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Bug 947341

Summary: sys-kernel/gentoo-kernel-6.1.122: zram BUG: kernel NULL pointer dereference
Product: Gentoo Linux Reporter: Luke-Jr <luke-jr+gentoobugs>
Component: Current packagesAssignee: Distribution Kernel Project <dist-kernel>
Status: UNCONFIRMED ---    
Severity: blocker CC: kernel, luke-jr+gentoobugs
Priority: Normal    
Version: unspecified   
Hardware: AMD64   
OS: Linux   
Whiteboard:
Package list:
Runtime testing required: ---

Description Luke-Jr 2025-01-02 05:34:32 UTC 
6.1.119 on the same machine works fine.
6.1.121 on similar configurations works fine.
6.6.68 on the same machine works fine.

Reproducable with: modprobe zram && rmmod zram
Or: /etc/init.d/zram-init start (including at boot if configured)
Or: zram-init 4096

[   93.953643] BUG: kernel NULL pointer dereference, address: 0000000000000000
[   93.954371] #PF: supervisor read access in kernel mode
[   93.955074] #PF: error_code(0x0000) - not-present page
[   93.955773] PGD 0 P4D 0 
[   93.956453] Oops: 0000 [#1] PREEMPT SMP NOPTI
[   93.957133] CPU: 0 PID: 3187 Comm: rmmod Tainted: P           O       6.1.122-gentoo-dist-hardened #1
(redacted)
[   93.966845] Call Trace:
[   93.967612]  <TASK>
[   93.968379]  ? __die_body.cold+0x1a/0x1f
[   93.969153]  ? page_fault_oops+0x15c/0x2a0
[   93.969928]  ? __wake_up_common_lock+0x8d/0xd0
[   93.970703]  ? exc_page_fault+0x72/0x170
[   93.971477]  ? asm_exc_page_fault+0x22/0x30
[   93.972253]  ? zcomp_cpu_up_prepare+0xa0/0xa0 [zram]
[   93.973033]  ? zcomp_cpu_dead+0x8/0x60 [zram]
[   93.973812]  cpuhp_invoke_callback+0x91/0x430
[   93.974592]  cpuhp_issue_call+0xfc/0x170
[   93.975369]  __cpuhp_state_remove_instance+0xd5/0x190
[   93.976149]  zcomp_destroy+0x1c/0x30 [zram]
[   93.976934]  zcomp_create+0xd4f/0x20d7 [zram]
[   93.977718]  zcomp_create+0xde4/0x20d7 [zram]
[   93.978501]  ? zcomp_create+0xf40/0x20d7 [zram]
[   93.979283]  zcomp_create+0xf4d/0x20d7 [zram]
[   93.980068]  idr_for_each+0x6b/0xf0
[   93.980852]  zcomp_create+0x2074/0x20d7 [zram]
[   93.981637]  __x64_sys_delete_module+0x19e/0x2e0
[   93.982421]  do_syscall_64+0x56/0x80
[   93.983206]  ? clear_bhb_loop+0x15/0x70
[   93.983987]  ? clear_bhb_loop+0x15/0x70
[   93.984764]  ? clear_bhb_loop+0x15/0x70
[   93.985538]  ? clear_bhb_loop+0x15/0x70
[   93.986310]  ? clear_bhb_loop+0x15/0x70
[   93.987076]  entry_SYSCALL_64_after_hwframe+0x6e/0xd8
(redacted)
[   94.013285] Kernel panic - not syncing: Fatal exception
[   94.014253] Kernel Offset: (redacted)
Comment 1 Luke-Jr 2025-01-02 06:01:40 UTC 
Verified that system with 6.1.121 reproduces this crash after updating to 6.1.122.