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Message-ID: <92d9f001-f77b-8263-53a6-aab83daccef9@huawei.com>
Date: Thu, 21 Oct 2021 21:37:26 +0800
From: "yukuai (C)" <yukuai3@...wei.com>
To: Pavel Skripkin <paskripkin@...il.com>, <josef@...icpanda.com>,
<axboe@...nel.dk>
CC: <linux-block@...r.kernel.org>, <nbd@...er.debian.org>,
<linux-kernel@...r.kernel.org>, <yi.zhang@...wei.com>,
<luomeng12@...wei.com>, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 0/2] nbd: fix sanity check for first_minor
On 2021/10/21 21:13, yukuai (C) wrote:
> On 2021/10/21 20:35, Pavel Skripkin wrote:
>> On 10/21/21 15:29, Yu Kuai wrote:
>>> Yu Kuai (2):
>>> nbd: fix max value for 'first_minor'
>>> nbd: fix possible overflow for 'first_minor' in nbd_dev_add()
>>>
>>> drivers/block/nbd.c | 6 +++---
>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>
>> Hi, Yu!
>>
>> Thank you for the fix, but this wrong check should be just removed,
>> since root case of wrong sysfs file creation was fixed, as Christoph
>> said [1]
Hi, Christoph
By the way, if we remove the checking, there will be two kernel warnings
when the problem happens. Maybe keeping the checking is better?
[ 19.860640] sysfs: cannot create duplicate filename '/dev/block/43:0'
[ 19.861659] CPU: 1 PID: 872 Comm: modprobe Not tainted
5.15.0-rc6-next-20211020-00001-g2f1
[ 19.863175] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS ?-20190727_0738364
[ 19.865183] Call Trace:
[ 19.866512] <TASK>
[ 19.866863] ? dump_stack_lvl+0x73/0x9f
[ 19.867941] ? dump_stack+0x13/0x1b
[ 19.868475] ? sysfs_warn_dup.cold+0x27/0x45
[ 19.869075] ? sysfs_do_create_link_sd.isra.0+0x131/0x150
[ 19.869818] ? sysfs_create_link+0x29/0x60
[ 19.870459] ? device_add+0xbd6/0xf60
[ 19.871032] ? _printk+0x5f/0x7d
[ 19.871518] ? device_add_disk+0x153/0x5d0
[ 19.872160] ? nbd_dev_add+0x30e/0x470 [nbd]
[ 19.872828] ? 0xffffffffc0060000
[ 19.873332] ? nbd_init+0x1dc/0x1000 [nbd]
[ 19.873924] ? do_one_initcall+0x71/0x3a0
[ 19.874534] ? gcov_event+0x70/0x690
[ 19.875058] ? do_init_module+0xa6/0x350
[ 19.875587] ? load_module+0x2587/0x2720
[ 19.876130] ? kernel_read+0x31/0xb0
[ 19.876638] ? kernel_read_file+0x15a/0x360
[ 19.877271] ? __do_sys_finit_module+0xe5/0x190
[ 19.877951] ? __do_sys_finit_module+0xe5/0x190
[ 19.878563] ? __x64_sys_finit_module+0x1e/0x30
[ 19.879182] ? do_syscall_64+0x35/0x80
[ 19.879700] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 19.880413] </TASK>
[ 19.880806] ------------[ cut here ]------------
[ 19.881502] WARNING: CPU: 1 PID: 872 at block/genhd.c:543
device_add_disk+0x2af/0x5d0
[ 19.882695] Modules linked in: nbd(+)
[ 19.883290] CPU: 1 PID: 872 Comm: modprobe Not tainted
5.15.0-rc6-next-20211020-00001-g2f1
[ 19.884823] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS ?-20190727_0738364
[ 19.886866] RIP: 0010:device_add_disk+0x2af/0x5d0
[ 19.887606] Code: 6e f2 f2 0b 01 49 8b 76 48 48 8b 3d db 03 f3 0b e8
f6 ec a9 ff 48 83 050
[ 19.890456] RSP: 0018:ffffc90000e47c70 EFLAGS: 00010202
[ 19.891293] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
00000000000ae001
[ 19.892274] RDX: 00000000000ac001 RSI: ffffffff91b5906b RDI:
0000000000000000
[ 19.893318] RBP: ffff8881034ad600 R08: 0000000000000000 R09:
ffffffff915e2e69
[ 19.894425] R10: 0000000000000014 R11: 0000000000000001 R12:
00000000ffffffef
[ 19.895544] R13: 0000000000000000 R14: ffff88817d720600 R15:
ffff88817d720648
[ 19.896652] FS: 00007fc08c7a7040(0000) GS:ffff88882f640000(0000)
knlGS:0000000000000000
[ 19.897902] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 19.898768] CR2: 00007fc08bcf0395 CR3: 000000017c467000 CR4:
00000000000006e0
[ 19.899754] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 19.900856] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[ 19.901989] Call Trace:
[ 19.902387] <TASK>
[ 19.902732] nbd_dev_add+0x30e/0x470 [nbd]
[ 19.903395] ? 0xffffffffc0060000
[ 19.903917] nbd_init+0x1dc/0x1000 [nbd]
[ 19.904536] do_one_initcall+0x71/0x3a0
[ 19.905166] ? gcov_event+0x70/0x690
[ 19.905745] do_init_module+0xa6/0x350
[ 19.906351] load_module+0x2587/0x2720
[ 19.906932] ? kernel_read+0x31/0xb0
[ 19.907509] ? kernel_read_file+0x15a/0x360
[ 19.908195] ? __do_sys_finit_module+0xe5/0x190
[ 19.908894] __do_sys_finit_module+0xe5/0x190
[ 19.909591] __x64_sys_finit_module+0x1e/0x30
[ 19.910289] do_syscall_64+0x35/0x80
[ 19.910855] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 19.911652] RIP: 0033:0x7fc08bc7a4e9
[ 19.912231] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00
48 89 f8 48 89 f7 488
[ 19.915026] RSP: 002b:00007fff0ddf6fd8 EFLAGS: 00000246 ORIG_RAX:
0000000000000139
[ 19.916080] RAX: ffffffffffffffda RBX: 00005596400853e0 RCX:
00007fc08bc7a4e9
[ 19.917180] RDX: 0000000000000000 RSI: 000055963fe1bc26 RDI:
0000000000000003
[ 19.918302] RBP: 000055963fe1bc26 R08: 0000000000000000 R09:
0000000000000000
[ 19.919412] R10: 0000000000000003 R11: 0000000000000246 R12:
0000000000000000
[ 19.920524] R13: 00005596400854f0 R14: 0000000000040000 R15:
00005596400853e0
[ 19.921629] </TASK>
[ 19.922005] ---[ end trace e09ecf130812479d ]---
Thanks,
Kuai
>
> Hi, Pavel
>
> Thanks for your response, with the root cause fixed, patch 1 is not
> needed anymore. However, the overflow case in patch 2 is still
> possible.
>
> Does anyone plan to remove the checking?
>
> Thanks,
> Kuai
>>
>>
>>
>>
>> [1] https://lore.kernel.org/lkml/20211011073556.GA10735@lst.de/
>>
>>
>>
>> With regards,
>> Pavel Skripkin
>> .
>>
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