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6419265899
linux/kernel/sched
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Kirill Tkhai 6419265899 sched/fair: Fix division by zero sysctl_numa_balancing_scan_size 
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>
2014-10-28 10:46:04 +01:00
..
auto_group.c sched: Change autogroup_move_group() to use for_each_thread() 2014-08-20 09:47:18 +02:00
auto_group.h Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled" 2012-12-11 10:23:45 +01:00
clock.c time: Replace __get_cpu_var uses 2014-08-26 13:45:44 -04:00
completion.c sched: Move completion code from core.c to completion.c 2013-11-06 07:49:19 +01:00
core.c sched: Fix race between task_group and sched_task_group 2014-10-28 10:45:59 +01:00
cpuacct.c cgroup: rename cgroup_subsys->base_cftypes to ->legacy_cftypes 2014-07-15 11:05:09 -04:00
cpuacct.h sched/cpuacct: Initialize root cpuacct earlier 2013-04-10 13:54:20 +02:00
cpudeadline.c sched/deadline: Fix inter- exclusive cpusets migrations 2014-09-24 14:46:57 +02:00
cpudeadline.h sched/deadline: Replace NR_CPUS arrays 2014-05-22 10:21:28 +02:00
cpupri.c Merge commit '3cf2f34' into sched/core, to fix build error 2014-06-12 13:46:37 +02:00
cpupri.h sched/cpupri: Replace NR_CPUS arrays 2014-05-22 10:21:29 +02:00
cputime.c sched, time: Fix build error with 64 bit cputime_t on 32 bit systems 2014-10-03 05:46:55 +02:00
deadline.c sched/deadline: Fix races between rt_mutex_setprio() and dl_task_timer() 2014-10-28 10:46:01 +01:00
debug.c sched: print_rq(): Don't use tasklist_lock 2014-09-24 14:47:04 +02:00
fair.c sched/fair: Fix division by zero sysctl_numa_balancing_scan_size 2014-10-28 10:46:04 +01:00
features.h sched: Rename capacity related flags 2014-06-05 11:52:32 +02:00
idle_task.c sched: Transform resched_task() into resched_curr() 2014-07-16 13:38:19 +02:00
idle.c sched: Let the scheduler see CPU idle states 2014-09-24 14:46:58 +02:00
Makefile sched/idle: Move cpu/idle.c to sched/idle.c 2014-02-11 09:58:30 +01:00
proc.c cpuidle: menu: Lookup CPU runqueues less 2014-08-06 21:17:45 +02:00
rt.c Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
sched.h Merge branch 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2014-10-15 07:48:18 +02:00
stats.c kernel: audit/fix non-modular users of module_init in core code 2014-04-03 16:21:07 -07:00
stats.h sched: Micro-optimize by dropping unnecessary task_rq() calls 2013-09-25 13:51:06 +02:00
stop_task.c sched: Add wrapper for checking task_struct::on_rq 2014-08-20 14:52:59 +02:00
wait.c SCHED: add some "wait..on_bit...timeout()" interfaces. 2014-09-25 08:23:57 -04:00