torvalds2017-08-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 6720a305df74ca30bcc10fc316881641b6ff0c80 upstream. None of the code actually wants a thread_info, it all wants a task_struct, and it's just converting back and forth between the two ("ti->task" to get the task_struct from the thread_info, and "task_thread_info(task)" to go the other way). No semantic change. Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Change-Id: Idd7d0fe0b2b57ece9a969d178576a12f3ae90701 Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
* | Merge tag 'v4.4.39' into android-4.4.yDmitry Shmidt2017-01-03
|\| | | | | | | | | | | This is the 4.4.39 stable release Change-Id: I36dd900bb57846dbbcd7b274774f1debef0f1f18
| * locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()Thomas Gleixner2016-12-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1be5d4fa0af34fb7bafa205aeb59f5c7cc7a089d upstream. While debugging the rtmutex unlock vs. dequeue race Will suggested to use READ_ONCE() in rt_mutex_owner() as it might race against the cmpxchg_release() in unlock_rt_mutex_safe(). Will: "It's a minor thing which will most likely not matter in practice" Careful search did not unearth an actual problem in todays code, but it's better to be safe than surprised. Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Daney <ddaney@caviumnetworks.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20161130210030.431379999@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * locking/rtmutex: Prevent dequeue vs. unlock raceThomas Gleixner2016-12-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit dbb26055defd03d59f678cb5f2c992abe05b064a upstream. David reported a futex/rtmutex state corruption. It's caused by the following problem: CPU0 CPU1 CPU2 l->owner=T1 rt_mutex_lock(l) lock(l->wait_lock) l->owner = T1 | HAS_WAITERS; enqueue(T2) boost() unlock(l->wait_lock) schedule() rt_mutex_lock(l) lock(l->wait_lock) l->owner = T1 | HAS_WAITERS; enqueue(T3) boost() unlock(l->wait_lock) schedule() signal(->T2) signal(->T3) lock(l->wait_lock) dequeue(T2) deboost() unlock(l->wait_lock) lock(l->wait_lock) dequeue(T3) ===> wait list is now empty deboost() unlock(l->wait_lock) lock(l->wait_lock) fixup_rt_mutex_waiters() if (wait_list_empty(l)) { owner = l->owner & ~HAS_WAITERS; l->owner = owner ==> l->owner = T1 } lock(l->wait_lock) rt_mutex_unlock(l) fixup_rt_mutex_waiters() if (wait_list_empty(l)) { owner = l->owner & ~HAS_WAITERS; cmpxchg(l->owner, T1, NULL) ===> Success (l->owner = NULL) l->owner = owner ==> l->owner = T1 } That means the problem is caused by fixup_rt_mutex_waiters() which does the RMW to clear the waiters bit unconditionally when there are no waiters in the rtmutexes rbtree. This can be fatal: A concurrent unlock can release the rtmutex in the fastpath because the waiters bit is not set. If the cmpxchg() gets in the middle of the RMW operation then the previous owner, which just unlocked the rtmutex is set as the owner again when the write takes place after the successfull cmpxchg(). The solution is rather trivial: verify that the owner member of the rtmutex has the waiters bit set before clearing it. This does not require a cmpxchg() or other atomic operations because the waiters bit can only be set and cleared with the rtmutex wait_lock held. It's also safe against the fast path unlock attempt. The unlock attempt via cmpxchg() will either see the bit set and take the slowpath or see the bit cleared and release it atomically in the fastpath. It's remarkable that the test program provided by David triggers on ARM64 and MIPS64 really quick, but it refuses to reproduce on x86-64, while the problem exists there as well. That refusal might explain that this got not discovered earlier despite the bug existing from day one of the rtmutex implementation more than 10 years ago. Thanks to David for meticulously instrumenting the code and providing the information which allowed to decode this subtle problem. Reported-by: David Daney <ddaney@caviumnetworks.com> Tested-by: David Daney <david.daney@cavium.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Fixes: 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") Link: http://lkml.kernel.org/r/20161130210030.351136722@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge remote-tracking branch 'common/android-4.4' into android-4.4.yDmitry Shmidt2016-08-30
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| * RFC: FROMLIST: locking/percpu-rwsem: Optimize readers and reduce global impactPeter Zijlstra2016-08-26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the percpu-rwsem switches to (global) atomic ops while a writer is waiting; which could be quite a while and slows down releasing the readers. This patch cures this problem by ordering the reader-state vs reader-count (see the comments in __percpu_down_read() and percpu_down_write()). This changes a global atomic op into a full memory barrier, which doesn't have the global cacheline contention. This also enables using the percpu-rwsem with rcu_sync disabled in order to bias the implementation differently, reducing the writer latency by adding some cost to readers. Mailing-list-URL: https://lkml.org/lkml/2016/8/9/181 Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [jstultz: Backported to 4.4] Change-Id: I8ea04b4dca2ec36f1c2469eccafde1423490572f Signed-off-by: John Stultz <john.stultz@linaro.org>
* | locking/qspinlock: Fix spin_unlock_wait() some morePeter Zijlstra2016-07-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 2c610022711675ee908b903d242f0b90e1db661f upstream. While this prior commit: 54cf809b9512 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()") ... fixes spin_is_locked() and spin_unlock_wait() for the usage in ipc/sem and netfilter, it does not in fact work right for the usage in task_work and futex. So while the 2 locks crossed problem: spin_lock(A) spin_lock(B) if (!spin_is_locked(B)) spin_unlock_wait(A) foo() foo(); ... works with the smp_mb() injected by both spin_is_locked() and spin_unlock_wait(), this is not sufficient for: flag = 1; smp_mb(); spin_lock() spin_unlock_wait() if (!flag) // add to lockless list // iterate lockless list ... because in this scenario, the store from spin_lock() can be delayed past the load of flag, uncrossing the variables and loosing the guarantee. This patch reworks spin_is_locked() and spin_unlock_wait() to work in both cases by exploiting the observation that while the lock byte store can be delayed, the contender must have registered itself visibly in other state contained in the word. It also allows for architectures to override both functions, as PPC and ARM64 have an additional issue for which we currently have no generic solution. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Giovanni Gherdovich <ggherdovich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <waiman.long@hpe.com> Cc: Will Deacon <will.deacon@arm.com> Fixes: 54cf809b9512 ("locking,qspinlock: Fix spin_is_locked() and spin_unlock_wait()") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | locking/ww_mutex: Report recursive ww_mutex locking earlyChris Wilson2016-07-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 0422e83d84ae24b933e4b0d4c1e0f0b4ae8a0a3b upstream. Recursive locking for ww_mutexes was originally conceived as an exception. However, it is heavily used by the DRM atomic modesetting code. Currently, the recursive deadlock is checked after we have queued up for a busy-spin and as we never release the lock, we spin until kicked, whereupon the deadlock is discovered and reported. A simple solution for the now common problem is to move the recursive deadlock discovery to the first action when taking the ww_mutex. Suggested-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1464293297-19777-1-git-send-email-chris@chris-wilson.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | locking/mcs: Fix mcs_spin_lock() orderingPeter Zijlstra2016-05-04
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 920c720aa5aa3900a7f1689228fdfc2580a91e7e upstream. Similar to commit b4b29f94856a ("locking/osq: Fix ordering of node initialisation in osq_lock") the use of xchg_acquire() is fundamentally broken with MCS like constructs. Furthermore, it turns out we rely on the global transitivity of this operation because the unlock path observes the pointer with a READ_ONCE(), not an smp_load_acquire(). This is non-critical because the MCS code isn't actually used and mostly serves as documentation, a stepping stone to the more complex things we've build on top of the idea. Reported-by: Andrea Parri <parri.andrea@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Fixes: 3552a07a9c4a ("locking/mcs: Use acquire/release semantics") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* locking/osq: Fix ordering of node initialisation in osq_lockWill Deacon2015-12-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Cavium guys reported a soft lockup on their arm64 machine, caused by commit c55a6ffa6285 ("locking/osq: Relax atomic semantics"): mutex_optimistic_spin+0x9c/0x1d0 __mutex_lock_slowpath+0x44/0x158 mutex_lock+0x54/0x58 kernfs_iop_permission+0x38/0x70 __inode_permission+0x88/0xd8 inode_permission+0x30/0x6c link_path_walk+0x68/0x4d4 path_openat+0xb4/0x2bc do_filp_open+0x74/0xd0 do_sys_open+0x14c/0x228 SyS_openat+0x3c/0x48 el0_svc_naked+0x24/0x28 This is because in osq_lock we initialise the node for the current CPU: node->locked = 0; node->next = NULL; node->cpu = curr; and then publish the current CPU in the lock tail: old = atomic_xchg_acquire(&lock->tail, curr); Once the update to lock->tail is visible to another CPU, the node is then live and can be both read and updated by concurrent lockers. Unfortunately, the ACQUIRE semantics of the xchg operation mean that there is no guarantee the contents of the node will be visible before lock tail is updated. This can lead to lock corruption when, for example, a concurrent locker races to set the next field. Fixes: c55a6ffa6285 ("locking/osq: Relax atomic semantics"): Reported-by: David Daney <ddaney@caviumnetworks.com> Reported-by: Andrew Pinski <andrew.pinski@caviumnetworks.com> Tested-by: Andrew Pinski <andrew.pinski@caviumnetworks.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1449856001-21177-1-git-send-email-will.deacon@arm.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* treewide: Remove old email addressPeter Zijlstra2015-11-23
| | | | | | | | | | | | | | | | | There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
* mm, page_alloc: distinguish between being unable to sleep, unwilling to ↵Mel Gorman2015-11-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2015-11-03
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: "The main changes in this cycle were: - sched/fair load tracking fixes and cleanups (Byungchul Park) - Make load tracking frequency scale invariant (Dietmar Eggemann) - sched/deadline updates (Juri Lelli) - stop machine fixes, cleanups and enhancements for bugs triggered by CPU hotplug stress testing (Oleg Nesterov) - scheduler preemption code rework: remove PREEMPT_ACTIVE and related cleanups (Peter Zijlstra) - Rework the sched_info::run_delay code to fix races (Peter Zijlstra) - Optimize per entity utilization tracking (Peter Zijlstra) - ... misc other fixes, cleanups and smaller updates" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits) sched: Don't scan all-offline ->cpus_allowed twice if !CONFIG_CPUSETS sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop() sched: Start stopper early stop_machine: Kill cpu_stop_threads->setup() and cpu_stop_unpark() stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark() stop_machine: Change cpu_stop_queue_two_works() to rely on stopper->enabled stop_machine: Introduce __cpu_stop_queue_work() and cpu_stop_queue_two_works() stop_machine: Ensure that a queued callback will be called before cpu_stop_park() sched/x86: Fix typo in __switch_to() comments sched/core: Remove a parameter in the migrate_task_rq() function sched/core: Drop unlikely behind BUG_ON() sched/core: Fix task and run queue sched_info::run_delay inconsistencies sched/numa: Fix task_tick_fair() from disabling numa_balancing sched/core: Add preempt_count invariant check sched/core: More notrace annotations sched/core: Kill PREEMPT_ACTIVE sched/core, sched/x86: Kill thread_info::saved_preempt_count sched/core: Simplify preempt_count tests sched/core: Robustify preemption leak checks sched/core: Stop setting PREEMPT_ACTIVE ...
| * Merge branch 'sched/urgent' into sched/core, to pick up fixes before ↵Ingo Molnar2015-10-06
| |\ | | | | | | | | | | | | | | | applying new changes Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/deadline, locking/rtmutex: Fix open coded check in rt_mutex_waiter_less()Juri Lelli2015-09-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rt_mutex_waiter_less() check of task deadlines is open coded. Since this is subject to wraparound bugs, make it use the correct helper. Reported-by: Luca Abeni <luca.abeni@unitn.it> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1441188096-23021-4-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | Merge branch 'locking-core-for-linus' of ↵Linus Torvalds2015-11-03
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking changes from Ingo Molnar: "The main changes in this cycle were: - More gradual enhancements to atomic ops: new atomic*_read_ctrl() ops, synchronize atomic_{read,set}() ordering requirements between architectures, add atomic_long_t bitops. (Peter Zijlstra) - Add _{relaxed|acquire|release}() variants for inc/dec atomics and use them in various locking primitives: mutex, rtmutex, mcs, rwsem. This enables weakly ordered architectures (such as arm64) to make use of more locking related optimizations. (Davidlohr Bueso) - Implement atomic[64]_{inc,dec}_relaxed() on ARM. (Will Deacon) - Futex kernel data cache footprint micro-optimization. (Rasmus Villemoes) - pvqspinlock runtime overhead micro-optimization. (Waiman Long) - misc smaller fixlets" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: ARM, locking/atomics: Implement _relaxed variants of atomic[64]_{inc,dec} locking/rwsem: Use acquire/release semantics locking/mcs: Use acquire/release semantics locking/rtmutex: Use acquire/release semantics locking/mutex: Use acquire/release semantics locking/asm-generic: Add _{relaxed|acquire|release}() variants for inc/dec atomics atomic: Implement atomic_read_ctrl() atomic, arch: Audit atomic_{read,set}() atomic: Add atomic_long_t bitops futex: Force hot variables into a single cache line locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VAL locking/osq: Relax atomic semantics locking/qrwlock: Rename ->lock to ->wait_lock locking/Documentation/lockstat: Fix typo - lokcing -> locking locking/atomics, cmpxchg: Privatize the inclusion of asm/cmpxchg.h
| * | | locking/rwsem: Use acquire/release semanticsDavidlohr Bueso2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As of 654672d4ba1 (locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations) and 6d79ef2d30e (locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'), weakly ordered archs can benefit from more relaxed use of barriers when locking and unlocking, instead of regular full barrier semantics. While currently only arm64 supports such optimizations, updating corresponding locking primitives serves for other archs to immediately benefit as well, once the necessary machinery is implemented of course. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E.McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443643395-17016-6-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/mcs: Use acquire/release semanticsDavidlohr Bueso2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As of 654672d4ba1 (locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations) and 6d79ef2d30e (locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'), weakly ordered archs can benefit from more relaxed use of barriers when locking and unlocking, instead of regular full barrier semantics. While currently only arm64 supports such optimizations, updating corresponding locking primitives serves for other archs to immediately benefit as well, once the necessary machinery is implemented of course. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E.McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443643395-17016-5-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/rtmutex: Use acquire/release semanticsDavidlohr Bueso2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As of 654672d4ba1 (locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations) and 6d79ef2d30e (locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'), weakly ordered archs can benefit from more relaxed use of barriers when locking and unlocking, instead of regular full barrier semantics. While currently only arm64 supports such optimizations, updating corresponding locking primitives serves for other archs to immediately benefit as well, once the necessary machinery is implemented of course. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E.McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443643395-17016-4-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/mutex: Use acquire/release semanticsDavidlohr Bueso2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As of 654672d4ba1 (locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations) and 6d79ef2d30e (locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'), weakly ordered archs can benefit from more relaxed use of barriers when locking and unlocking, instead of regular full barrier semantics. While currently only arm64 supports such optimizations, updating corresponding locking primitives serves for other archs to immediately benefit as well, once the necessary machinery is implemented of course. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul E.McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1443643395-17016-3-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | Merge branch 'locking/urgent' into locking/core, to pick up fixes before ↵Ingo Molnar2015-09-23
| |\ \ \ | | | |/ | | |/| | | | | | | | | | | | | applying new changes Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/pvqspinlock: Kick the PV CPU unconditionally when _Q_SLOW_VALWaiman Long2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If _Q_SLOW_VAL has been set, the vCPU state must have been vcpu_hashed. The extra check at the end of __pv_queued_spin_unlock() is unnecessary and can be removed. Signed-off-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1441996658-62854-3-git-send-email-Waiman.Long@hpe.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/osq: Relax atomic semanticsDavidlohr Bueso2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ... by using acquire/release for ops around the lock->tail. As such, weakly ordered archs can benefit from more relaxed use of barriers when issuing atomics. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <Waiman.Long@hpe.com> Link: http://lkml.kernel.org/r/1442216244-4409-3-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | locking/qrwlock: Rename ->lock to ->wait_lockDavidlohr Bueso2015-09-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ... trivial, but reads a little nicer when we name our actual primitive 'lock'. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <Waiman.Long@hpe.com> Link: http://lkml.kernel.org/r/1442216244-4409-1-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | Merge tag 'v4.3-rc1' into locking/core, to refresh the treeIngo Molnar2015-09-13
| |\ \ \ | | | | | | | | | | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | \ \ \ Merge branch 'for-mingo' of ↵Ingo Molnar2015-10-19
|\ \ \ \ \ | |_|_|/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU updates from Paul E. McKenney: - Miscellaneous fixes. (Paul E. McKenney, Boqun Feng, Oleg Nesterov, Patrick Marlier) - Improvements to expedited grace periods. (Paul E. McKenney) - Performance improvements to and locktorture tests for percpu-rwsem. (Oleg Nesterov, Paul E. McKenney) - Torture-test changes. (Paul E. McKenney, Davidlohr Bueso) - Documentation updates. (Paul E. McKenney) Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | | | |
| | \ \ \
| *-. \ \ \ Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and ↵Paul E. McKenney2015-10-07
| |\ \ \ \ \ | | |_|_|_|/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'torture.2015.10.06a' into HEAD doc.2015.10.06a: Documentation updates. percpu-rwsem.2015.10.06a: Optimization of per-CPU reader-writer semaphores. torture.2015.10.06a: Torture-test updates.
