Hi Joonsoo,
On Wed, Jun 15, 2016 at 4:23 AM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
> On Tue, Jun 14, 2016 at 12:45:14PM +0200, Geert Uytterhoeven wrote:
>> On Tue, Jun 14, 2016 at 10:11 AM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
>> > On Tue, Jun 14, 2016 at 09:31:23AM +0200, Geert Uytterhoeven wrote:
>> >> On Tue, Jun 14, 2016 at 8:24 AM, Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
>> >> > On Mon, Jun 13, 2016 at 09:43:13PM +0200, Geert Uytterhoeven wrote:
>> >> >> On Tue, Apr 12, 2016 at 6:51 AM, <js1304@xxxxxxxxx> wrote:
>> >> >> > From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
>> >> >> > To check whther free objects exist or not precisely, we need to grab a
>> >> >> > lock. But, accuracy isn't that important because race window would be
>> >> >> > even small and if there is too much free object, cache reaper would reap
>> >> >> > it. So, this patch makes the check for free object exisistence not to
>> >> >> > hold a lock. This will reduce lock contention in heavily allocation case.
>> >> >> I've bisected a boot failure (no output at all) in v4.7-rc2 on emev2/kzm9d
>> >> >> (Renesas dual Cortex A9) to this patch, which is upstream commit
>> >> >> 801faf0db8947e01877920e848a4d338dd7a99e7.
> It's curious that synchronize_sched() has some effect in this early
> phase. In synchronize_sched(), rcu_blocking_is_gp() is called and
> it checks num_online_cpus <= 1. If so, synchronize_sched() does nothing.
>
> It would be related to might_sleep() in rcu_blocking_is_gp() but I'm not sure now.
>
> First, I'd like to confirm that num_online_cpus() is correct.
> Could you try following patch and give me a dmesg?
>
> Thanks.
>
> ------->8----------
> diff --git a/mm/slab.c b/mm/slab.c
> index 763096a..5b7300a 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -964,8 +964,10 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep,
> * guaranteed to be valid until irq is re-enabled, because it will be
> * freed after synchronize_sched().
> */
> - if (force_change)
> - synchronize_sched();
> + if (force_change) {
> + WARN_ON_ONCE(num_online_cpus() <= 1);
> + WARN_ON_ONCE(num_online_cpus() > 1);
> + }
Full dmesg output below.
I also tested whether it's the call to synchronize_sched() before or after
secondary CPU bringup that hangs.
if (force_change && num_online_cpus() <= 1)
synchronize_sched();
boots.
if (force_change && num_online_cpus() > 1)
synchronize_sched();
hangs.
Booting Linux on physical CPU 0x0
Linux version 4.6.0-kzm9d-05060-g801faf0db8947e01-dirty (geert@ramsan)
(gcc version 4.9.0 (GCC) ) #84 SMP Wed Jun 15 10:20:12 CEST 2016
CPU: ARMv7 Processor [411fc093] revision 3 (ARMv7), cr=10c5387d
CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
Machine model: EMEV2 KZM9D Board
debug: ignoring loglevel setting.
Memory policy: Data cache writealloc
On node 0 totalpages: 32768
free_area_init_node: node 0, pgdat c09286c0, node_mem_map c7efa000
Normal zone: 256 pages used for memmap
Normal zone: 0 pages reserved
Normal zone: 32768 pages, LIFO batch:7
percpu: Embedded 12 pages/cpu @c7ed9000 s19264 r8192 d21696 u49152
pcpu-alloc: s19264 r8192 d21696 u49152 alloc=12*4096
pcpu-alloc: [0] 0 [0] 1
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 32512
Kernel command line: console=ttyS1,115200n81 ignore_loglevel
root=/dev/nfs ip=dhcp
PID hash table entries: 512 (order: -1, 2048 bytes)
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Memory: 121144K/131072K available (4243K kernel code, 165K rwdata,
1344K rodata, 2048K init, 264K bss, 9928K reserved, 0K cma-reserved,
0K highmem)
Virtual kernel memory layout:
vector : 0xffff0000 - 0xffff1000 ( 4 kB)
fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
vmalloc : 0xc8800000 - 0xff800000 ( 880 MB)
lowmem : 0xc0000000 - 0xc8000000 ( 128 MB)
pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
.text : 0xc0008000 - 0xc0674eb8 (6580 kB)
.init : 0xc0700000 - 0xc0900000 (2048 kB)
.data : 0xc0900000 - 0xc0929420 ( 166 kB)
.bss : 0xc092b000 - 0xc096d1e8 ( 265 kB)
Hierarchical RCU implementation.
Build-time adjustment of leaf fanout to 32.
RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
RCU: Adjusting geometry for rcu_fanout_leaf=32, nr_cpu_ids=2
NR_IRQS:16 nr_irqs:16 16
clocksource_probe: no matching clocksources found
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every
21474836475000000ns
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at mm/slab.c:975 setup_kmem_cache_node+0x160/0x1c8
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.6.0-kzm9d-05060-g801faf0db8947e01-dirty #84
Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree)
[<c010de08>] (unwind_backtrace) from [<c010a620>] (show_stack+0x10/0x14)
[<c010a620>] (show_stack) from [<c02b3178>] (dump_stack+0x7c/0x9c)
[<c02b3178>] (dump_stack) from [<c011f9fc>] (__warn+0xcc/0xfc)
[<c011f9fc>] (__warn) from [<c011fad0>] (warn_slowpath_null+0x1c/0x24)
[<c011fad0>] (warn_slowpath_null) from [<c01ced4c>]
(setup_kmem_cache_node+0x160/0x1c8)
[<c01ced4c>] (setup_kmem_cache_node) from [<c01cf02c>]
(__do_tune_cpucache+0xf4/0x114)
[<c01cf02c>] (__do_tune_cpucache) from [<c01cf0b0>] (enable_cpucache+0x64/0xb4)
[<c01cf0b0>] (enable_cpucache) from [<c0710324>]
(kmem_cache_init_late+0x40/0x84)
[<c0710324>] (kmem_cache_init_late) from [<c0700af8>] (start_kernel+0x238/0x36c)
[<c0700af8>] (start_kernel) from [<4000807c>] (0x4000807c)
---[ end trace cb88537fdc8fa200 ]---
Console: colour dummy device 80x30
Calibrating delay loop (skipped) preset value.. 1066.00 BogoMIPS (lpj=5330000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x40100000 - 0x40100058
CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
Brought up 2 CPUs
SMP: Total of 2 processors activated (2132.00 BogoMIPS).
CPU: All CPU(s) started in SVC mode.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at mm/slab.c:976 setup_kmem_cache_node+0x198/0x1c8
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W
4.6.0-kzm9d-05060-g801faf0db8947e01-dirty #84
Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree)
[<c010de08>] (unwind_backtrace) from [<c010a620>] (show_stack+0x10/0x14)
[<c010a620>] (show_stack) from [<c02b3178>] (dump_stack+0x7c/0x9c)
[<c02b3178>] (dump_stack) from [<c011f9fc>] (__warn+0xcc/0xfc)
[<c011f9fc>] (__warn) from [<c011fad0>] (warn_slowpath_null+0x1c/0x24)
[<c011fad0>] (warn_slowpath_null) from [<c01ced84>]
(setup_kmem_cache_node+0x198/0x1c8)
[<c01ced84>] (setup_kmem_cache_node) from [<c01cf02c>]
(__do_tune_cpucache+0xf4/0x114)
[<c01cf02c>] (__do_tune_cpucache) from [<c01cf0b0>] (enable_cpucache+0x64/0xb4)
[<c01cf0b0>] (enable_cpucache) from [<c01cf4cc>]
(__kmem_cache_create+0x1a0/0x1c8)
[<c01cf4cc>] (__kmem_cache_create) from [<c01b2904>]
(kmem_cache_create+0xbc/0x190)
[<c01b2904>] (kmem_cache_create) from [<c070d724>] (shmem_init+0x34/0xb0)
[<c070d724>] (shmem_init) from [<c0700cc4>] (kernel_init_freeable+0x98/0x1ec)
[<c0700cc4>] (kernel_init_freeable) from [<c0497760>] (kernel_init+0x8/0x110)
[<c0497760>] (kernel_init) from [<c0106c78>] (ret_from_fork+0x14/0x3c)
---[ end trace cb88537fdc8fa201 ]---
devtmpfs: initialized
VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 1
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff,
max_idle_ns: 19112604462750000 ns
pinctrl core: initialized pinctrl subsystem
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
sh-pfc e0140200.pfc: emev2_pfc support registered
gpiochip_find_base: found new base at 992
gpio gpiochip0: (e0050000.gpio): created GPIO range 0->31 ==>
e0140200.pfc PIN 0->31
gpio gpiochip0: (e0050000.gpio): added GPIO chardev (254:0)
gpiochip_setup_dev: registered GPIOs 992 to 1023 on device: gpiochip0
(e0050000.gpio)
gpiochip_find_base: found new base at 960
gpio gpiochip1: (e0050080.gpio): created GPIO range 0->31 ==>
e0140200.pfc PIN 32->63
gpio gpiochip1: (e0050080.gpio): added GPIO chardev (254:1)
gpiochip_setup_dev: registered GPIOs 960 to 991 on device: gpiochip1
(e0050080.gpio)
gpiochip_find_base: found new base at 928
gpio gpiochip2: (e0050100.gpio): created GPIO range 0->31 ==>
e0140200.pfc PIN 64->95
gpio gpiochip2: (e0050100.gpio): added GPIO chardev (254:2)
gpiochip_setup_dev: registered GPIOs 928 to 959 on device: gpiochip2
(e0050100.gpio)
gpiochip_find_base: found new base at 896
gpio gpiochip3: (e0050180.gpio): created GPIO range 0->31 ==>
e0140200.pfc PIN 96->127
gpio gpiochip3: (e0050180.gpio): added GPIO chardev (254:3)
gpiochip_setup_dev: registered GPIOs 896 to 927 on device: gpiochip3
(e0050180.gpio)
gpiochip_find_base: found new base at 865
gpio gpiochip4: (e0050200.gpio): created GPIO range 0->30 ==>
e0140200.pfc PIN 128->158
gpio gpiochip4: (e0050200.gpio): added GPIO chardev (254:4)
gpiochip_setup_dev: registered GPIOs 865 to 895 on device: gpiochip4
(e0050200.gpio)
gio: map hw irq = 1, irq = 35
gio: sense irq = 1, mode = 8
No ATAGs?
hw-breakpoint: found 5 (+1 reserved) breakpoint and 1 watchpoint registers.
hw-breakpoint: maximum watchpoint size is 4 bytes.
of_get_named_gpiod_flags: can't parse 'gpio' property of node '/regulator@0[0]'
of_get_named_gpiod_flags: can't parse 'gpio' property of node '/regulator@1[0]'
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
em_sti e0180000.timer: used for clock events
em_sti e0180000.timer: used for oneshot clock events
em_sti e0180000.timer: used as clock source
clocksource: e0180000.timer: mask: 0xffffffffffff max_cycles:
0x1ef4687b1, max_idle_ns: 3697658158765000000 ns
Advanced Linux Sound Architecture Driver Initialized.
NET: Registered protocol family 23
clocksource: e0180000.timer: mask: 0xffffffffffff max_cycles:
0x1ef4687b1, max_idle_ns: 112843571739654 ns
clocksource: Switched to clocksource e0180000.timer
NET: Registered protocol family 2
TCP established hash table entries: 1024 (order: 0, 4096 bytes)
TCP bind hash table entries: 1024 (order: 2, 20480 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
UDP hash table entries: 256 (order: 1, 12288 bytes)
UDP-Lite hash table entries: 256 (order: 1, 12288 bytes)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
Clockevents: could not switch to one-shot mode:
Clockevents: could not switch to one-shot mode: dummy_timer is not functional.
Could not switch to high resolution mode on CPU 0
dummy_timer is not functional.
Could not switch to high resolution mode on CPU 1
hw perfevents: enabled with armv7_cortex_a9 PMU driver, 7 counters available
futex hash table entries: 512 (order: 3, 32768 bytes)
workingset: timestamp_bits=28 max_order=15 bucket_order=0
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
nfs4filelayout_init: NFSv4 File Layout Driver Registering...
io scheduler noop registered (default)
Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
e1020000.serial: ttyS0 at MMIO 0xe1020000 (irq = 19, base_baud =
796444) is a 16550A
e1030000.serial: ttyS1 at MMIO 0xe1030000 (irq = 20, base_baud =
7168000) is a 16550A
console [ttyS1] enabled
e1040000.serial: ttyS2 at MMIO 0xe1040000 (irq = 21, base_baud =
14336000) is a 16550A
e1050000.serial: ttyS3 at MMIO 0xe1050000 (irq = 22, base_baud =
2389333) is a 16550A
gio: sense irq = 1, mode = 8
libphy: smsc911x-mdio: probed
Generic PHY 20000000.etherne:01: attached PHY driver [Generic PHY]
(mii_bus:phy_addr=20000000.etherne:01, irq=-1)
smsc911x 20000000.ethernet eth0: MAC Address: 00:01:9b:04:03:cf
usbcore: registered new interface driver usb-storage
i2c /dev entries driver
em-i2c e0070000.i2c: Added i2c controller 0, irq 33
em-i2c e10a0000.i2c: Added i2c controller 1, irq 34
cpu cpu0: failed to get clock: -2
cpufreq-dt: probe of cpufreq-dt failed with error -2
ledtrig-cpu: registered to indicate activity on CPUs
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
NET: Registered protocol family 17
Key type dns_resolver registered
Registering SWP/SWPB emulation handler
of_get_named_gpiod_flags: parsed 'gpios' property of node
'/gpio_keys/button@1[0]' - status (0)
of_get_named_gpiod_flags: parsed 'gpios' property of node
'/gpio_keys/button@2[0]' - status (0)
of_get_named_gpiod_flags: parsed 'gpios' property of node
'/gpio_keys/button@3[0]' - status (0)
of_get_named_gpiod_flags: parsed 'gpios' property of node
'/gpio_keys/button@4[0]' - status (0)
gpio-1006 (DSW2-1): gpiod_set_debounce: missing set() or
set_debounce() operations
gio: map hw irq = 14, irq = 36
gio: sense irq = 14, mode = 12
gpio-1007 (DSW2-2): gpiod_set_debounce: missing set() or
set_debounce() operations
gio: map hw irq = 15, irq = 37
gio: sense irq = 15, mode = 12
gpio-1008 (DSW2-3): gpiod_set_debounce: missing set() or
set_debounce() operations
gio: map hw irq = 16, irq = 38
gio: sense irq = 16, mode = 12
gpio-1009 (DSW2-4): gpiod_set_debounce: missing set() or
set_debounce() operations
gio: map hw irq = 17, irq = 39
gio: sense irq = 17, mode = 12
input: gpio_keys as /devices/platform/gpio_keys/input/input0
hctosys: unable to open rtc device (rtc0)
smsc911x 20000000.ethernet eth0: SMSC911x/921x identified at 0xc8880000, IRQ: 35
Sending DHCP requests .., OK
IP-Config: Got DHCP answer from 192.168.97.254, my address is 192.168.97.215
IP-Config: Complete:
device=eth0, hwaddr=00:01:9b:04:03:cf, ipaddr=192.168.97.215,
mask=255.255.255.0, gw=192.168.97.254
host=192.168.97.215, domain=of.borg, nis-domain=(none)
bootserver=192.168.97.254, rootserver=192.168.97.254, rootpath=
nameserver0=192.168.97.254
ALSA device list:
No soundcards found.
Freeing unused kernel memory: 2048K (c0700000 - c0900000)
sysctl: error: 'kernel.hotplug' is an unknown key
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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