+ lib-alloc_tag_module_unload-must-wait-for-pending-kfree_rcu-calls.patch added to mm-hotfixes-unstable branch

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Florian Westphal <fw@xxxxxxxxx>
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@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>
---

 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@xxxxxxxxx are

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





[Index of Archives]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux