Paul E. McKenney [Fri, 23 Aug 2024 21:15:12 +0000 (14:15 -0700)]
rcu: Defer printing stall-warning backtrace when holding rcu_node lock
The rcu_dump_cpu_stacks() holds the leaf rcu_node structure's ->lock
when dumping the stakcks of any CPUs stalling the current grace period.
This lock is held to prevent confusion that would otherwise occur when
the stalled CPU reported its quiescent state (and then went on to do
unrelated things) just as the backtrace NMI was heading towards it.
This has worked well, but on larger systems has recently been observed
to cause severe lock contention resulting in CSD-lock stalls and other
general unhappiness.
This commit therefore does printk_deferred_enter() before acquiring
the lock and printk_deferred_exit() after releasing it, thus deferring
the overhead of actually outputting the stack trace out of that lock's
critical section.
Reported-by: Rik van Riel <riel@surriel.com> Suggested-by: Rik van Riel <riel@surriel.com> Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Tue, 13 Aug 2024 22:56:42 +0000 (00:56 +0200)]
rcu/nocb: Remove superfluous memory barrier after bypass enqueue
Pre-GP accesses performed by the update side must be ordered against
post-GP accesses performed by the readers. This is ensured by the
bypass or nocb locking on enqueue time, followed by the fully ordered
rnp locking initiated while callbacks are accelerated, and then
propagated throughout the whole GP lifecyle associated with the
callbacks.
Therefore the explicit barrier advertizing ordering between bypass
enqueue and rcuo wakeup is superfluous. If anything, it would even only
order the first bypass callback enqueue against the rcuo wakeup and
ignore all the subsequent ones.
Frederic Weisbecker [Tue, 13 Aug 2024 22:56:41 +0000 (00:56 +0200)]
rcu/nocb: Conditionally wake up rcuo if not already waiting on GP
A callback enqueuer currently wakes up the rcuo kthread if it is adding
the first non-done callback of a CPU, whether the kthread is waiting on
a grace period or not (unless the CPU is offline).
This looks like a desired behaviour because then the rcuo kthread
doesn't wait for the end of the current grace period to handle the
callback. It is accelerated right away and assigned to the next grace
period. The GP kthread is notified about that fact and iterates with
the upcoming GP without sleeping in-between.
However this best-case scenario is contradicted by a few details,
depending on the situation:
1) If the callback is a non-bypass one queued with IRQs enabled, the
wake up only occurs if no other pending callbacks are on the list.
Therefore the theoretical "optimization" actually applies on rare
occasions.
2) If the callback is a non-bypass one queued with IRQs disabled, the
situation is similar with even more uncertainty due to the deferred
wake up.
3) If the callback is lazy, a few jiffies don't make any difference.
4) If the callback is bypass, the wake up timer is programmed 2 jiffies
ahead by rcuo in case the regular pending queue has been handled
in the meantime. The rare storm of callbacks can otherwise wait for
the currently elapsing grace period to be flushed and handled.
For all those reasons, the optimization is only theoretical and
occasional. Therefore it is reasonable that callbacks enqueuers only
wake up the rcuo kthread when it is not already waiting on a grace
period to complete.
Frederic Weisbecker [Tue, 13 Aug 2024 22:56:40 +0000 (00:56 +0200)]
rcu/nocb: Fix RT throttling hrtimer armed from offline CPU
After a CPU is marked offline and until it reaches its final trip to
idle, rcuo has several opportunities to be woken up, either because
a callback has been queued in the meantime or because
rcutree_report_cpu_dead() has issued the final deferred NOCB wake up.
If RCU-boosting is enabled, RCU kthreads are set to SCHED_FIFO policy.
And if RT-bandwidth is enabled, the related hrtimer might be armed.
However this then happens after hrtimers have been migrated at the
CPUHP_AP_HRTIMERS_DYING stage, which is broken as reported by the
following warning:
Fix this with waking up rcuo using an IPI if necessary. Since the
existing API to deal with this situation only handles swait queue, rcuo
is only woken up from offline CPUs if it's not already waiting on a
grace period. In the worst case some callbacks will just wait for a
grace period to complete before being assigned to a subsequent one.
Reported-by: "Cheng-Jui Wang (王正睿)" <Cheng-Jui.Wang@mediatek.com> Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Now that the (de-)offloading process can only apply to offline CPUs,
there is no more concurrency between rcu_core and nocb kthreads. Also
the mutation now happens on empty queues.
Therefore the state machine can be reduced to a single bit called
SEGCBLIST_OFFLOADED. Simplify the transition as follows:
* Upon offloading: queue the rdp to be added to the rcuog list and
wait for the rcuog kthread to set the SEGCBLIST_OFFLOADED bit. Unpark
rcuo kthread.
