modules: lockdep: Suppress suspicious RCU usage warning
[ Upstream commit bf08949cc8
]
While running kprobe module test, find_module_all() caused
a suspicious RCU usage warning.
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=============================
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
parent
fa0316aaf0
commit
4c50665fc9
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@ -214,7 +214,8 @@ static struct module *mod_find(unsigned long addr)
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{
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struct module *mod;
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list_for_each_entry_rcu(mod, &modules, list) {
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list_for_each_entry_rcu(mod, &modules, list,
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lockdep_is_held(&module_mutex)) {
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if (within_module(addr, mod))
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return mod;
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}
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@ -448,7 +449,8 @@ bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
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if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
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return true;
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list_for_each_entry_rcu(mod, &modules, list) {
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list_for_each_entry_rcu(mod, &modules, list,
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lockdep_is_held(&module_mutex)) {
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struct symsearch arr[] = {
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{ mod->syms, mod->syms + mod->num_syms, mod->crcs,
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NOT_GPL_ONLY, false },
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@ -616,7 +618,8 @@ static struct module *find_module_all(const char *name, size_t len,
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module_assert_mutex_or_preempt();
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list_for_each_entry_rcu(mod, &modules, list) {
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list_for_each_entry_rcu(mod, &modules, list,
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lockdep_is_held(&module_mutex)) {
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if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
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continue;
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if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
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