diff mbox series

[net,4/7] net/mlx5e: kTLS, Fix incorrect page refcounting

Message ID 20241107183527.676877-5-tariqt@nvidia.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series mlx5 misc fixes 2024-11-07 | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 3 this patch: 3
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 2 maintainers not CCed: linux-rdma@vger.kernel.org borisp@nvidia.com
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch warning WARNING: line length of 94 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-11-08--06-00 (tests: 783)

Commit Message

Tariq Toukan Nov. 7, 2024, 6:35 p.m. UTC 
From: Dragos Tatulea <dtatulea@nvidia.com>

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 49b29a573da8 ("nfs: add support for large folios")).

Fixes: 84d1bb2b139e ("net/mlx5e: kTLS, Limit DUMP wqe size")
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 .../net/ethernet/mellanox/mlx5/core/en_accel/ktls_tx.c    | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
diff mbox series

Patch

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 d61be26a4df1..3db31cc10719 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
@@ -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;
 }