Oleg Nesterov 84455e6923 uprobes: document the usage of mm->mmap_lock
The comment above uprobe_write_opcode() is wrong, unapply_uprobe() calls
it under mmap_read_lock() and this is correct.

And it is completely unclear why register_for_each_vma() takes mmap_lock
for writing, add a comment to explain that mmap_write_lock() is needed to
avoid the following race:

	- A task T hits the bp installed by uprobe and calls
	  find_active_uprobe()

	- uprobe_unregister() removes this uprobe/bp

	- T calls find_uprobe() which returns NULL

	- another uprobe_register() installs the bp at the same address

	- T calls is_trap_at_addr() which returns true

	- T returns to handle_swbp() and gets SIGTRAP.

Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20240801132709.GA8780@redhat.com
2024-08-02 11:30:30 +02:00
2022-09-28 09:02:20 +02:00
2024-07-28 14:19:55 -07:00
2024-03-18 03:36:32 -06:00

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 reStructuredText 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.
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