* Re: [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection
2026-06-05 10:21 [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection Fushuai Wang
@ 2026-06-05 12:25 ` Shay Drori
2026-06-07 8:39 ` Tariq Toukan
2026-06-09 2:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Shay Drori @ 2026-06-05 12:25 UTC (permalink / raw)
To: Fushuai Wang, saeedm, leon, tariqt, mbloch, andrew+netdev, davem,
edumazet, kuba, pabeni, parav, moshe
Cc: netdev, linux-rdma, linux-kernel, wangfushuai
On 05/06/2026 13:21, Fushuai Wang wrote:
> External email: Use caution opening links or attachments
>
>
> From: Fushuai Wang <wangfushuai@baidu.com>
>
> When a sf is created after a CPU has been taken offline, the IRQ pool may
> contain IRQs with affinity masks that include the offline CPU. Since only
> online CPUs should be considered for IRQ placement, cpumask_subset() check
> would fail because the iter_mask contains offline CPUs that are not present
> in req_mask, causing sf creation to fail.
>
> This is an example:
> 1. When mlx5 driver loads, it initializes the IRQ pools.
> For sf_ctrl_pool with ≤64 sf:
> - xa_num_irqs = {N, N} (There is only one slot)
> 2. When the first SF is created:
> - The ctrl IRQ is allocated with mask=cpu_online_mask={0-191}
> 2. We take CPU 20 offline
> 3. Existing ctl irq still have mask={0-191}
> 4. Create a new SF:
> - req_mask={0-19,21-191}
> - iter_mask={0-191}
> - {0-191} is NOT a subset of {0-19,21-191}
> - least_loaded_irq=NULL
> 5. Try to allocate a new irq via irq_pool_request_irq()
> 6. xa_alloc() fails because the pool is full(There is only one slot)
> 7. sf creation fails with error
>
> Use irq_get_effective_affinity_mask() instead, which returns the IRQ's
> actual effective affinity that already excludes offline CPUs.
>
> Fixes: 061f5b23588a ("net/mlx5: SF, Use all available cpu for setting cpu affinity")
> Suggested-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
> Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
> ---
> v2->v3: Separate the patchset to two patches, reverse xmas tree coding style fix.
> v1->v2: Use mlx5_irq_get_affinity_mask() api
>
> previous discussion:
> https://lore.kernel.org/all/20260603072657.10868-1-fushuai.wang@linux.dev/T/#u
> https://lore.kernel.org/all/20260604125705.21241-1-fushuai.wang@linux.dev/T/#u
>
> drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> index 994fe83da4be..a0bb8ee44e35 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> @@ -105,9 +105,12 @@ irq_pool_find_least_loaded(struct mlx5_irq_pool *pool, const struct cpumask *req
>
> lockdep_assert_held(&pool->lock);
> xa_for_each_range(&pool->irqs, index, iter, start, end) {
> - struct cpumask *iter_mask = mlx5_irq_get_affinity_mask(iter);
> int iter_refcount = mlx5_irq_read_locked(iter);
> + const struct cpumask *iter_mask;
>
> + iter_mask = irq_get_effective_affinity_mask(mlx5_irq_get_irq(iter));
> + if (!iter_mask)
> + continue;
> if (!cpumask_subset(iter_mask, req_mask))
> /* skip IRQs with a mask which is not subset of req_mask */
> continue;
> --
> 2.36.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection
2026-06-05 10:21 [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection Fushuai Wang
2026-06-05 12:25 ` Shay Drori
@ 2026-06-07 8:39 ` Tariq Toukan
2026-06-09 2:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: Tariq Toukan @ 2026-06-07 8:39 UTC (permalink / raw)
To: Fushuai Wang, saeedm, leon, tariqt, mbloch, andrew+netdev, davem,
edumazet, kuba, pabeni, shayd, parav, moshe
Cc: netdev, linux-rdma, linux-kernel, wangfushuai
On 05/06/2026 13:21, Fushuai Wang wrote:
> From: Fushuai Wang <wangfushuai@baidu.com>
>
> When a sf is created after a CPU has been taken offline, the IRQ pool may
> contain IRQs with affinity masks that include the offline CPU. Since only
> online CPUs should be considered for IRQ placement, cpumask_subset() check
> would fail because the iter_mask contains offline CPUs that are not present
> in req_mask, causing sf creation to fail.
