user/sven/linux.git/kernel/locking, branch v5.9.8

lockdep: Fix preemption WARN for spurious IRQ-enable

2020-11-05T10:51:12Z

[ Upstream commit f8e48a3dca060e80f672d398d181db1298fbc86c ] It is valid (albeit uncommon) to call local_irq_enable() without first having called local_irq_disable(). In this case we enter lockdep_hardirqs_on*() with IRQs enabled and trip a preemption warning for using __this_cpu_read(). Use this_cpu_read() instead to avoid the warning. Fixes: 4d004099a6 ("lockdep: Fix lockdep recursion") Reported-by: syzbot+53f8ce8bbc07924b6417@syzkaller.appspotmail.com Reported-by: kernel test robot Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Sasha Levin

lockdep: Fix lockdep recursion

2020-10-29T09:11:03Z

[ Upstream commit 4d004099a668c41522242aa146a38cc4eb59cb1e ] Steve reported that lockdep_assert*irq*(), when nested inside lockdep itself, will trigger a false-positive. One example is the stack-trace code, as called from inside lockdep, triggering tracing, which in turn calls RCU, which then uses lockdep_assert_irqs_disabled(). Fixes: a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") Reported-by: Steven Rostedt Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin

lockdep: Fix usage_traceoverflow

2020-10-29T09:11:03Z

[ Upstream commit 2bb8945bcc1a768f2bc402a16c9610bba8d5187d ] Basically print_lock_class_header()'s for loop is out of sync with the the size of of ->usage_traces[]. Also clean things up a bit while at it, to avoid such mishaps in the future. Fixes: 23870f122768 ("locking/lockdep: Fix "USED" <- "IN-NMI" inversions") Reported-by: Qian Cai Debugged-by: Boqun Feng Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Tested-by: Qian Cai Link: https://lkml.kernel.org/r/20200930094937.GE2651@hirez.programming.kicks-ass.net Signed-off-by: Sasha Levin

locking/percpu-rwsem: Use this_cpu_{inc,dec}() for read_count

2020-09-16T14:26:56Z

The __this_cpu*() accessors are (in general) IRQ-unsafe which, given that percpu-rwsem is a blocking primitive, should be just fine. However, file_end_write() is used from IRQ context and will cause load-store issues on architectures where the per-cpu accessors are not natively irq-safe. Fix it by using the IRQ-safe this_cpu_*() for operations on read_count. This will generate more expensive code on a number of platforms, which might cause a performance regression for some of the other percpu-rwsem users. If any such is reported, we can consider alternative solutions. Fixes: 70fe2f48152e ("aio: fix freeze protection of aio writes") Signed-off-by: Hou Tao Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Acked-by: Oleg Nesterov Link: https://lkml.kernel.org/r/20200915140750.137881-1-houtao1@huawei.com

locking/lockdep: Fix "USED" <- "IN-NMI" inversions

2020-09-03T09:19:42Z

During the LPC RCU BoF Paul asked how come the "USED" <- "IN-NMI" detector doesn't trip over rcu_read_lock()'s lockdep annotation. Looking into this I found a very embarrasing typo in verify_lock_unused(): - if (!(class->usage_mask & LOCK_USED)) + if (!(class->usage_mask & LOCKF_USED)) fixing that will indeed cause rcu_read_lock() to insta-splat :/ The above typo means that instead of testing for: 0x100 (1 << LOCK_USED), we test for 8 (LOCK_USED), which corresponds to (1 << LOCK_ENABLED_HARDIRQ). So instead of testing for _any_ used lock, it will only match any lock used with interrupts enabled. The rcu_read_lock() annotation uses .check=0, which means it will not set any of the interrupt bits and will thus never match. In order to properly fix the situation and allow rcu_read_lock() to correctly work, split LOCK_USED into LOCK_USED and LOCK_USED_READ and by having .read users set USED_READ and test USED, pure read-recursive locks are permitted. Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Tested-by: Masami Hiramatsu Acked-by: Paul E. McKenney Link: https://lore.kernel.org/r/20200902160323.GK1362448@hirez.programming.kicks-ass.net

lockdep,trace: Expose tracepoints

2020-08-26T10:41:56Z

The lockdep tracepoints are under the lockdep recursion counter, this has a bunch of nasty side effects: - TRACE_IRQFLAGS doesn't work across the entire tracepoint - RCU-lockdep doesn't see the tracepoints either, hiding numerous "suspicious RCU usage" warnings. Pull the trace_lock_*() tracepoints completely out from under the lockdep recursion handling and completely rely on the trace level recusion handling -- also, tracing *SHOULD* not be taking locks in any case. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Thomas Gleixner Acked-by: Rafael J. Wysocki Tested-by: Marco Elver Link: https://lkml.kernel.org/r/20200821085348.782688941@infradead.org