* Upon de-offloading: Park rcuo kthread. Queue the rdp to be removed
from the rcuog list and wait for the rcuog kthread to clear the
SEGCBLIST_OFFLOADED bit.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Sean Christopherson [Mon, 17 Jun 2024 15:51:14 +0000 (08:51 -0700)]
context_tracking: Tag context_tracking_enabled_this_cpu() __always_inline
Force context_tracking_enabled_this_cpu() to be inlined so that invoking
it from guest_context_enter_irqoff(), which KVM uses in non-instrumentable
code, doesn't unexpectedly leave a noinstr section.
vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1c7: call to
context_tracking_enabled_this_cpu() leaves .noinstr.text section
vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x83: call to
context_tracking_enabled_this_cpu() leaves .noinstr.text section
Note, the CONFIG_CONTEXT_TRACKING_USER=n stub is already __always_inline.
Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
rcu: Rename rcu_implicit_dynticks_qs() into rcu_watching_snap_recheck()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, drop the dyntick reference and update the name of this helper
to express that it rechecks rdp->watching_snap after an earlier
rcu_watching_snap_save().
rcu: Rename dyntick_save_progress_counter() into rcu_watching_snap_save()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
rcu: Rename struct rcu_data .exp_dynticks_snap into .exp_watching_snap
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the snapshot helpers are now prefix by
"rcu_watching". Reflect that change into the storage variables for these
snapshots.
rcu: Rename struct rcu_data .dynticks_snap into .watching_snap
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the snapshot helpers are now prefix by
"rcu_watching". Reflect that change into the storage variables for these
snapshots.
rcu: Rename rcu_dynticks_in_eqs_since() into rcu_watching_snap_stopped_since()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, the dynticks prefix can go.
While at it, this helper is only meant to be called after failing an
earlier call to rcu_watching_snap_in_eqs(), document this in the comments
and add a WARN_ON_ONCE() for good measure.
context_tracking, rcu: Rename rcu_dynticks_task*() into rcu_task*()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
While at it, flip the suffixes of these helpers. We are not telling
that we are entering dynticks mode from an RCU-task perspective anymore; we
are telling that we are exiting RCU-tasks because we are in eqs mode.
Paul E. McKenney [Fri, 2 Aug 2024 00:43:08 +0000 (17:43 -0700)]
rcuscale: Count outstanding callbacks per-task rather than per-CPU
The current rcu_scale_writer() asynchronous grace-period testing uses a
per-CPU counter to track the number of outstanding callbacks. This is
subject to CPU-imbalance errors when tasks migrate from one CPU to another
between the time that the counter is incremented and the callback is
queued, and additionally in kernels configured such that callbacks can
be invoked on some CPU other than the one that queued it.
This commit therefore arranges for per-task callback counts, thus avoiding
any issues with migration of either tasks or callbacks.
Paul E. McKenney [Fri, 2 Aug 2024 00:43:07 +0000 (17:43 -0700)]
rcuscale: NULL out top-level pointers to heap memory
Currently, if someone modprobes and rmmods rcuscale successfully, but
the next run errors out during the modprobe, non-NULL pointers to freed
memory will remain. If the run after that also errors out during the
modprobe, there will be double-free bugs.
This commit therefore NULLs out top-level pointers to memory that has
just been freed.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:06 +0000 (17:43 -0700)]
rcuscale: Use special allocator for rcu_scale_writer()
The rcu_scale_writer() function needs only a fixed number of rcu_head
structures per kthread, which means that a trivial allocator suffices.
This commit therefore uses an llist-based allocator using a fixed array of
structures per kthread. This allows aggressive testing of RCU performance
without stressing the slab allocators.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:05 +0000 (17:43 -0700)]
rcuscale: Make rcu_scale_writer() tolerate repeated GFP_KERNEL failure
Under some conditions, kmalloc(GFP_KERNEL) allocations have been
observed to repeatedly fail. This situation has been observed to
cause one of the rcu_scale_writer() instances to loop indefinitely
retrying memory allocation for an asynchronous grace-period primitive.
The problem is that if memory is short, all the other instances will
allocate all available memory before the looping task is awakened from
its rcu_barrier*() call. This in turn results in hangs, so that rcuscale
fails to complete.
This commit therefore removes the tight retry loop, so that when this
condition occurs, the affected task is still passing through the full
loop with its full set of termination checks. This spreads the risk
of indefinite memory-allocation retry failures across all instances of
rcu_scale_writer() tasks, which in turn prevents the hangs.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:03 +0000 (17:43 -0700)]
rcuscale: Provide clear error when async specified without primitives
Currently, if the rcuscale module's async module parameter is specified
for RCU implementations that do not have async primitives such as RCU
Tasks Rude (which now lacks a call_rcu_tasks_rude() function), there
will be a series of splats due to calls to a NULL pointer. This commit
therefore warns of this situation, but switches to non-async testing.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Ryo Takakura [Fri, 28 Jun 2024 04:18:26 +0000 (13:18 +0900)]
rcu: Let dump_cpu_task() be used without preemption disabled
The commit 2d7f00b2f0130 ("rcu: Suppress smp_processor_id() complaint
in synchronize_rcu_expedited_wait()") disabled preemption around
dump_cpu_task() to suppress warning on its usage within preemtible context.
Calling dump_cpu_task() doesn't required to be in non-preemptible context
except for suppressing the smp_processor_id() warning.
As the smp_processor_id() is evaluated along with in_hardirq()
to check if it's in interrupt context, this patch removes the need
for its preemtion disablement by reordering the condition so that
smp_processor_id() only gets evaluated when it's in interrupt context.
Signed-off-by: Ryo Takakura <takakura@valinux.co.jp> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Tue, 2 Jul 2024 04:24:29 +0000 (21:24 -0700)]
rcu: Summarize expedited RCU CPU stall warnings during CSD-lock stalls
During CSD-lock stalls, the additional information output by expedited
RCU CPU stall warnings is usually redundant, flooding the console for
not good reason. However, this has been the way things work for a few
years. This commit therefore uses rcutree.csd_lock_suppress_rcu_stall
kernel boot parameter that causes expedited RCU CPU stall warnings to
be abbreviated to a single line when there is at least one CPU that has
been stuck waiting for CSD lock for more than five seconds.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Tue, 2 Jul 2024 04:19:06 +0000 (21:19 -0700)]
rcu: Extract synchronize_rcu_expedited_stall() from synchronize_rcu_expedited_wait()
This commit extracts the RCU CPU stall-warning report code from
synchronize_rcu_expedited_wait() and places it in a new function named
synchronize_rcu_expedited_stall(). This is strictly a code-movement
commit. A later commit will use this reorganization to avoid printing
expedited RCU CPU stall warnings while there are ongoing CSD-lock stall
reports.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Tue, 2 Jul 2024 02:30:56 +0000 (19:30 -0700)]
rcu: Summarize RCU CPU stall warnings during CSD-lock stalls
During CSD-lock stalls, the additional information output by RCU CPU
stall warnings is usually redundant, flooding the console for not good
reason. However, this has been the way things work for a few years.
This commit therefore adds an rcutree.csd_lock_suppress_rcu_stall kernel
boot parameter that causes RCU CPU stall warnings to be abbreviated to
a single line when there is at least one CPU that has been stuck waiting
for CSD lock for more than five seconds.
To make this abbreviated message happen with decent probability:
smp: print only local CPU info when sched_clock goes backward
About 40% of all csd_lock warnings observed in our fleet appear to
be due to sched_clock() going backward in time (usually only a little
bit), resulting in ts0 being larger than ts2.
When the local CPU is at fault, we should print out a message reflecting
that, rather than trying to get the remote CPU's stack trace.
Signed-off-by: Rik van Riel <riel@surriel.com> Tested-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Tue, 2 Jul 2024 21:32:20 +0000 (14:32 -0700)]
locking/csd-lock: Use backoff for repeated reports of same incident
Currently, the CSD-lock diagnostics in CONFIG_CSD_LOCK_WAIT_DEBUG=y
kernels are emitted at five-second intervals. Although this has proven
to be a good time interval for the first diagnostic, if the target CPU
keeps interrupts disabled for way longer than five seconds, the ratio
of useful new information to pointless repetition increases considerably.
Therefore, back off the time period for repeated reports of the same
incident, increasing linearly with the number of reports and logarithmicly
with the number of online CPUs.
[ paulmck: Apply Dan Carpenter feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Leonardo Bras <leobras@redhat.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Reviewed-by: Rik van Riel <riel@surriel.com> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Mon, 1 Jul 2024 20:33:58 +0000 (13:33 -0700)]
locking/csd_lock: Provide an indication of ongoing CSD-lock stall
If a CSD-lock stall goes on long enough, it will cause an RCU CPU
stall warning. This additional warning provides much additional
console-log traffic and little additional information. Therefore,
provide a new csd_lock_is_stuck() function that returns true if there
is an ongoing CSD-lock stall. This function will be used by the RCU
CPU stall warnings to provide a one-line indication of the stall when
this function returns true.
[ neeraj.upadhyay: Apply Rik van Riel feedback. ]
[ neeraj.upadhyay: Apply kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Leonardo Bras <leobras@redhat.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:02 +0000 (17:43 -0700)]
rcuscale: Print detailed grace-period and barrier diagnostics
This commit uses the new rcu_tasks_torture_stats_print(),
rcu_tasks_trace_torture_stats_print(), and
rcu_tasks_rude_torture_stats_print() functions in order to provide
detailed diagnostics on grace-period, callback, and barrier state when
rcu_scale_writer() hangs.
[ paulmck: Apply kernel test robot feedback. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:01 +0000 (17:43 -0700)]
rcu: Mark callbacks not currently participating in barrier operation
RCU keeps a count of the number of callbacks that the current
rcu_barrier() is waiting on, but there is currently no easy way to
work out which callback is stuck. One way to do this is to mark idle
RCU-barrier callbacks by making the ->next pointer point to the callback
itself, and this commit does just that.
Later commits will use this for debug output.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:43:00 +0000 (17:43 -0700)]
rcuscale: Dump grace-period statistics when rcu_scale_writer() stalls
This commit adds a .stats function pointer to the rcu_scale_ops structure,
and if this is non-NULL, it is invoked after stack traces are dumped in
response to a rcu_scale_writer() stall.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:42:59 +0000 (17:42 -0700)]
rcuscale: Dump stacks of stalled rcu_scale_writer() instances
This commit improves debuggability by dumping the stacks of
rcu_scale_writer() instances that have not completed in a reasonable
timeframe. These stacks are dumped remotely, but they will be accurate
in the thus-far common case where the stalled rcu_scale_writer() instances
are blocked.
[ paulmck: Apply kernel test robot feedback. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:26 +0000 (17:34 -0700)]
rcu/tasks: Add rcu_barrier_tasks*() start time to diagnostics
This commit adds the start time, in jiffies, of the most recently started
rcu_barrier_tasks*() operation to the diagnostic output used by rcuscale.
This information can be helpful in distinguishing a hung barrier operation
from a long series of barrier operations.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:25 +0000 (17:34 -0700)]
rcu/tasks: Add detailed grace-period and barrier diagnostics
This commit adds rcu_tasks_torture_stats_print(),
rcu_tasks_trace_torture_stats_print(), and
rcu_tasks_rude_torture_stats_print() functions that provide detailed
diagnostics on grace-period, callback, and barrier state.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:24 +0000 (17:34 -0700)]
rcu/tasks: Mark callbacks not currently participating in barrier operation
Each Tasks RCU flavor keeps a count of the number of callbacks that the
current rcu_barrier_tasks*() is waiting on, but there is currently no
easy way to work out which callback is stuck. One way to do this is to
mark idle RCU-barrier callbacks by making the ->next pointer point to
the callback itself, and this commit does just that.
Later commits will use this for debug output.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:23 +0000 (17:34 -0700)]
rcu: Provide rcu_barrier_cb_is_done() to check rcu_barrier() CBs
This commit provides a rcu_barrier_cb_is_done() function that returns
true if the *rcu_barrier*() callback passed in is done. This will be
used when printing grace-period debugging information.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:22 +0000 (17:34 -0700)]
rcu/tasks: Update rtp->tasks_gp_seq comment
The rtp->tasks_gp_seq grace-period sequence number is not a strict count,
but rather the usual RCU sequence number with the lower few bits tracking
per-grace-period state and the upper bits the count of grace periods
since boot, give or take the initial value. This commit therefore
adjusts this comment.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:34:21 +0000 (17:34 -0700)]
rcu/tasks: Check processor-ID assumptions
The current mapping of smp_processor_id() to a CPU processing Tasks-RCU
callbacks makes some assumptions about layout. This commit therefore
adds a WARN_ON() to check these assumptions.
[ neeraj.upadhyay: Replace nr_cpu_ids with rcu_task_cpu_ids. ]
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()
For kernels built with CONFIG_FORCE_NR_CPUS=y, the nr_cpu_ids is
defined as NR_CPUS instead of the number of possible cpus, this
will cause the following system panic:
Considering that there may be holes in the CPU numbers, use the
maximum possible cpu number, instead of nr_cpu_ids, for configuring
enqueue and dequeue limits.
[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]
The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently
unused. This commit therefore removes their definitions and boot-time
self-tests.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently
unused. Furthermore, the idea is to get rid of RCU Tasks Rude entirely
once all architectures have their deep-idle and entry/exit code correctly
marked as inline or noinstr. As a step towards this goal, this commit
therefore removes these two functions from rcuscale testing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently
unused. Furthermore, the idea is to get rid of RCU Tasks Rude entirely
once all architectures have their deep-idle and entry/exit code correctly
marked as inline or noinstr. As a first step towards this goal, this
commit therefore removes these two functions from rcutorture testing.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:37:50 +0000 (17:37 -0700)]
torture: Add torture.sh --guest-cpu-limit argument for limited hosts
Some servers have limitations on the number of CPUs a given guest OS
can use. In my earlier experience, such limitations have been at least
half of the host's CPUs, but in a recent example, this limit is less
than 40%. This commit therefore adds a --guest-cpu-limit argument that
allows such low limits to be made known to torture.sh.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:37:49 +0000 (17:37 -0700)]
rcutorture: Add a stall_cpu_repeat module parameter
This commit adds an stall_cpu_repeat kernel, which is also the
rcutorture.stall_cpu_repeat boot parameter, to test repeated CPU stalls.
Note that only the first stall will pay attention to the stall_cpu_irqsoff
module parameter. For the second and subsequent stalls, interrupts will
be enabled. This is helpful when testing the interaction between RCU
CPU stall warnings and CSD-lock stall warnings.
