Gokul krishna Krishnakumar fe9df687e7 locking/rwsem: Disable preemption while trying for rwsem lock ... commit 48dfb5d256 upstream. Make the region inside the rwsem_write_trylock non preemptible. We observe RT task is hogging CPU when trying to acquire rwsem lock which was acquired by a kworker task but before the rwsem owner was set. Here is the scenario: 1. CFS task (affined to a particular CPU) takes rwsem lock. 2. CFS task gets preempted by a RT task before setting owner. 3. RT task (FIFO) is trying to acquire the lock, but spinning until RT throttling happens for the lock as the lock was taken by CFS task. This patch attempts to fix the above issue by disabling preemption until owner is set for the lock. While at it also fix the issues at the places where rwsem_{set,clear}_owner() are called. This also adds lockdep annotation of preemption disable in rwsem_{set,clear}_owner() on Peter Z. suggestion. Signed-off-by: Gokul krishna Krishnakumar <quic_gokukris@quicinc.com> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/1662661467-24203-1-git-send-email-quic_mojha@quicinc.com Cc: Aaro Koskinen <aaro.koskinen@iki.fi> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2024-04-10 16:19:37 +02:00
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Makefile	…
irqflag-debug.c	…
lock_events.c	…
lock_events.h	…
lock_events_list.h	…
lockdep.c	…
lockdep_internals.h	…
lockdep_proc.c	…
lockdep_states.h	…
locktorture.c	…
mcs_spinlock.h	…
mutex-debug.c	…
mutex.c	…
mutex.h	…
osq_lock.c	…
percpu-rwsem.c	…
qrwlock.c	…
qspinlock.c	…
qspinlock_paravirt.h	…
qspinlock_stat.h	…
rtmutex.c	…
rtmutex_api.c	…
rtmutex_common.h	…
rwbase_rt.c	…
rwsem.c	locking/rwsem: Disable preemption while trying for rwsem lock	2024-04-10 16:19:37 +02:00
semaphore.c	…
spinlock.c	…
spinlock_debug.c	…
spinlock_rt.c	…
test-ww_mutex.c	…
ww_mutex.h	…
ww_rt_mutex.c	…