Re: [PATCH] ublk: hold RCU read lock in ublk_try_buf_match()

[Jens Axboe]

On Tue, 22 Sep 2026 18:17:43 +0000, Paolo Bertinetti wrote:
> syzbot reports a lockdep splat when I/O is dispatched to a ublk device
> with UBLK_F_SHMEM_ZC enabled:
> 
>   WARNING: suspicious RCU usage
>   lib/maple_tree.c:720 suspicious rcu_dereference_check() usage!
>   ...
>   Call Trace:
>    mas_root lib/maple_tree.c:720 [inline]
>    mas_start+0x3cc/0x640 lib/maple_tree.c:1250
>    mas_state_walk lib/maple_tree.c:3006 [inline]
>    mas_walk+0x1db/0x490 lib/maple_tree.c:4458
>    ublk_try_buf_match drivers/block/ublk_drv.c:5639 [inline]
>    ublk_init_iod+0x5d2/0x1120 drivers/block/ublk_drv.c:521
>    ublk_dispatch_req+0x97/0x9c0 drivers/block/ublk_drv.c:1776
>    tctx_task_work_run+0x73d/0xa80 io_uring/tw.c:96
> 
> [...]

Applied, thanks!

[1/1] ublk: hold RCU read lock in ublk_try_buf_match()
      commit: aaf49023041bc1f887a028a164d3bac714b65508

Best regards,
-- 
Jens Axboe