Reported-by: Rik van Riel <riel@surriel.com> Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:36:22 +0000 (17:36 -0700)]
srcu: Mark callbacks not currently participating in barrier operation
SRCU keeps a count of the number of callbacks that the current
srcu_barrier() is waiting on, but there is currently no easy way to
work out which callback is stuck. One way to do this is to mark idle
SRCU-barrier callbacks by making the ->next pointer point to the callback
itself, and this commit does just that.
Later commits will use this for debug output.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 2 Aug 2024 00:36:21 +0000 (17:36 -0700)]
srcu: Check for concurrent updates of heuristics
SRCU maintains the ->srcu_n_exp_nodelay and ->reschedule_count values
to guide heuristics governing auto-expediting of normal SRCU grace
periods and grace-period-state-machine delays. This commit adds KCSAN
ASSERT_EXCLUSIVE_WRITER() calls to check for concurrent updates to
these fields.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Using a higher value for the initial gp sequence counters allows for
wrapping to occur faster. It can help with surfacing any issues that may
be happening as a result of the wrap around.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com> Tested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Waiman Long [Tue, 23 Jul 2024 18:10:25 +0000 (14:10 -0400)]
rcu: Use system_unbound_wq to avoid disturbing isolated CPUs
It was discovered that isolated CPUs could sometimes be disturbed by
kworkers processing kfree_rcu() works causing higher than expected
latency. It is because the RCU core uses "system_wq" which doesn't have
the WQ_UNBOUND flag to handle all its work items. Fix this violation of
latency limits by using "system_unbound_wq" in the RCU core instead.
This will ensure that those work items will not be run on CPUs marked
as isolated.
Beside the WQ_UNBOUND flag, the other major difference between system_wq
and system_unbound_wq is their max_active count. The system_unbound_wq
has a max_active of WQ_MAX_ACTIVE (512) while system_wq's max_active
is WQ_DFL_ACTIVE (256) which is half of WQ_MAX_ACTIVE.
Thorsten Blum [Wed, 7 Aug 2024 09:55:00 +0000 (11:55 +0200)]
rcu: Annotate struct kvfree_rcu_bulk_data with __counted_by()
Add the __counted_by compiler attribute to the flexible array member
records to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.
Increment nr_records before adding a new pointer to the records array.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org> Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
context_tracking, rcu: Rename DYNTICK_IRQ_NONIDLE into CT_NESTING_IRQ_NONIDLE
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
context_tracking, rcu: Rename ct_dynticks_nmi_nesting_cpu() into ct_nmi_nesting_cpu()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
context_tracking, rcu: Rename ct_dynticks_nmi_nesting() into ct_nmi_nesting()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
context_tracking, rcu: Rename struct context_tracking .dynticks_nmi_nesting into .nmi_nesting
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]
context_tracking, rcu: Rename ct_dynticks_nesting_cpu() into ct_nesting_cpu()
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
Paul E. McKenney [Fri, 2 Aug 2024 00:37:48 +0000 (17:37 -0700)]
rcutorture: Add rcutree.nohz_full_patience_delay to TREE07
This commit adds the rcutree.nohz_full_patience_delay=1000 kernel boot
parameter to the TREE07 scenario, on the observation that "if it ain't
tested, it don't work".
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Wed, 3 Jul 2024 01:49:35 +0000 (18:49 -0700)]
rcu: Better define "atomic" for list replacement
The kernel-doc headers for list_replace_rcu() and hlist_replace_rcu()
claim that the replacement is atomic, which it is, but only for readers.
Avoid confusion by making it clear that the atomic nature of these
functions applies only to readers, not to concurrent updaters.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Mon, 1 Jul 2024 16:49:49 +0000 (09:49 -0700)]
locking/csd_lock: Print large numbers as negatives
The CSD-lock-hold diagnostics from CONFIG_CSD_LOCK_WAIT_DEBUG are
printed in nanoseconds as unsigned long longs, which is a bit obtuse for
human readers when timing bugs result in negative CSD-lock hold times.
Yes, there are some people to whom it is immediately obvious that 18446744073709551615 is really -1, but for the rest of us...
Therefore, print these numbers as signed long longs, making the negative
hold times immediately apparent.
Reported-by: Rik van Riel <riel@surriel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Leonardo Bras <leobras@redhat.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Reviewed-by: Rik van Riel <riel@surriel.com> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Tue, 18 Jun 2024 17:40:30 +0000 (10:40 -0700)]
rcu/kfree: Warn on unexpected tail state
Within the rcu_sr_normal_gp_cleanup_work() function, there is an acquire
load from rcu_state.srs_done_tail, which is expected to be non-NULL.
This commit adds a WARN_ON_ONCE() to check this expectation.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Zhouyi Zhou [Wed, 19 Jun 2024 23:06:58 +0000 (23:06 +0000)]
rcutorture: Add CFcommon.arch for arch-specific Kconfig options
Add CFcommon.arch for arch-specific Kconfig options.
In accordance with [1], [2] and [3], move the x86-specific kernel option
CONFIG_HYPERVISOR_GUEST to CFcommon.i686 and CFcommon.x86_64, and also
move the x86/PowerPC CONFIG_KVM_GUEST Kconfig option to CFcommon.i686,
CFcommon.x86_64, and CFcommon.ppc64le.
The "arch" in CFcommon.arch is taken from the "uname -m" command.
Paul E. McKenney [Sat, 15 Jun 2024 04:34:17 +0000 (21:34 -0700)]
rcutorture: Generic test for NUM_ACTIVE_*RCU_POLL*
The rcutorture test suite has specific tests for both of the
NUM_ACTIVE_RCU_POLL_OLDSTATE and NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE
macros provided for RCU polled grace periods. However, with the
advent of NUM_ACTIVE_SRCU_POLL_OLDSTATE, a more generic test is needed.
This commit therefore adds ->poll_active and ->poll_active_full fields
to the rcu_torture_ops structure and converts the existing specific
tests to use these fields, when present.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Paul E. McKenney [Fri, 14 Jun 2024 23:47:12 +0000 (16:47 -0700)]
rcutorture: Add SRCU ->same_gp_state and ->get_comp_state functions
This commit points the SRCU ->same_gp_state and ->get_comp_state fields
to same_state_synchronize_srcu() and get_completed_synchronize_srcu(),
allowing them to be tested.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The rcu_torture_ops structure's ->get_gp_completed and
->get_gp_completed_full fields are redundant with its ->get_comp_state
and ->get_comp_state_full fields. This commit therefore removes the
former in favor of the latter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:51 +0000 (15:45 +0200)]
rcu/nocb: Remove SEGCBLIST_KTHREAD_CB
This state excerpt from the (de-)offloading state machine was used to
implement an ad-hoc kthread parking of rcuo kthreads. This code has
been removed and therefore the related state can be erased as well.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:50 +0000 (15:45 +0200)]
rcu/nocb: Remove SEGCBLIST_RCU_CORE
RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.
The SEGCBLIST_RCU_CORE state can therefore be removed.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:49 +0000 (15:45 +0200)]
rcu/nocb: Remove halfway (de-)offloading handling from rcu_core
RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.
The locked callback acceleration handling during the transition can
therefore be removed, along with concurrent batch execution.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:48 +0000 (15:45 +0200)]
rcu/nocb: Remove halfway (de-)offloading handling from rcu_core()'s QS reporting
RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.
The locked callback acceleration handling during the transition can
therefore be removed.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:47 +0000 (15:45 +0200)]
rcu/nocb: Remove halfway (de-)offloading handling from bypass
Bypass enqueue can't happen anymore in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.
The related safety check can therefore be removed.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:46 +0000 (15:45 +0200)]
rcu/nocb: (De-)offload callbacks on offline CPUs only
Currently callbacks can be (de-)offloaded only on online CPUs. This
involves an overly elaborated state machine in order to make sure that
callbacks are always handled during the process while ensuring
synchronization between rcu_core and NOCB kthreads.
The only potential user of NOCB (de-)offloading appears to be a
nohz_full toggling interface through cpusets. And the general agreement
is now to work toward toggling the nohz_full state on offline CPUs to
simplify the whole picture.
Therefore, convert the (de-)offloading to only support offline CPUs.
This involves the following changes:
* Call rcu_barrier() before deoffloading. An offline offloaded CPU may
still carry callbacks in its queue ignored by
rcutree_migrate_callbacks(). Those callbacks must all be flushed
before switching to a regular queue because no more kthreads will
handle those before the CPU ever gets re-onlined.
This means that further calls to rcu_barrier() will find an empty
queue until the CPU goes through rcutree_report_cpu_starting(). As a
result it is guaranteed that further rcu_barrier() won't try to lock
the nocb_lock for that target and thus won't risk an imbalance.
Therefore barrier_mutex doesn't need to be locked anymore upon
deoffloading.
* Assume the queue is empty before offloading, as
rcutree_migrate_callbacks() took care of everything.
This means that further calls to rcu_barrier() will find an empty
queue until the CPU goes through rcutree_report_cpu_starting(). As a
result it is guaranteed that further rcu_barrier() won't risk a
nocb_lock imbalance.
Therefore barrier_mutex doesn't need to be locked anymore upon
offloading.
* No need to flush bypass anymore.
Further simplifications will follow in upcoming patches.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:45 +0000 (15:45 +0200)]
rcu/nocb: Introduce nocb mutex
The barrier_mutex is used currently to protect (de-)offloading
operations and prevent from nocb_lock locking imbalance in rcu_barrier()
and shrinker, and also from misordered RCU barrier invocation.
Now since RCU (de-)offloading is going to happen on offline CPUs, an RCU
barrier will have to be executed while transitionning from offloaded to
de-offloaded state. And this can't happen while holding the
barrier_mutex.
Introduce a NOCB mutex to protect (de-)offloading transitions. The
barrier_mutex is still held for now when necessary to avoid barrier
callbacks reordering and nocb_lock imbalance.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:44 +0000 (15:45 +0200)]
rcu/nocb: Assert no callbacks while nocb kthread allocation fails
When a NOCB CPU fails to create a nocb kthread on bringup, the CPU is
then deoffloaded. The barrier mutex is locked at this stage. It is
typically used to protect against concurrent (de-)offloading and/or
concurrent rcu_barrier() that would otherwise risk a nocb locking
imbalance. However:
* rcu_barrier() can't run concurrently if it's the boot CPU on early
boot-up.
* rcu_barrier() can run concurrently if it's a secondary CPU but it is
expected to see 0 callbacks on this target because it's the first
time it boots.
* (de-)offloading can't happen concurrently with smp_init(), as
rcutorture is initialized later, at least not before device_initcall(),
and userspace isn't available yet.
* (de-)offloading can't happen concurrently with cpu_up(), courtesy of
cpu_hotplug_lock.
But:
* The lazy shrinker might run concurrently with cpu_up(). It shouldn't
try to grab the nocb_lock and risk an imbalance due to lazy_len
supposed to be 0 but be extra cautious.
* Also be cautious against resume from hibernation potential subtleties.
So keep the locking and add some assertions and comments.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:43 +0000 (15:45 +0200)]
rcu/nocb: Move nocb field at the end of state struct
nocb_is_setup is a rarely used field, mostly on boot and CPU hotplug.
It shouldn't occupy the middle of the rcu state hot fields cacheline.
Move it to the end and build it conditionally while at it. More cold
NOCB fields are to come.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Frederic Weisbecker [Thu, 30 May 2024 13:45:42 +0000 (15:45 +0200)]
rcu/nocb: Introduce RCU_NOCB_LOCKDEP_WARN()
Checking for races against concurrent (de-)offloading implies the
creation of !CONFIG_RCU_NOCB_CPU stubs to check if each relevant lock
is held. For now this only implies the nocb_lock but more are to be
expected.
Create instead a NOCB specific version of RCU_LOCKDEP_WARN() to avoid
the proliferation of stubs.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
context_tracking, rcu: Rename RCU_DYNTICKS_IDX into CT_RCU_WATCHING
The symbols relating to the CT_STATE part of context_tracking.state are now
all prefixed with CT_STATE.
The RCU dynticks counter part of that atomic variable still involves
symbols with different prefixes, align them all to be prefixed with
CT_RCU_WATCHING.
Merge tag 'kbuild-fixes-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada:
- Fix RPM package build error caused by an incorrect locale setup
- Mark modules.weakdep as ghost in RPM package
- Fix the odd combination of -S and -c in stack protector scripts,
which is an error with the latest Clang
* tag 'kbuild-fixes-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: Fix '-S -c' in x86 stack protector scripts
kbuild: rpm-pkg: ghost modules.weakdep file
kbuild: rpm-pkg: Fix C locale setup
minmax: simplify and clarify min_t()/max_t() implementation
This simplifies the min_t() and max_t() macros by no longer making them
work in the context of a C constant expression.
That means that you can no longer use them for static initializers or
for array sizes in type definitions, but there were only a couple of
such uses, and all of them were converted (famous last words) to use
MIN_T/MAX_T instead.
Cc: David Laight <David.Laight@aculab.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 3a7e02c040b1 ("minmax: avoid overly complicated constant
expressions in VM code") added the simpler MIN_T/MAX_T macros in order
to avoid some excessive expansion from the rather complicated regular
min/max macros.
The complexity of those macros stems from two issues:
(a) trying to use them in situations that require a C constant
expression (in static initializers and for array sizes)
(b) the type sanity checking
and MIN_T/MAX_T avoids both of these issues.
Now, in the whole (long) discussion about all this, it was pointed out
that the whole type sanity checking is entirely unnecessary for
min_t/max_t which get a fixed type that the comparison is done in.
But that still leaves min_t/max_t unnecessarily complicated due to
worries about the C constant expression case.
However, it turns out that there really aren't very many cases that use
min_t/max_t for this, and we can just force-convert those.
This does exactly that.
Which in turn will then allow for much simpler implementations of
min_t()/max_t(). All the usual "macros in all upper case will evaluate
the arguments multiple times" rules apply.
