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2020-11-17lockdep: Put graph lock/unlock under lock_recursion protectionBoqun Feng1-2/+4
A warning was hit when running xfstests/generic/068 in a Hyper-V guest: [...] ------------[ cut here ]------------ [...] DEBUG_LOCKS_WARN_ON(lockdep_hardirqs_enabled()) [...] WARNING: CPU: 2 PID: 1350 at kernel/locking/lockdep.c:5280 check_flags.part.0+0x165/0x170 [...] ... [...] Workqueue: events pwq_unbound_release_workfn [...] RIP: 0010:check_flags.part.0+0x165/0x170 [...] ... [...] Call Trace: [...] lock_is_held_type+0x72/0x150 [...] ? lock_acquire+0x16e/0x4a0 [...] rcu_read_lock_sched_held+0x3f/0x80 [...] __send_ipi_one+0x14d/0x1b0 [...] hv_send_ipi+0x12/0x30 [...] __pv_queued_spin_unlock_slowpath+0xd1/0x110 [...] __raw_callee_save___pv_queued_spin_unlock_slowpath+0x11/0x20 [...] .slowpath+0x9/0xe [...] lockdep_unregister_key+0x128/0x180 [...] pwq_unbound_release_workfn+0xbb/0xf0 [...] process_one_work+0x227/0x5c0 [...] worker_thread+0x55/0x3c0 [...] ? process_one_work+0x5c0/0x5c0 [...] kthread+0x153/0x170 [...] ? __kthread_bind_mask+0x60/0x60 [...] ret_from_fork+0x1f/0x30 The cause of the problem is we have call chain lockdep_unregister_key() -> <irq disabled by raw_local_irq_save()> lockdep_unlock() -> arch_spin_unlock() -> __pv_queued_spin_unlock_slowpath() -> pv_kick() -> __send_ipi_one() -> trace_hyperv_send_ipi_one(). Although this particular warning is triggered because Hyper-V has a trace point in ipi sending, but in general arch_spin_unlock() may call another function having a trace point in it, so put the arch_spin_lock() and arch_spin_unlock() after lock_recursion protection to fix this problem and avoid similiar problems. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201113110512.1056501-1-boqun.feng@gmail.com
2020-11-10lockdep: Avoid to modify chain keys in validate_chain()Boqun Feng1-10/+9
Chris Wilson reported a problem spotted by check_chain_key(): a chain key got changed in validate_chain() because we modify the ->read in validate_chain() to skip checks for dependency adding, and ->read is taken into calculation for chain key since commit f611e8cf98ec ("lockdep: Take read/write status in consideration when generate chainkey"). Fix this by avoiding to modify ->read in validate_chain() based on two facts: a) since we now support recursive read lock detection, there is no need to skip checks for dependency adding for recursive readers, b) since we have a), there is only one case left (nest_lock) where we want to skip checks in validate_chain(), we simply remove the modification for ->read and rely on the return value of check_deadlock() to skip the dependency adding. Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201102053743.450459-1-boqun.feng@gmail.com
2020-10-30lockdep: Fix nr_unused_locks accountingPeter Zijlstra1-10/+4
Chris reported that commit 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow") breaks the nr_unused_locks validation code triggered by /proc/lockdep_stats. By fully splitting LOCK_USED and LOCK_USED_READ it becomes a bad indicator for accounting nr_unused_locks; simplyfy by using any first bit. Fixes: 24d5a3bffef1 ("lockdep: Fix usage_traceoverflow") Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://lkml.kernel.org/r/20201027124834.GL2628@hirez.programming.kicks-ass.net
2020-10-30locking/lockdep: Remove more raw_cpu_read() usagePeter Zijlstra1-1/+1
I initially thought raw_cpu_read() was OK, since if it is !0 we have IRQs disabled and can't get migrated, so if we get migrated both CPUs must have 0 and it doesn't matter which 0 we read. And while that is true; it isn't the whole store, on pretty much all architectures (except x86) this can result in computing the address for one CPU, getting migrated, the old CPU continuing execution with another task (possibly setting recursion) and then the new CPU reading the value of the old CPU, which is no longer 0. Similer to: baffd723e44d ("lockdep: Revert "lockdep: Use raw_cpu_*() for per-cpu variables"") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20201026152256.GB2651@hirez.programming.kicks-ass.net
2020-10-22lockdep: Fix preemption WARN for spurious IRQ-enablePeter Zijlstra1-2/+2
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 <lkp@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-10-09Merge branch 'locking/urgent' into locking/core, to pick up fixesIngo Molnar1-52/+92
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-10-09lockdep: Fix lockdep recursionPeter Zijlstra1-40/+59
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 <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-10-09lockdep: Fix usage_traceoverflowPeter Zijlstra1-17/+15
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 <cai@redhat.com> Debugged-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Qian Cai <cai@redhat.com> Link: https://lkml.kernel.org/r/20200930094937.GE2651@hirez.programming.kicks-ass.net
2020-09-29lockdep: Optimize the memory usage of circular queueBoqun Feng1-39/+60
