From: Florian Westphal fw@strlen.de
From: Florian Westphal fw@strlen.de
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@strlen.de Fixes: a473573964e5 ("lib: code tagging module support") Signed-off-by: Florian Westphal fw@strlen.de Reported-by: Ben Greear greearb@candelatech.com Closes: https://lore.kernel.org/netdev/bdaaef9d-4364-4171-b82b-bcfc12e207eb@candelat... Cc: Uladzislau Rezki urezki@gmail.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Suren Baghdasaryan surenb@google.com Cc: Kent Overstreet kent.overstreet@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org --- 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;