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| author | Oleg Nesterov <oleg@redhat.com> | 2024-08-01 15:27:09 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-08-02 11:30:30 +0200 |
| commit | 84455e6923c79a37812930787aaa141e82afe315 (patch) | |
| tree | b7096be1b261a75c1e08f64e6801d66b016086c4 /tools/perf/scripts/python/export-to-postgresql.py | |
| parent | cfa7f3d2c526c224a6271cc78a4a27a0de06f4f0 (diff) | |
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
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions