On Wed, Aug 19, 2026 at 08:36:25PM +0900, Sungho Bae 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 <[email protected]>
>
> Acked-by: Sungho Bae <[email protected]>
Greg, are you the one that should pick this up?
The regression fixed here is now on Linus' tree.
Thanks
--breno
