From: Masami Hiramatsu <mhiramat@kernel.org>
To: Jessica Yu <jeyu@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Ingo Molnar <mingo@kernel.org>,
Anders Roxell <anders.roxell@linaro.org>,
paulmck@kernel.org, "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
David Miller <davem@davemloft.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
mhiramat@kernel.org
Subject: [PATCH] modules: lockdep: Suppress suspicious RCU usage warning
Date: Tue, 3 Dec 2019 15:14:04 +0900 [thread overview]
Message-ID: <157535364480.17342.7937104819926015512.stgit@devnote2> (raw)
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_lock) 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>
---
kernel/module.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index cb6250be6ee9..38e5c6a7451b 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))
next reply other threads:[~2019-12-03 6:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 6:14 Masami Hiramatsu [this message]
2019-12-05 19:17 ` [PATCH] modules: lockdep: Suppress suspicious RCU usage warning Jessica Yu
2019-12-06 1:21 ` Masami Hiramatsu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=157535364480.17342.7937104819926015512.stgit@devnote2 \
--to=mhiramat@kernel.org \
--cc=anders.roxell@linaro.org \
--cc=anil.s.keshavamurthy@intel.com \
--cc=davem@davemloft.net \
--cc=jeyu@kernel.org \
--cc=joel@joelfernandes.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=naveen.n.rao@linux.ibm.com \
--cc=paulmck@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).