Hi Simon,
> I have observed what appears to be a regression while testing next-20150702
> which seems to be caused by 2951d5c031a3 ("tick: broadcast: Prevent
> livelock from event handler").Does reverting help? I see a similar case with your branch renesas-devel-20150629-v4.1 which does not include both commits. For this branch, if I select CONFIG_NO_HZ_IDLE and *no* CONFIG_HIGH_RES_TIMERS, I see the case you described: > input: gpio_keys as /devices/platform/gpio_keys/input/input0 > hctosys: unable to open rtc device (rtc0) > > The boot hangs here. > The next line should be: > > smsc911x 20000000.ethernet eth0: SMSC911x/921x identified at 0xc8880000, IRQ: > 33 There is no OOPS, it just stops here. With CONFIG_HIGH_RES_TIMERS, the system boots to the prompt. Enabling all lockdep features doesn't show anything for the non-working case. However, I get warning for the working case: [ 2.560000] input: gpio_keys as /devices/platform/gpio_keys/input/input0 [ 2.610000] smsc911x 20000000.ethernet eth0: SMSC911x/921x identified at 0xc8880000, IRQ: 33 [ 5.510000] Sending DHCP requests ., OK [ 5.580000] IP-Config: Got DHCP answer from 192.168.64.1, my address is 192.168.64.14 [ 5.580000] IP-Config: Complete: [ 5.590000] device=eth0, hwaddr=00:01:9b:04:03:ce, ipaddr=192.168.64.14, mask=255.255.255.0, gw=192.168.64.1 [ 5.600000] host=192.168.64.14, domain=local, nis-domain=(none) [ 5.600000] bootserver=192.168.64.1, rootserver=192.168.64.1, rootpath= [ 5.610000] nameserver0=192.168.64.1 [ 5.630000] Freeing unused kernel memory: 632K (c0306000 - c03a4000) [ 5.660000] random: init urandom read with 14 bits of entropy available [ 5.820000] ------------[ cut here ]------------ [ 5.820000] WARNING: CPU: 0 PID: 282 at kernel/locking/lockdep.c:3557 check_flags+0x84/0x1f4() [ 5.820000] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 5.820000] CPU: 0 PID: 282 Comm: rcS Tainted: G W 4.1.0-00002-g5b076054611833 #179 [ 5.820000] Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree) [ 5.820000] Backtrace: [ 5.820000] [<c0012c94>] (dump_backtrace) from [<c0012e3c>] (show_stack+0x18/0x1c) [ 5.820000] r6:c02dcc67 r5:00000009 r4:00000000 r3:00400000 [ 5.820000] [<c0012e24>] (show_stack) from [<c02510c8>] (dump_stack+0x20/0x28) [ 5.820000] [<c02510a8>] (dump_stack) from [<c0022c44>] (warn_slowpath_common+0x8c/0xb4) [ 5.820000] [<c0022bb8>] (warn_slowpath_common) from [<c0022cd8>] (warn_slowpath_fmt+0x38/0x40) [ 5.820000] r8:c780f470 r7:00000000 r6:00000000 r5:c03b0570 r4:c0b7ec04 [ 5.820000] [<c0022ca4>] (warn_slowpath_fmt) from [<c004cd38>] (check_flags+0x84/0x1f4) [ 5.820000] r3:c02e13d8 r2:c02dceaa [ 5.820000] [<c004ccb4>] (check_flags) from [<c0050e50>] (lock_acquire+0x4c/0xbc) [ 5.820000] r5:00000000 r4:60000193 [ 5.820000] [<c0050e04>] (lock_acquire) from [<c0256000>] (_raw_spin_lock+0x34/0x44) [ 5.820000] r9:000a8d5c r8:00000001 r7:c7806000 r6:c780f460 r5:c03b06a0 r4:c780f460 [ 5.820000] [<c0255fcc>] (_raw_spin_lock) from [<c005a8cc>] (handle_fasteoi_irq+0x20/0x11c) [ 5.820000] r4:c780f400 [ 5.820000] [<c005a8ac>] (handle_fasteoi_irq) from [<c0057a4c>] (generic_handle_irq+0x28/0x38) [ 5.820000] r6:00000000 r5:c03b038c r4:00000012 r3:c005a8ac [ 5.820000] [<c0057a24>] (generic_handle_irq) from [<c0057ae4>] (__handle_domain_irq+0x88/0xa8) [ 5.820000] r4:00000000 r3:00000026 [ 5.820000] [<c0057a5c>] (__handle_domain_irq) from [<c000a3cc>] (gic_handle_irq+0x40/0x58) [ 5.820000] r8:10c5347d r7:10c5347d r6:c35b1fb0 r5:c03a6304 r4:c8802000 r3:c35b1fb0 [ 5.820000] [<c000a38c>] (gic_handle_irq) from [<c0013bc8>] (__irq_usr+0x48/0x60) [ 5.820000] Exception stack(0xc35b1fb0 to 0xc35b1ff8) [ 5.820000] 1fa0: 00000061 00000000 000ab736 00000066 [ 5.820000] 1fc0: 00000061 000aa1f0 000a8d54 000a8d54 000a8d88 000a8d5c 000a8cc8 000a8d68 [ 5.820000] 1fe0: 72727272 bef8a528 000398c0 00031334 20000010 ffffffff [ 5.820000] r6:ffffffff r5:20000010 r4:00031334 r3:00000061 [ 5.820000] ---[ end trace cb88537fdc8fa202 ]--- [ 5.820000] possible reason: unannotated irqs-off. [ 5.820000] irq event stamp: 769 [ 5.820000] hardirqs last enabled at (769): [<c000f82c>] ret_fast_syscall+0x2c/0x54 [ 5.820000] hardirqs last disabled at (768): [<c000f80c>] ret_fast_syscall+0xc/0x54 [ 5.820000] softirqs last enabled at (0): [<c0020ec4>] copy_process.part.65+0x2e8/0x11dc [ 5.820000] softirqs last disabled at (0): [< (null)>] (null) I haven't further researched, but wanted to share this already. All the best, Wolfram#
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