On Wed, 2018-05-16 at 06:35:18 UTC, Anju T Sudhakar wrote: > Currently memory is allocated for core-imc based on cpu_present_mask, > which has bit 'cpu' set iff cpu is populated. We use (cpu number / threads > per core) as the array index to access the memory. > > Under some circumstances firmware marks a CPU as GUARDed CPU and boot the > system, until cleared of errors, these CPU's are unavailable for all > subsequent boots. GUARDed CPUs are possible but not present from linux > view, so it blows a hole when we assume the max length of our allocation > is driven by our max present cpus, where as one of the cpus might be online > and be beyond the max present cpus, due to the hole. > So (cpu number / threads per core) value bounds the array index and leads > to memory overflow. > > Call trace observed during a guard test: > > Faulting instruction address: 0xc000000000149f1c > cpu 0x69: Vector: 380 (Data Access Out of Range) at [c000003fea303420] > pc:c000000000149f1c: prefetch_freepointer+0x14/0x30 > lr:c00000000014e0f8: __kmalloc+0x1a8/0x1ac > sp:c000003fea3036a0 > msr:9000000000009033 > dar:c9c54b2c91dbf6b7 > current = 0xc000003fea2c0000 > paca = 0xc00000000fddd880 softe: 3 irq_happened: 0x01 > pid = 1, comm = swapper/104 > Linux version 4.16.7-openpower1 (smc@smc-desktop) (gcc version 6.4.0 > (Buildroot 2018.02.1-00006-ga8d1126)) #2 SMP Fri May 4 16:44:54 PDT 2018 > enter ? for help > call trace: > __kmalloc+0x1a8/0x1ac > (unreliable) > init_imc_pmu+0x7f4/0xbf0 > opal_imc_counters_probe+0x3fc/0x43c > platform_drv_probe+0x48/0x80 > driver_probe_device+0x22c/0x308 > __driver_attach+0xa0/0xd8 > bus_for_each_dev+0x88/0xb4 > driver_attach+0x2c/0x40 > bus_add_driver+0x1e8/0x228 > driver_register+0xd0/0x114 > __platform_driver_register+0x50/0x64 > opal_imc_driver_init+0x24/0x38 > do_one_initcall+0x150/0x15c > kernel_init_freeable+0x250/0x254 > kernel_init+0x1c/0x150 > ret_from_kernel_thread+0x5c/0xc8 > > Allocating memory for core-imc based on cpu_possible_mask, which has > bit 'cpu' set iff cpu is populatable, will fix this issue. > > Reported-by: Pridhiviraj Paidipeddi <ppaid...@linux.vnet.ibm.com> > Signed-off-by: Anju T Sudhakar <a...@linux.vnet.ibm.com> > Reviewed-by: Balbir Singh <bsinghar...@gmail.com> > Tested-by: Pridhiviraj Paidipeddi <ppaid...@linux.vnet.ibm.com>
Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/d2032678e57fc508d7878307badde8 cheers
