On Tue, 2017-12-12 at 12:29:15 UTC, Ravi Bangoria wrote: > It may very well happen that branch instructions recorded by > bhrb entries already get unmapped before they get processed by > the kernel. Hence, trying to dereference such memory location > will endup in a crash. Ex, > > Unable to handle kernel paging request for data at address > 0xc008000019c41764 > Faulting instruction address: 0xc000000000084a14 > NIP [c000000000084a14] branch_target+0x4/0x70 > LR [c0000000000eb828] record_and_restart+0x568/0x5c0 > Call Trace: > [c0000000000eb3b4] record_and_restart+0xf4/0x5c0 (unreliable) > [c0000000000ec378] perf_event_interrupt+0x298/0x460 > [c000000000027964] performance_monitor_exception+0x54/0x70 > [c000000000009ba4] performance_monitor_common+0x114/0x120 > > Fix this by deferefencing them safely. > > Suggested-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com> > Signed-off-by: Ravi Bangoria <ravi.bango...@linux.vnet.ibm.com> > Reviewed-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/f41d84dddc66b164ac16acf3f584c2 cheers
