user/sven/linux.git/kernel/rcu/update.c, branch v5.15.141

Merge branches 'bitmaprange.2021.05.10c', 'doc.2021.05.10c', 'fixes.2021.05.13a', 'kvfree_rcu.2021.05.10c', 'mmdumpobj.2021.05.10c', 'nocb.2021.05.12a', 'srcu.2021.05.12a', 'tasks.2021.05.18a' and 'torture.2021.05.10c' into HEAD

2021-05-18T17:56:19Z

bitmaprange.2021.05.10c: Allow "all" for bitmap ranges. doc.2021.05.10c: Documentation updates. fixes.2021.05.13a: Miscellaneous fixes. kvfree_rcu.2021.05.10c: kvfree_rcu() updates. mmdumpobj.2021.05.10c: mem_dump_obj() updates. nocb.2021.05.12a: RCU NOCB CPU updates, including limited deoffloading. srcu.2021.05.12a: SRCU updates. tasks.2021.05.18a: Tasks-RCU updates. torture.2021.05.10c: Torture-test updates.

srcu: Early test SRCU polling start

2021-05-12T19:12:33Z

Place an early call to start_poll_synchronize_srcu() before the invocation of call_srcu() on the same srcu_struct structure. After the later call to srcu_barrier(), the completion of the first grace period should be visible to a subsequent invocation of poll_state_synchronize_srcu(), and if not, warn. Signed-off-by: Frederic Weisbecker Cc: Boqun Feng Cc: Lai Jiangshan Cc: Neeraj Upadhyay Cc: Josh Triplett Cc: Joel Fernandes Cc: Uladzislau Rezki Signed-off-by: Paul E. McKenney

rcu: Reject RCU_LOCKDEP_WARN() false positives

2021-05-10T23:22:54Z

If another lockdep report runs concurrently with an RCU lockdep report from RCU_LOCKDEP_WARN(), the following sequence of events can occur: 1. debug_lockdep_rcu_enabled() sees that lockdep is enabled when called from (say) synchronize_rcu(). 2. Lockdep is disabled by a concurrent lockdep report. 3. debug_lockdep_rcu_enabled() evaluates its lockdep-expression argument, for example, lock_is_held(&rcu_bh_lock_map). 4. Because lockdep is now disabled, lock_is_held() plays it safe and returns the constant 1. 5. But in this case, the constant 1 is not safe, because invoking synchronize_rcu() under rcu_read_lock_bh() is disallowed. 6. debug_lockdep_rcu_enabled() wrongly invokes lockdep_rcu_suspicious(), resulting in a false-positive splat. This commit therefore changes RCU_LOCKDEP_WARN() to check debug_lockdep_rcu_enabled() after checking the lockdep expression, so that any "safe" returns from lock_is_held() are rejected by debug_lockdep_rcu_enabled(). This requires memory ordering, which is supplied by READ_ONCE(debug_locks). The resulting volatile accesses prevent the compiler from reordering and the fact that only one variable is being accessed prevents the underlying hardware from reordering. The combination works for IA64, which can reorder reads to the same location, but this is defeated by the volatile accesses, which compile to load instructions that provide ordering. Reported-by: syzbot+dde0cc33951735441301@syzkaller.appspotmail.com Reported-by: Matthew Wilcox Reported-by: syzbot+88e4f02896967fe1ab0d@syzkaller.appspotmail.com Reported-by: Thomas Gleixner Suggested-by: Boqun Feng Reviewed-by: Boqun Feng Signed-off-by: Paul E. McKenney

