On Wed, Aug 24, 2022 at 09:10:36AM +0300, Leon Romanovsky wrote:
> From: Yishai Hadas <yishaih@xxxxxxxxxx>
>
> Fix a nested dead lock as part of ODP flow by using mmput_async().
>
> From the below call trace [1] can see that calling mmput() once we have
> the umem_odp->umem_mutex locked as required by
> ib_umem_odp_map_dma_and_lock() might trigger in the same task the
> exit_mmap()->__mmu_notifier_release()->mlx5_ib_invalidate_range() which
> may dead lock when trying to lock the same mutex.
>
> Moving to use mmput_async() will solve the problem as the above
> exit_mmap() flow will be called in other task and will be executed once
> the lock will be available.
>
> [1]
> [64843.077665] task:kworker/u133:2 state:D stack: 0 pid:80906 ppid:
> 2 flags:0x00004000
> [64843.077672] Workqueue: mlx5_ib_page_fault mlx5_ib_eqe_pf_action [mlx5_ib]
> [64843.077719] Call Trace:
> [64843.077722] <TASK>
> [64843.077724] __schedule+0x23d/0x590
> [64843.077729] schedule+0x4e/0xb0
> [64843.077735] schedule_preempt_disabled+0xe/0x10
> [64843.077740] __mutex_lock.constprop.0+0x263/0x490
> [64843.077747] __mutex_lock_slowpath+0x13/0x20
> [64843.077752] mutex_lock+0x34/0x40
> [64843.077758] mlx5_ib_invalidate_range+0x48/0x270 [mlx5_ib]
> [64843.077808] __mmu_notifier_release+0x1a4/0x200
> [64843.077816] exit_mmap+0x1bc/0x200
> [64843.077822] ? walk_page_range+0x9c/0x120
> [64843.077828] ? __cond_resched+0x1a/0x50
> [64843.077833] ? mutex_lock+0x13/0x40
> [64843.077839] ? uprobe_clear_state+0xac/0x120
> [64843.077860] mmput+0x5f/0x140
> [64843.077867] ib_umem_odp_map_dma_and_lock+0x21b/0x580 [ib_core]
> [64843.077931] pagefault_real_mr+0x9a/0x140 [mlx5_ib]
> [64843.077962] pagefault_mr+0xb4/0x550 [mlx5_ib]
> [64843.077992] pagefault_single_data_segment.constprop.0+0x2ac/0x560
> [mlx5_ib]
> [64843.078022] mlx5_ib_eqe_pf_action+0x528/0x780 [mlx5_ib]
> [64843.078051] process_one_work+0x22b/0x3d0
> [64843.078059] worker_thread+0x53/0x410
> [64843.078065] ? process_one_work+0x3d0/0x3d0
> [64843.078073] kthread+0x12a/0x150
> [64843.078079] ? set_kthread_struct+0x50/0x50
> [64843.078085] ret_from_fork+0x22/0x30
> [64843.078093] </TASK>
>
> Fixes: 36f30e486dce ("IB/core: Improve ODP to use hmm_range_fault()")
> Reviewed-by: Maor Gottlieb <maorg@xxxxxxxxxx>
> Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> ---
> Resend to larger forum.
> https://lore.kernel.org/all/74d93541ea533ef7daec6f126deb1072500aeb16.1661251841.git.leonro@xxxxxxxxxx
> ---
> drivers/infiniband/core/umem_odp.c | 2 +-
> kernel/fork.c | 1 +
> 2 files changed, 2 insertions(+), 1 deletion(-)
Any objections?
Thanks
>
> diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
> index 186ed8859920..d39e16c211e8 100644
> --- a/drivers/infiniband/core/umem_odp.c
> +++ b/drivers/infiniband/core/umem_odp.c
> @@ -462,7 +462,7 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
> mutex_unlock(&umem_odp->umem_mutex);
>
> out_put_mm:
> - mmput(owning_mm);
> + mmput_async(owning_mm);
> out_put_task:
> if (owning_process)
> put_task_struct(owning_process);
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 90c85b17bf69..8a9e92068b15 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1225,6 +1225,7 @@ void mmput_async(struct mm_struct *mm)
> schedule_work(&mm->async_put_work);
> }
> }
> +EXPORT_SYMBOL_GPL(mmput_async);
> #endif
>
> /**
> --
> 2.37.2
>
