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* context_tracking: Restore previous state in schedule_userAndy Lutomirski2014-12-031-2/+6
| | | | | | | | | | | | | | | | It appears that some SCHEDULE_USER (asm for schedule_user) callers in arch/x86/kernel/entry_64.S are called from RCU kernel context, and schedule_user will return in RCU user context. This causes RCU warnings and possible failures. This is intended to be a minimal fix suitable for 3.18. Reported-and-tested-by: Dave Jones <davej@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched: Provide update_curr callbacks for stop/idle scheduling classesThomas Gleixner2014-11-232-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Chris bisected a NULL pointer deference in task_sched_runtime() to commit 6e998916dfe3 'sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency'. Chris observed crashes in atop or other /proc walking programs when he started fork bombs on his machine. He assumed that this is a new exit race, but that does not make any sense when looking at that commit. What's interesting is that, the commit provides update_curr callbacks for all scheduling classes except stop_task and idle_task. While nothing can ever hit that via the clock_nanosleep() and clock_gettime() interfaces, which have been the target of the commit in question, the author obviously forgot that there are other code paths which invoke task_sched_runtime() do_task_stat(() thread_group_cputime_adjusted() thread_group_cputime() task_cputime() task_sched_runtime() if (task_current(rq, p) && task_on_rq_queued(p)) { update_rq_clock(rq); up->sched_class->update_curr(rq); } If the stats are read for a stomp machine task, aka 'migration/N' and that task is current on its cpu, this will happily call the NULL pointer of stop_task->update_curr. Ooops. Chris observation that this happens faster when he runs the fork bomb makes sense as the fork bomb will kick migration threads more often so the probability to hit the issue will increase. Add the missing update_curr callbacks to the scheduler classes stop_task and idle_task. While idle tasks cannot be monitored via /proc we have other means to hit the idle case. Fixes: 6e998916dfe3 'sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency' Reported-by: Chris Mason <clm@fb.com> Reported-and-tested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistencyStanislaw Gruszka2014-11-165-27/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit d670ec13178d0 "posix-cpu-timers: Cure SMP wobbles" fixes one glibc test case in cost of breaking another one. After that commit, calling clock_nanosleep(TIMER_ABSTIME, X) and then clock_gettime(&Y) can result of Y time being smaller than X time. Reproducer/tester can be found further below, it can be compiled and ran by: gcc -o tst-cpuclock2 tst-cpuclock2.c -pthread while ./tst-cpuclock2 ; do : ; done This reproducer, when running on a buggy kernel, will complain about "clock_gettime difference too small". Issue happens because on start in thread_group_cputimer() we initialize sum_exec_runtime of cputimer with threads runtime not yet accounted and then add the threads runtime to running cputimer again on scheduler tick, making it's sum_exec_runtime bigger than actual threads runtime. KOSAKI Motohiro posted a fix for this problem, but that patch was never applied: https://lkml.org/lkml/2013/5/26/191 . This patch takes different approach to cure the problem. It calls update_curr() when cputimer starts, that assure we will have updated stats of running threads and on the next schedule tick we will account only the runtime that elapsed from cputimer start. That also assure we have consistent state between cpu times of individual threads and cpu time of the process consisted by those threads. Full reproducer (tst-cpuclock2.c): #define _GNU_SOURCE #include <unistd.h> #include <sys/syscall.h> #include <stdio.h> #include <time.h> #include <pthread.h> #include <stdint.h> #include <inttypes.h> /* Parameters for the Linux kernel ABI for CPU clocks. */ #define CPUCLOCK_SCHED 2 #define MAKE_PROCESS_CPUCLOCK(pid, clock) \ ((~(clockid_t) (pid) << 3) | (clockid_t) (clock)) static pthread_barrier_t barrier; /* Help advance the clock. */ static void *chew_cpu(void *arg) { pthread_barrier_wait(&barrier); while (1) ; return NULL; } /* Don't use the glibc wrapper. */ static int do_nanosleep(int flags, const struct timespec *req) { clockid_t clock_id = MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED); return syscall(SYS_clock_nanosleep, clock_id, flags, req, NULL); } static int64_t tsdiff(const struct timespec *before, const struct timespec *after) { int64_t before_i = before->tv_sec * 1000000000ULL + before->tv_nsec; int64_t after_i = after->tv_sec * 1000000000ULL + after->tv_nsec; return after_i - before_i; } int main(void) { int result = 0; pthread_t th; pthread_barrier_init(&barrier, NULL, 2); if (pthread_create(&th, NULL, chew_cpu, NULL) != 0) { perror("pthread_create"); return 1; } pthread_barrier_wait(&barrier); /* The test. */ struct timespec before, after, sleeptimeabs; int64_t sleepdiff, diffabs; const struct timespec sleeptime = {.tv_sec = 0,.tv_nsec = 100000000 }; /* The relative nanosleep. Not sure why this is needed, but its presence seems to make it easier to reproduce the problem. */ if (do_nanosleep(0, &sleeptime) != 0) { perror("clock_nanosleep"); return 1; } /* Get the current time. */ if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &before) < 0) { perror("clock_gettime[2]"); return 1; } /* Compute the absolute sleep time based on the current time. */ uint64_t nsec = before.tv_nsec + sleeptime.tv_nsec; sleeptimeabs.tv_sec = before.tv_sec + nsec / 1000000000; sleeptimeabs.tv_nsec = nsec % 1000000000; /* Sleep for the computed time. */ if (do_nanosleep(TIMER_ABSTIME, &sleeptimeabs) != 0) { perror("absolute clock_nanosleep"); return 1; } /* Get the time after the sleep. */ if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &after) < 0) { perror("clock_gettime[3]"); return 1; } /* The time after sleep should always be equal to or after the absolute sleep time passed to clock_nanosleep. */ sleepdiff = tsdiff(&sleeptimeabs, &after); if (sleepdiff < 0) { printf("absolute clock_nanosleep woke too early: %" PRId64 "\n", sleepdiff); result = 1; printf("Before %llu.%09llu\n", before.tv_sec, before.tv_nsec); printf("After %llu.%09llu\n", after.tv_sec, after.tv_nsec); printf("Sleep %llu.%09llu\n", sleeptimeabs.tv_sec, sleeptimeabs.tv_nsec); } /* The difference between the timestamps taken before and after the clock_nanosleep call should be equal to or more than the duration of the sleep. */ diffabs = tsdiff(&before, &after); if (diffabs < sleeptime.tv_nsec) { printf("clock_gettime difference too small: %" PRId64 "\n", diffabs); result = 1; } pthread_cancel(th); return result; } Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20141112155843.GA24803@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/cputime: Fix cpu_timer_sample_group() double accountingPeter Zijlstra2014-11-161-13/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | While looking over the cpu-timer code I found that we appear to add the delta for the calling task twice, through: cpu_timer_sample_group() thread_group_cputimer() thread_group_cputime() times->sum_exec_runtime += task_sched_runtime(); *sample = cputime.sum_exec_runtime + task_delta_exec(); Which would make the sample run ahead, making the sleep short. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Link: http://lkml.kernel.org/r/20141112113737.GI10476@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/numa: Avoid selecting oneself as swap targetPeter Zijlstra2014-11-161-0/+7
| | | | | | | | | | | | | | Because the whole numa task selection stuff runs with preemption enabled (its long and expensive) we can end up migrating and selecting oneself as a swap target. This doesn't really work out well -- we end up trying to acquire the same lock twice for the swap migrate -- so avoid this. Reported-and-Tested-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20141110100328.GF29390@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/numa: Fix out of bounds read in sched_init_numa()Andrey Ryabinin2014-11-101-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On latest mm + KASan patchset I've got this: ================================================================== BUG: AddressSanitizer: out of bounds access in sched_init_smp+0x3ba/0x62c at addr ffff88006d4bee6c ============================================================================= BUG kmalloc-8 (Not tainted): kasan error ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Allocated in alloc_vfsmnt+0xb0/0x2c0 age=75 cpu=0 pid=0 __slab_alloc+0x4b4/0x4f0 __kmalloc_track_caller+0x15f/0x1e0 kstrdup+0x44/0x90 alloc_vfsmnt+0xb0/0x2c0 vfs_kern_mount+0x35/0x190 kern_mount_data+0x25/0x50 pid_ns_prepare_proc+0x19/0x50 alloc_pid+0x5e2/0x630 copy_process.part.41+0xdf5/0x2aa0 do_fork+0xf5/0x460 kernel_thread+0x21/0x30 rest_init+0x1e/0x90 start_kernel+0x522/0x531 x86_64_start_reservations+0x2a/0x2c x86_64_start_kernel+0x15b/0x16a INFO: Slab 0xffffea0001b52f80 objects=24 used=22 fp=0xffff88006d4befc0 flags=0x100000000004080 INFO: Object 0xffff88006d4bed20 @offset=3360 fp=0xffff88006d4bee70 Bytes b4 ffff88006d4bed10: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ Object ffff88006d4bed20: 70 72 6f 63 00 6b 6b a5 proc.kk. Redzone ffff88006d4bed28: cc cc cc cc cc cc cc cc ........ Padding ffff88006d4bee68: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ CPU: 0 PID: 1 Comm: swapper/0 Tainted: G B 3.18.0-rc3-mm1+ #108 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 ffff88006d4be000 0000000000000000 ffff88006d4bed20 ffff88006c86fd18 ffffffff81cd0a59 0000000000000058 ffff88006d404240 ffff88006c86fd48 ffffffff811fa3a8 ffff88006d404240 ffffea0001b52f80 ffff88006d4bed20 Call Trace: dump_stack (lib/dump_stack.c:52) print_trailer (mm/slub.c:645) object_err (mm/slub.c:652) ? sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063) kasan_report_error (mm/kasan/report.c:102 mm/kasan/report.c:178) ? kasan_poison_shadow (mm/kasan/kasan.c:48) ? kasan_unpoison_shadow (mm/kasan/kasan.c:54) ? kasan_poison_shadow (mm/kasan/kasan.c:48) ? kasan_kmalloc (mm/kasan/kasan.c:311) __asan_load4 (mm/kasan/kasan.c:371) ? sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063) sched_init_smp (kernel/sched/core.c:6552 kernel/sched/core.c:7063) kernel_init_freeable (init/main.c:869 init/main.c:997) ? finish_task_switch (kernel/sched/sched.h:1036 kernel/sched/core.c:2248) ? rest_init (init/main.c:924) kernel_init (init/main.c:929) ? rest_init (init/main.c:924) ret_from_fork (arch/x86/kernel/entry_64.S:348) ? rest_init (init/main.c:924) Read of size 4 by task swapper/0: Memory state around the buggy address: ffff88006d4beb80: fc fc fc fc fc fc fc fc fc fc 00 fc fc fc fc fc ffff88006d4bec00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88006d4bec80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88006d4bed00: fc fc fc fc 00 fc fc fc fc fc fc fc fc fc fc fc ffff88006d4bed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88006d4bee00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc 04 fc ^ ffff88006d4bee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88006d4bef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88006d4bef80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff88006d4bf000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88006d4bf080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Zero 'level' (e.g. on non-NUMA system) causing out of bounds access in this line: sched_max_numa_distance = sched_domains_numa_distance[level - 1]; Fix this by exiting from sched_init_numa() earlier. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Reviewed-by: Rik van Riel <riel@redhat.com> Fixes: 9942f79ba ("sched/numa: Export info needed for NUMA balancing on complex topologies") Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1415372020-1871-1-git-send-email-a.ryabinin@samsung.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched: Remove lockdep check in sched_move_task()Kirill Tkhai2014-11-041-2/+6
