[LU-19922] mdc should free stats after procfs entries removal

• Type: Bug
• Resolution: Unresolved
• Priority: Medium
• Severity: 3
• Assignee: WC Triage
• Reporter: Alex Zhuravlev

Description

otherwise procfs can access just freed memory:

[  484.300549] BUG: unable to handle page fault for address: 0000004000000020
[  484.300553] #PF: supervisor read access in kernel mode
[  484.300554] #PF: error_code(0x0000) - not-present page
[  484.300556] PGD 155d4b067 P4D 155d4b067 PUD 0 
[  484.300558] Oops: 0000 [#1] SMP
[  484.300560] CPU: 3 PID: 277668 Comm: lctl Tainted: G        W  O      -------  ---  5.14.0 #24
[  484.300563] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014
[  484.300564] RIP: 0010:string+0x49/0xd0
[  484.300571] Code: ff 77 36 45 89 d1 31 f6 49 01 f9 66 45 85 d2 75 19 eb 1e 49 39 f8 76 02 88 07 48 83 c7 01 83 c6 01 48 83 c2 01 4c 39 cf 74 07 <0f> b6 02 84 c0 75 e2 4c 89 c2 e9 c8 e4 ff ff 66 41 83 fa ff 48 c7
[  484.300572] RSP: 0018:ffff8db7927afc98 EFLAGS: 00010286
[  484.300574] RAX: 0000003ffffff020 RBX: ffff8db7927afcf0 RCX: ffff0a0200001904
[  484.300575] RDX: 0000004000000020 RSI: 0000000000000000 RDI: ffff8db77fee728f
[  484.300576] RBP: ffffffffc074b3d1 R08: ffff8db77fee8000 R09: ffff8db87fee728e
[  484.300576] R10: ffffffffffffffff R11: 0000000000000400 R12: ffff8db77fee8000
[  484.300577] R13: ffffffffc074b3d1 R14: 0000000000000d71 R15: ffff8db77fee728f
[  484.300579] FS:  00007fd596371940(0000) GS:ffff8db890780000(0000) knlGS:0000000000000000
[  484.300581] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  484.300582] CR2: 0000004000000020 CR3: 0000000150ba3000 CR4: 0000000000350eb0
[  484.300585] Call Trace:
[  484.301082]  <TASK>
[  484.301105]  vsnprintf+0x263/0x4e0
[  484.301107]  seq_printf+0x68/0x90
[  484.301112]  lprocfs_stats_seq_show+0xc3/0x230 [obdclass]
[  484.301182]  seq_read_iter+0x29a/0x460
[  484.301185]  seq_read+0x131/0x160
[  484.301187]  proc_reg_read+0x4a/0x90
[  484.301190]  vfs_read+0x8e/0x3b0
[  484.301196]  ksys_read+0x50/0xc0
[  484.301198]  do_syscall_64+0x38/0xe0
[  484.301200]  entry_SYSCALL_64_after_hwframe+0x4b/0x53

Issue Links

• is related to: LU-8066 Move lustre procfs handling to sysfs and debugfs.