The patch titled Subject: lib: alloc_tag_module_unload must wait for pending kfree_rcu calls has been added to the -mm mm-hotfixes-unstable branch. Its filename is lib-alloc_tag_module_unload-must-wait-for-pending-kfree_rcu-calls.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Florian Westphal fw@strlen.de Subject: lib: alloc_tag_module_unload must wait for pending kfree_rcu calls Date: Mon, 7 Oct 2024 22:52:24 +0200

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 | 2 ++ 1 file changed, 2 insertions(+)

--- a/lib/codetag.c~lib-alloc_tag_module_unload-must-wait-for-pending-kfree_rcu-calls +++ a/lib/codetag.c @@ -228,6 +228,8 @@ bool codetag_unload_module(struct module if (!mod) return true;

+ kvfree_rcu_barrier(); + mutex_lock(&codetag_lock); list_for_each_entry(cttype, &codetag_types, link) { struct codetag_module *found = NULL; _

Patches currently in -mm which might be from fw@strlen.de are

lib-alloc_tag_module_unload-must-wait-for-pending-kfree_rcu-calls.patch