From: Florian Westphal <fw@xxxxxxxxx> commit dc783ba4b9df3fb3e76e968b2cbeb9960069263c upstream. Ben Greear reports following splat: ------------[ cut here ]------------ net/netfilter/nf_nat_core.c:1114 module nf_nat func:nf_nat_register_fn has 256 allocated at module unload WARNING: CPU: 1 PID: 10421 at lib/alloc_tag.c:168 alloc_tag_module_unload+0x22b/0x3f0 Modules linked in: nf_nat(-) btrfs ufs qnx4 hfsplus hfs minix vfat msdos fat ... Hardware name: Default string Default string/SKYBAY, BIOS 5.12 08/04/2020 RIP: 0010:alloc_tag_module_unload+0x22b/0x3f0 codetag_unload_module+0x19b/0x2a0 ? codetag_load_module+0x80/0x80 nf_nat module exit calls kfree_rcu on those addresses, but the free operation is likely still pending by the time alloc_tag checks for leaks. Wait for outstanding kfree_rcu operations to complete before checking resolves this warning. Reproducer: unshare -n iptables-nft -t nat -A PREROUTING -p tcp grep nf_nat /proc/allocinfo # will list 4 allocations rmmod nft_chain_nat rmmod nf_nat # will WARN. Link: https://lkml.kernel.org/r/20241007205236.11847-1-fw@xxxxxxxxx Fixes: a473573964e5 ("lib: code tagging module support") Signed-off-by: Florian Westphal <fw@xxxxxxxxx> Reported-by: Ben Greear <greearb@xxxxxxxxxxxxxxx> Closes: https://lore.kernel.org/netdev/bdaaef9d-4364-4171-b82b-bcfc12e207eb@xxxxxxxxxxxxxxx/ Cc: Uladzislau Rezki <urezki@xxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> --- Changes since v1 [1]: - Added SOB, per Greg KH [1] https://lore.kernel.org/all/20241021171003.2907935-2-surenb@xxxxxxxxxx/ lib/codetag.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/lib/codetag.c b/lib/codetag.c index afa8a2d4f317..d1fbbb7c2ec3 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -228,6 +228,9 @@ bool codetag_unload_module(struct module *mod) if (!mod) return true; + /* await any module's kfree_rcu() operations to complete */ + kvfree_rcu_barrier(); + mutex_lock(&codetag_lock); list_for_each_entry(cttype, &codetag_types, link) { struct codetag_module *found = NULL; -- 2.47.0.199.ga7371fff76-goog
