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* [PATCH]netfilter module-autoload: duplicate request for netfilter module
@ 2026-04-14 12:36 Zhe Zhao
  0 siblings, 0 replies; 2+ messages in thread
From: Zhe Zhao @ 2026-04-14 12:36 UTC (permalink / raw)
  To: pablo@netfilter.org; +Cc: netfilter-devel

Hi, Pablo

When boot up linux computer with netfilter there is below kernel
messages show up on my desktop

kernel: ------------[ cut here ]------------
kernel: module-autoload: duplicate request for module net-pf-16-proto-12
kernel: WARNING: kernel/module/dups.c:184 at
kmod_dup_request_exists_wait+0x18a/0x320, CPU#4: firewalld/1071
kernel: Modules linked in: snd_hda_codec_intelhdmi snd_hda_codec_hdmi
intel_rapl_msr intel_rapl_common snd_hda_codec_alc662 binfmt_misc
snd_hda_codec_realtek_lib intel_uncore_frequency ommon
snd_hda_codec_generic snd_hda_intel vfat sn>
kernel: platform_profile snd igb intel_uncore i2c_i801 dca soundcore
i2c_smbus mei_me mei idma64 intel_pch_thermal intel_pmc_core
pmt_telemetry pmt_discovery pmt_class acpi_tad acpi_pad y intel_vsec
loop zram xfs i915 i2c_algo_bit dr>
kernel: CPU: 4 UID: 0 PID: 1071 Comm: firewalld Tainted: G W 7.0.0 #4
PREEMPT(lazy)
kernel: Tainted: [W]=WARN
kernel: Hardware name: HP HP ZHAN 99 Pro G1 MT/843C, BIOS F.48 07/27/2022
kernel: RIP: 0010:kmod_dup_request_exists_wait+0x18d/0x320
kernel: Code: c7 c7 00 0b 1c 8e e8 32 10 ce 00 48 89 df e8 ba ec 26 00
80 3d 13 e3 dc 01 00 0f 84 17 12 e2 ff 48 8d 3d 06 2f f7 01 48 89 ee
<67> 48 0f b9 3a 45 84 e4 75 6b 41 c7 45 00 00 00 00 00 b8 01
kernel: RSP: 0018:ffffb254449d3ce0 EFLAGS: 00010202
kernel: RAX: 0000000000000000 RBX: ffffa24ae080e300 RCX: 0000000000000000
kernel: RDX: 0000000000000000 RSI: ffffb254449d3d48 RDI: ffffffff8e365720
kernel: RBP: ffffb254449d3d48 R08: 0000000000000000 R09: 0000000000000000
kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
kernel: R13: ffffb254449d3d2c R14: ffffa2483b0f8b00 R15: ffffa248c4830000
kernel: FS: 00007f633ca875c0(0000) GS:ffffa24b92b3e000(0000)
knlGS:0000000000000000
kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 00007f463be5fc00 CR3: 00000001de71e003 CR4: 00000000003726f0
kernel: Call Trace:
kernel: <TASK>
kernel: __request_module+0x189/0x400
kernel: netlink_create+0xaf/0x240
kernel: ? alloc_inode+0x38/0x150
kernel: __sock_create+0x126/0x1d0
kernel: __sys_socket+0x92/0x110
kernel: __x64_sys_socket+0x13/0x20
kernel: do_syscall_64+0x125/0x1200
kernel: entry_SYSCALL_64_after_hwframe+0x6c/0x74
kernel: RIP: 0033:0x7f633c3060db
kernel: Code: 48 8b 55 f8 64 48 2b 14 25 28 00 00 00 75 02 c9 c3 e8 19
ae 00 00 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 29 00 00 00 0f 05
<48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f5 fc 0e 00 f7 d8 64 89
kernel: RSP: 002b:00007ffe0d24d668 EFLAGS: 00000202 ORIG_RAX: 0000000000000029
kernel: RAX: ffffffffffffffda RBX: 00007f573be0df70 RCX: 00007f633c3060db
kernel: RDX: 000000000000000c RSI: 0000000000000003 RDI: 0000000000000010
kernel: RBP: 00007ffe0d24d680 R08: 00007f573be0df70 R09: 0000000000000001
kernel: R10: 00007f573be0df60 R11: 0000000000000202 R12: 0000000000000000
kernel: R13: 00007ffe0d24d858 R14: 000000000000000c R15: 0000000000000000
kernel: </TASK>
kernel: ---[ end trace 0000000000000000 ]---

It is always show up during Fedora system bootup, it seems there is
duplication module loading in the kernel for the netfilter module, I
write a patch for this message fix
below patch codes is based on new relesed Linux kernel 7.0, the above
message can be seen in linux 6.5 and linux 7.0, It maybe a common
issue.