| | | | | | | | | | | | | | | | | | | | | | sched_move_task() is the only interface to change sched_task_group: cpu_cgrp_subsys methods and autogroup_move_group() use it. Everything is synchronized by task_rq_lock(), so cpu_cgroup_attach() is ordered with other users of sched_move_task(). This means we do no need RCU here: if we've dereferenced a tg here, the .attach method hasn't been called for it yet. Thus, we should pass "true" to task_css_check() to silence lockdep warnings. Fixes: eeb61e53ea19 ("sched: Fix race between task_group and sched_task_group") Reported-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1414473874.8574.2.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/dl: Fix preemption checksKirill Tkhai2014-10-281-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1) switched_to_dl() check is wrong. We reschedule only if rq->curr is deadline task, and we do not reschedule if it's a lower priority task. But we must always preempt a task of other classes. 2) dl_task_timer(): Policy does not change in case of priority inheritance. rt_mutex_setprio() changes prio, while policy remains old. So we lose some balancing logic in dl_task_timer() and switched_to_dl() when we check policy instead of priority. Boosted task may be rq->curr. (I didn't change switched_from_dl() because no check is necessary there at all). I've looked at this place(switched_to_dl) several times and even fixed this function, but found just now... I suppose some performance tests may work better after this. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1413909356.19914.128.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched: stop the unbound recursion in preempt_schedule_context()Oleg Nesterov2014-10-281-0/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | preempt_schedule_context() does preempt_enable_notrace() at the end and this can call the same function again; exception_exit() is heavy and it is quite possible that need-resched is true again. 1. Change this code to dec preempt_count() and check need_resched() by hand. 2. As Linus suggested, we can use the PREEMPT_ACTIVE bit and avoid the enable/disable dance around __schedule(). But in this case we need to move into sched/core.c. 3. Cosmetic, but x86 forgets to declare this function. This doesn't really matter because it is only called by asm helpers, still it make sense to add the declaration into asm/preempt.h to match preempt_schedule(). Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Graf <agraf@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Chuck Ebbert <cebbert.lkml@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20141005202322.GB27962@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/fair: Fix division by zero sysctl_numa_balancing_scan_sizeKirill Tkhai2014-10-281-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | File /proc/sys/kernel/numa_balancing_scan_size_mb allows writing of zero. This bash command reproduces problem: $ while :; do echo 0 > /proc/sys/kernel/numa_balancing_scan_size_mb; \ echo 256 > /proc/sys/kernel/numa_balancing_scan_size_mb; done divide error: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 24112 Comm: bash Not tainted 3.17.0+ #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88013c852600 ti: ffff880037a68000 task.ti: ffff880037a68000 RIP: 0010:[<ffffffff81074191>] [<ffffffff81074191>] task_scan_min+0x21/0x50 RSP: 0000:ffff880037a6bce0 EFLAGS: 00010246 RAX: 0000000000000a00 RBX: 00000000000003e8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88013c852600 RBP: ffff880037a6bcf0 R08: 0000000000000001 R09: 0000000000015c90 R10: ffff880239bf6c00 R11: 0000000000000016 R12: 0000000000003fff R13: ffff88013c852600 R14: ffffea0008d1b000 R15: 0000000000000003 FS: 00007f12bb048700(0000) GS:ffff88007da00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000001505678 CR3: 0000000234770000 CR4: 00000000000006f0 Stack: ffff88013c852600 0000000000003fff ffff880037a6bd18 ffffffff810741d1 ffff88013c852600 0000000000003fff 000000000002bfff ffff880037a6bda8 ffffffff81077ef7 ffffea0008a56d40 0000000000000001 0000000000000001 Call Trace: [<ffffffff810741d1>] task_scan_max+0x11/0x40 [<ffffffff81077ef7>] task_numa_fault+0x1f7/0xae0 [<ffffffff8115a896>] ? migrate_misplaced_page+0x276/0x300 [<ffffffff81134a4d>] handle_mm_fault+0x62d/0xba0 [<ffffffff8103e2f1>] __do_page_fault+0x191/0x510 [<ffffffff81030122>] ? native_smp_send_reschedule+0x42/0x60 [<ffffffff8106dc00>] ? check_preempt_curr+0x80/0xa0 [<ffffffff8107092c>] ? wake_up_new_task+0x11c/0x1a0 [<ffffffff8104887d>] ? do_fork+0x14d/0x340 [<ffffffff811799bb>] ? get_unused_fd_flags+0x2b/0x30 [<ffffffff811799df>] ? __fd_install+0x1f/0x60 [<ffffffff8103e67c>] do_page_fault+0xc/0x10 [<ffffffff8150d322>] page_fault+0x22/0x30 RIP [<ffffffff81074191>] task_scan_min+0x21/0x50 RSP <ffff880037a6bce0> ---[ end trace 9a826d16936c04de ]--- Also fix race in task_scan_min (it depends on compiler behaviour). Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dario Faggioli <raistlin@linux.it> Cc: David Rientjes <rientjes@google.com> Cc: Jens Axboe <axboe@fb.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Link: http://lkml.kernel.org/r/1413455977.24793.78.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/fair: Care divide error in update_task_scan_period()Yasuaki Ishimatsu2014-10-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While offling node by hot removing memory, the following divide error occurs: divide error: 0000 [#1] SMP [...] Call Trace: [...] handle_mm_fault [...] ? try_to_wake_up [...] ? wake_up_state [...] __do_page_fault [...] ? do_futex [...] ? put_prev_entity [...] ? __switch_to [...] do_page_fault [...] page_fault [...] RIP [<ffffffff810a7081>] task_numa_fault RSP <ffff88084eb2bcb0> The issue occurs as follows: 1. When page fault occurs and page is allocated from node 1, task_struct->numa_faults_buffer_memory[] of node 1 is incremented and p->numa_faults_locality[] is also incremented as follows: o numa_faults_buffer_memory[] o numa_faults_locality[] NR_NUMA_HINT_FAULT_TYPES | 0 | 1 | ---------------------------------- ---------------------- node 0 | 0 | 0 | remote | 0 | node 1 | 0 | 1 | locale | 1 | ---------------------------------- ---------------------- 2. node 1 is offlined by hot removing memory. 3. When page fault occurs, fault_types[] is calculated by using p->numa_faults_buffer_memory[] of all online nodes in task_numa_placement(). But node 1 was offline by step 2. So the fault_types[] is calculated by using only p->numa_faults_buffer_memory[] of node 0. So both of fault_types[] are set to 0. 4. The values(0) of fault_types[] pass to update_task_scan_period(). 5. numa_faults_locality[1] is set to 1. So the following division is calculated. static void update_task_scan_period(struct task_struct *p, unsigned long shared, unsigned long private){ ... ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared)); } 6. But both of private and shared are set to 0. So divide error occurs here. The divide error is rare case because the trigger is node offline. This patch always increments denominator for avoiding divide error. Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/54475703.8000505@jp.fujitsu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/numa: Fix unsafe get_task_struct() in task_numa_assign()Kirill Tkhai2014-10-281-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unlocked access to dst_rq->curr in task_numa_compare() is racy. If curr task is exiting this may be a reason of use-after-free: task_numa_compare() do_exit() ... current->flags |= PF_EXITING; ... release_task() ... ~~delayed_put_task_struct()~~ ... schedule() rcu_read_lock() ... cur = ACCESS_ONCE(dst_rq->curr) ... ... rq->curr = next; ... context_switch() ... finish_task_switch() ... put_task_struct() ... __put_task_struct() ... free_task_struct() task_numa_assign() ... get_task_struct() ... As noted by Oleg: <<The lockless get_task_struct(tsk) is only safe if tsk == current and didn't pass exit_notify(), or if this tsk was found on a rcu protected list (say, for_each_process() or find_task_by_vpid()). IOW, it is only safe if release_task() was not called before we take rcu_read_lock(), in this case we can rely on the fact that delayed_put_pid() can not drop the (potentially) last reference until rcu_read_unlock(). And as Kirill pointed out task_numa_compare()->task_numa_assign() path does get_task_struct(dst_rq->curr) and this is not safe. The task_struct itself can't go away, but rcu_read_lock() can't save us from the final put_task_struct() in finish_task_switch(); this reference goes away without rcu gp>> The patch provides simple check of PF_EXITING flag. If it's not set, this guarantees that call_rcu() of delayed_put_task_struct() callback hasn't happened yet, so we can safely do get_task_struct() in task_numa_assign(). Locked dst_rq->lock protects from concurrency with the last schedule(). Reusing or unmapping of cur's memory may happen without it. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1413962231.19914.130.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/deadline: Fix races between rt_mutex_setprio() and dl_task_timer()Juri Lelli2014-10-281-5/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | dl_task_timer() is racy against several paths. Daniel noticed that the replenishment timer may experience a race condition against an enqueue_dl_entity() called from rt_mutex_setprio(). With his own words: rt_mutex_setprio() resets p->dl.dl_throttled. So the pattern is: start_dl_timer() throttled = 1, rt_mutex_setprio() throlled = 0, sched_switch() -> enqueue_task(), dl_task_timer-> enqueue_task() throttled is 0 => BUG_ON(on_dl_rq(dl_se)) fires as the scheduling entity is already enqueued on the -deadline runqueue. As we do for the other races, we just bail out in the replenishment timer code. Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: vincent@legout.info Cc: Dario Faggioli <raistlin@linux.it> Cc: Michael Trimarchi <michael@amarulasolutions.com> Cc: Fabio Checconi <fchecconi@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1414142198-18552-5-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched/deadline: Don't replenish from a !SCHED_DEADLINE entityJuri Lelli2014-10-281-1/+12
| | | | | | | | | | | | | | | | | | | | | | | In the deboost path, right after the dl_boosted flag has been reset, we can currently end up replenishing using -deadline parameters of a !SCHED_DEADLINE entity. This of course causes a bug, as those parameters are empty. In the case depicted above it is safe to simply bail out, as the deboosted task is going to be back to its original scheduling class anyway. Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: vincent@legout.info Cc: Dario Faggioli <raistlin@linux.it> Cc: Michael Trimarchi <michael@amarulasolutions.com> Cc: Fabio Checconi <fchecconi@gmail.com> Link: http://lkml.kernel.org/r/1414142198-18552-4-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* sched: Fix race between task_group and sched_task_groupKirill Tkhai2014-10-281-0/+6
| | | | | | | | | | | | | | | | | | | | | | | The race may happen when somebody is changing task_group of a forking task. Child's cgroup is the same as parent's after dup_task_struct() (there just memory copying). Also, cfs_rq and rt_rq are the same as parent's. But if parent changes its task_group before it's called cgroup_post_fork(), we do not reflect this situation on child. Child's cfs_rq and rt_rq remain the same, while child's task_group changes in cgroup_post_fork(). To fix this we introduce fork() method, which calls sched_move_task() directly. This function changes sched_task_group on appropriate (also its logic has no problem with freshly created tasks, so we shouldn't introduce something special; we are able just to use it). Possibly, this decides the Burke Libbey's problem: https://lkml.org/lkml/2014/10/24/456 Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'for-3.18-consistent-ops' of ↵Linus Torvalds2014-10-155-6/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu Pull percpu consistent-ops changes from Tejun Heo: "Way back, before the current percpu allocator was implemented, static and dynamic percpu memory areas were allocated and handled separately and had their own accessors. The distinction has been gone for many years now; however, the now duplicate two sets of accessors remained with the pointer based ones - this_cpu_*() - evolving various other operations over time. During the process, we also accumulated other inconsistent operations. This pull request contains Christoph's patches to clean up the duplicate accessor situation. __get_cpu_var() uses are replaced with with this_cpu_ptr() and __this_cpu_ptr() with raw_cpu_ptr(). Unfortunately, the former sometimes is tricky thanks to C being a bit messy with the distinction between lvalues and pointers, which led to a rather ugly solution for cpumask_var_t involving the introduction of this_cpu_cpumask_var_ptr(). This converts most of the uses but not all. Christoph will follow up with the remaining conversions in this merge window and hopefully remove the obsolete accessors" * 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (38 commits) irqchip: Properly fetch the per cpu offset percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t -fix ia64: sn_nodepda cannot be assigned to after this_cpu conversion. Use __this_cpu_write. percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t Revert "powerpc: Replace __get_cpu_var uses" percpu: Remove __this_cpu_ptr clocksource: Replace __this_cpu_ptr with raw_cpu_ptr sparc: Replace __get_cpu_var uses avr32: Replace __get_cpu_var with __this_cpu_write blackfin: Replace __get_cpu_var uses tile: Use this_cpu_ptr() for hardware counters tile: Replace __get_cpu_var uses powerpc: Replace __get_cpu_var uses alpha: Replace __get_cpu_var ia64: Replace __get_cpu_var uses s390: cio driver &__get_cpu_var replacements s390: Replace __get_cpu_var uses mips: Replace __get_cpu_var uses MIPS: Replace __get_cpu_var uses in FPU emulator. arm: Replace __this_cpu_ptr with raw_cpu_ptr ...
| * percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_tChristoph Lameter2014-08-283-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __get_cpu_var can paper over differences in the definitions of cpumask_var_t and either use the address of the cpumask variable directly or perform a fetch of the address of the struct cpumask allocated elsewhere. This is important particularly when using per cpu cpumask_var_t declarations because in one case we have an offset into a per cpu area to handle and in the other case we need to fetch a pointer from the offset. This patch introduces a new macro this_cpu_cpumask_var_ptr() that is defined where cpumask_var_t is defined and performs the proper actions. All use cases where __get_cpu_var is used with cpumask_var_t are converted to the use of this_cpu_cpumask_var_ptr(). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * scheduler: Replace __get_cpu_var with this_cpu_ptrChristoph Lameter2014-08-261-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Convert all uses of __get_cpu_var for address calculation to use this_cpu_ptr instead. [Uses of __get_cpu_var with cpumask_var_t are no longer handled by this patch] Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * time: Replace __get_cpu_var usesChristoph Lameter2014-08-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Convert uses of __get_cpu_var for creating a address from a percpu offset to this_cpu_ptr. The two cases where get_cpu_var is used to actually access a percpu variable are changed to use this_cpu_read/raw_cpu_read. Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2014-10-1311-393/+609
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes in this cycle were: - Optimized support for Intel "Cluster-on-Die" (CoD) topologies (Dave Hansen) - Various sched/idle refinements for better idle handling (Nicolas Pitre, Daniel Lezcano, Chuansheng Liu, Vincent Guittot) - sched/numa updates and optimizations (Rik van Riel) - sysbench speedup (Vincent Guittot) - capacity calculation cleanups/refactoring (Vincent Guittot) - Various cleanups to thread group iteration (Oleg Nesterov) - Double-rq-lock removal optimization and various refactorings (Kirill Tkhai) - various sched/deadline fixes ... and lots of other changes" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits) sched/dl: Use dl_bw_of() under rcu_read_lock_sched() sched/fair: Delete resched_cpu() from idle_balance() sched, time: Fix build error with 64 bit cputime_t on 32 bit systems sched: Improve sysbench performance by fixing spurious active migration sched/x86: Fix up typo in topology detection x86, sched: Add new topology for multi-NUMA-node CPUs sched/rt: Use resched_curr() in task_tick_rt() sched: Use rq->rd in sched_setaffinity() under RCU read lock sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask' sched: Use dl_bw_of() under RCU read lock sched/fair: Remove duplicate code from can_migrate_task() sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW sched: print_rq(): Don't use tasklist_lock sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock() sched: Fix the task-group check in tg_has_rt_tasks() sched/fair: Leverage the idle state info when choosing the "idlest" cpu sched: Let the scheduler see CPU idle states sched/deadline: Fix inter- exclusive cpusets migrations sched/deadline: Clear dl_entity params when setscheduling to different class sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault() ...
| * | sched/dl: Use dl_bw_of() under rcu_read_lock_sched()Kirill Tkhai2014-10-031-9/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rq->rd is freed using call_rcu_sched(), so rcu_read_lock() to access it is not enough. We should use either rcu_read_lock_sched() or preempt_disable(). Reported-by: Sasha Levin <sasha.levin@oracle.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Kirill Tkhai <ktkhai@parallels.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Fixes: 66339c31bc39 "sched: Use dl_bw_of() under RCU read lock" Link: http://lkml.kernel.org/r/1412065417.20287.24.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Delete resched_cpu() from idle_balance()Kirill Tkhai2014-10-031-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We already reschedule env.dst_cpu in attach_tasks()->check_preempt_curr() if this is necessary. Furthermore, a higher priority class task may be current on dest rq, we shouldn't disturb it. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Cc: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140930210441.5258.55054.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched, time: Fix build error with 64 bit cputime_t on 32 bit systemsRik van Riel2014-10-031-10/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On 32 bit systems cmpxchg cannot handle 64 bit values, so some additional magic is required to allow a 32 bit system with CONFIG_VIRT_CPU_ACCOUNTING_GEN=y enabled to build. Make sure the correct cmpxchg function is used when doing an atomic swap of a cputime_t. Reported-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: umgwanakikbuti@gmail.com Cc: fweisbec@gmail.com Cc: srao@redhat.com Cc: lwoodman@redhat.com Cc: atheurer@redhat.com Cc: oleg@redhat.com Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: linux390@de.ibm.com Cc: linux-arch@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Link: http://lkml.kernel.org/r/20140930155947.070cdb1f@annuminas.surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Improve sysbench performance by fixing spurious active migrationVincent Guittot2014-10-031-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit caeb178c60f4 ("sched/fair: Make update_sd_pick_busiest() ...") sd_pick_busiest returns a group that can be neither imbalanced nor overloaded but is only more loaded than others. This change has been introduced to ensure a better load balance in system that are not overloaded but as a side effect, it can also generate useless active migration between groups. Let take the example of 3 tasks on a quad cores system. We will always have an idle core so the load balance will find a busiest group (core) whenever an ILB is triggered and it will force an active migration (once above nr_balance_failed threshold) so the idle core becomes busy but another core will become idle. With the next ILB, the freshly idle core will try to pull the task of a busy CPU. The number of spurious active migration is not so huge in quad core system because the ILB is not triggered so much. But it becomes significant as soon as you have more than one sched_domain level like on a dual cluster of quad cores where the ILB is triggered every tick when you have more than 1 busy_cpu We need to ensure that the migration generate a real improveùent and will not only move the avg_load imbalance on another CPU. Before caeb178c60f4f93f1b45c0bc056b5cf6d217b67f, the filtering of such use case was ensured by the following test in f_b_g: if ((local->idle_cpus < busiest->idle_cpus) && busiest->sum_nr_running <= busiest->group_weight) This patch modified the condition to take into account situation where busiest group is not overloaded: If the diff between the number of idle cpus in 2 groups is less than or equal to 1 and the busiest group is not overloaded, moving a task will not improve the load balance but just move it. A test with sysbench on a dual clusters of quad cores gives the following results: command: sysbench --test=cpu --num-threads=5 --max-time=5 run The HZ is 200 which means that 1000 ticks has fired during the test. With Mainline, perf gives the following figures: Samples: 727 of event 'sched:sched_migrate_task' Event count (approx.): 727 Overhead Command Shared Object Symbol ........ ............... ............. .............. 12.52% migration/1 [unknown] [.] 00000000 12.52% migration/5 [unknown] [.] 00000000 12.52% migration/7 [unknown] [.] 00000000 12.10% migration/6 [unknown] [.] 00000000 11.83% migration/0 [unknown] [.] 00000000 11.83% migration/3 [unknown] [.] 00000000 11.14% migration/4 [unknown] [.] 00000000 10.87% migration/2 [unknown] [.] 00000000 2.75% sysbench [unknown] [.] 00000000 0.83% swapper [unknown] [.] 00000000 0.55% ktps65090charge [unknown] [.] 00000000 0.41% mmcqd/1 [unknown] [.] 00000000 0.14% perf [unknown] [.] 00000000 With this patch, perf gives the following figures Samples: 20 of event 'sched:sched_migrate_task' Event count (approx.): 20 Overhead Command Shared Object Symbol ........ ............... ............. .............. 80.00% sysbench [unknown] [.] 00000000 10.00% swapper [unknown] [.] 00000000 5.00% ktps65090charge [unknown] [.] 00000000 5.00% migration/1 [unknown] [.] 00000000 Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Rik van Riel <riel@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1412170735-5356-1-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/rt: Use resched_curr() in task_tick_rt()Kirill Tkhai2014-09-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some time ago PREEMPT_NEED_RESCHED was implemented, so reschedule technics is a little more difficult now. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140922183642.11015.66039.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Use rq->rd in sched_setaffinity() under RCU read lockKirill Tkhai2014-09-241-4/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Probability of use-after-free isn't zero in this place. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v3.14+ Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140922183636.11015.83611.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask'Kirill Tkhai2014-09-241-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | Nothing is locked there, so label's name only confuses a reader. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140922183630.11015.59500.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Use dl_bw_of() under RCU read lockKirill Tkhai2014-09-241-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | dl_bw_of() dereferences rq->rd which has to have RCU read lock held. Probability of use-after-free isn't zero here. Also add lockdep assert into dl_bw_cpus(). Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v3.14+ Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140922183624.11015.71558.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Remove duplicate code from can_migrate_task()Kirill Tkhai2014-09-241-14/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Combine two branches which do the same. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140922183612.11015.64200.stgit@localhost Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSWPeter Zijlstra2014-09-242-36/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Kirill found that there's a subtle race in the __ARCH_WANT_UNLOCKED_CTXSW code, and instead of fixing it, remove the entire exception because neither arch that uses it seems to actually still require it. Boot tested on mips64el (qemu) only. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kirill Tkhai <tkhai@yandex.ru> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Burton <paul.burton@imgtec.com> Cc: Qais Yousef <qais.yousef@imgtec.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Tony Luck <tony.luck@intel.com> Cc: oleg@redhat.com Cc: linux@roeck-us.net Cc: linux-ia64@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Link: http://lkml.kernel.org/r/20140923150641.GH3312@worktop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: print_rq(): Don't use tasklist_lockOleg Nesterov2014-09-241-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | read_lock_irqsave(tasklist_lock) in print_rq() looks strange. We do not need to disable irqs, and they are already disabled by the caller. And afaics this lock buys nothing, we can rely on rcu_read_lock(). In this case it makes sense to also move rcu_read_lock/unlock from the caller to print_rq(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140921193341.GA28628@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use ↵Oleg Nesterov2014-09-241-10/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | task_rq_lock() 1. read_lock(tasklist_lock) does not need to disable irqs. 2. ->mm != NULL is a common mistake, use PF_KTHREAD. 