----- Original Message ----- > From: "Michael Ellerman" <m...@ellerman.id.au> > To: "Jan Stancek" <jstan...@redhat.com>, linuxppc-dev@lists.ozlabs.org > Cc: linux-ker...@vger.kernel.org, pau...@samba.org, an...@samba.org, > t...@kernel.org, c...@linux.com, jo...@redhat.com, > jstan...@redhat.com, j...@jms.id.au > Sent: Wednesday, 25 March, 2015 6:25:09 AM > Subject: Re: powerpc/perf: add missing put_cpu_var in power_pmu_event_init > > On Tue, 2015-24-03 at 12:33:22 UTC, Jan Stancek wrote: > > One path in power_pmu_event_init() calls get_cpu_var(), but is > > missing matching call to put_cpu_var(), which causes preemption > > imbalance and crash in user-space: > > > > Page fault in user mode with in_atomic() = 1 mm = c000001fefa5a280 > > NIP = 3fff9bf2cae0 MSR = 900000014280f032 > > Oops: Weird page fault, sig: 11 [#23] > > <snip> > > Thanks. But I don't see this. I guess you have CONFIG_PREEMPT enabled?
Hi, CONFIG_PREEMPT_NOTIFIERS=y # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set CONFIG_PREEMPT_COUNT=y but I think the difference comes from: CONFIG_DEBUG_ATOMIC_SLEEP=y I did following: - took the default config from RHEL7.1 kernel - ran 'make oldnoconfig'. - reproducer didn't trigger anything - then I added "CONFIG_DEBUG_ATOMIC_SLEEP=y" - this time reproducer triggered a panic (3 out of 3 attempts) Here's config from panic-ing kernel: http://fpaste.org/202543/ [ 133.957305] Page fault in user mode with in_atomic() = 1 mm = c000000005fc7e80 [ 133.957399] NIP = 3fff9be0cae0 MSR = 900000014280f032 [ 133.957405] Oops: Weird page fault, sig: 11 [#1] [ 133.957409] SMP NR_CPUS=2048 NUMA PowerNV [ 133.957414] Modules linked in: ses enclosure shpchp uio_pdrv_genirq powernv_rng uio xfs libcrc32c sr_mod sd_mod cdrom ipr libata tg3 ptp pps_core dm_mirror dm_region_hash dm_log dm_mod [ 133.957638] CPU: 16 PID: 6035 Comm: a.out Not tainted 4.0.0-rc5+ #4 [ 133.957693] task: c000000fea44b640 ti: c000000fea5e4000 task.ti: c000000fea5e4000 [ 133.957759] NIP: 00003fff9be0cae0 LR: 00003fff9bdc4898 CTR: 00003fff9be0cae0 [ 133.957825] REGS: c000000fea5e7ea0 TRAP: 0401 Not tainted (4.0.0-rc5+) [ 133.957880] MSR: 900000014280f032 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI> CR: 22000028 XER: 00000000 [ 133.958079] CFAR: 00003fff9bdc4894 SOFTE: 1 GPR00: 00003fff9bdc494c 00003ffff1fef3e0 00003fff9bf64410 0000000010020068 GPR04: 0000000000000000 0000000000000002 0000000000000008 0000000000000001 GPR08: 0000000000000001 00003fff9bf54a30 00003fff9be0cae0 00003fff9be0cd70 GPR12: 0000000052000022 00003fff9bfeb700 [ 133.958485] NIP [00003fff9be0cae0] 0x3fff9be0cae0 [ 133.958530] LR [00003fff9bdc4898] 0x3fff9bdc4898 [ 133.958574] Call Trace: [ 133.958597] ---[ end trace 56ec543903422cd9 ]--- [ 133.958642] [ 135.958709] Kernel panic - not syncing: Fatal exception [ 135.958863] Rebooting in 10 seconds.. [ 145.970348] BUG: sleeping function called from invalid context at kernel/irq/manage.c:104 [ 145.970453] in_atomic(): 1, irqs_disabled(): 1, pid: 6035, name: a.out [ 145.970515] CPU: 16 PID: 6035 Comm: a.out Tainted: G D 4.0.0-rc5+ #4 [ 145.970588] Call Trace: [ 145.970618] [c000000fea5e76d0] [c0000000007c2090] .dump_stack+0x98/0xd4 (unreliable) [ 145.970707] [c000000fea5e7750] [c0000000000d5fe4] .___might_sleep+0x124/0x170 [ 145.970782] [c000000fea5e77c0] [c000000000112860] .synchronize_irq+0x40/0xe0 [ 145.970857] [c000000fea5e7880] [c000000000112fa8] .__free_irq+0xf8/0x2b0 [ 145.970931] [c000000fea5e7920] [c000000000113258] .free_irq+0x78/0x100 [ 145.971007] [c000000fea5e79b0] [c000000000067ae8] .opal_shutdown+0x88/0x120 [ 145.971081] [c000000fea5e7a40] [c000000000063e88] .pnv_shutdown+0x18/0x30 [ 145.971157] [c000000fea5e7ab0] [c000000000020c98] .machine_shutdown+0x38/0x50 [ 145.971231] [c000000fea5e7b20] [c000000000020d24] .machine_restart+0x14/0x70 [ 145.971307] [c000000fea5e7ba0] [c0000000000cdc10] .emergency_restart+0x20/0x40 [ 145.971393] [c000000fea5e7c10] [c0000000007bb0a4] .panic+0x224/0x2a4 [ 145.971468] [c000000fea5e7cb0] [c00000000001e1fc] .die+0x43c/0x450 [ 145.971543] [c000000fea5e7d60] [c0000000007b62c4] .do_page_fault+0x2d4/0x8f0 [ 145.971618] [c000000fea5e7e30] [c000000000008664] handle_page_fault+0x10/0x30 Regards, Jan _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev