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Breno Leitao says: ==================== net: do not warn on best-effort skb allocation failures Both netconsole and netpoll keep a small preallocated pool of skbs (skb_pool) so they can still get a buffer under memory pressure. On the hot path they first attempt a normal GFP_ATOMIC allocation and only fall back to the pool when that fails, keeping the pool as a last resort. This is where the problem happens. If alloc_skb() fails, we now have more than 100 message coming from the page=0 failure, which consumes the scarce pool of skb, making the real issue disappear. So the noise (memory allocation failure) deplets the SKB buffer and crowds out the real message we were trying to deliver. This is happening on the Meta fleet. The stack trace looks like: pr/netcon_ext0: page allocation failure: order:0, mode:0x40820(GFP_ATOMIC|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0 ... dump_stack_lvl warn_alloc __alloc_pages_slowpath __alloc_frozen_pages_noprof alloc_pages_mpol alloc_slab_page allocate_slab kmem_cache_alloc_node_noprof __alloc_skb send_udp netconsole_write nbcon_emit_next_record nbcon_emit_one nbcon_kthread_func kthread Solution: Do not warn if netconsole/netpoll fails to allocate these SKBs. Pass __GFP_NOWARN on these best-effort allocations -- both the hot-path attempt in netconsole's find_skb() and the pool refill in netpoll's refill_skbs() -- and let the existing fallback paths do their job quietly. The allocation will happen on SKB refill workqueue. Given I am touching this code, if alloc_skb() fails, reschedule the workqueue to try later. ==================== Link: https://patch.msgid.link/20260629-netpoll_no_warn-v1-0-f380f0b2cd0c@debian.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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