On Thu, Oct 24, 2019 at 11:49:13PM +0000, Jason Gunthorpe wrote:
> The mkey_table xarray is touched by the reg_mr_callback() function which
> is called from a hard irq. Thus all other uses of xa_lock must use the
> _irq variants.
>
> WARNING: inconsistent lock state
> 5.4.0-rc1 #12 Not tainted
> --------------------------------
> inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
> python3/343 [HC0[0]:SC0[0]:HE1:SE1] takes:
> ffff888182be1d40 (&(&xa->xa_lock)->rlock#3){?.-.}, at: xa_erase+0x12/0x30
> {IN-HARDIRQ-W} state was registered at:
> lock_acquire+0xe1/0x200
> _raw_spin_lock_irqsave+0x35/0x50
> reg_mr_callback+0x2dd/0x450 [mlx5_ib]
> mlx5_cmd_exec_cb_handler+0x2c/0x70 [mlx5_core]
> mlx5_cmd_comp_handler+0x355/0x840 [mlx5_core]
> [..]
>
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(&(&xa->xa_lock)->rlock#3);
> <Interrupt>
> lock(&(&xa->xa_lock)->rlock#3);
>
> *** DEADLOCK ***
>
> 2 locks held by python3/343:
> #0: ffff88818eb4bd38 (&uverbs_dev->disassociate_srcu){....}, at: ib_uverbs_ioctl+0xe5/0x1e0 [ib_uverbs]
> #1: ffff888176c76d38 (&file->hw_destroy_rwsem){++++}, at: uobj_destroy+0x2d/0x90 [ib_uverbs]
>
> stack backtrace:
> CPU: 3 PID: 343 Comm: python3 Not tainted 5.4.0-rc1 #12
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
> Call Trace:
> dump_stack+0x86/0xca
> print_usage_bug.cold.50+0x2e5/0x355
> mark_lock+0x871/0xb50
> ? match_held_lock+0x20/0x250
> ? check_usage_forwards+0x240/0x240
> __lock_acquire+0x7de/0x23a0
> ? __kasan_check_read+0x11/0x20
> ? mark_lock+0xae/0xb50
> ? mark_held_locks+0xb0/0xb0
> ? find_held_lock+0xca/0xf0
> lock_acquire+0xe1/0x200
> ? xa_erase+0x12/0x30
> _raw_spin_lock+0x2a/0x40
> ? xa_erase+0x12/0x30
> xa_erase+0x12/0x30
> mlx5_ib_dealloc_mw+0x55/0xa0 [mlx5_ib]
> uverbs_dealloc_mw+0x3c/0x70 [ib_uverbs]
> uverbs_free_mw+0x1a/0x20 [ib_uverbs]
> destroy_hw_idr_uobject+0x49/0xa0 [ib_uverbs]
> [..]
>
> Fixes: 0417791536ae ("RDMA/mlx5: Add missing synchronize_srcu() for MW cases")
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> Acked-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> ---
> drivers/infiniband/hw/mlx5/mr.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Applied to for-rc
Jason
