Messages in this thread | | | From | David Laight <> | Subject | Stack backtrace is using the user RIP to read kernel instructions | Date | Thu, 10 Feb 2022 11:27:48 +0000 |
| |
I got the following 'splat' on a 5.17.0-rc3 kernel:
BUG: scheduling while atomic: xxx Modules linked in: xxx Preemption disabled at: xxx+0x3c/0xd0 [xxx] CPU: 5 PID: 28197 Comm: xxx Tainted: P OE 5.16.0-rc7+ #29 Hardware name: Supermicro X11SSV-Q/X11SSV-Q, BIOS 2.2b 02/12/2018 Call Trace: <TASK> dump_stack_lvl+0x4c/0x63 (valid kernel stack) entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f90ea1febd6 Code: Unable to access opcode bytes at RIP 0x7f90ea1febac. RSP: 002b:00007ffde8cd8188 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f90ea501740 RCX: 00007f90ea1febd6 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 0000000000000000 R08: 00000000000000e7 R09: ffffffffffffff80 R10: 00007f90ea1152a0 R11: 0000000000000246 R12: 00007f90ea501740 R13: 0000000000000001 R14: 00007f90ea50a708 R15: 0000000000000000 </TASK>
The problem is all mine :-) (Someone added a spin_lock_irqsave() around code that does msleep(1).)
But the dump of the opcode bytes is missing. I think these would be the user code for the syscall (so boring). OTOH I can't really imagine the code got swapped out.
I can't quite decide whether copy_code() (in dumpstack.c) tried to call copy_from_kernel_nofault() and failed because of the user address, or copy_from_user_nmi() failed.
But something is awry somewhere.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
| |