rcu: Enable rcu_normal_after_boot unconditionally for RT

2021-01-04T21:43:51Z

Expedited RCU grace periods send IPIs to all non-idle CPUs, and thus can disrupt time-critical code in real-time applications. However, there is a portion of boot-time processing (presumably before any real-time applications have started) where expedited RCU grace periods are the only option. And so it is that experience with the -rt patchset indicates that PREEMPT_RT systems should always set the rcupdate.rcu_normal_after_boot kernel boot parameter. This commit therefore makes the post-boot application environment safe for real-time applications by making PREEMPT_RT systems disable the rcupdate.rcu_normal_after_boot kernel boot parameter and acting as if this parameter had been set. This means that post-boot calls to synchronize_rcu_expedited() will be treated as if they were instead calls to synchronize_rcu(), thus preventing the IPIs, and thus avoiding disrupting real-time applications. Suggested-by: Luiz Capitulino Acked-by: Paul E. McKenney Signed-off-by: Julia Cartwright Signed-off-by: Sebastian Andrzej Siewior [ paulmck: Update kernel-parameters.txt accordingly. ] Signed-off-by: Paul E. McKenney

Merge tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-10-18T21:34:50Z

Pull RCU changes from Ingo Molnar: - Debugging for smp_call_function() - RT raw/non-raw lock ordering fixes - Strict grace periods for KASAN - New smp_call_function() torture test - Torture-test updates - Documentation updates - Miscellaneous fixes [ This doesn't actually pull the tag - I've dropped the last merge from the RCU branch due to questions about the series. - Linus ] * tag 'core-rcu-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) smp: Make symbol 'csd_bug_count' static kernel/smp: Provide CSD lock timeout diagnostics smp: Add source and destination CPUs to __call_single_data rcu: Shrink each possible cpu krcp rcu/segcblist: Prevent useless GP start if no CBs to accelerate torture: Add gdb support rcutorture: Allow pointer leaks to test diagnostic code rcutorture: Hoist OOM registry up one level refperf: Avoid null pointer dereference when buf fails to allocate rcutorture: Properly synchronize with OOM notifier rcutorture: Properly set rcu_fwds for OOM handling torture: Add kvm.sh --help and update help message rcutorture: Add CONFIG_PROVE_RCU_LIST to TREE05 torture: Update initrd documentation rcutorture: Replace HTTP links with HTTPS ones locktorture: Make function torture_percpu_rwsem_init() static torture: document --allcpus argument added to the kvm.sh script rcutorture: Output number of elapsed grace periods rcutorture: Remove KCSAN stubs rcu: Remove unused "cpu" parameter from rcu_report_qs_rdp() ...

treewide: Make all debug_obj_descriptors const

2020-09-24T19:56:25Z

This should make it harder for the kernel to corrupt the debug object descriptor, used to call functions to fixup state and track debug objects, by moving the structure to read-only memory. Signed-off-by: Stephen Boyd Signed-off-by: Thomas Gleixner Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20200815004027.2046113-3-swboyd@chromium.org

rcu: Remove KCSAN stubs from update.c

2020-08-25T01:36:03Z

KCSAN is now in mainline, so this commit removes the stubs for the data_race(), ASSERT_EXCLUSIVE_WRITER(), and ASSERT_EXCLUSIVE_ACCESS() macros. Signed-off-by: Paul E. McKenney

Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD

2020-06-29T19:03:15Z

doc.2020.06.29a: Documentation updates. fixes.2020.06.29a: Miscellaneous fixes. kfree_rcu.2020.06.29a: kfree_rcu() updates. rcu-tasks.2020.06.29a: RCU Tasks updates. scale.2020.06.29a: Read-side scalability tests. srcu.2020.06.29a: SRCU updates. torture.2020.06.29a: Torture-test updates.

rcu-tasks: Add #include of rcupdate_trace.h to update.c

2020-06-29T19:00:22Z

Although this is in some strict sense unnecessary, it is good to allow the compiler to compare the function declaration with its definition. This commit therefore adds a #include of linux/rcupdate_trace.h to kernel/rcu/update.c. Reported-by: kbuild test robot Signed-off-by: Paul E. McKenney

rcu: Replace 1 with true

2020-06-29T18:58:51Z

Coccinelle reports a warning WARNING: Assignment of 0/1 to bool variable The root cause is that the variable lastphase is a bool, but is initialised with integer 1. This commit therefore replaces the 1 with a true. Signed-off-by: Jules Irenge Signed-off-by: Paul E. McKenney