[PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[Tariq Toukan]

From: Dragos Tatulea <dtatulea@nvidia.com>

net_iovs should have the dma address set to 0 so that
netmem_dma_unmap_page_attrs() correctly skips the unmap. This was
not done in mlx5 when support for devmem tx was added and resulted
in the splat below when the platform iommu was enabled.

This patch addresses the issue by using netmem_dma_unmap_addr_set()
which handles the net_iov case when setting the dma address. A small
refactoring of mlx5e_dma_push() was required to be able to use this API.
The function was split in two versions and each version called
accordingly. Note that netmem_dma_unmap_addr_set() introduces an
additional if case.

Splat:
  WARNING: CPU: 14 PID: 2587 at drivers/iommu/dma-iommu.c:1228 iommu_dma_unmap_page+0x7d/0x90
  Modules linked in: [...]
  Unloaded tainted modules: i10nm_edac(E):1 fjes(E):1
  CPU: 14 UID: 0 PID: 2587 Comm: ncdevmem Tainted: G S          E       6.15.0+ #3 PREEMPT(voluntary)
  Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
  Hardware name: HPE ProLiant DL380 Gen10 Plus/ProLiant DL380 Gen10 Plus, BIOS U46 06/01/2022
  RIP: 0010:iommu_dma_unmap_page+0x7d/0x90
  Code: [...]
  RSP: 0000:ff6b1e3ea0b2fc58 EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ff46ef2d0a2340c8 RCX: 0000000000000000
  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
  RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8827a120
  R10: 0000000000000000 R11: 0000000000000000 R12: 00000000d8000000
  R13: 0000000000000008 R14: 0000000000000001 R15: 0000000000000000
  FS:  00007feb69adf740(0000) GS:ff46ef2c779f1000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007feb69cca000 CR3: 0000000154b97006 CR4: 0000000000773ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
   <TASK>
   dma_unmap_page_attrs+0x227/0x250
   mlx5e_poll_tx_cq+0x163/0x510 [mlx5_core]
   mlx5e_napi_poll+0x94/0x720 [mlx5_core]
   __napi_poll+0x28/0x1f0
   net_rx_action+0x33a/0x420
   ? mlx5e_completion_event+0x3d/0x40 [mlx5_core]
   handle_softirqs+0xe8/0x2f0
   __irq_exit_rcu+0xcd/0xf0
   common_interrupt+0x47/0xa0
   asm_common_interrupt+0x26/0x40
  RIP: 0033:0x7feb69cd08ec
  Code: [...]
  RSP: 002b:00007ffc01b8c880 EFLAGS: 00000246
  RAX: 00000000c3a60cf7 RBX: 0000000000045e12 RCX: 000000000000000e
  RDX: 00000000000035b4 RSI: 0000000000000000 RDI: 00007ffc01b8c8c0
  RBP: 00007ffc01b8c8b0 R08: 0000000000000000 R09: 0000000000000064
  R10: 00007ffc01b8c8c0 R11: 0000000000000000 R12: 00007feb69cca000
  R13: 00007ffc01b90e48 R14: 0000000000427e18 R15: 00007feb69d07000
   </TASK>

Cc: Mina Almasry <almasrymina@google.com>
Reported-by: Stanislav Fomichev <stfomichev@gmail.com>
Closes: https://lore.kernel.org/all/aFM6r9kFHeTdj-25@mini-arch/
Fixes: 5a842c288cfa ("net/mlx5e: Add TX support for netmems")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/en/txrx.h    | 16 +++++++++++++---
 .../mellanox/mlx5/core/en_accel/ktls_tx.c        |  2 +-
 drivers/net/ethernet/mellanox/mlx5/core/en_tx.c  |  6 +++---
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h b/drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h
index 6501252359b0..5dc04bbfc71b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h
@@ -322,14 +322,24 @@ mlx5e_dma_get(struct mlx5e_txqsq *sq, u32 i)
 }
 
 static inline void
-mlx5e_dma_push(struct mlx5e_txqsq *sq, dma_addr_t addr, u32 size,
-	       enum mlx5e_dma_map_type map_type)
+mlx5e_dma_push_single(struct mlx5e_txqsq *sq, dma_addr_t addr, u32 size)
 {
 	struct mlx5e_sq_dma *dma = mlx5e_dma_get(sq, sq->dma_fifo_pc++);
 
 	dma->addr = addr;
 	dma->size = size;
-	dma->type = map_type;
+	dma->type = MLX5E_DMA_MAP_SINGLE;
+}
+
+static inline void
+mlx5e_dma_push_netmem(struct mlx5e_txqsq *sq, netmem_ref netmem,
+		      dma_addr_t addr, u32 size)
+{
+	struct mlx5e_sq_dma *dma = mlx5e_dma_get(sq, sq->dma_fifo_pc++);
+
+	netmem_dma_unmap_addr_set(netmem, dma, addr, addr);
+	dma->size = size;
+	dma->type = MLX5E_DMA_MAP_PAGE;
 }
 
 static inline
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
index 3db31cc10719..08f06984407b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
@@ -744,7 +744,7 @@ tx_post_resync_dump(struct mlx5e_txqsq *sq, skb_frag_t *frag, u32 tisn)
 	dseg->addr       = cpu_to_be64(dma_addr);
 	dseg->lkey       = sq->mkey_be;
 	dseg->byte_count = cpu_to_be32(fsz);
-	mlx5e_dma_push(sq, dma_addr, fsz, MLX5E_DMA_MAP_PAGE);
+	mlx5e_dma_push_netmem(sq, skb_frag_netmem(frag), dma_addr, fsz);
 
 	tx_fill_wi(sq, pi, MLX5E_KTLS_DUMP_WQEBBS, fsz, skb_frag_page(frag));
 	sq->pc += MLX5E_KTLS_DUMP_WQEBBS;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
index e6a301ba3254..319061d31602 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
@@ -196,7 +196,7 @@ mlx5e_txwqe_build_dsegs(struct mlx5e_txqsq *sq, struct sk_buff *skb,
 		dseg->lkey       = sq->mkey_be;
 		dseg->byte_count = cpu_to_be32(headlen);
 
-		mlx5e_dma_push(sq, dma_addr, headlen, MLX5E_DMA_MAP_SINGLE);
+		mlx5e_dma_push_single(sq, dma_addr, headlen);
 		num_dma++;
 		dseg++;
 	}
@@ -214,7 +214,7 @@ mlx5e_txwqe_build_dsegs(struct mlx5e_txqsq *sq, struct sk_buff *skb,
 		dseg->lkey       = sq->mkey_be;
 		dseg->byte_count = cpu_to_be32(fsz);
 
-		mlx5e_dma_push(sq, dma_addr, fsz, MLX5E_DMA_MAP_PAGE);
+		mlx5e_dma_push_netmem(sq, skb_frag_netmem(frag), dma_addr, fsz);
 		num_dma++;
 		dseg++;
 	}
@@ -616,7 +616,7 @@ mlx5e_sq_xmit_mpwqe(struct mlx5e_txqsq *sq, struct sk_buff *skb,
 
 	sq->stats->xmit_more += xmit_more;
 
-	mlx5e_dma_push(sq, txd.dma_addr, txd.len, MLX5E_DMA_MAP_SINGLE);
+	mlx5e_dma_push_single(sq, txd.dma_addr, txd.len);
 	mlx5e_skb_fifo_push(&sq->db.skb_fifo, skb);
 	mlx5e_tx_mpwqe_add_dseg(sq, &txd);
 	mlx5e_tx_skb_update_ts_flags(skb);

base-commit: c3886ccaadf8fdc2c91bfbdcdca36ccdc6ef8f70
-- 
2.31.1

Re: [PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[Mina Almasry]

