user/sven/linux.git/kernel/sched, branch v4.14.45

sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning

2018-05-30T05:52:25Z

[ Upstream commit d29a20645d5e929aa7e8616f28e5d8e1c49263ec ] While running rt-tests' pi_stress program I got the following splat: rq->clock_update_flags < RQCF_ACT_SKIP WARNING: CPU: 27 PID: 0 at kernel/sched/sched.h:960 assert_clock_updated.isra.38.part.39+0x13/0x20 [...] enqueue_top_rt_rq+0xf4/0x150 ? cpufreq_dbs_governor_start+0x170/0x170 sched_rt_rq_enqueue+0x65/0x80 sched_rt_period_timer+0x156/0x360 ? sched_rt_rq_enqueue+0x80/0x80 __hrtimer_run_queues+0xfa/0x260 hrtimer_interrupt+0xcb/0x220 smp_apic_timer_interrupt+0x62/0x120 apic_timer_interrupt+0xf/0x20 [...] do_idle+0x183/0x1e0 cpu_startup_entry+0x5f/0x70 start_secondary+0x192/0x1d0 secondary_startup_64+0xa5/0xb0 We can get rid of it be the "traditional" means of adding an update_rq_clock() call after acquiring the rq->lock in do_sched_rt_period_timer(). The case for the RT task throttling (which this workload also hits) can be ignored in that the skip_update call is actually bogus and quite the contrary (the request bits are removed/reverted). By setting RQCF_UPDATED we really don't care if the skip is happening or not and will therefore make the assert_clock_updated() check happy. Signed-off-by: Davidlohr Bueso Reviewed-by: Matt Fleming Acked-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Thomas Gleixner Cc: dave@stgolabs.net Cc: linux-kernel@vger.kernel.org Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/20180402164954.16255-1-dave@stgolabs.net Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]

2018-05-16T08:10:30Z

commit 354d7793070611b4df5a79fbb0f12752d0ed0cc5 upstream. > kernel/sched/autogroup.c:230 proc_sched_autogroup_set_nice() warn: potential spectre issue 'sched_prio_to_weight' Userspace controls @nice, sanitize the array index. Reported-by: Dan Carpenter Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

cpufreq: schedutil: Avoid using invalid next_freq

2018-05-16T08:10:29Z

commit 97739501f207efe33145b918817f305b822987f8 upstream. If the next_freq field of struct sugov_policy is set to UINT_MAX, it shouldn't be used for updating the CPU frequency (this is a special "invalid" value), but after commit b7eaf1aab9f8 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely) it may be passed as the new frequency to sugov_update_commit() in sugov_update_single(). Fix that by adding an extra check for the special UINT_MAX value of next_freq to sugov_update_single(). Fixes: b7eaf1aab9f8 (cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely) Reported-by: Viresh Kumar Cc: 4.12+ # 4.12+ Signed-off-by: Rafael J. Wysocki Acked-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

sched: Stop resched_cpu() from sending IPIs to offline CPUs

2018-03-19T07:42:49Z

[ Upstream commit a0982dfa03efca6c239c52cabebcea4afb93ea6b ] The rcutorture test suite occasionally provokes a splat due to invoking resched_cpu() on an offline CPU: WARNING: CPU: 2 PID: 8 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:128 native_smp_send_reschedule+0x37/0x40 Modules linked in: CPU: 2 PID: 8 Comm: rcu_preempt Not tainted 4.14.0-rc4+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 task: ffff902ede9daf00 task.stack: ffff96c50010c000 RIP: 0010:native_smp_send_reschedule+0x37/0x40 RSP: 0018:ffff96c50010fdb8 EFLAGS: 00010096 RAX: 000000000000002e RBX: ffff902edaab4680 RCX: 0000000000000003 RDX: 0000000080000003 RSI: 0000000000000000 RDI: 00000000ffffffff RBP: ffff96c50010fdb8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 00000000299f36ae R12: 0000000000000001 R13: ffffffff9de64240 R14: 0000000000000001 R15: ffffffff9de64240 FS: 0000000000000000(0000) GS:ffff902edfc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000f7d4c642 CR3: 000000001e0e2000 CR4: 00000000000006e0 Call Trace: resched_curr+0x8f/0x1c0 resched_cpu+0x2c/0x40 rcu_implicit_dynticks_qs+0x152/0x220 force_qs_rnp+0x147/0x1d0 ? sync_rcu_exp_select_cpus+0x450/0x450 rcu_gp_kthread+0x5a9/0x950 kthread+0x142/0x180 ? force_qs_rnp+0x1d0/0x1d0 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x27/0x40 Code: 14 01 0f 92 c0 84 c0 74 14 48 8b 05 14 4f f4 00 be fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 38 89 ca 9d e8 e5 56 08 00 <0f> ff 5d c3 0f 1f 44 00 00 8b 05 52 9e 37 02 85 c0 75 38 55 48 ---[ end trace 26df9e5df4bba4ac ]--- This splat cannot be generated by expedited grace periods because they always invoke resched_cpu() on the current CPU, which is good because expedited grace periods require that resched_cpu() unconditionally succeed. However, other parts of RCU can tolerate resched_cpu() acting as a no-op, at least as long as it doesn't happen too often. This commit therefore makes resched_cpu() invoke resched_curr() only if the CPU is either online or is the current CPU. Signed-off-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched: Stop switched_to_rt() from sending IPIs to offline CPUs