Qian Cai reported a BFS_EQUEUEFULL warning [1] after read recursive deadlock detection merged into tip tree recently. Unlike the previous lockep graph searching, which iterate every lock class (every node in the graph) exactly once, the graph searching for read recurisve deadlock detection needs to iterate every lock dependency (every edge in the graph) once, as a result, the maximum memory cost of the circular queue changes from O(V), where V is the number of lock classes (nodes or vertices) in the graph, to O(E), where E is the number of lock dependencies (edges), because every lock class or dependency gets enqueued once in the BFS. Therefore we hit the BFS_EQUEUEFULL case. However, actually we don't need to enqueue all dependencies for the BFS, because every time we enqueue a dependency, we almostly enqueue all other dependencies in the same dependency list ("almostly" is because we currently check before enqueue, so if a dependency doesn't pass the check stage we won't enqueue it, however, we can always do in reverse ordering), based on this, we can only enqueue the first dependency from a dependency list and every time we want to fetch a new dependency to work, we can either: 1) fetch the dependency next to the current dependency in the dependency list or 2) if the dependency in 1) doesn't exist, fetch the dependency from the queue. With this approach, the "max bfs queue depth" for a x86_64_defconfig + lockdep and selftest config kernel can get descreased from: max bfs queue depth: 201 to (after apply this patch) max bfs queue depth: 61 While I'm at it, clean up the code logic a little (e.g. directly return other than set a "ret" value and goto the "exit" label). [1]: https://lore.kernel.org/lkml/17343f6f7f2438fc376125384133c5ba70c2a681.camel@redhat.com/ Reported-by: Qian Cai <cai@redhat.com> Reported-by: syzbot+62ebe501c1ce9a91f68c@syzkaller.appspotmail.com Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200917080210.108095-1-boqun.feng@gmail.com
2020-09-03locking/lockdep: Fix "USED" <- "IN-NMI" inversionspeterz@infradead.org1-6/+29
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) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/20200902160323.GK1362448@hirez.programming.kicks-ass.net
2020-08-26lockdep: Take read/write status in consideration when generate chainkeyBoqun Feng1-18/+35
Currently, the chainkey of a lock chain is a hash sum of the class_idx of all the held locks, the read/write status are not taken in to consideration while generating the chainkey. This could result into a problem, if we have: P1() { read_lock(B); lock(A); } P2() { lock(A); read_lock(B); } P3() { lock(A); write_lock(B); } , and P1(), P2(), P3() run one by one. And when running P2(), lockdep detects such a lock chain A -> B is not a deadlock, then it's added in the chain cache, and then when running P3(), even if it's a deadlock, we could miss it because of the hit of chain cache. This could be confirmed by self testcase "chain cached mixed R-L/L-W ". To resolve this, we use concept "hlock_id" to generate the chainkey, the hlock_id is a tuple (hlock->class_idx, hlock->read), which fits in a u16 type. With this, the chainkeys are different is the lock sequences have the same locks but different read/write status. Besides, since we use "hlock_id" to generate chainkeys, the chain_hlocks array now store the "hlock_id"s rather than lock_class indexes. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-15-boqun.feng@gmail.com
2020-08-26lockdep: Add recursive read locks into dependency graphBoqun Feng1-17/+2
Since we have all the fundamental to handle recursive read locks, we now add them into the dependency graph. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-13-boqun.feng@gmail.com
2020-08-26lockdep: Fix recursive read lock related safe->unsafe detectionBoqun Feng1-47/+141
Currently, in safe->unsafe detection, lockdep misses the fact that a LOCK_ENABLED_IRQ_*_READ usage and a LOCK_USED_IN_IRQ_*_READ usage may cause deadlock too, for example: P1 P2 <irq disabled> write_lock(l1); <irq enabled> read_lock(l2); write_lock(l2); <in irq> read_lock(l1); Actually, all of the following cases may cause deadlocks: LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_* LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_* LOCK_USED_IN_IRQ_* -> LOCK_ENABLED_IRQ_*_READ LOCK_USED_IN_IRQ_*_READ -> LOCK_ENABLED_IRQ_*_READ To fix this, we need to 1) change the calculation of exclusive_mask() so that READ bits are not dropped and 2) always call usage() in mark_lock_irq() to check usage deadlocks, even when the new usage of the lock is READ. Besides, adjust usage_match() and usage_acculumate() to recursive read lock changes. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-12-boqun.feng@gmail.com
2020-08-26lockdep: Adjust check_redundant() for recursive read changeBoqun Feng1-3/+44
check_redundant() will report redundancy if it finds a path could replace the about-to-add dependency in the BFS search. With recursive read lock changes, we certainly need to change the match function for the check_redundant(), because the path needs to match not only the lock class but also the dependency kinds. For example, if the about-to-add dependency @prev -> @next is A -(SN)-> B, and we find a path A -(S*)-> .. -(*R)->B in the dependency graph with __bfs() (for simplicity, we can also say we find an -(SR)-> path from A to B), we can not replace the dependency with that path in the BFS search. Because the -(SN)-> dependency can make a strong path with a following -(S*)-> dependency, however an -(SR)-> path cannot. Further, we can replace an -(SN)-> dependency with a -(EN)-> path, that means if we find a path which is stronger than or equal to the about-to-add dependency, we can report the redundancy. By "stronger", it means both the start and the end of the path are not weaker than the start and the end of the dependency (E is "stronger" than S and N is "stronger" than R), so that we can replace the dependency with that path. To make sure we find a path whose start point is not weaker than the about-to-add dependency, we use a trick: the ->only_xr of the root (start point) of __bfs() is initialized as @prev-> == 0, therefore if @prev is E, __bfs() will pick only -(E*)-> for the first dependency, otherwise, __bfs() can pick -(E*)-> or -(S*)-> for the first dependency. To make sure we find a path whose end point is not weaker than the about-to-add dependency, we replace the match function for __bfs() check_redundant(), we check for the case that either @next is R (anything is not weaker than it) or the end point of the path is N (which is not weaker than anything). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-11-boqun.feng@gmail.com
2020-08-26lockdep: Support deadlock detection for recursive read locks in check_noncircular()Boqun Feng1-8/+35
Currently, lockdep only has limit support for deadlock detection for recursive read locks. This patch support deadlock detection for recursive read locks. The basic idea is: We are about to add dependency B -> A in to the dependency graph, we use check_noncircular() to find whether we have a strong dependency path A -> .. -> B so that we have a strong dependency circle (a closed strong dependency path): A -> .. -> B -> A , which doesn't have two adjacent dependencies as -(*R)-> L -(S*)->. Since A -> .. -> B is already a strong dependency path, so if either B -> A is -(E*)-> or A -> .. -> B is -(*N)->, the circle A -> .. -> B -> A is strong, otherwise not. So we introduce a new match function hlock_conflict() to replace the class_equal() for the deadlock check in check_noncircular(). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-10-boqun.feng@gmail.com
2020-08-26lockdep: Make __bfs(.match) return boolBoqun Feng1-10/+10
The "match" parameter of __bfs() is used for checking whether we hit a match in the search, therefore it should return a boolean value rather than an integer for better readability. This patch then changes the return type of the function parameter and the match functions to bool. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-9-boqun.feng@gmail.com
2020-08-26lockdep: Extend __bfs() to work with multiple types of dependenciesBoqun Feng1-19/+94
Now we have four types of dependencies in the dependency graph, and not all the pathes carry real dependencies (the dependencies that may cause a deadlock), for example: Given lock A and B, if we have: CPU1 CPU2 ============= ============== write_lock(A); read_lock(B); read_lock(B); write_lock(A); (assuming read_lock(B) is a recursive reader) then we have dependencies A -(ER)-> B, and B -(SN)-> A, and a dependency path A -(ER)-> B -(SN)-> A. In lockdep w/o recursive locks, a dependency path from A to A means a deadlock. However, the above case is obviously not a deadlock, because no one holds B exclusively, therefore no one waits for the other to release B, so who get A first in CPU1 and CPU2 will run non-blockingly. As a result, dependency path A -(ER)-> B -(SN)-> A is not a real/strong dependency that could cause a deadlock. From the observation above, we know that for a dependency path to be real/strong, no two adjacent dependencies can be as -(*R)-> -(S*)->. Now our mission is to make __bfs() traverse only the strong dependency paths, which is simple: we record whether we only have -(*R)-> for the previous lock_list of the path in lock_list::only_xr, and when we pick a dependency in the traverse, we 1) filter out -(S*)-> dependency if the previous lock_list only has -(*R)-> dependency (i.e. ->only_xr is true) and 2) set the next lock_list::only_xr to true if we only have -(*R)-> left after we filter out dependencies based on 1), otherwise, set it to false. With this extension for __bfs(), we now need to initialize the root of __bfs() properly (with a correct ->only_xr), to do so, we introduce some helper functions, which also cleans up a little bit for the __bfs() root initialization code. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-8-boqun.feng@gmail.com
2020-08-26lockdep: Introduce lock_list::depBoqun Feng1-4/+88
To add recursive read locks into the dependency graph, we need to store the types of dependencies for the BFS later. There are four types of dependencies: * Exclusive -> Non-recursive dependencies: EN e.g. write_lock(prev) held and try to acquire write_lock(next) or non-recursive read_lock(next), which can be represented as "prev -(EN)-> next" * Shared -> Non-recursive dependencies: SN e.g. read_lock(prev) held and try to acquire write_lock(next) or non-recursive read_lock(next), which can be represented as "prev -(SN)-> next" * Exclusive -> Recursive dependencies: ER e.g. write_lock(prev) held and try to acquire recursive read_lock(next), which can be represented as "prev -(ER)-> next" * Shared -> Recursive dependencies: SR e.g. read_lock(prev) held and try to acquire recursive read_lock(next), which can be represented as "prev -(SR)-> next" So we use 4 bits for the presence of each type in lock_list::dep. Helper functions and macros are also introduced to convert a pair of locks into lock_list::dep bit and maintain the addition of different types of dependencies. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-7-boqun.feng@gmail.com
2020-08-26lockdep: Reduce the size of lock_list::distanceBoqun Feng1-3/+3
lock_list::distance is always not greater than MAX_LOCK_DEPTH (which is 48 right now), so a u16 will fit. This patch reduces the size of lock_list::distance to save space, so that we can introduce other fields to help detect recursive read lock deadlocks without increasing the size of lock_list structure. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-6-boqun.feng@gmail.com
2020-08-26lockdep: Make __bfs() visit every dependency until a matchBoqun Feng1-26/+35
Currently, __bfs() will do a breadth-first search in the dependency graph and visit each lock class in the graph exactly once, so for example, in the following graph: A ---------> B | ^ | | +----------> C a __bfs() call starts at A, will visit B through dependency A -> B and visit C through dependency A -> C and that's it, IOW, __bfs() will not visit dependency C -> B. This is OK for now, as we only have strong dependencies in the dependency graph, so whenever there is a traverse path from A to B in __bfs(), it means A has strong dependencies to B (IOW, B depends on A strongly). So no need to visit all dependencies in the graph. However, as we are going to add recursive-read lock into the dependency graph, as a result, not all the paths mean strong dependencies, in the same example above, dependency A -> B may be a weak dependency and traverse A -> C -> B may be a strong dependency path. And with the old way of __bfs() (i.e. visiting every lock class exactly once), we will miss the strong dependency path, which will result into failing to find a deadlock. To cure this for the future, we need to find a way for __bfs() to visit each dependency, rather than each class, exactly once in the search until we find a match. The solution is simple: We used to mark lock_class::lockdep_dependency_gen_id to indicate a class has been visited in __bfs(), now we change the semantics a little bit: we now mark lock_class::lockdep_dependency_gen_id to indicate _all the dependencies_ in its lock_{after,before} have been visited in the __bfs() (note we only take one direction in a __bfs() search). In this way, every dependency is guaranteed to be visited until we find a match. Note: the checks in mark_lock_accessed() and lock_accessed() are removed, because after this modification, we may call these two functions on @source_entry of __bfs(), which may not be the entry in "list_entries" Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-5-boqun.feng@gmail.com
2020-08-26lockdep: Demagic the return value of BFSBoqun Feng1-66/+89
__bfs() could return four magic numbers: 1: search succeeds, but none match. 0: search succeeds, find one match. -1: search fails because of the cq is full. -2: search fails because a invalid node is found. This patch cleans things up by using a enum type for the return value of __bfs() and its friends, this improves the code readability of the code, and further, could help if we want to extend the BFS. Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-4-boqun.feng@gmail.com
2020-08-26locking: More accurate annotations for read_lock()Boqun Feng1-0/+14
On the archs using QUEUED_RWLOCKS, read_lock() is not always a recursive read lock, actually it's only recursive if in_interrupt() is true. So change the annotation accordingly to catch more deadlocks. Note we used to treat read_lock() as pure recursive read locks in lib/locking-seftest.c, and this is useful, especially for the lockdep development selftest, so we keep this via a variable to force switching lock annotation for read_lock(). Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200807074238.1632519-2-boqun.feng@gmail.com
2020-08-26lockdep,trace: Expose tracepointsPeter Zijlstra1-5/+9
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) <peterz@infradead.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Marco Elver <elver@google.com> Link: https://lkml.kernel.org/r/20200821085348.782688941@infradead.org
2020-08-26lockdep: Use raw_cpu_*() for per-cpu variablesPeter Zijlstra1-2/+2
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 <svens@linux.ibm.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200821085348.192346882@infradead.org
2020-08-04Merge tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linuxLinus Torvalds1-8/+8
Pull uninitialized_var() macro removal from Kees Cook: "This is long overdue, and has hidden too many bugs over the years. The series has several "by hand" fixes, and then a trivial treewide replacement. - Clean up non-trivial uses of uninitialized_var() - Update documentation and checkpatch for uninitialized_var() removal - Treewide removal of uninitialized_var()" * tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: compiler: Remove uninitialized_var() macro treewide: Remove uninitialized_var() usage checkpatch: Remove awareness of uninitialized_var() macro mm/debug_vm_pgtable: Remove uninitialized_var() usage f2fs: Eliminate usage of uninitialized_var() macro media: sur40: Remove uninitialized_var() usage KVM: PPC: Book3S PR: Remove uninitialized_var() usage clk: spear: Remove uninitialized_var() usage clk: st: Remove uninitialized_var() usage spi: davinci: Remove uninitialized_var() usage ide: Remove uninitialized_var() usage rtlwifi: rtl8192cu: Remove uninitialized_var() usage b43: Remove uninitialized_var() usage drbd: Remove uninitialized_var() usage x86/mm/numa: Remove uninitialized_var() usage docs: deprecated.rst: Add uninitialized_var()
2020-08-03Merge tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-48/+94
Pull locking updates from Ingo Molnar: - LKMM updates: mostly documentation changes, but also some new litmus tests for atomic ops. - KCSAN updates: the most important change is that GCC 11 now has all fixes in place to support KCSAN, so GCC support can be enabled again. Also more annotations. - futex updates: minor cleanups and simplifications - seqlock updates: merge preparatory changes/cleanups for the 'associated locks' facilities. - lockdep updates: - simplify IRQ trace event handling - add various new debug checks - simplify header dependencies, split out <linux/lockdep_types.h>, decouple lockdep from other low level headers some more - fix NMI handling - misc cleanups and smaller fixes * tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) kcsan: Improve IRQ state trace reporting lockdep: Refactor IRQ trace events fields into struct seqlock: lockdep assert non-preemptibility on seqcount_t write lockdep: Add preemption enabled/disabled assertion APIs seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount() seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs seqlock: Reorder seqcount_t and seqlock_t API definitions seqlock: seqcount_t latch: End read sections with read_seqcount_retry() seqlock: Properly format kernel-doc code samples Documentation: locking: Describe seqlock design and usage locking/qspinlock: Do not include atomic.h from qspinlock_types.h locking/atomic: Move ATOMIC_INIT into linux/types.h lockdep: Move list.h inclusion into lockdep.h locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs futex: Remove unused or redundant includes futex: Consistently use fshared as boolean futex: Remove needless goto's futex: Remove put_futex_key() rwsem: fix commas in initialisation docs: locking: Replace HTTP links with HTTPS ones ...
2020-08-03Merge branch 'locking/nmi' into locking/core, to pick up completed topic branchIngo Molnar1-1/+7
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-07-31lockdep: Refactor IRQ trace events fields into structMarco Elver1-28/+30
Refactor the IRQ trace events fields, used for printing information about the IRQ trace events, into a separate struct 'irqtrace_events'. This improves readability by separating the information only used in reporting, as well as enables (simplified) storing/restoring of irqtrace_events snapshots. No functional change intended. Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200729110916.3920464-1-elver@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-07-27locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIspeterz@infradead.org1-1/+7
Prior to commit: 859d069ee1dd ("lockdep: Prepare for NMI IRQ state tracking") IRQ state tracking was disabled in NMIs due to nmi_enter() doing lockdep_off() -- with the obvious requirement that NMI entry call nmi_enter() before trace_hardirqs_off(). [ AFAICT, PowerPC and SH violate this order on their NMI entry ] However, that commit explicitly changed lockdep_hardirqs_*() to ignore lockdep_off() and breaks every architecture that has irq-tracing in it's NMI entry that hasn't been fixed up (x86 being the only fixed one at this point). The reason for this change is that by ignoring lockdep_off() we can: - get rid of 'current->lockdep_recursion' in lockdep_assert_irqs*() which was going to to give header-recursion issues with the seqlock rework. - allow these lockdep_assert_*() macros to function in NMI context. Restore the previous state of things and allow an architecture to opt-in to the NMI IRQ tracking support, however instead of relying on lockdep_off(), rely on in_nmi(), both are part of nmi_enter() and so over-all entry ordering doesn't need to change. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200727124852.GK119549@hirez.programming.kicks-ass.net
2020-07-16treewide: Remove uninitialized_var() usageKees Cook1-8/+8
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
2020-07-10lockdep: Remove lockdep_hardirq{s_enabled,_context}() argumentPeter Zijlstra1-15/+15
Now that the macros use per-cpu data, we no longer need the argument. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200623083721.571835311@infradead.org
2020-07-10lockdep: Change hardirq{s_enabled,_context} to per-cpu variablesPeter Zijlstra1-15/+15
Currently all IRQ-tracking state is in task_struct, this means that task_struct needs to be defined before we use it. Especially for lockdep_assert_irq*() this can lead to header-hell. Move the hardirq state into per-cpu variables to avoid the task_struct dependency. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200623083721.512673481@infradead.org
2020-07-10lockdep: Prepare for NMI IRQ state trackingPeter Zijlstra1-4/+42
There is no reason not to always, accurately, track IRQ state. This change also makes IRQ state tracking ignore lockdep_off(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20200623083721.155449112@infradead.org
2020-06-29lockdep: Complain only once about RCU in extended quiescent statePaul E. McKenney1-3/+1
Currently, lockdep_rcu_suspicious() complains twice about RCU read-side critical sections being invoked from within extended quiescent states, for example: RCU used illegally from idle CPU! rcu_scheduler_active = 2, debug_locks = 1 RCU used illegally from extended quiescent state! This commit therefore saves a couple lines of code and one line of console-log output by eliminating the first of these two complaints. Link: https://lore.kernel.org/lkml/87wo4wnpzb.fsf@nanos.tec.linutronix.de Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-06-11lockdep: __always_inline more for noinstrPeter Zijlstra1-2/+2
vmlinux.o: warning: objtool: debug_locks_off()+0xd: call to __debug_locks_off() leaves .noinstr.text section vmlinux.o: warning: objtool: match_held_lock()+0x6a: call to look_up_lock_class.isra.0() leaves .noinstr.text section vmlinux.o: warning: objtool: lock_is_held_type()+0x90: call to lockdep_recursion_finish() leaves .noinstr.text section Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200603114052.185201076@infradead.org