We should do all the same things for the regular min/max() vs MIN/MAX()
cases, but that has the added complexity of various drivers defining
their own local versions of MIN/MAX, so that needs another level of
fixes first.
kbuild: Fix '-S -c' in x86 stack protector scripts
After a recent change in clang to stop consuming all instances of '-S'
and '-c' [1], the stack protector scripts break due to the kernel's use
of -Werror=unused-command-line-argument to catch cases where flags are
not being properly consumed by the compiler driver:
$ echo | clang -o - -x c - -S -c -Werror=unused-command-line-argument
clang: error: argument unused during compilation: '-c' [-Werror,-Wunused-command-line-argument]
This results in CONFIG_STACKPROTECTOR getting disabled because
CONFIG_CC_HAS_SANE_STACKPROTECTOR is no longer set.
'-c' and '-S' both instruct the compiler to stop at different stages of
the pipeline ('-S' after compiling, '-c' after assembling), so having
them present together in the same command makes little sense. In this
case, the test wants to stop before assembling because it is looking at
the textual assembly output of the compiler for either '%fs' or '%gs',
so remove '-c' from the list of arguments to resolve the error.
All versions of GCC continue to work after this change, along with
versions of clang that do or do not contain the change mentioned above.
Cc: stable@vger.kernel.org Fixes: 4f7fd4d7a791 ("[PATCH] Add the -fstack-protector option to the CFLAGS") Fixes: 60a5317ff0f4 ("x86: implement x86_32 stack protector") Link: https://github.com/llvm/llvm-project/commit/6461e537815f7fa68cef06842505353cf5600e9c Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Merge tag 'v6.11-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux
Pull turbostat updates from Len Brown:
- Enable turbostat extensions to add both perf and PMT (Intel
Platform Monitoring Technology) counters via the cmdline
- Demonstrate PMT access with built-in support for Meteor Lake's
Die C6 counter
* tag 'v6.11-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
tools/power turbostat: version 2024.07.26
tools/power turbostat: Include umask=%x in perf counter's config
tools/power turbostat: Document PMT in turbostat.8
tools/power turbostat: Add MTL's PMT DC6 builtin counter
tools/power turbostat: Add early support for PMT counters
tools/power turbostat: Add selftests for added perf counters
tools/power turbostat: Add selftests for SMI, APERF and MPERF counters
tools/power turbostat: Move verbose counter messages to level 2
tools/power turbostat: Move debug prints from stdout to stderr
tools/power turbostat: Fix typo in turbostat.8
tools/power turbostat: Add perf added counter example to turbostat.8
tools/power turbostat: Fix formatting in turbostat.8
tools/power turbostat: Extend --add option with perf counters
tools/power turbostat: Group SMI counter with APERF and MPERF
tools/power turbostat: Add ZERO_ARRAY for zero initializing builtin array
tools/power turbostat: Replace enum rapl_source and cstate_source with counter_source
tools/power turbostat: Remove anonymous union from rapl_counter_info_t
tools/power/turbostat: Switch to new Intel CPU model defines
Merge tag 'cxl-for-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
Pull CXL updates from Dave Jiang:
"Core:
- A CXL maturity map has been added to the documentation to detail
the current state of CXL enabling.
It provides the status of the current state of various CXL features
to inform current and future contributors of where things are and
which areas need contribution.
- A notifier handler has been added in order for a newly created CXL
memory region to trigger the abstract distance metrics calculation.
This should bring parity for CXL memory to the same level vs
hotplugged DRAM for NUMA abstract distance calculation. The
abstract distance reflects relative performance used for memory
tiering handling.
- An addition for XOR math has been added to address the CXL DPA to
SPA translation.
CXL address translation did not support address interleave math
with XOR prior to this change.
Fixes:
- Fix to address race condition in the CXL memory hotplug notifier
- Add missing MODULE_DESCRIPTION() for CXL modules
- Fix incorrect vendor debug UUID define
Misc:
- A warning has been added to inform users of an unsupported
configuration when mixing CXL VH and RCH/RCD hierarchies
- The ENXIO error code has been replaced with EBUSY for inject poison
limit reached via debugfs and cxl-test support
- Moving the PCI config read in cxl_dvsec_rr_decode() to avoid
unnecessary PCI config reads
- A refactor to a common struct for DRAM and general media CXL
events"
* tag 'cxl-for-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
cxl/core/pci: Move reading of control register to immediately before usage
cxl: Remove defunct code calculating host bridge target positions
cxl/region: Verify target positions using the ordered target list
cxl: Restore XOR'd position bits during address translation
cxl/core: Fold cxl_trace_hpa() into cxl_dpa_to_hpa()
cxl/test: Replace ENXIO with EBUSY for inject poison limit reached
cxl/memdev: Replace ENXIO with EBUSY for inject poison limit reached
cxl/acpi: Warn on mixed CXL VH and RCH/RCD Hierarchy
cxl/core: Fix incorrect vendor debug UUID define
Documentation: CXL Maturity Map
cxl/region: Simplify cxl_region_nid()
cxl/region: Support to calculate memory tier abstract distance
cxl/region: Fix a race condition in memory hotplug notifier
cxl: add missing MODULE_DESCRIPTION() macros
cxl/events: Use a common struct for DRAM and General Media events
projects / linux.git / log