3. The second ->mm check can be simply removed. 4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) + __task_rq_lock(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140921193338.GA28621@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix the task-group check in tg_has_rt_tasks()Oleg Nesterov2014-09-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | tg_has_rt_tasks() wants to find an RT task in this task_group, but task_rq(p)->rt.tg wrongly checks the root rt_rq. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Link: http://lkml.kernel.org/r/20140921193336.GA28618@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Leverage the idle state info when choosing the "idlest" cpuNicolas Pitre2014-09-241-7/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code in find_idlest_cpu() looks for the CPU with the smallest load. However, if multiple CPUs are idle, the first idle CPU is selected irrespective of the depth of its idle state. Among the idle CPUs we should pick the one with with the shallowest idle state, or the latest to have gone idle if all idle CPUs are in the same state. The later applies even when cpuidle is configured out. This patch doesn't cover the following issues: - The idle exit latency of a CPU might be larger than the time needed to migrate the waking task to an already running CPU with sufficient capacity, and therefore performance would benefit from task packing in such case (in most cases task packing is about power saving). - Some idle states have a non negligible and non abortable entry latency which needs to run to completion before the exit latency can start. A concurrent patch series is making this info available to the cpuidle core. Once available, the entry latency with the idle timestamp could determine when the exit latency may be effective. Those issues will be handled in due course. In the mean time, what is implemented here should improve things already compared to the current state of affairs. Based on an initial patch from Daniel Lezcano. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-pm@vger.kernel.org Cc: linaro-kernel@lists.linaro.org Link: http://lkml.kernel.org/n/tip-@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Let the scheduler see CPU idle statesDaniel Lezcano2014-09-242-0/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the cpu enters idle, it stores the cpuidle state pointer in its struct rq instance which in turn could be used to make a better decision when balancing tasks. As soon as the cpu exits its idle state, the struct rq reference is cleared. There are a couple of situations where the idle state pointer could be changed while it is being consulted: 1. For x86/acpi with dynamic c-states, when a laptop switches from battery to AC that could result on removing the deeper idle state. The acpi driver triggers: 'acpi_processor_cst_has_changed' 'cpuidle_pause_and_lock' 'cpuidle_uninstall_idle_handler' 'kick_all_cpus_sync'. All cpus will exit their idle state and the pointed object will be set to NULL. 2. The cpuidle driver is unloaded. Logically that could happen but not in practice because the drivers are always compiled in and 95% of them are not coded to unregister themselves. In any case, the unloading code must call 'cpuidle_unregister_device', that calls 'cpuidle_pause_and_lock' leading to 'kick_all_cpus_sync' as mentioned above. A race can happen if we use the pointer and then one of these two scenarios occurs at the same moment. In order to be safe, the idle state pointer stored in the rq must be used inside a rcu_read_lock section where we are protected with the 'rcu_barrier' in the 'cpuidle_uninstall_idle_handler' function. The idle_get_state() and idle_put_state() accessors should be used to that effect. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: linux-pm@vger.kernel.org Cc: linaro-kernel@lists.linaro.org Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/deadline: Fix inter- exclusive cpusets migrationsJuri Lelli2014-09-242-3/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Users can perform clustered scheduling using the cpuset facility. After an exclusive cpuset is created, task migrations happen only between CPUs belonging to the same cpuset. Inter- cpuset migrations can only happen when the user requires so, moving a task between different cpusets. This behaviour is broken in SCHED_DEADLINE, as currently spurious inter- cpuset migration may happen without user intervention. This patch fix the problem (and shuffles the code a bit to improve clarity). Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: raistlin@linux.it Cc: michael@amarulasolutions.com Cc: fchecconi@gmail.com Cc: daniel.wagner@bmw-carit.de Cc: vincent@legout.info Cc: luca.abeni@unitn.it Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1411118561-26323-4-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/deadline: Clear dl_entity params when setscheduling to different classJuri Lelli2014-09-243-4/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a task is using SCHED_DEADLINE and the user setschedules it to a different class its sched_dl_entity static parameters are not cleaned up. This causes a bug if the user sets it back to SCHED_DEADLINE with the same parameters again. The problem resides in the check we perform at the very beginning of dl_overflow(): if (new_bw == p->dl.dl_bw) return 0; This condition is met in the case depicted above, so the function returns and dl_b->total_bw is not updated (the p->dl.dl_bw is not added to it). After this, admission control is broken. This patch fixes the thing, properly clearing static parameters for a task that ceases to use SCHED_DEADLINE. Reported-by: Daniele Alessandrelli <daniele.alessandrelli@gmail.com> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Reported-by: Vincent Legout <vincent@legout.info> Tested-by: Luca Abeni <luca.abeni@unitn.it> Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Tested-by: Vincent Legout <vincent@legout.info> Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Fabio Checconi <fchecconi@gmail.com> Cc: Dario Faggioli <raistlin@linux.it> Cc: Michael Trimarchi <michael@amarulasolutions.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1411118561-26323-2-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()Oleg Nesterov2014-09-241-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | current->state == TASK_DEAD means that the task is doing its last schedule(), page fault is obviously impossible at this stage. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140921194743.GA30114@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Clean up some typos and grammatical errors in code/commentsZhihui Zhang2014-09-213-6/+6
| | | | | | | | | | | | | | | | | | | | | Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com> Cc: peterz@infradead.org Link: http://lkml.kernel.org/r/1411262676-19928-1-git-send-email-zzhsuny@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Test the CPU's capacity in wake_affine()Vincent Guittot2014-09-191-9/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the task always wakes affine on this_cpu if the latter is idle. Before waking up the task on this_cpu, we check that this_cpu capacity is not significantly reduced because of RT tasks or irq activity. Use case where the number of irq and/or the time spent under irq is important will take benefit of this because the task that is woken up by irq or softirq will not use the same CPU than irq (and softirq) but a idle one. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: preeti@linux.vnet.ibm.com Cc: riel@redhat.com Cc: Morten.Rasmussen@arm.com Cc: efault@gmx.de Cc: nicolas.pitre@linaro.org Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409051215-16788-8-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Allow all architectures to set 'capacity_orig'Vincent Guittot2014-09-191-16/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'capacity_orig' is only changed for systems with an SMT sched_domain level in order to reflect the lower capacity of CPUs. Heterogenous systems also have to reflect an original capacity that is different from the default value. Create a more generic function arch_scale_cpu_capacity that can be also used by non SMT platforms to set capacity_orig. The __weak implementation of arch_scale_cpu_capacity() is the previous SMT variant, in order to keep backward compatibility with the use of capacity_orig. arch_scale_smt_capacity() and default_scale_smt_capacity() have been removed as they were not used elsewhere than in arch_scale_cpu_capacity(). Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com> [ Added default_scale_cpu_capacity() back. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: riel@redhat.com Cc: Morten.Rasmussen@arm.com Cc: efault@gmx.de Cc: nicolas.pitre@linaro.org Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409051215-16788-5-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix avg_load computationVincent Guittot2014-09-191-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The computation of avg_load and avg_load_per_task should only take into account the number of CFS tasks. The non-CFS tasks are already taken into account by decreasing the CPU's capacity and they will be tracked in the CPU's utilization (group_utilization) of the next patches. Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: riel@redhat.com Cc: Morten.Rasmussen@arm.com Cc: efault@gmx.de Cc: nicolas.pitre@linaro.org Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409051215-16788-4-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Remove a wake_affine() conditionVincent Guittot2014-09-191-24/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In wake_affine() I have tried to understand the meaning of the condition: (this_load <= load && this_load + target_load(prev_cpu, idx) <= tl_per_task) but I failed to find a use case that can take advantage of it and I haven't found clear description in the previous commit's log. Futhermore, the comment of the condition refers to the task_hot function that was used before being replaced by the current condition: /* * This domain has SD_WAKE_AFFINE and * p is cache cold in this domain, and * there is no bad imbalance. */ If we look more deeply the below condition: this_load + target_load(prev_cpu, idx) <= tl_per_task When sync is clear, we have: tl_per_task = runnable_load_avg / nr_running this_load = max(runnable_load_avg, cpuload[idx]) target_load = max(runnable_load_avg', cpuload'[idx]) It implies that runnable_load_avg == 0 and nr_running <= 1 in order to match the condition. This implies that runnable_load_avg == 0 too because of the condition: this_load <= load. but if this _load is null, 'balanced' is already set and the test is redundant. If sync is set, it's not as straight forward as above (especially if cgroup are involved) but the policy should be similar as we have removed a task that's going to sleep in order to get a more accurate load and this_load values. The current conclusion is that these additional condition don't give any benefit so we can remove them. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: preeti@linux.vnet.ibm.com Cc: riel@redhat.com Cc: Morten.Rasmussen@arm.com Cc: efault@gmx.de Cc: nicolas.pitre@linaro.org Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409051215-16788-3-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Fix imbalance flag resetVincent Guittot2014-09-191-4/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The imbalance flag can stay set whereas there is no imbalance. Let assume that we have 3 tasks that run on a dual cores /dual cluster system. We will have some idle load balance which are triggered during tick. Unfortunately, the tick is also used to queue background work so we can reach the situation where short work has been queued on a CPU which already runs a task. The load balance will detect this imbalance (2 tasks on 1 CPU and an idle CPU) and will try to pull the waiting task on the idle CPU. The waiting task is a worker thread that is pinned on a CPU so an imbalance due to pinned task is detected and the imbalance flag is set. Then, we will not be able to clear the flag because we have at most 1 task on each CPU but the imbalance flag will trig to useless active load balance between the idle CPU and the busy CPU. We need to reset of the imbalance flag as soon as we have reached a balanced state. If all tasks are pinned, we don't consider that as a balanced state and let the imbalance flag set. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: riel@redhat.com Cc: Morten.Rasmussen@arm.com Cc: efault@gmx.de Cc: nicolas.pitre@linaro.org Cc: daniel.lezcano@linaro.org Cc: dietmar.eggemann@arm.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1409051215-16788-2-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Add default-disabled option to BUG() when stack end location is ↵Aaron Tomlin2014-09-191-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | overwritten Currently in the event of a stack overrun a call to schedule() does not check for this type of corruption. This corruption is often silent and can go unnoticed. However once the corrupted region is examined at a later stage, the outcome is undefined and often results in a sporadic page fault which cannot be handled. This patch checks for a stack overrun and takes appropriate action since the damage is already done, there is no point in continuing. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: aneesh.kumar@linux.vnet.ibm.com Cc: dzickus@redhat.com Cc: bmr@redhat.com Cc: jcastillo@redhat.com Cc: oleg@redhat.com Cc: riel@redhat.com Cc: prarit@redhat.com Cc: jgh@redhat.com Cc: minchan@kernel.org Cc: mpe@ellerman.id.au Cc: tglx@linutronix.de Cc: rostedt@goodmis.org Cc: hannes@cmpxchg.org Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: David S. Miller <davem@davemloft.net> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lubomir Rintel <lkundrak@v3.sk> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/r/1410527779-8133-4-git-send-email-atomlin@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Do not stop cpu in set_cpus_allowed_ptr() if task is not runningKirill Tkhai2014-09-191-15/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a task is queued but not running on it rq, we can simply migrate it without migration thread and switching of context. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1410519814.3569.7.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/dl: Simplify pick_dl_task()Kirill Tkhai2014-09-191-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1) Nobody calls pick_dl_task() with negative cpu, it's old RT leftover. 2) If p->nr_cpus_allowed is 1, than the affinity has just been changed in set_cpus_allowed_ptr(); we'll pick it just earlier than migration thread. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1410529340.3569.27.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/rt: Remove useless if from cleanup pick_next_task_rt()Kirill Tkhai2014-09-191-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | _pick_next_task_rt() never returns NULL. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1410529321.3569.26.camel@tkhai Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/core: Use put_prev_task() accessor where possibleKirill Tkhai2014-09-191-4/+4
| | | | | | | | | | | | | | | | | | | | | Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1410529300.3569.25.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: cleanup: Remove useless assignment in select_task_rq_fair()Kirill Tkhai2014-09-191-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | new_cpu is reassigned below, so we do not need this here. Signed-off-by: Kirill Tkhai <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: http://lkml.kernel.org/r/1410529276.3569.24.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-11 03:19:45 +0000