Re: [PATCH] virtio_console: allocate the port_buffer with the caller's gfp

[Sungho Bae]

I am sorry for the late reply.
I fully agree with your patch.
It was my mistake. I should have to allocate the buffer with gfp flags.
Thank you for the corrections.


On 2026년 8월 18일 오후 6시 6분 37초 GMT+09:00, Breno Leitao <leitao@xxxxxxxxxx> 작성함:
>On Mon, Aug 10, 2026 at 09:40:00AM -0700, Breno Leitao wrote:
>> put_chars() runs from the hvc console write path with preemption
>> disabled, so it asks alloc_buf() for GFP_ATOMIC. Only the data buffer
>> gets it: the struct port_buffer itself keeps the GFP_KERNEL default, so
>> the allocation can enter direct reclaim and sleep. A write to /dev/kmsg
>> on a CONFIG_DEBUG_ATOMIC_SLEEP kernel splats:
>> 
>>   BUG: sleeping function called from invalid context at ./include/linux/sched/mm.h:320
>>   in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: virtme-ng-init
>>   preempt_count: 1, expected: 0
>>   Preemption disabled at:
>>   [<ffffffff813fd90d>] vprintk_emit+0x17d/0x510
>>   Call Trace:
>>    <TASK>
>>    dump_stack_lvl+0x69/0xa0
>>    __might_resched+0x37a/0x4d0
>>    __kmalloc_cache_noprof+0x94/0x5f0
>>    put_chars+0x209/0x3e0
>>    hvc_console_print+0x234/0x640
>>    console_flush_all+0x4fc/0x950
>>    console_unlock+0xbf/0x1b0
>>    vprintk_emit+0x312/0x510
>>    devkmsg_emit+0xba/0x110
>>    devkmsg_write+0x21b/0x2e0
>>    vfs_write+0x4dc/0x9d0
>>    ksys_write+0x108/0x1e0
>>    do_syscall_64+0xfa/0x460
>>    </TASK>
>> 
>> Pass gfp on to that allocation too.
>> 
>> Fixes: fc220d6be3c7 ("virtio_console: refactor __send_to_port() buffer ownership")
>> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
>
>Ping? 
>