On Wed, Jul 16, 2025 at 12:01 AM Tariq Toukan <tariqt@nvidia.com> wrote:
>
> From: Dragos Tatulea <dtatulea@nvidia.com>
>
> net_iovs should have the dma address set to 0 so that
> netmem_dma_unmap_page_attrs() correctly skips the unmap. This was
> not done in mlx5 when support for devmem tx was added and resulted
> in the splat below when the platform iommu was enabled.
>
> This patch addresses the issue by using netmem_dma_unmap_addr_set()
> which handles the net_iov case when setting the dma address. A small
> refactoring of mlx5e_dma_push() was required to be able to use this API.
> The function was split in two versions and each version called
> accordingly. Note that netmem_dma_unmap_addr_set() introduces an
> additional if case.
>
> Splat:
>   WARNING: CPU: 14 PID: 2587 at drivers/iommu/dma-iommu.c:1228 iommu_dma_unmap_page+0x7d/0x90
>   Modules linked in: [...]
>   Unloaded tainted modules: i10nm_edac(E):1 fjes(E):1
>   CPU: 14 UID: 0 PID: 2587 Comm: ncdevmem Tainted: G S          E       6.15.0+ #3 PREEMPT(voluntary)
>   Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
>   Hardware name: HPE ProLiant DL380 Gen10 Plus/ProLiant DL380 Gen10 Plus, BIOS U46 06/01/2022
>   RIP: 0010:iommu_dma_unmap_page+0x7d/0x90
>   Code: [...]
>   RSP: 0000:ff6b1e3ea0b2fc58 EFLAGS: 00010246
>   RAX: 0000000000000000 RBX: ff46ef2d0a2340c8 RCX: 0000000000000000
>   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
>   RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8827a120
>   R10: 0000000000000000 R11: 0000000000000000 R12: 00000000d8000000
>   R13: 0000000000000008 R14: 0000000000000001 R15: 0000000000000000
>   FS:  00007feb69adf740(0000) GS:ff46ef2c779f1000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007feb69cca000 CR3: 0000000154b97006 CR4: 0000000000773ef0
>   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>   PKRU: 55555554
>   Call Trace:
>    <TASK>
>    dma_unmap_page_attrs+0x227/0x250
>    mlx5e_poll_tx_cq+0x163/0x510 [mlx5_core]
>    mlx5e_napi_poll+0x94/0x720 [mlx5_core]
>    __napi_poll+0x28/0x1f0
>    net_rx_action+0x33a/0x420
>    ? mlx5e_completion_event+0x3d/0x40 [mlx5_core]
>    handle_softirqs+0xe8/0x2f0
>    __irq_exit_rcu+0xcd/0xf0
>    common_interrupt+0x47/0xa0
>    asm_common_interrupt+0x26/0x40
>   RIP: 0033:0x7feb69cd08ec
>   Code: [...]
>   RSP: 002b:00007ffc01b8c880 EFLAGS: 00000246
>   RAX: 00000000c3a60cf7 RBX: 0000000000045e12 RCX: 000000000000000e
>   RDX: 00000000000035b4 RSI: 0000000000000000 RDI: 00007ffc01b8c8c0
>   RBP: 00007ffc01b8c8b0 R08: 0000000000000000 R09: 0000000000000064
>   R10: 00007ffc01b8c8c0 R11: 0000000000000000 R12: 00007feb69cca000
>   R13: 00007ffc01b90e48 R14: 0000000000427e18 R15: 00007feb69d07000
>    </TASK>
>
> Cc: Mina Almasry <almasrymina@google.com>
> Reported-by: Stanislav Fomichev <stfomichev@gmail.com>
> Closes: https://lore.kernel.org/all/aFM6r9kFHeTdj-25@mini-arch/
> Fixes: 5a842c288cfa ("net/mlx5e: Add TX support for netmems")
> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>


Hmm, a couple of issues I see, but I'm not sure if it's really wrong
or my own non-understanding.

I don't see  netmem_dma_unmap_page_attrs called anywhere in your
driver. The point of  netmem_dma_unmap_addr_set setting the addr to 0
is that a later call to netmem_dma_unmap_page_attrs skips the
dma-unmap call if it's 0.

I could not understand why the mlx5/core/* files still used the
non-netmem variant. The netdev->netmem_tx was set to true in
mlx5/core/en_main.c, so I would have thought at least all the
mlx5/core/en_tx.c callsites should have gone to that.

-- 
Thanks,
Mina

Re: [PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[Stanislav Fomichev]

On 07/16, Tariq Toukan wrote:
> From: Dragos Tatulea <dtatulea@nvidia.com>
> 
> net_iovs should have the dma address set to 0 so that
> netmem_dma_unmap_page_attrs() correctly skips the unmap. This was
> not done in mlx5 when support for devmem tx was added and resulted
> in the splat below when the platform iommu was enabled.
> 
> This patch addresses the issue by using netmem_dma_unmap_addr_set()
> which handles the net_iov case when setting the dma address. A small
> refactoring of mlx5e_dma_push() was required to be able to use this API.
> The function was split in two versions and each version called
> accordingly. Note that netmem_dma_unmap_addr_set() introduces an
> additional if case.
> 
> Splat:
>   WARNING: CPU: 14 PID: 2587 at drivers/iommu/dma-iommu.c:1228 iommu_dma_unmap_page+0x7d/0x90
>   Modules linked in: [...]
>   Unloaded tainted modules: i10nm_edac(E):1 fjes(E):1
>   CPU: 14 UID: 0 PID: 2587 Comm: ncdevmem Tainted: G S          E       6.15.0+ #3 PREEMPT(voluntary)
>   Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
>   Hardware name: HPE ProLiant DL380 Gen10 Plus/ProLiant DL380 Gen10 Plus, BIOS U46 06/01/2022
>   RIP: 0010:iommu_dma_unmap_page+0x7d/0x90
>   Code: [...]
>   RSP: 0000:ff6b1e3ea0b2fc58 EFLAGS: 00010246
>   RAX: 0000000000000000 RBX: ff46ef2d0a2340c8 RCX: 0000000000000000
>   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
>   RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8827a120
>   R10: 0000000000000000 R11: 0000000000000000 R12: 00000000d8000000
>   R13: 0000000000000008 R14: 0000000000000001 R15: 0000000000000000
>   FS:  00007feb69adf740(0000) GS:ff46ef2c779f1000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007feb69cca000 CR3: 0000000154b97006 CR4: 0000000000773ef0
>   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>   PKRU: 55555554
>   Call Trace:
>    <TASK>
>    dma_unmap_page_attrs+0x227/0x250
>    mlx5e_poll_tx_cq+0x163/0x510 [mlx5_core]
>    mlx5e_napi_poll+0x94/0x720 [mlx5_core]
>    __napi_poll+0x28/0x1f0
>    net_rx_action+0x33a/0x420
>    ? mlx5e_completion_event+0x3d/0x40 [mlx5_core]
>    handle_softirqs+0xe8/0x2f0
>    __irq_exit_rcu+0xcd/0xf0
>    common_interrupt+0x47/0xa0
>    asm_common_interrupt+0x26/0x40
>   RIP: 0033:0x7feb69cd08ec
>   Code: [...]
>   RSP: 002b:00007ffc01b8c880 EFLAGS: 00000246
>   RAX: 00000000c3a60cf7 RBX: 0000000000045e12 RCX: 000000000000000e
>   RDX: 00000000000035b4 RSI: 0000000000000000 RDI: 00007ffc01b8c8c0
>   RBP: 00007ffc01b8c8b0 R08: 0000000000000000 R09: 0000000000000064
>   R10: 00007ffc01b8c8c0 R11: 0000000000000000 R12: 00007feb69cca000
>   R13: 00007ffc01b90e48 R14: 0000000000427e18 R15: 00007feb69d07000
>    </TASK>
> 
> Cc: Mina Almasry <almasrymina@google.com>
> Reported-by: Stanislav Fomichev <stfomichev@gmail.com>
> Closes: https://lore.kernel.org/all/aFM6r9kFHeTdj-25@mini-arch/
> Fixes: 5a842c288cfa ("net/mlx5e: Add TX support for netmems")
> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Acked-by: Stanislav Fomichev <sdf@fomichev.me>

Re: [PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 16 Jul 2025 10:00:42 +0300 you wrote:
> From: Dragos Tatulea <dtatulea@nvidia.com>
> 
> net_iovs should have the dma address set to 0 so that
> netmem_dma_unmap_page_attrs() correctly skips the unmap. This was
> not done in mlx5 when support for devmem tx was added and resulted
> in the splat below when the platform iommu was enabled.
> 
> [...]

Here is the summary with links:
  - [net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx
    https://git.kernel.org/netdev/net-next/c/870bc1aaa0f9

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH net-next] net/mlx5e: TX, Fix dma unmapping for devmem tx

[Dragos Tatulea]

