From: Jens Axboe <[email protected]>
To: Xiaoguang Wang <[email protected]>,
[email protected]
Cc: [email protected], [email protected]
Subject: Re: [PATCH] io_uring: don't modify identity's files uncess identity is cowed
Date: Thu, 4 Feb 2021 07:43:57 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 2/4/21 2:20 AM, Xiaoguang Wang wrote:
> Abaci Robot reported following panic:
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> PGD 800000010ef3f067 P4D 800000010ef3f067 PUD 10d9df067 PMD 0
> Oops: 0002 [#1] SMP PTI
> CPU: 0 PID: 1869 Comm: io_wqe_worker-0 Not tainted 5.11.0-rc3+ #1
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> RIP: 0010:put_files_struct+0x1b/0x120
> Code: 24 18 c7 00 f4 ff ff ff e9 4d fd ff ff 66 90 0f 1f 44 00 00 41 57 41 56 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 b5 6b db ff 41 ff 0e 74 13 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f e9 9c
> RSP: 0000:ffffc90002147d48 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88810d9a5300 RCX: 0000000000000000
> RDX: ffff88810d87c280 RSI: ffffffff8144ba6b RDI: 0000000000000000
> RBP: 0000000000000080 R08: 0000000000000001 R09: ffffffff81431500
> R10: ffff8881001be000 R11: 0000000000000000 R12: ffff88810ac2f800
> R13: ffff88810af38a00 R14: 0000000000000000 R15: ffff8881057130c0
> FS: 0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000010dbaa002 CR4: 00000000003706f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> __io_clean_op+0x10c/0x2a0
> io_dismantle_req+0x3c7/0x600
> __io_free_req+0x34/0x280
> io_put_req+0x63/0xb0
> io_worker_handle_work+0x60e/0x830
> ? io_wqe_worker+0x135/0x520
> io_wqe_worker+0x158/0x520
> ? __kthread_parkme+0x96/0xc0
> ? io_worker_handle_work+0x830/0x830
> kthread+0x134/0x180
> ? kthread_create_worker_on_cpu+0x90/0x90
> ret_from_fork+0x1f/0x30
> Modules linked in:
> CR2: 0000000000000000
> ---[ end trace c358ca86af95b1e7 ]---
>
> I guess case below can trigger above panic: there're two threads which
> operates different io_uring ctxs and share same sqthread identity, and
> later one thread exits, io_uring_cancel_task_requests() will clear
> task->io_uring->identity->files to be NULL in sqpoll mode, then another
> ctx that uses same identity will panic.
>
> Indeed we don't need to clear task->io_uring->identity->files here,
> io_grab_identity() should handle identity->files changes well, if
> task->io_uring->identity->files is not equal to current->files,
> io_cow_identity() should handle this changes well.
Applied, thanks.
--
Jens Axboe
next prev parent reply other threads:[~2021-02-04 14:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 9:20 [PATCH] io_uring: don't modify identity's files uncess identity is cowed Xiaoguang Wang
2021-02-04 11:05 ` Pavel Begunkov
2021-02-04 13:54 ` Pavel Begunkov
2021-02-04 14:43 ` Jens Axboe [this message]
2021-02-05 1:34 ` Joseph Qi
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