Re: [v5.3-rc1 regression] Hitting a kernel BUG() when trying to load a module on DaVinci SoC

[Bartosz Golaszewski]

pon., 22 lip 2019 o 14:12 Bartosz Golaszewski <brgl@xxxxxxxx> napisaÅ(a):
>
> Hi,
>
> with v5.3-rc1 I'm hitting the following BUG() when trying to load the
> gpio-backlight module:
>
> kernel BUG at kernel/module.c:1919!
> Internal error: Oops - BUG: 0 [#1] PREEMPT ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: systemd Tainted: G        W
> 5.2.0-rc2-00005-g7dabaa5ce05a #19
> Hardware name: DaVinci DA850/OMAP-L138/AM18x EVM
> PC is at frob_text.constprop.16+0x2c/0x34
> LR is at load_module+0x1888/0x21b4
> pc : [<c0081bbc>]    lr : [<c0083c4c>]    psr: 20000013
> sp : c6837e58  ip : c6b4fa80  fp : bf00574c
> r10: c0601008  r9 : bf005740  r8 : c0493e38
> r7 : c00807f8  r6 : 00000000  r5 : 00000001  r4 : c6837f38
> r3 : 00000fff  r2 : bf000000  r1 : 00004b80  r0 : bf005818
> Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> Control: 0005317f  Table: c6b78000  DAC: 00000051
> Process systemd (pid: 1, stack limit = 0x(ptrval))
> Stack: (0xc6837e58 to 0xc6838000)
> 7e40:                                                       bf005740 c6492a90
> 7e60: 00000001 c6bf5788 00000003 c6837f38 bf0058c0 bf0058a8 bf00a495 c0493e38
> 7e80: 00000000 c05368c0 00000001 00000000 c0580030 c0574b28 00000000 00000000
> 7ea0: 00000000 00000000 00000000 00000000 6e72656b 00006c65 00000000 00000000
> 7ec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 7ee0: 00000000 00000000 00000000 aefb2bb8 7fffffff c0601008 00000000 00000004
> 7f00: b6cee714 c00091e4 c6836000 00000000 005bc668 c00847b0 7fffffff 00000000
> 7f20: 00000003 00000000 0000b2d0 c884e000 0000b2d0 00000000 c8852dcb c88533a0
> 7f40: c884e000 0000b2d0 c8858cb8 c8858b34 c88568d4 000058c0 00006190 000023b8
> 7f60: 00006713 00000000 00000000 00000000 000023a8 00000024 00000025 00000019
> 7f80: 0000001d 00000011 00000000 aefb2bb8 00000000 00000000 00000000 00000000
> 7fa0: 0000017b c0009000 00000000 00000000 00000004 b6cee714 00000000 00000000
> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0 60000010 00000004 00000000 00000000
> [<c0081bbc>] (frob_text.constprop.16) from [<c0083c4c>]
> (load_module+0x1888/0x21b4)
> [<c0083c4c>] (load_module) from [<c00847b0>] (sys_finit_module+0xbc/0xdc)
> [<c00847b0>] (sys_finit_module) from [<c0009000>] (ret_fast_syscall+0x0/0x50)
> Exception stack(0xc6837fa8 to 0xc6837ff0)
> 7fa0:                   00000000 00000000 00000004 b6cee714 00000000 00000000
> 7fc0: 00000000 00000000 00000000 0000017b 00000000 00000000 00000001 005bc668
> 7fe0: be907b00 be907af0 b6ce66b0 b6c3fac0
> Code: e1a01621 e1a00002 eafe4531 e7f001f2 (e7f001f2)
> ---[ end trace 2cbefb0005882c52 ]---
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x0000000b ]---
>
> I bisected it to commit 06bd260e836d ("modules: fix BUG when load
> module with rodata=n") with commit 7dabaa5ce05a ("modules: fix compile
> error if don't have strict module rwx") on top to make it build.
>

I got the commit hashes wrong, because I was playing with a modified
tree. They are 2eef1399a866 ("modules: fix BUG when load module with
rodata=n") and 93651f80dcb6 ("modules: fix compile error if don't have
strict module rwx") respectively.

Bart

> Let me know if you need me to provide more info.
>
> Best regards,
> Bartosz Golaszewski