diff options
| author | Jesper Dangaard Brouer <hawk@kernel.org> | 2025-07-16 18:26:53 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-07-18 16:59:05 -0700 |
| commit | a6f190630d070173897a7e98a30188b7638ba0a1 (patch) | |
| tree | 72e6fadd557f4929f49bca1fff592c1d34be0e3f /net/core/dev.c | |
| parent | 8b7ab8eb52b51a7058edf0035e47b281f9fc9a19 (diff) | |
net: track pfmemalloc drops via SKB_DROP_REASON_PFMEMALLOC
Add a new SKB drop reason (SKB_DROP_REASON_PFMEMALLOC) to track packets
dropped due to memory pressure. In production environments, we've observed
memory exhaustion reported by memory layer stack traces, but these drops
were not properly tracked in the SKB drop reason infrastructure.
While most network code paths now properly report pfmemalloc drops, some
protocol-specific socket implementations still use sk_filter() without
drop reason tracking:
- Bluetooth L2CAP sockets
- CAIF sockets
- IUCV sockets
- Netlink sockets
- SCTP sockets
- Unix domain sockets
These remaining cases represent less common paths and could be converted
in a follow-up patch if needed. The current implementation provides
significantly improved observability into memory pressure events in the
network stack, especially for key protocols like TCP and UDP, helping to
diagnose problems in production environments.
Reported-by: Matt Fleming <mfleming@cloudflare.com>
Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://patch.msgid.link/175268316579.2407873.11634752355644843509.stgit@firesoul
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 621a639aeba1..59a9089117de 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5749,6 +5749,7 @@ static inline int nf_ingress(struct sk_buff *skb, struct packet_type **pt_prev, static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, struct packet_type **ppt_prev) { + enum skb_drop_reason drop_reason = SKB_DROP_REASON_UNHANDLED_PROTO; struct packet_type *ptype, *pt_prev; rx_handler_func_t *rx_handler; struct sk_buff *skb = *pskb; @@ -5840,8 +5841,10 @@ skip_taps: #endif skb_reset_redirect(skb); skip_classify: - if (pfmemalloc && !skb_pfmemalloc_protocol(skb)) + if (pfmemalloc && !skb_pfmemalloc_protocol(skb)) { + drop_reason = SKB_DROP_REASON_PFMEMALLOC; goto drop; + } if (skb_vlan_tag_present(skb)) { if (pt_prev) { @@ -5946,7 +5949,8 @@ drop: dev_core_stats_rx_dropped_inc(skb->dev); else dev_core_stats_rx_nohandler_inc(skb->dev); - kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO); + + kfree_skb_reason(skb, drop_reason); /* Jamal, now you will not able to escape explaining * me how you were going to use this. :-) */ |