Hi, I have been running into a kernel panic when probing a USB flash drive, and was after some advice or suggestions on what might be going wrong. First up, the details of my setup: * Initially seen on Linux 5.7.19, but I've tested on a vanilla copy of Linux 5.15.0 without any extra modules, and the panic still occurs. * Flash drive (lsusb): Bus 001 Device 002: ID 1005:b113 Apacer Technology, Inc. Handy Steno 2.0/HT203 * Our system is based on the Marvell 98DX323x SoC (Arm v7, based on the Armada 370/XP) The panic occurs after sd_probe() gets called, with the USB flash drive attached. This occurs around 1 time out of 100. We first saw this during a reboot, but it can be reproduced much faster by loading and unloading the sd_mod module in a loop, to exercise the probe function. When adding some diagnostic print statements, I found that adding a delay into sd_probe(), just after the call to device_add_disk(), seems to prevent the issue. The actual headline of the panic is not always the same, we have seen: * Unhandled fault: external abort on non-linefetch (0x808) at 0x9fbfa73c * Unhandled fault: imprecise external abort (0x1416) at 0x76f5e508 * Unhandled prefetch abort: external abort on non-linefetch (0x1008) at 0x803c8a88 Included below is an example of the panic output. Thank you, Joshua Scott Unhandled prefetch abort: external abort on non-linefetch (0x1008) at 0x8018fe20 Internal error: : 1008 [#1] PREEMPT SMP ARM Modules linked in: sd_mod(+) diag tipc platform_driver(O) ipifwd(PO) usb_storage scsi_mod [last unloaded: sd_mod] CPU: 0 PID: 178 Comm: udevd Tainted: P O 5.7.19-at1 #39 Hardware name: Marvell Armada 370/XP (Device Tree) PC is at sys_clock_gettime32+0x58/0xc4 LR is at ret_fast_syscall+0x0/0x54 pc : [<8018fe20>] lr : [<80100060>] psr: a00e0013 sp : 9dfcdf80 ip : 10c5387d fp : 00041150 r10: 00000107 r9 : 9dfcc000 r8 : 80100288 r7 : 00000107 r6 : 00000000 r5 : 7eddb208 r4 : 80c052c8 r3 : 8018ea90 r2 : 00000001 r1 : 7eddb208 r0 : 00000001 Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: 1dfc006a DAC: 00000051 Process udevd (pid: 178, stack limit = 0xfbd1de7a) Stack: (0x9dfcdf80 to 0x9dfce000) df80: 00000000 00000000 00000000 ed40bc3c 000000fc ed40bc3c 00000008 00000001 dfa0: 7eddb208 80100060 00000001 7eddb208 00000001 7eddb208 eec19c0e eec19c0e dfc0: 00000001 7eddb208 00000000 00000107 000402c4 00040308 7eddbcd0 00041150 dfe0: 76f38060 7eddb1f0 0002505c 76ed9bc4 600e0010 00000001 00000000 00000000 [<8018fe20>] (sys_clock_gettime32) from [<80100060>] (ret_fast_syscall+0x0/0x54) Exception stack(0x9dfcdfa8 to 0x9dfcdff0) dfa0: 00000001 7eddb208 00000001 7eddb208 eec19c0e eec19c0e dfc0: 00000001 7eddb208 00000000 00000107 000402c4 00040308 7eddbcd0 00041150 dfe0: 76f38060 7eddb1f0 0002505c 76ed9bc4 Code: e5933080 e3530000 0a000018 e5933008 (e1a0100d) ---[ end trace 98c4e7c1cd29d9e3 ]---
