Re: [PATCH v8 11/12] zram: fix crashes with cpu hotplug multistate

[Luis Chamberlain]

On Tue, Oct 19, 2021 at 10:34:41AM +0800, Ming Lei wrote:
> Please try the following patch against upstream(linus or next) tree(basically
> fold revised 2 and 3 of V1, and cover two issues: not fail zram_remove in
> module_exit(), race between zram_remove() and disksize_store()), and see if
> everything is fine for you:

Page fault ...

[   18.284256] zram: Removed device: zram0
[   18.312974] BUG: unable to handle page fault for address:
ffffad86de903008
[   18.313707] #PF: supervisor read access in kernel mode
[   18.314248] #PF: error_code(0x0000) - not-present page
[   18.314797] PGD 100000067 P4D 100000067 PUD 10031e067 PMD 136a28067
PTE 0
[   18.315538] Oops: 0000 [#1] PREEMPT SMP NOPTI
[   18.316012] CPU: 3 PID: 1198 Comm: rmmod Tainted: G            E
5.15.0-rc3-next-20210927+ #89
[   18.316979] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.14.0-2 04/01/2014
[   18.317876] RIP: 0010:zram_free_page+0x1b/0xf0 [zram]
[   18.318430] Code: 1f 44 00 00 48 89 c8 c3 0f 1f 80 00 00 00 00 0f 1f
44 00 00 41 54 49 89 f4 55 89 f5 53 48 8b 17 48 c1 e5 04 48 89 fb 48 01
ea <48> 8b 42 08 a9 00 00 00 20 74 14 48 25 ff ff ff df 48 89 42 08 48
[   18.320412] RSP: 0018:ffffad86f8013df8 EFLAGS: 00010286
[   18.320978] RAX: 0000000000000001 RBX: ffff9b7b435c7800 RCX:
0000000000000200
[   18.321758] RDX: ffffad86de903000 RSI: 0000000000000000 RDI:
ffff9b7b435c7800
[   18.322524] RBP: 0000000000000000 R08: 0000000000000200 R09:
0000000000000000
[   18.323299] R10: 0000000000000200 R11: 0000000000000000 R12:
0000000000000000
[   18.324030] R13: ffff9b7b55191800 R14: ffff9b7b435c7820 R15:
ffff9b7b4677f960
[   18.324784] FS:  00007fc8e4c90580(0000) GS:ffff9b7c77cc0000(0000)
knlGS:0000000000000000
[   18.325651] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.326272] CR2: ffffad86de903008 CR3: 000000014f1de003 CR4:
0000000000370ee0
[   18.327047] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[   18.327818] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[   18.328586] Call Trace:
[   18.328852]  <TASK>
[   18.329284]  zram_reset_device+0xd8/0x140 [zram]
[   18.329983]  zram_remove.cold+0xa/0x20 [zram]
[   18.330644]  ? hot_remove_store+0xe0/0xe0 [zram]
[   18.331367]  zram_remove_cb+0xd/0x10 [zram]
[   18.332010]  idr_for_each+0x5b/0xd0
[   18.332578]  destroy_devices+0x26/0x50 [zram]
[   18.333238]  __do_sys_delete_module+0x18d/0x2a0
[   18.333913]  ? fpregs_assert_state_consistent+0x1e/0x40
[   18.334665]  ? exit_to_user_mode_prepare+0x3a/0x180
[   18.335395]  do_syscall_64+0x38/0xc0
[   18.335966]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   18.336681] RIP: 0033:0x7fc8e4db64a7