Re: [PATCH net-next] page_pool: add debug for release to cache from wrong CPU
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2025-09-18 09:13:44
Also in:
linux-rt-devel, lkml
On 2025-09-18 11:48:21 [+0300], Dragos Tatulea wrote:
quoted hunk ↗ jump to hunk
diff --git a/net/core/page_pool.c b/net/core/page_pool.c index ba70569bd4b0..404064d893d6 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c@@ -768,6 +795,18 @@ static bool page_pool_recycle_in_cache(netmem_ref netmem, return false; } +#ifdef CONFIG_DEBUG_PAGE_POOL_CACHE_RELEASE + if (unlikely(!page_pool_napi_local(pool))) {
if you do IS_ENABLED(CONFIG_DEBUG_PAGE_POOL_CACHE_RELEASE) you could avoid the ifdef. A quick question, where is this allow_direct argument supposed to come from? I just noticed that mlx5 does page_pool_put_unrefed_netmem(, true); which then does not consider page_pool_napi_local(). But your proposed change here will complain as it should.
+ u32 pp_cpuid = READ_ONCE(pool->cpuid); + u32 cpuid = smp_processor_id(); + + WARN_RATELIMIT(1, "page_pool %d: direct page release from wrong CPU %d, expected CPU %d", + pool->user.id, cpuid, pp_cpuid); + + return false; + } +#endif + /* Caller MUST have verified/know (page_ref_count(page) == 1) */ pool->alloc.cache[pool->alloc.count++] = netmem; recycle_stat_inc(pool, cached);
Sebastian