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net/mlx5e: kTLS, Fix incorrect page refcounting

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The kTLS tx handling code is using a mix of get_page() and
page_ref_inc() APIs to increment the page reference. But on the release
path (mlx5e_ktls_tx_handle_resync_dump_comp()), only put_page() is used.

This is an issue when using pages from large folios: the get_page()
references are stored on the folio page while the page_ref_inc()
references are stored directly in the given page. On release the folio
page will be dereferenced too many times.

This was found while doing kTLS testing with sendfile() + ZC when the
served file was read from NFS on a kernel with NFS large folios support
(commit 49b29a573d ("nfs: add support for large folios")).

Fixes: 84d1bb2b13 ("net/mlx5e: kTLS, Limit DUMP wqe size")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20241107183527.676877-5-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Dragos Tatulea 2024-11-07 20:35:24 +02:00 committed by Jakub Kicinski
parent 9ca3144199
commit dd6e972cc5
1 changed files with 4 additions and 4 deletions
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8
drivers/net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c
View File

@ -660,7 +660,7 @@ tx_sync_info_get(struct mlx5e_ktls_offload_context_tx *priv_tx,
while (remaining > 0) {
skb_frag_t *frag = &record->frags[i];
get_page(skb_frag_page(frag));
page_ref_inc(skb_frag_page(frag));
remaining -= skb_frag_size(frag);
info->frags[i++] = *frag;
}
@ -763,7 +763,7 @@ void mlx5e_ktls_tx_handle_resync_dump_comp(struct mlx5e_txqsq *sq,
stats = sq->stats;
mlx5e_tx_dma_unmap(sq->pdev, dma);
put_page(wi->resync_dump_frag_page);
page_ref_dec(wi->resync_dump_frag_page);
stats->tls_dump_packets++;
stats->tls_dump_bytes += wi->num_bytes;
}
@ -816,12 +816,12 @@ mlx5e_ktls_tx_handle_ooo(struct mlx5e_ktls_offload_context_tx *priv_tx,
err_out:
for (; i < info.nr_frags; i++)
/* The put_page() here undoes the page ref obtained in tx_sync_info_get().
/* The page_ref_dec() here undoes the page ref obtained in tx_sync_info_get().
* Page refs obtained for the DUMP WQEs above (by page_ref_add) will be
* released only upon their completions (or in mlx5e_free_txqsq_descs,
* if channel closes).
*/
put_page(skb_frag_page(&info.frags[i]));
page_ref_dec(skb_frag_page(&info.frags[i]));
return MLX5E_KTLS_SYNC_FAIL;
}