71b8355ba6
[ Upstream commit 78af4dc949daaa37b3fcd5f348f373085b4e858f ] Syzbot reported a lock inversion involving perf. The sore point being perf holding exec_update_mutex() for a very long time, specifically across a whole bunch of filesystem ops in pmu::event_init() (uprobes) and anon_inode_getfile(). This then inverts against procfs code trying to take exec_update_mutex. Move the permission checks later, such that we need to hold the mutex over less code. Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.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.