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virtio_console: allocate the port_buffer with the caller's gfp

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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>
This commit is contained in:
Breno Leitao 2026-08-10 09:40:00 -07:00 committed by Greg Kroah-Hartman
parent cee9395acd
commit b144dc5a24
1 changed files with 1 additions and 1 deletions
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2
drivers/char/virtio_console.c
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@ -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;