[Solved] kallsyms kernel crash

[cyring]

This is linked to the issue #214 from my project CoreFreq. Issue I don't have solved.

Any code making use of symbols, through kallsyms for instance, is crashing as below when my driver corefreqk.ko is already running:

Crash dump when using the mainstream Linux kernel provided with ArchLinux

BUG: unable to handle page fault for address: ffffffffc5e594e0
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 2c15067 P4D 2c15067 PUD 2c17067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 4 PID: 2248 Comm: perf Tainted: G           OE     5.17.5-arch1-1 #1 bff91b48f6c3cb8d3bfd68f772f9c0a96e684769
Hardware name: LENOVO 82KU/LNVNB161216, BIOS GLCN22WW 03/17/2021
RIP: 0010:strlcpy+0x0/0x50
Code: e2 07 74 b1 89 d2 48 01 c2 eb 09 48 83 c0 01 48 39 d0 74 a1 40 3a 38 74 f2 c3 48 85 c0 74 b7 c3 48 89 c8 c3 66 0
f 1f 44 00 00 <80> 3e 00 41 54 55 53 48 89 fb 74 39 48 89 f0 48 83 c0 01 80 38 00
RSP: 0018:ffffc9000174bcb8 EFLAGS: 00010282
RAX: 0000000000000180 RBX: ffffffffc15eba00 RCX: ffffffffc15ec000
RDX: 0000000000000080 RSI: ffffffffc5e594e0 RDI: ffff888103146135
RBP: ffff8881031461f0 R08: ffff8881031461b5 R09: ffff8881031461f0
R10: 0000000000025a8d R11: ffff8881052e4a6c R12: ffff888103146135
R13: ffff888103146128 R14: ffff8881031461b5 R15: ffff8881031461b5
FS:  00007f57b73377c0(0000) GS:ffff8881a8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffc5e594e0 CR3: 00000001395c2000 CR4: 0000000000350fe0
Call Trace:
 <TASK>
 module_get_kallsym+0xb9/0x1b0
 update_iter+0x171/0x280
 s_next+0x1d/0x30
 seq_read_iter+0x2f6/0x4b0
 seq_read+0x12a/0x170
 proc_reg_read+0x52/0xa0
 vfs_read+0x92/0x190
 ksys_read+0x67/0xe0
 do_syscall_64+0x59/0x80
 ? ksys_read+0x67/0xe0
 ? syscall_exit_to_user_mode+0x23/0x40
 ? do_syscall_64+0x69/0x80
 ? syscall_exit_to_user_mode+0x23/0x40
 ? do_syscall_64+0x69/0x80
 ? do_syscall_64+0x69/0x80
 ? do_syscall_64+0x69/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f57b812b1b2

At first I was suspecting bad programming in my driver but using xanmod 5.15 no such crash happens!

I have reviewed xanmod patch for any clue about strlcpy or the choice of others kernel build directives but I'm still without an understanding why xanmod is doing OK with my driver.

Can anyone provides me some help ?

[cyring]

Solved using no-inline compiler flag.