On Wed, Jul 16, 2025 at 12:16:11PM -0700, Mina Almasry wrote:
> On Wed, Jul 16, 2025 at 12:01 AM Tariq Toukan <tariqt@nvidia.com> wrote:
> >
> > From: Dragos Tatulea <dtatulea@nvidia.com>
> >
> > net_iovs should have the dma address set to 0 so that
> > netmem_dma_unmap_page_attrs() correctly skips the unmap. This was
> > not done in mlx5 when support for devmem tx was added and resulted
> > in the splat below when the platform iommu was enabled.
> >
> > This patch addresses the issue by using netmem_dma_unmap_addr_set()
> > which handles the net_iov case when setting the dma address. A small
> > refactoring of mlx5e_dma_push() was required to be able to use this API.
> > The function was split in two versions and each version called
> > accordingly. Note that netmem_dma_unmap_addr_set() introduces an
> > additional if case.
> >
> > Splat:
> >   WARNING: CPU: 14 PID: 2587 at drivers/iommu/dma-iommu.c:1228 iommu_dma_unmap_page+0x7d/0x90
> >   Modules linked in: [...]
> >   Unloaded tainted modules: i10nm_edac(E):1 fjes(E):1
> >   CPU: 14 UID: 0 PID: 2587 Comm: ncdevmem Tainted: G S          E       6.15.0+ #3 PREEMPT(voluntary)
> >   Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE
> >   Hardware name: HPE ProLiant DL380 Gen10 Plus/ProLiant DL380 Gen10 Plus, BIOS U46 06/01/2022
> >   RIP: 0010:iommu_dma_unmap_page+0x7d/0x90
> >   Code: [...]
> >   RSP: 0000:ff6b1e3ea0b2fc58 EFLAGS: 00010246
> >   RAX: 0000000000000000 RBX: ff46ef2d0a2340c8 RCX: 0000000000000000
> >   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
> >   RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8827a120
> >   R10: 0000000000000000 R11: 0000000000000000 R12: 00000000d8000000
> >   R13: 0000000000000008 R14: 0000000000000001 R15: 0000000000000000
> >   FS:  00007feb69adf740(0000) GS:ff46ef2c779f1000(0000) knlGS:0000000000000000
> >   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >   CR2: 00007feb69cca000 CR3: 0000000154b97006 CR4: 0000000000773ef0
> >   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >   PKRU: 55555554
> >   Call Trace:
> >    <TASK>
> >    dma_unmap_page_attrs+0x227/0x250
> >    mlx5e_poll_tx_cq+0x163/0x510 [mlx5_core]
> >    mlx5e_napi_poll+0x94/0x720 [mlx5_core]
> >    __napi_poll+0x28/0x1f0
> >    net_rx_action+0x33a/0x420
> >    ? mlx5e_completion_event+0x3d/0x40 [mlx5_core]
> >    handle_softirqs+0xe8/0x2f0
> >    __irq_exit_rcu+0xcd/0xf0
> >    common_interrupt+0x47/0xa0
> >    asm_common_interrupt+0x26/0x40
> >   RIP: 0033:0x7feb69cd08ec
> >   Code: [...]
> >   RSP: 002b:00007ffc01b8c880 EFLAGS: 00000246
> >   RAX: 00000000c3a60cf7 RBX: 0000000000045e12 RCX: 000000000000000e
> >   RDX: 00000000000035b4 RSI: 0000000000000000 RDI: 00007ffc01b8c8c0
> >   RBP: 00007ffc01b8c8b0 R08: 0000000000000000 R09: 0000000000000064
> >   R10: 00007ffc01b8c8c0 R11: 0000000000000000 R12: 00007feb69cca000
> >   R13: 00007ffc01b90e48 R14: 0000000000427e18 R15: 00007feb69d07000
> >    </TASK>
> >
> > Cc: Mina Almasry <almasrymina@google.com>
> > Reported-by: Stanislav Fomichev <stfomichev@gmail.com>
> > Closes: https://lore.kernel.org/all/aFM6r9kFHeTdj-25@mini-arch/
> > Fixes: 5a842c288cfa ("net/mlx5e: Add TX support for netmems")
> > Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> > Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
> > Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
> 
> 
> Hmm, a couple of issues I see, but I'm not sure if it's really wrong
> or my own non-understanding.
> 
> I don't see  netmem_dma_unmap_page_attrs called anywhere in your
> driver. The point of  netmem_dma_unmap_addr_set setting the addr to 0
> is that a later call to netmem_dma_unmap_page_attrs skips the
> dma-unmap call if it's 0.
It is called in mlx5e_tx_dma_unmap() [1]. This was added previously in
commit 5a842c288cfa ("net/mlx5e: Add TX support for netmems") and Stan
noticed that the required netmem_dma_unmap_addr_set() is missing.

> 
> I could not understand why the mlx5/core/* files still used the
> non-netmem variant. The netdev->netmem_tx was set to true in
> mlx5/core/en_main.c, so I would have thought at least all the
> mlx5/core/en_tx.c callsites should have gone to that.
> 
Only the skb frags use the netmem variants. The headers still use the
dma_map/unmap_single() API.


[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/net/ethernet/mellanox/mlx5/core/en/txrx.h#n375

Thanks,
Dragos