>
> This is an example:
> 1. When mlx5 driver loads, it initializes the IRQ pools.
> For sf_ctrl_pool with ≤64 sf:
> - xa_num_irqs = {N, N} (There is only one slot)
> 2. When the first SF is created:
> - The ctrl IRQ is allocated with mask=cpu_online_mask={0-191}
> 2. We take CPU 20 offline
> 3. Existing ctl irq still have mask={0-191}
> 4. Create a new SF:
> - req_mask={0-19,21-191}
> - iter_mask={0-191}
> - {0-191} is NOT a subset of {0-19,21-191}
> - least_loaded_irq=NULL
> 5. Try to allocate a new irq via irq_pool_request_irq()
> 6. xa_alloc() fails because the pool is full(There is only one slot)
> 7. sf creation fails with error
>
> Use irq_get_effective_affinity_mask() instead, which returns the IRQ's
> actual effective affinity that already excludes offline CPUs.
>
> Fixes: 061f5b23588a ("net/mlx5: SF, Use all available cpu for setting cpu affinity")
> Suggested-by: Shay Drory <shayd@nvidia.com>
> Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
> ---
> v2->v3: Separate the patchset to two patches, reverse xmas tree coding style fix.
> v1->v2: Use mlx5_irq_get_affinity_mask() api
>
> previous discussion:
> https://lore.kernel.org/all/20260603072657.10868-1-fushuai.wang@linux.dev/T/#u
> https://lore.kernel.org/all/20260604125705.21241-1-fushuai.wang@linux.dev/T/#u
>
> drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> index 994fe83da4be..a0bb8ee44e35 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/irq_affinity.c
> @@ -105,9 +105,12 @@ irq_pool_find_least_loaded(struct mlx5_irq_pool *pool, const struct cpumask *req
>
> lockdep_assert_held(&pool->lock);
> xa_for_each_range(&pool->irqs, index, iter, start, end) {
> - struct cpumask *iter_mask = mlx5_irq_get_affinity_mask(iter);
> int iter_refcount = mlx5_irq_read_locked(iter);
> + const struct cpumask *iter_mask;
>
> + iter_mask = irq_get_effective_affinity_mask(mlx5_irq_get_irq(iter));
> + if (!iter_mask)
> + continue;
> if (!cpumask_subset(iter_mask, req_mask))
> /* skip IRQs with a mask which is not subset of req_mask */
> continue;
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Thanks for your patch.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection
2026-06-05 10:21 [PATCH net v3] net/mlx5: Use effective affinity mask for IRQ selection Fushuai Wang
2026-06-05 12:25 ` Shay Drori
2026-06-07 8:39 ` Tariq Toukan
@ 2026-06-09 2:10 ` patchwork-bot+netdevbpf
2 siblings, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2026-06-09 2:10 UTC (permalink / raw)
To: Fushuai Wang
Cc: saeedm, leon, tariqt, mbloch, andrew+netdev, davem, edumazet,
kuba, pabeni, shayd, parav, moshe, netdev, linux-rdma,
linux-kernel, wangfushuai
Hello:
This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Fri, 5 Jun 2026 18:21:12 +0800 you wrote:
> From: Fushuai Wang <wangfushuai@baidu.com>
>
> When a sf is created after a CPU has been taken offline, the IRQ pool may
> contain IRQs with affinity masks that include the offline CPU. Since only
> online CPUs should be considered for IRQ placement, cpumask_subset() check
> would fail because the iter_mask contains offline CPUs that are not present
> in req_mask, causing sf creation to fail.
>
> [...]
Here is the summary with links:
- [net,v3] net/mlx5: Use effective affinity mask for IRQ selection
https://git.kernel.org/netdev/net/c/a7767290e77c
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread