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authorMasami Hiramatsu <mhiramat@kernel.org>2019-12-03 15:14:04 +0900
committerJessica Yu <jeyu@kernel.org>2019-12-09 10:51:23 +0100
commitbf08949cc8b98b7d1e20cfbba169a5938d42dae8 (patch)
treeb27d0aa4e2f0324cd2b2941a524360f789f49fb5 /kernel/module.c
parente42617b825f8073569da76dc4510bfa019b1c35a (diff)
modules: lockdep: Suppress suspicious RCU usage warning
While running kprobe module test, find_module_all() caused a suspicious RCU usage warning. ----- ============================= WARNING: suspicious RCU usage 5.4.0-next-20191202+ #63 Not tainted ----------------------------- kernel/module.c:619 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by rmmod/642: #0: ffffffff8227da80 (module_mutex){+.+.}, at: __x64_sys_delete_module+0x9a/0x230 stack backtrace: CPU: 0 PID: 642 Comm: rmmod Not tainted 5.4.0-next-20191202+ #63 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack+0x71/0xa0 find_module_all+0xc1/0xd0 __x64_sys_delete_module+0xac/0x230 ? do_syscall_64+0x12/0x1f0 do_syscall_64+0x50/0x1f0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4b6d49 ----- This is because list_for_each_entry_rcu(modules) is called without rcu_read_lock(). This is safe because the module_mutex is locked. Pass lockdep_is_held(&module_mutex) to the list_for_each_entry_rcu() to suppress this warning, This also fixes similar issue in mod_find() and each_symbol_section(). Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Jessica Yu <jeyu@kernel.org>
Diffstat (limited to 'kernel/module.c')
-rw-r--r--kernel/module.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 3a486f826224..155349275b8e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -214,7 +214,8 @@ static struct module *mod_find(unsigned long addr)
{
struct module *mod;
- list_for_each_entry_rcu(mod, &modules, list) {
+ list_for_each_entry_rcu(mod, &modules, list,
+ lockdep_is_held(&module_mutex)) {
if (within_module(addr, mod))
return mod;
}
@@ -448,7 +449,8 @@ bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
return true;
- list_for_each_entry_rcu(mod, &modules, list) {
+ list_for_each_entry_rcu(mod, &modules, list,
+ lockdep_is_held(&module_mutex)) {
struct symsearch arr[] = {
{ mod->syms, mod->syms + mod->num_syms, mod->crcs,
NOT_GPL_ONLY, false },
@@ -616,7 +618,8 @@ static struct module *find_module_all(const char *name, size_t len,
module_assert_mutex_or_preempt();
- list_for_each_entry_rcu(mod, &modules, list) {
+ list_for_each_entry_rcu(mod, &modules, list,
+ lockdep_is_held(&module_mutex)) {
if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
continue;
if (strlen(mod->name) == len && !memcmp(mod->name, name, len))