2020-06-09kallsyms/printk: add loglvl to print_ip_sym()Dmitry Safonov1-2/+2
Patch series "Add log level to show_stack()", v3. Add log level argument to show_stack(). Done in three stages: 1. Introducing show_stack_loglvl() for every architecture 2. Migrating old users with an explicit log level 3. Renaming show_stack_loglvl() into show_stack() Justification: - It's a design mistake to move a business-logic decision into platform realization detail. - I have currently two patches sets that would benefit from this work: Removing console_loglevel jumps in sysrq driver [1] Hung task warning before panic [2] - suggested by Tetsuo (but he probably didn't realise what it would involve). - While doing (1), (2) the backtraces were adjusted to headers and other messages for each situation - so there won't be a situation when the backtrace is printed, but the headers are missing because they have lesser log level (or the reverse). - As the result in (2) plays with console_loglevel for kdb are removed. The least important for upstream, but maybe still worth to note that every company I've worked in so far had an off-list patch to print backtrace with the needed log level (but only for the architecture they cared about). If you have other ideas how you will benefit from show_stack() with a log level - please, reply to this cover letter. See also discussion on v1: https://lore.kernel.org/linux-riscv/20191106083538.z5nlpuf64cigxigh@pathway.suse.cz/ This patch (of 50): print_ip_sym() needs to have a log level parameter to comply with other parts being printed. Otherwise, half of the expected backtrace would be printed and other may be missing with some logging level. The following callee(s) are using now the adjusted log level: - microblaze/unwind: the same level as headers & userspace unwind. Note that pr_debug()'s there are for debugging the unwinder itself. - nds32/traps: symbol addresses are printed with the same log level as backtrace headers. - lockdep: ip for locking issues is printed with the same log level as other part of the warning. - sched: ip where preemption was disabled is printed as error like the rest part of the message. - ftrace: bug reports are now consistent in the log level being used. Signed-off-by: Dmitry Safonov <dima@arista.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Ben Segall <bsegall@google.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Hogan <jhogan@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Burton <paulburton@kernel.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Will Deacon <will@kernel.org> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Dmitry Safonov <dima@arista.com> Cc: Jiri Slaby <jslaby@suse.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Aurelien Jacquiot <jacquiot.aurelien@gmail.com> Cc: Mark Salter <msalter@redhat.com> Cc: Guo Ren <guoren@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Brian Cain <bcain@codeaurora.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ley Foon Tan <lftan@altera.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stafford Horne <shorne@gmail.com> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Chris Zankel <chris@zankel.net> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Douglas Anderson <dianders@chromium.org> Cc: Jason Wessel <jason.wessel@windriver.com> Link: http://lkml.kernel.org/r/20200418201944.482088-2-dima@arista.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-03Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-21/+65
Pull kvm updates from Paolo Bonzini: "ARM: - Move the arch-specific code into arch/arm64/kvm - Start the post-32bit cleanup - Cherry-pick a few non-invasive pre-NV patches x86: - Rework of TLB flushing - Rework of event injection, especially with respect to nested virtualization - Nested AMD event injection facelift, building on the rework of generic code and fixing a lot of corner cases - Nested AMD live migration support - Optimization for TSC deadline MSR writes and IPIs - Various cleanups - Asynchronous page fault cleanups (from tglx, common topic branch with tip tree) - Interrupt-based delivery of asynchronous "page ready" events (host side) - Hyper-V MSRs and hypercalls for guest debugging - VMX preemption timer fixes s390: - Cleanups Generic: - switch vCPU thread wakeup from swait to rcuwait The other architectures, and the guest side of the asynchronous page fault work, will come next week" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (256 commits) KVM: selftests: fix rdtsc() for vmx_tsc_adjust_test KVM: check userspace_addr for all memslots KVM: selftests: update hyperv_cpuid with SynDBG tests x86/kvm/hyper-v: Add support for synthetic debugger via hypercalls x86/kvm/hyper-v: enable hypercalls regardless of hypercall page x86/kvm/hyper-v: Add support for synthetic debugger interface x86/hyper-v: Add synthetic debugger definitions KVM: selftests: VMX preemption timer migration test KVM: nVMX: Fix VMX preemption timer migration x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit KVM: x86/pmu: Support full width counting KVM: x86/pmu: Tweak kvm_pmu_get_msr to pass 'struct msr_data' in KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT KVM: x86: acknowledgment mechanism for async pf page ready notifications KVM: x86: interrupt based APF 'page ready' event delivery KVM: introduce kvm_read_guest_offset_cached() KVM: rename kvm_arch_can_inject_async_page_present() to kvm_arch_can_dequeue_async_page_present() KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously" KVM: VMX: Replace zero-length array with flexible-array ...
2020-06-01Merge tag 'locking-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-1/+1
Pull locking updates from Ingo Molnar: "The biggest change to core locking facilities in this cycle is the introduction of local_lock_t - this primitive comes from the -rt project and identifies CPU-local locking dependencies normally handled opaquely beind preempt_disable() or local_irq_save/disable() critical sections. The generated code on mainline kernels doesn't change as a result, but still there are benefits: improved debugging and better documentation of data structure accesses. The new local_lock_t primitives are introduced and then utilized in a couple of kernel subsystems. No change in functionality is intended. There's also other smaller changes and cleanups" * tag 'locking-core-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: zram: Use local lock to protect per-CPU data zram: Allocate struct zcomp_strm as per-CPU memory connector/cn_proc: Protect send_msg() with a local lock squashfs: Make use of local lock in multi_cpu decompressor mm/swap: Use local_lock for protection radix-tree: Use local_lock for protection locking: Introduce local_lock() locking/lockdep: Replace zero-length array with flexible-array locking/rtmutex: Remove unused rt_mutex_cmpxchg_relaxed()
2020-05-19locking/lockdep: Replace zero-length array with flexible-arrayGustavo A. R. Silva1-1/+1
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200507185804.GA15036@embeddedor
2020-05-19lockdep: Always inline lockdep_{off,on}()Peter Zijlstra1-19/+0
These functions are called {early,late} in nmi_{enter,exit} and should not be traced or probed. They are also puny, so 'inline' them. Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134101.048523500@linutronix.de
2020-05-19lockdep: Prepare for noinstr sectionsPeter Zijlstra1-21/+65
Force inlining and prevent instrumentation of all sorts by marking the functions which are invoked from low level entry code with 'noinstr'. Split the irqflags tracking into two parts. One which does the heavy lifting while RCU is watching and the final one which can be invoked after RCU is turned off. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Link: https://lkml.kernel.org/r/20200505134100.484532537@linutronix.de
2020-04-08locking/lockdep: Improve 'invalid wait context' splatPeter Zijlstra1-20/+31
The 'invalid wait context' splat doesn't print all the information required to reconstruct / validate the error, specifically the irq-context state is missing. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-03-30Merge tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds1-6/+6
Pull x86 entry code updates from Thomas Gleixner: - Convert the 32bit syscalls to be pt_regs based which removes the requirement to push all 6 potential arguments onto the stack and consolidates the interface with the 64bit variant - The first small portion of the exception and syscall related entry code consolidation which aims to address the recently discovered issues vs. RCU, int3, NMI and some other exceptions which can interrupt any context. The bulk of the changes is still work in progress and aimed for 5.8. - A few lockdep namespace cleanups which have been applied into this branch to keep the prerequisites for the ongoing work confined. * tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits) x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}() lockdep: Rename trace_softirqs_{on,off}() lockdep: Rename trace_hardirq_{enter,exit}() x86/entry: Rename ___preempt_schedule x86: Remove unneeded includes x86/entry: Drop asmlinkage from syscalls x86/entry/32: Enable pt_regs based syscalls x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments x86/entry/32: Rename 32-bit specific syscalls x86/entry/32: Clean up syscall_32.tbl x86/entry: Remove ABI prefixes from functions in syscall tables x86/entry/64: Add __SYSCALL_COMMON() x86/entry: Remove syscall qualifier support x86/entry/64: Remove ptregs qualifier from syscall table x86/entry: Move max syscall number calculation to syscallhdr.sh x86/entry/64: Split X32 syscall table into its own file x86/entry/64: Move sys_ni_syscall stub to common.c x86/entry/64: Use syscall wrappers for x32_rt_sigreturn x86/entry: Refactor SYS_NI macros ...
2020-03-21lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}()Peter Zijlstra1-4/+4
Continue what commit: d820ac4c2fa8 ("locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit]") started, rename these to avoid confusing them with tracepoints. git grep -l "trace_\(soft\|hard\)\(irq_context\|irqs_enabled\)" | while read file; do sed -ie 's/trace_\(soft\|hard\)\(irq_context\|irqs_enabled\)/lockdep_\1\2/g' $file; done Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Will Deacon <will@kernel.org> Link: https://lkml.kernel.org/r/20200320115859.178626842@infradead.org
2020-03-21lockdep: Rename trace_softirqs_{on,off}()Peter Zijlstra1-2/+2
Continue what commit: d820ac4c2fa8 ("locking: rename trace_softirq_[enter|exit] => lockdep_softirq_[enter|exit]") started, rename these to avoid confusing them with tracepoints. git grep -l "trace_softirqs_\(on\|off\)" | while read file; do sed -ie 's/trace_softirqs_\(on\|off\)/lockdep_softirqs_\1/g' $file; done Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Will Deacon <will@kernel.org> Link: https://lkml.kernel.org/r/20200320115859.119434738@infradead.org
2020-03-21lockdep: Add hrtimer context tracing bitsSebastian Andrzej Siewior1-1/+1
Set current->irq_config = 1 for hrtimers which are not marked to expire in hard interrupt context during hrtimer_init(). These timers will expire in softirq context on PREEMPT_RT. Setting this allows lockdep to differentiate these timers. If a timer is marked to expire in hard interrupt context then the timer callback is not supposed to acquire a regular spinlock instead of a raw_spinlock in the expiry callback. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200321113242.534508206@linutronix.de
2020-03-21lockdep: Introduce wait-type checksPeter Zijlstra1-6/+132
Extend lockdep to validate lock wait-type context. The current wait-types are: LD_WAIT_FREE, /* wait free, rcu etc.. */ LD_WAIT_SPIN, /* spin loops, raw_spinlock_t etc.. */ LD_WAIT_CONFIG, /* CONFIG_PREEMPT_LOCK, spinlock_t etc.. */ LD_WAIT_SLEEP, /* sleeping locks, mutex_t etc.. */ Where lockdep validates that the current lock (the one being acquired) fits in the current wait-context (as generated by the held stack). This ensures that there is no attempt to acquire mutexes while holding spinlocks, to acquire spinlocks while holding raw_spinlocks and so on. In other words, its a more fancy might_sleep(). Obviously RCU made the entire ordeal more complex than a simple single value test because RCU can be acquired in (pretty much) any context and while it presents a context to nested locks it is not the same as it got acquired in. Therefore its necessary to split the wait_type into two values, one representing the acquire (outer) and one representing the nested context (inner). For most 'normal' locks these two are the same. [ To make static initialization easier we have the rule that: .outer == INV means .outer == .inner; because INV == 0. ] It further means that its required to find the minimal .inner of the held stack to compare against the outer of the new lock; because while 'normal' RCU presents a CONFIG type to nested locks, if it is taken while already holding a SPIN type it obviously doesn't relax the rules. Below is an example output generated by the trivial test code: raw_spin_lock(&foo); spin_lock(&bar); spin_unlock(&bar); raw_spin_unlock(&foo); [ BUG: Invalid wait context ] ----------------------------- swapper/0/1 is trying to lock: ffffc90000013f20 (&bar){....}-{3:3}, at: kernel_init+0xdb/0x187 other info that might help us debug this: 1 lock held by swapper/0/1: #0: ffffc90000013ee0 (&foo){+.+.}-{2:2}, at: kernel_init+0xd1/0x187 The way to read it is to look at the new -{n,m} part in the lock description; -{3:3} for the attempted lock, and try and match that up to the held locks, which in this case is the one: -{2,2}. This tells that the acquiring lock requires a more relaxed environment than presented by the lock stack. Currently only the normal locks and RCU are converted, the rest of the lockdep users defaults to .inner = INV which is ignored. More conversions can be done when desired. The check for spinlock_t nesting is not enabled by default. It's a separate config option for now as there are known problems which are currently addressed. The config option allows to identify these problems and to verify that the solutions found are indeed solving them. The config switch will be removed and the checks will permanently enabled once the vast majority of issues has been addressed. [ bigeasy: Move LD_WAIT_FREE,… out of CONFIG_LOCKDEP to avoid compile failure with CONFIG_DEBUG_SPINLOCK + !CONFIG_LOCKDEP] [ tglx: Add the config option ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200321113242.427089655@linutronix.de
2020-03-20lockdep: Teach lockdep about "USED" <- "IN-NMI" inversionsPeter Zijlstra1-3/+59
nmi_enter() does lockdep_off() and hence lockdep ignores everything. And NMI context makes it impossible to do full IN-NMI tracking like we do IN-HARDIRQ, that could result in graph_lock recursion. However, since look_up_lock_class() is lockless, we can find the class of a lock that has prior use and detect IN-NMI after USED, just not USED after IN-NMI. NOTE: By shifting the lockdep_off() recursion count to bit-16, we can easily differentiate between actual recursion and off. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lkml.kernel.org/r/20200221134215.090538203@infradead.org
2020-03-20locking/lockdep: Rework lockdep_lockPeter Zijlstra1-41/+48
A few sites want to assert we own the graph_lock/lockdep_lock, provide a more conventional lock interface for it with a number of trivial debug checks. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200313102107.GX12561@hirez.programming.kicks-ass.net
2020-03-20locking/lockdep: Fix bad recursion patternPeter Zijlstra1-34/+40
There were two patterns for lockdep_recursion: Pattern-A: if (current->lockdep_recursion) return current->lockdep_recursion = 1; /* do stuff */ current->lockdep_recursion = 0; Pattern-B: current->lockdep_recursion++; /* do stuff */ current->lockdep_recursion--; But a third pattern has emerged: Pattern-C: current->lockdep_recursion = 1; /* do stuff */ current->lockdep_recursion = 0; And while this isn't broken per-se, it is highly dangerous because it doesn't nest properly. Get rid of all Pattern-C instances and shore up Pattern-A with a warning. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200313093325.GW12561@hirez.programming.kicks-ass.net
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