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 9a07c3215..a07497cb2 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -22,7 +22,7 @@ int __request_module(bool wait, const char *name, ...);
 #define request_module(mod...) __request_module(true, mod)
 #define request_module_nowait(mod...) __request_module(false, mod)
 #define try_then_request_module(x, mod...) \
- ((x) ?: (__request_module(true, mod), (x)))
+ ((x) ? (x) : (__request_module(true, mod), (x)))
 #else
 static inline int request_module(const char *name, ...) { return -ENOSYS; }
 static inline int request_module_nowait(const char *name, ...) {
return -ENOSYS; }
diff --git a/include/linux/module.h b/include/linux/module.h
index 14f391b18..a71cf6172 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -588,6 +588,8 @@ struct module {
 #endif

 #ifdef CONFIG_MODULES
+/* not reentry load module */
+bool kmod_dup_request_exists(const char *fmt, ...);

 /* Get/put a kernel symbol (calls must be symmetric) */
 void *__symbol_get(const char *symbol);
diff --git a/kernel/module/dups.c b/kernel/module/dups.c
index 1d720a531..fcee60254 100644
--- a/kernel/module/dups.c
+++ b/kernel/module/dups.c
@@ -116,6 +116,23 @@ static void kmod_dup_request_complete(struct
work_struct *work)
  queue_delayed_work(system_dfl_wq, &kmod_req->delete_work, 60 * HZ);
 }

+bool kmod_dup_request_exists(const char *fmt, ...)
+{
+        bool existed = false;
+        char module_name[MODULE_NAME_LEN];
+        va_list args;
+        va_start(args, fmt);
+        vsnprintf(module_name, sizeof(module_name), fmt, args);
+        va_end(args);
+
+        mutex_lock(&kmod_dup_mutex);
+        existed = kmod_dup_request_lookup(module_name) != NULL;
+        mutex_unlock(&kmod_dup_mutex);
+
+        return existed;
+}
+EXPORT_SYMBOL_GPL(kmod_dup_request_exists);
+
 bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
 {
  struct kmod_dup_req *kmod_req, *new_kmod_req;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 4d609d5cf..9d57add89 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -664,7 +664,8 @@ static int netlink_create(struct net *net, struct
socket *sock, int protocol,
 #ifdef CONFIG_MODULES
  if (!nl_table[protocol].registered) {
  netlink_unlock_table();
- request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
+ try_then_request_module(kmod_dup_request_exists("net-pf-%d-proto-%d",
PF_NETLINK, protocol),
+                                                "net-pf-%d-proto-%d",
PF_NETLINK, protocol);
  netlink_lock_table();
  }
 #endif
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index a23d4c51c..8c2c8767a 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1446,8 +1446,9 @@ static int ctrl_getfamily(struct sk_buff *skb,
struct genl_info *info)
  if (res == NULL) {
  genl_unlock();
  up_read(&cb_lock);
- request_module("net-pf-%d-proto-%d-family-%s",
-       PF_NETLINK, NETLINK_GENERIC, name);
+ try_then_request_module(kmod_dup_request_exists("net-pf-%d-proto-%d-family-%s",
+       PF_NETLINK, NETLINK_GENERIC, name), "net-pf-%d-proto-%d-family-%s",
+                                       PF_NETLINK, NETLINK_GENERIC, name);
  down_read(&cb_lock);
  genl_lock();
  res = genl_family_find_byname(name);


The patch mainly check is there already netfilter kmod under loading,
if there is it will not load it again, can you check is this message a
known issue or not?  And this patch tested on my desktop, please check
is it reasonable to fix this issue.

Thanks
Br
Alex

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2026-04-15 11:13 ` [PATCH]netfilter module-autoload: duplicate request for netfilter module Pablo Neira Ayuso
2026-04-14 12:36 Zhe Zhao

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