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]>
---
drivers/char/virtio_console.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 62eecfa61646d..7f6cbe851d1e1 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -426,7 +426,7 @@ static struct port_buffer *alloc_buf(struct virtio_device
*vdev, size_t buf_size
* Allocate buffer and the sg list. The sg list array is allocated
* directly after the port_buffer struct.
*/
- buf = kmalloc_flex(*buf, sg, pages);
+ buf = kmalloc_flex(*buf, sg, pages, gfp);
if (!buf)
goto fail;
---
base-commit: 6b8c8af514d739d0335f5579b585e02babe8a727
change-id: 20260810-serial-d9b259ec9100
Best regards,
--
Breno Leitao <[email protected]>