lockdep: Use raw_cpu_*() for per-cpu variables

2020-08-26T10:41:53Z

Sven reported that commit a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") caused trouble on s390 because their this_cpu_*() primitives disable preemption which then lands back tracing. On the one hand, per-cpu ops should use preempt_*able_notrace() and raw_local_irq_*(), on the other hand, we can trivialy use raw_cpu_*() ops for this. Fixes: a21ee6055c30 ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables") Reported-by: Sven Schnelle Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Thomas Gleixner Acked-by: Rafael J. Wysocki Tested-by: Marco Elver Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200821085348.192346882@infradead.org

Merge tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-11T02:07:44Z

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 ...

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2020-08-06T19:59:31Z

Pull KVM updates from Paolo Bonzini: "s390: - implement diag318 x86: - Report last CPU for debugging - Emulate smaller MAXPHYADDR in the guest than in the host - .noinstr and tracing fixes from Thomas - nested SVM page table switching optimization and fixes Generic: - Unify shadow MMU cache data structures across architectures" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (127 commits) KVM: SVM: Fix sev_pin_memory() error handling KVM: LAPIC: Set the TDCR settable bits KVM: x86: Specify max TDP level via kvm_configure_mmu() KVM: x86/mmu: Rename max_page_level to max_huge_page_level KVM: x86: Dynamically calculate TDP level from max level and MAXPHYADDR KVM: VXM: Remove temporary WARN on expected vs. actual EPTP level mismatch KVM: x86: Pull the PGD's level from the MMU instead of recalculating it KVM: VMX: Make vmx_load_mmu_pgd() static KVM: x86/mmu: Add separate helper for shadow NPT root page role calc KVM: VMX: Drop a duplicate declaration of construct_eptp() KVM: nSVM: Correctly set the shadow NPT root level in its MMU role KVM: Using macros instead of magic values MIPS: KVM: Fix build error caused by 'kvm_run' cleanup KVM: nSVM: remove nonsensical EXITINFO1 adjustment on nested NPF KVM: x86: Add a capability for GUEST_MAXPHYADDR < HOST_MAXPHYADDR support KVM: VMX: optimize #PF injection when MAXPHYADDR does not match KVM: VMX: Add guest physical address check in EPT violation and misconfig KVM: VMX: introduce vmx_need_pf_intercept KVM: x86: update exception bitmap on CPUID changes KVM: x86: rename update_bp_intercept to update_exception_bitmap ...

Merge tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-06T18:55:43Z

Pull sched/fifo updates from Ingo Molnar: "This adds the sched_set_fifo*() encapsulation APIs to remove static priority level knowledge from non-scheduler code. The three APIs for non-scheduler code to set SCHED_FIFO are: - sched_set_fifo() - sched_set_fifo_low() - sched_set_normal() These are two FIFO priority levels: default (high), and a 'low' priority level, plus sched_set_normal() to set the policy back to non-SCHED_FIFO. Since the changes affect a lot of non-scheduler code, we kept this in a separate tree" * tag 'sched-fifo-2020-08-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) sched,tracing: Convert to sched_set_fifo() sched: Remove sched_set_*() return value sched: Remove sched_setscheduler*() EXPORTs sched,psi: Convert to sched_set_fifo_low() sched,rcutorture: Convert to sched_set_fifo_low() sched,rcuperf: Convert to sched_set_fifo_low() sched,locktorture: Convert to sched_set_fifo() sched,irq: Convert to sched_set_fifo() sched,watchdog: Convert to sched_set_fifo() sched,serial: Convert to sched_set_fifo() sched,powerclamp: Convert to sched_set_fifo() sched,ion: Convert to sched_set_normal() sched,powercap: Convert to sched_set_fifo*() sched,spi: Convert to sched_set_fifo*() sched,mmc: Convert to sched_set_fifo*() sched,ivtv: Convert to sched_set_fifo*() sched,drm/scheduler: Convert to sched_set_fifo*() sched,msm: Convert to sched_set_fifo*() sched,psci: Convert to sched_set_fifo*() sched,drbd: Convert to sched_set_fifo*() ...