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Andrey reported this kernel warning:
WARNING: CPU: 0 PID: 4114 at kernel/sched/core.c:7737 __might_sleep+0x149/0x1a0
do not call blocking ops when !TASK_RUNNING; state=1 set at
[<ffffffff813fcb22>] prepare_to_wait+0x182/0x530
The deeply nested alloc_skb is a problem.
Diagnosis: nesting is wrong. It makes zero sense. Fix it and the
implicit task state change problem automagically goes away.
alloc_skb() does not need to be in the "while" loop.
alloc_skb() does not need to be in the {prepare_to_wait/add_wait_queue ...
finish_wait/remove_wait_queue} block.
I claim that:
- alloc_tx() should only perform the "wait_for_decent_tx_drain" part
- alloc_skb() ought to be done directly in vcc_sendmsg
- alloc_skb() failure can be handled gracefully in vcc_sendmsg
- alloc_skb() may use a (m->msg_flags & MSG_DONTWAIT) dependent
GFP_{KERNEL / ATOMIC} flag
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-and-Tested-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.