On Fri, Nov 1, 2024 at 6:58 AM Sasha Levin <sashal@xxxxxxxxxx> wrote: > > 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. Thanks Sasha! Could you please double-check that the prerequisite patch https://lore.kernel.org/all/20241021171003.2907935-1-surenb@xxxxxxxxxx/ was also picked up? I don't see it in the queue-6.11 directory. Without that patch this one will cause build errors, that's why I sent them as a patchset. Thanks, Suren. > > 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;
