embedded resource_error ai_generated true

lwIP：pbuf_alloc失败：PBUF_POOL耗尽，总计16，空闲0，最低0

lwIP: pbuf_alloc failed: PBUF_POOL exhausted, total=16, free=0, low=0

ID: embedded/lwip-pbuf-pool-exhaustion

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82%修复率
86%置信度
1证据数
2024-08-05首次发现

版本兼容性

版本状态引入弃用备注
lwIP 2.1.3 active — — —
lwIP 2.2.0 active — — —
STM32Cube_FW_H7_V1.11.0 active — — —

根因分析

lwIP的PBUF_POOL内存池为空，因为所有缓冲区都在使用中，通常由于网络流量峰值、未处理数据包的内存泄漏或池大小配置不足引起。

English

The lwIP PBUF_POOL memory pool is empty because all buffers are in use, typically due to network traffic spikes, memory leaks from unprocessed packets, or insufficient pool size configuration.

generic

官方文档

https://www.nongnu.org/lwip/2_1_x/group__pbuf.html

解决方案

  1. Increase PBUF_POOL_SIZE in lwipopts.h (e.g., from 16 to 32 or 64) to handle burst traffic, and reduce PBUF_POOL_BUFSIZE if packet sizes are small.
  2. Add a check in the Ethernet ISR to drop packets if pool is low, preventing system lockup: `if (pbuf_alloc(PBUF_RAW, 0, PBUF_POOL) == NULL) { return ERR_MEM; }`
  3. Implement a periodic task to free orphaned pbufs by checking `lwip_stats.mem.used` and calling `tcpip_thread()` processing to flush queues.

无效尝试

常见但无效的做法:

  1. 80% 失败

    Larger windows require more buffers; if the pool size isn't increased, exhaustion still occurs under load.

  2. 90% 失败

    This shifts computation to CPU but doesn't affect buffer allocation; pool exhaustion persists.

  3. 95% 失败

    ARP cache management doesn't free PBUF_POOL buffers; those are for packet data, not ARP entries.