linux-kernel - Re: [PATCH -next v2] io-wq: Fix memory leak in create_io

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Date:   Fri, 10 Sep 2021 06:22:50 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Bixuan Cui <cuibixuan@...wei.com>, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org
Cc:     asml.silence@...il.com, john.wanghui@...wei.com
Subject: Re: [PATCH -next v2] io-wq: Fix memory leak in create_io_worker

On 9/10/21 1:29 AM, Bixuan Cui wrote:
> Kmemleak tool detected a memory leak.
> 
> ====================
> unreferenced object 0xffff888126fcd6c0 (size 192):
>   comm "syz-executor.1", pid 11934, jiffies 4294983026 (age 15.690s)
>   hex dump (first 32 bytes):
>     01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff81632c91>] kmalloc_node include/linux/slab.h:609 [inline]
>     [<ffffffff81632c91>] kzalloc_node include/linux/slab.h:732 [inline]
>     [<ffffffff81632c91>] create_io_worker+0x41/0x1e0 fs/io-wq.c:739
>     [<ffffffff8163311e>] io_wqe_create_worker fs/io-wq.c:267 [inline]
>     [<ffffffff8163311e>] io_wqe_enqueue+0x1fe/0x330 fs/io-wq.c:866
>     [<ffffffff81620b64>] io_queue_async_work+0xc4/0x200 fs/io_uring.c:1473
>     [<ffffffff8162c59c>] __io_queue_sqe+0x34c/0x510 fs/io_uring.c:6933
>     [<ffffffff8162c7ab>] io_req_task_submit+0x4b/0xa0 fs/io_uring.c:2233
>     [<ffffffff8162cb48>] io_async_task_func+0x108/0x1c0 fs/io_uring.c:5462
>     [<ffffffff816259e3>] tctx_task_work+0x1b3/0x3a0 fs/io_uring.c:2158
>     [<ffffffff81269b43>] task_work_run+0x73/0xb0 kernel/task_work.c:164
>     [<ffffffff812dcdd1>] tracehook_notify_signal include/linux/tracehook.h:212 [inline]
>     [<ffffffff812dcdd1>] handle_signal_work kernel/entry/common.c:146 [inline]
>     [<ffffffff812dcdd1>] exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>     [<ffffffff812dcdd1>] exit_to_user_mode_prepare+0x151/0x180 kernel/entry/common.c:209
>     [<ffffffff843ff25d>] __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>     [<ffffffff843ff25d>] syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:302
>     [<ffffffff843fa4a2>] do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
>     [<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae
> ====================
> 
> If io_should_retry_thread is false in create_io_worker() and
> io_queue_worker_create is false in io_workqueue_create(), free the worker.

A fix for this was already merged:

https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.15&id=66e70be722886e4f134350212baa13f217e39e42

-- 
Jens Axboe