linux-stable.git/include/linux/rcupdate.h, branch v6.6.26

rcu: add a helper to report consolidated flavor QS

2024-03-26T22:20:12+00:00

[ Upstream commit 1a77557d48cff187a169c2aec01c0dd78a5e7e50 ]

When under heavy load, network processing can run CPU-bound for many
tens of seconds. Even in preemptible kernels (non-RT kernel), this can
block RCU Tasks grace periods, which can cause trace-event removal to
take more than a minute, which is unacceptably long.

This commit therefore creates a new helper function that passes through
both RCU and RCU-Tasks quiescent states every 100 milliseconds. This
hard-coded value suffices for current workloads.

Suggested-by: Paul E. McKenney 
Reviewed-by: Jesper Dangaard Brouer 
Signed-off-by: Yan Zhai 
Reviewed-by: Paul E. McKenney 
Acked-by: Jesper Dangaard Brouer 
Link: https://lore.kernel.org/r/90431d46ee112d2b0af04dbfe936faaca11810a5.1710877680.git.yan@cloudflare.com
Signed-off-by: Jakub Kicinski 
Stable-dep-of: d6dbbb11247c ("net: report RCU QS on threaded NAPI repolling")
Signed-off-by: Sasha Levin

srcu: Use try-lock lockdep annotation for NMI-safe access.

2024-01-25T23:35:49+00:00

[ Upstream commit 3c6b0c1c28184038d90dffe8eb542bedcb8ccf98 ]

It is claimed that srcu_read_lock_nmisafe() NMI-safe. However it
triggers a lockdep if used from NMI because lockdep expects a deadlock
since nothing disables NMIs while the lock is acquired.

This is because commit f0f44752f5f61 ("rcu: Annotate SRCU's update-side
lockdep dependencies") annotates synchronize_srcu() as a write lock
usage. This helps to detect a deadlocks such as
	srcu_read_lock();
	synchronize_srcu();
	srcu_read_unlock();

The side effect is that the lock srcu_struct now has a USED usage in normal
contexts, so it conflicts with a USED_READ usage in NMI. But this shouldn't
cause a real deadlock because the write lock usage from synchronize_srcu()
is a fake one and only used for read/write deadlock detection.

Use a try-lock annotation for srcu_read_lock_nmisafe() to avoid lockdep
complains if used from NMI.

Fixes: f0f44752f5f6 ("rcu: Annotate SRCU's update-side lockdep dependencies")
Link: https://lore.kernel.org/r/20230927160231.XRCDDSK4@linutronix.de
Reviewed-by: Boqun Feng 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Neeraj Upadhyay (AMD) 
Signed-off-by: Sasha Levin

Merge tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue

2023-07-04T20:50:38+00:00

Pull scope-based resource management infrastructure from Peter Zijlstra:
 "These are the first few patches in the Scope-based Resource Management
  series that introduce the infrastructure but not any conversions as of
  yet.

  Adding the infrastructure now allows multiple people to start using
  them.

  Of note is that Sparse will need some work since it doesn't yet
  understand this attribute and might have decl-after-stmt issues"

* tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue:
  kbuild: Drop -Wdeclaration-after-statement
  locking: Introduce __cleanup() based infrastructure
  apparmor: Free up __cleanup() name
  dmaengine: ioat: Free up __cleanup() name

locking: Introduce __cleanup() based infrastructure

2023-06-26T09:14:18+00:00

Use __attribute__((__cleanup__(func))) to build:

 - simple auto-release pointers using __free()

 - 'classes' with constructor and destructor semantics for
   scope-based resource management.

 - lock guards based on the above classes.

Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org

Merge branches 'doc.2023.05.10a', 'fixes.2023.05.11a', 'kvfree.2023.05.10a', 'nocb.2023.05.11a', 'rcu-tasks.2023.05.10a', 'torture.2023.05.15a' and 'rcu-urgent.2023.06.06a' into HEAD

2023-06-07T20:44:06+00:00

doc.2023.05.10a: Documentation updates
fixes.2023.05.11a: Miscellaneous fixes
kvfree.2023.05.10a: kvfree_rcu updates
nocb.2023.05.11a: Callback-offloading updates
rcu-tasks.2023.05.10a: Tasks RCU updates
torture.2023.05.15a: Torture-test updates
rcu-urgent.2023.06.06a: Urgent SRCU fix

rcu: Remove RCU_NONIDLE()

2023-05-11T20:42:04+00:00

Since there are now exactly _zero_ users of RCU_NONIDLE(), make it go
away before someone else decides to (ab)use it.

[ paulmck: Remove extraneous whitespace. ]

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Mark Rutland 
Acked-by: Frederic Weisbecker 
Signed-off-by: Paul E. McKenney

rcu/kvfree: Eliminate k[v]free_rcu() single argument macro

2023-05-10T00:26:20+00:00

The kvfree_rcu() and kfree_rcu() APIs are hazardous in that if you forget
the second argument, it works, but might sleep.  This sleeping can be a
correctness bug from atomic contexts, and even in non-atomic contexts it
might introduce unacceptable latencies.  This commit therefore removes the
single-argument kvfree_rcu() and kfree_rcu() macros.  Code that would have
previously used these single-argument kvfree_rcu() and kfree_rcu() macros
should instead use kvfree_rcu_mightsleep() or kfree_rcu_mightsleep().

[ paulmck: Apply Joel Fernandes feedback. ]

Signed-off-by: Uladzislau Rezki (Sony) 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Joel Fernandes (Google)

mm/slab: document kfree() as allowed for kmem_cache_alloc() objects

2023-03-29T08:35:41+00:00

This will make it easier to free objects in situations when they can
come from either kmalloc() or kmem_cache_alloc(), and also allow
kfree_rcu() for freeing objects from kmem_cache_alloc().

For the SLAB and SLUB allocators this was always possible so with SLOB
gone, we can document it as supported.

Signed-off-by: Vlastimil Babka 
Reviewed-by: Mike Rapoport (IBM) 
Cc: Jonathan Corbet 
Cc: "Paul E. McKenney" 
Cc: Frederic Weisbecker 
Cc: Neeraj Upadhyay 
Cc: Josh Triplett 
Cc: Steven Rostedt 
Cc: Mathieu Desnoyers 
Cc: Lai Jiangshan 
Cc: Joel Fernandes

Merge branches 'doc.2023.01.05a', 'fixes.2023.01.23a', 'kvfree.2023.01.03a', 'srcu.2023.01.03a', 'srcu-always.2023.02.02a', 'tasks.2023.01.03a', 'torture.2023.01.05a' and 'torturescript.2023.01.03a' into HEAD

2023-02-03T00:33:43+00:00

doc.2023.01.05a: Documentation update.
fixes.2023.01.23a: Miscellaneous fixes.
kvfree.2023.01.03a: kvfree_rcu() updates.
srcu.2023.01.03a: SRCU updates.
srcu-always.2023.02.02a: Finish making SRCU be unconditionally available.
tasks.2023.01.03a: Tasks-RCU updates.
torture.2023.01.05a: Torture-test updates.
torturescript.2023.01.03a: Torture-test scripting updates.

rcu/kvfree: Add kvfree_rcu_mightsleep() and kfree_rcu_mightsleep()

2023-02-03T00:28:07+00:00

The kvfree_rcu() and kfree_rcu() APIs are hazardous in that if you forget
the second argument, it works, but might sleep.  This sleeping can be a
correctness bug from atomic contexts, and even in non-atomic contexts
it might introduce unacceptable latencies.  This commit therefore adds
kvfree_rcu_mightsleep() and kfree_rcu_mightsleep(), which will replace
the single-argument kvfree_rcu() and kfree_rcu(), respectively.

This commit enables a series of commits that switch from single-argument
kvfree_rcu() and kfree_rcu() to their _mightsleep() counterparts.  Once
all of these commits land, the single-argument versions will be removed.

Signed-off-by: Uladzislau Rezki (Sony) 
Signed-off-by: Paul E. McKenney