This is a note to let you know that I've just added the patch titled
lib: alloc_tag_module_unload must wait for pending kfree_rcu calls
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
lib-alloc_tag_module_unload-must-wait-for-pending-kf.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 536dfe685ebd28b27ebfbc3d4b9168207b7e28a3
Author: Florian Westphal <fw@xxxxxxxxx>
Date: Mon Oct 7 22:52:24 2024 +0200
lib: alloc_tag_module_unload must wait for pending kfree_rcu calls
[ Upstream commit dc783ba4b9df3fb3e76e968b2cbeb9960069263c ]
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.
[akpm@xxxxxxxxxxxxxxxxxxxx: add comment]
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: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/lib/codetag.c b/lib/codetag.c
index afa8a2d4f3173..d1fbbb7c2ec3d 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;