2018-03-19T07:42:49Z

[ Upstream commit 2fe2582649aa2355f79acddb86bd4d6c5363eb63 ] The rcutorture test suite occasionally provokes a splat due to invoking rt_mutex_lock() which needs to boost the priority of a task currently sitting on a runqueue that belongs to an offline CPU: WARNING: CPU: 0 PID: 12 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:128 native_smp_send_reschedule+0x37/0x40 Modules linked in: CPU: 0 PID: 12 Comm: rcub/7 Not tainted 4.14.0-rc4+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 task: ffff9ed3de5f8cc0 task.stack: ffffbbf80012c000 RIP: 0010:native_smp_send_reschedule+0x37/0x40 RSP: 0018:ffffbbf80012fd10 EFLAGS: 00010082 RAX: 000000000000002f RBX: ffff9ed3dd9cb300 RCX: 0000000000000004 RDX: 0000000080000004 RSI: 0000000000000086 RDI: 00000000ffffffff RBP: ffffbbf80012fd10 R08: 000000000009da7a R09: 0000000000007b9d R10: 0000000000000001 R11: ffffffffbb57c2cd R12: 000000000000000d R13: ffff9ed3de5f8cc0 R14: 0000000000000061 R15: ffff9ed3ded59200 FS: 0000000000000000(0000) GS:ffff9ed3dea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000080686f0 CR3: 000000001b9e0000 CR4: 00000000000006f0 Call Trace: resched_curr+0x61/0xd0 switched_to_rt+0x8f/0xa0 rt_mutex_setprio+0x25c/0x410 task_blocks_on_rt_mutex+0x1b3/0x1f0 rt_mutex_slowlock+0xa9/0x1e0 rt_mutex_lock+0x29/0x30 rcu_boost_kthread+0x127/0x3c0 kthread+0x104/0x140 ? rcu_report_unblock_qs_rnp+0x90/0x90 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x22/0x30 Code: f0 00 0f 92 c0 84 c0 74 14 48 8b 05 34 74 c5 00 be fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 a0 c6 fc b9 e8 d5 b5 06 00 <0f> ff 5d c3 0f 1f 44 00 00 8b 05 a2 d1 13 02 85 c0 75 38 55 48 But the target task's priority has already been adjusted, so the only purpose of switched_to_rt() invoking resched_curr() is to wake up the CPU running some task that needs to be preempted by the boosted task. But the CPU is offline, which presumably means that the task must be migrated to some other CPU, and that this other CPU will undertake any needed preemption at the time of migration. Because the runqueue lock is held when resched_curr() is invoked, we know that the boosted task cannot go anywhere, so it is not necessary to invoke resched_curr() in this particular case. This commit therefore makes switched_to_rt() refrain from invoking resched_curr() when the target CPU is offline. Signed-off-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched/rt: Up the root domain ref count when passing it around via IPIs

