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b144dc5a24
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: fc220d6be3 ("virtio_console: refactor __send_to_port() buffer ownership")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Sungho Bae <baver.bae@lge.com>
Tested-by: Florian Westphal <fw@strlen.de>
Link: https://patch.msgid.link/20260810-serial-v1-1-abbe51602c13@debian.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>