| | | * | | locktorture: Fix module unwind when bad torture_type specifiedPaul E. McKenney2015-10-06
| | |/ / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The locktorture module has a list of torture types, and specifying a type not on this list is supposed to cleanly fail the module load. Unfortunately, the "fail" happens without the "cleanly". This commit therefore adds the needed clean-up after an incorrect torture_type. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locking/percpu-rwsem: Clean up the lockdep annotations in percpu_down_read()Oleg Nesterov2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Based on Peter Zijlstra's earlier patch. Change percpu_down_read() to use __down_read(), this way we can do rwsem_acquire_read() unconditionally at the start to make this code more symmetric and clean. Originally-From: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locking/percpu-rwsem: Fix the comments outdated by rcu_syncOleg Nesterov2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update the comments broken by the previous change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locking/percpu-rwsem: Make use of the rcu_sync infrastructureOleg Nesterov2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently down_write/up_write calls synchronize_sched_expedited() twice, which is evil. Change this code to rely on rcu-sync primitives. This avoids the _expedited "big hammer", and this can be faster in the contended case or even in the case when a single thread does down_write/up_write in a loop. Of course, a single down_write() will take more time, but otoh it will be much more friendly to the whole system. To simplify the review this patch doesn't update the comments, fixed by the next change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locking/percpu-rwsem: Make percpu_free_rwsem() after kzalloc() safeOleg Nesterov2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the temporary ugly hack which will be reverted later. We only need it to ensure that the next patch will not break "change sb_writers to use percpu_rw_semaphore" patches routed via the VFS tree. The alloc_super()->destroy_super() error path assumes that it is safe to call percpu_free_rwsem() after kzalloc() without percpu_init_rwsem(), so let's not disappoint it. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locktorture: Add torture tests for percpu_rwsemPaul E. McKenney2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds percpu_rwsem tests based on the earlier rwsem tests. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locking/percpu-rwsem: Export symbols for locktorturePaul E. McKenney2015-10-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit exports percpu_down_read(), percpu_down_write(), __percpu_init_rwsem(), percpu_up_read(), and percpu_up_write() to allow locktorture to test them when built as a module. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * | | locktorture: Support rtmutex torturingDavidlohr Bueso2015-10-06
| |/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Real time mutexes is one of the few general primitives that we do not have in locktorture. Address this -- a few considerations: o To spice things up, enable competing thread(s) to become rt, such that we can stress different prio boosting paths in the rtmutex code. Introduce a ->task_boost callback, only used by rtmutex-torturer. Tasks will boost/deboost around every 50k (arbitrarily) lock/unlock operations. o Hold times are similar to what we have for other locks: only occasionally having longer hold times (per ~200k ops). So we roughly do two full rt boost+deboosting ops with short hold times. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* / / / locking/lockdep: Fix hlock->pin_count reset on lock stack rebuildsPeter Zijlstra2015-09-23
|/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Various people reported hitting the "unpinning an unpinned lock" warning. As it turns out there are 2 places where we take a lock out of the middle of a stack, and in those cases it would fail to preserve the pin_count when rebuilding the lock stack. Reported-by: Sasha Levin <sasha.levin@oracle.com> Reported-by: Tim Spriggs <tspriggs@apple.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davej@codemonkey.org.uk Link: http://lkml.kernel.org/r/20150916141040.GA11639@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | / Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds2015-09-17
|\| | | |/ |/| | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Ingo Molnar: "Spinlock performance regression fix, plus documentation fixes" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/static_keys: Fix up the static keys documentation locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support locking/qspinlock/x86: Fix performance regression under unaccelerated VMs locking/static_keys: Fix a silly typo
| * locking/qspinlock/x86: Fix performance regression under unaccelerated VMsPeter Zijlstra2015-09-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Dave ran into horrible performance on a VM without PARAVIRT_SPINLOCKS set and Linus noted that the test-and-set implementation was retarded. One should spin on the variable with a load, not a RMW. While there, remove 'queued' from the name, as the lock isn't queued at all, but a simple test-and-set. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Dave Chinner <david@fromorbit.com> Tested-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <Waiman.Long@hp.com> Cc: stable@vger.kernel.org # v4.2+ Link: http://lkml.kernel.org/r/20150904152523.GR18673@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | Merge branch 'for-linus' of ↵Linus Torvalds2015-09-05
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "In this one: - d_move fixes (Eric Biederman) - UFS fixes (me; locking is mostly sane now, a bunch of bugs in error handling ought to be fixed) - switch of sb_writers to percpu rwsem (Oleg Nesterov) - superblock scalability (Josef Bacik and Dave Chinner) - swapon(2) race fix (Hugh Dickins)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits) vfs: Test for and handle paths that are unreachable from their mnt_root dcache: Reduce the scope of i_lock in d_splice_alias dcache: Handle escaped paths in prepend_path mm: fix potential data race in SyS_swapon inode: don't softlockup when evicting inodes inode: rename i_wb_list to i_io_list sync: serialise per-superblock sync operations inode: convert inode_sb_list_lock to per-sb inode: add hlist_fake to avoid the inode hash lock in evict writeback: plug writeback at a high level change sb_writers to use percpu_rw_semaphore shift percpu_counter_destroy() into destroy_super_work() percpu-rwsem: kill CONFIG_PERCPU_RWSEM percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire() percpu-rwsem: introduce percpu_down_read_trylock() document rwsem_release() in sb_wait_write() fix the broken lockdep logic in __sb_start_write() introduce __sb_writers_{acquired,release}() helpers ufs_inode_get{frag,block}(): get rid of 'phys' argument ufs_getfrag_block(): tidy up a bit ...
| * percpu-rwsem: kill CONFIG_PERCPU_RWSEMOleg Nesterov2015-08-15
| | | | | | | | | | | | | | Remove CONFIG_PERCPU_RWSEM, the next patch adds the unconditional user of percpu_rw_semaphore. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
| * percpu-rwsem: introduce percpu_down_read_trylock()Oleg Nesterov2015-08-15
| | | | | | | | | | | | Add percpu_down_read_trylock(), it will have the user soon. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
* | locking/qrwlock: Make use of _{acquire|release|relaxed}() atomicsWill Deacon2015-08-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The qrwlock implementation is slightly heavy in its use of memory barriers, mainly through the use of _cmpxchg() and _return() atomics, which imply full barrier semantics. This patch modifies the qrwlock code to use the more relaxed atomic routines so that we can reduce the unnecessary barrier overhead on weakly-ordered architectures. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman.Long@hp.com Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1438880084-18856-7-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | locking/pvqspinlock: Only kick CPU at unlock timeWaiman Long2015-08-03
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For an over-committed guest with more vCPUs than physical CPUs available, it is possible that a vCPU may be kicked twice before getting the lock - once before it becomes queue head and once again before it gets the lock. All these CPU kicking and halting (VMEXIT) can be expensive and slow down system performance. This patch adds a new vCPU state (vcpu_hashed) which enables the code to delay CPU kicking until at unlock time. Once this state is set, the new lock holder will set _Q_SLOW_VAL and fill in the hash table on behalf of the halted queue head vCPU. The original vcpu_halted state will be used by pv_wait_node() only to differentiate other queue nodes from the qeue head. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1436647018-49734-2-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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