4c50665fc9
[ Upstream commit bf08949cc8b98b7d1e20cfbba169a5938d42dae8 ] 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> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.