2018-02-16T19:22:44Z

commit 364f56653708ba8bcdefd4f0da2a42904baa8eeb upstream. When issuing an IPI RT push, where an IPI is sent to each CPU that has more than one RT task scheduled on it, it references the root domain's rto_mask, that contains all the CPUs within the root domain that has more than one RT task in the runable state. The problem is, after the IPIs are initiated, the rq->lock is released. This means that the root domain that is associated to the run queue could be freed while the IPIs are going around. Add a sched_get_rd() and a sched_put_rd() that will increment and decrement the root domain's ref count respectively. This way when initiating the IPIs, the scheduler will up the root domain's ref count before releasing the rq->lock, ensuring that the root domain does not go away until the IPI round is complete. Reported-by: Pavan Kondeti Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 4bdced5c9a292 ("sched/rt: Simplify the IPI based RT balancing logic") Link: http://lkml.kernel.org/r/CAEU1=PkiHO35Dzna8EQqNSKW1fr1y1zRQ5y66X117MG06sQtNA@mail.gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched/rt: Use container_of() to get root domain in rto_push_irq_work_func()

2018-02-16T19:22:44Z

commit ad0f1d9d65938aec72a698116cd73a980916895e upstream. When the rto_push_irq_work_func() is called, it looks at the RT overloaded bitmask in the root domain via the runqueue (rq->rd). The problem is that during CPU up and down, nothing here stops rq->rd from changing between taking the rq->rd->rto_lock and releasing it. That means the lock that is released is not the same lock that was taken. Instead of using this_rq()->rd to get the root domain, as the irq work is part of the root domain, we can simply get the root domain from the irq work that is passed to the routine: container_of(work, struct root_domain, rto_push_work) This keeps the root domain consistent. Reported-by: Pavan Kondeti Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 4bdced5c9a292 ("sched/rt: Simplify the IPI based RT balancing logic") Link: http://lkml.kernel.org/r/CAEU1=PkiHO35Dzna8EQqNSKW1fr1y1zRQ5y66X117MG06sQtNA@mail.gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched/wait: Fix add_wait_queue() behavioral change

2018-02-16T19:22:43Z

commit c6b9d9a33029014446bd9ed84c1688f6d3d4eab9 upstream. The following cleanup commit: 50816c48997a ("sched/wait: Standardize internal naming of wait-queue entries") ... unintentionally changed the behavior of add_wait_queue() from inserting the wait entry at the head of the wait queue to the tail of the wait queue. Beyond a negative performance impact this change in behavior theoretically also breaks wait queues which mix exclusive and non-exclusive waiters, as non-exclusive waiters will not be woken up if they are queued behind enough exclusive waiters. Signed-off-by: Omar Sandoval Reviewed-by: Jens Axboe Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Thomas Gleixner Cc: kernel-team@fb.com Fixes: ("sched/wait: Standardize internal naming of wait-queue entries") Link: http://lkml.kernel.org/r/a16c8ccffd39bd08fdaa45a5192294c784b803a7.1512544324.git.osandov@fb.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

delayacct: Account blkio completion on the correct task

2018-01-23T18:58:13Z

commit c96f5471ce7d2aefd0dda560cc23f08ab00bc65d upstream. Before commit: e33a9bba85a8 ("sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler") delayacct_blkio_end() was called after context-switching into the task which completed I/O. This resulted in double counting: the task would account a delay both waiting for I/O and for time spent in the runqueue. With e33a9bba85a8, delayacct_blkio_end() is called by try_to_wake_up(). In ttwu, we have not yet context-switched. This is more correct, in that the delay accounting ends when the I/O is complete. But delayacct_blkio_end() relies on 'get_current()', and we have not yet context-switched into the task whose I/O completed. This results in the wrong task having its delay accounting statistics updated. Instead of doing that, pass the task_struct being woken to delayacct_blkio_end(), so that it can update the statistics of the correct task. Signed-off-by: Josh Snyder Acked-by: Tejun Heo Acked-by: Balbir Singh Cc: Brendan Gregg Cc: Jens Axboe Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-block@vger.kernel.org Fixes: e33a9bba85a8 ("sched/core: move IO scheduling accounting from io_schedule_timeout() into scheduler") Link: http://lkml.kernel.org/r/1513613712-571-1-git-send-email-joshs@netflix.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

membarrier: Disable preemption when calling smp_call_function_many()

2018-01-17T08:45:23Z

commit 541676078b52f365f53d46ee5517d305cd1b6350 upstream. smp_call_function_many() requires disabling preemption around the call. Signed-off-by: Mathieu Desnoyers Cc: Andrea Parri Cc: Andrew Hunter Cc: Avi Kivity Cc: Benjamin Herrenschmidt Cc: Boqun Feng Cc: Dave Watson Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Maged Michael Cc: Michael Ellerman Cc: Paul E . McKenney Cc: Paul E. McKenney Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20171215192310.25293-1-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman