Re: [PATCH v10 01/15] fs/resctrl: Return -EBUSY when per-CLOSID RMIDs are in limbo

[Jinjie Ruan <2118537295@qq.com>]

This patch is part of the v10 series. For the main thread, see:

https://lore.kernel.org/all/tencent_28FE31D80A7A9AEEC43B22D0AD8894E30C06@qq.com/#t

在 2026/10/19 15:33, Jinjie Ruan 写道:
> From: Jinjie Ruan <ruanjinjie@huawei.com>
>
> resctrl_find_free_rmid() returns ERR_PTR(-ENOSPC) when no matching RMID
> is found in the free list. On systems where RMIDs depend on CLOSIDs
> (CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID), the target CLOSID may have RMIDs
> temporarily in limbo rather than permanently exhausted.
>
> When userspace attempts to create a new monitoring group, a permanent
> -ENOSPC failure prevents retry even though the CLOSID's RMIDs may become
> available once the limbo handler completes.
>
> Check closid_num_dirty_rmid[] before returning -ENOSPC. If the target
> CLOSID has dirty RMIDs, return -EBUSY to signal a retryable condition.
>
> Fixes: c4c0376eefe1 ("x86/resctrl: Allow RMID allocation to be scoped by CLOSID")
> Cc: James Morse <james.morse@arm.com>
> Cc: Reinette Chatre <reinette.chatre@intel.com>
> Cc: Babu Moger <babu.moger@amd.com>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>   fs/resctrl/monitor.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index 73413cb128ea..da883adc3adc 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -225,6 +225,14 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid)
>   			return itr;
>   	}
>   
> +	/*
> +	 * If this CLOSID has RMIDs in limbo, return -EBUSY so userspace can
> +	 * retry. Otherwise, the CLOSID is genuinely out of RMIDs.
> +	 */
> +	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) &&
> +	    closid_num_dirty_rmid[closid])
> +		return ERR_PTR(-EBUSY);
> +
>   	return ERR_PTR(-ENOSPC);
>   }
>