Re: [PATCH] RDMA/core: Prevent soft lockup during large user memory region cleanup

[Leon Romanovsky <leon@kernel.org>]

On Tue, Nov 11, 2025 at 03:01:07PM +0800, lirongqing wrote:
> From: Li RongQing <lirongqing@baidu.com>
> 
> When a process exits with numerous large, pinned memory regions consisting
> of 4KB pages, the cleanup of the memory region through __ib_umem_release()
> may cause soft lockups. This is because unpin_user_page_range_dirty_lock()

Do you have soft lookup splat?

> is called in a tight loop for unpin and releasing page without yielding the
> CPU.
> 
> Fix the soft lockup by adding cond_resched() calls in __ib_umem_release
> 
> Signed-off-by: Li RongQing <lirongqing@baidu.com>
> ---
>  drivers/infiniband/core/umem.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index c5b6863..70c1520 100644
> --- a/drivers/infiniband/core/umem.c
> +++ b/drivers/infiniband/core/umem.c
> @@ -59,6 +59,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
>  		unpin_user_page_range_dirty_lock(sg_page(sg),
>  			DIV_ROUND_UP(sg->length, PAGE_SIZE), make_dirty);
>  
> +	cond_resched();
>  	sg_free_append_table(&umem->sgt_append);
>  }
>  
> -- 
> 2.9.4
>