Re: [syzbot] [mm?] possible deadlock in __mmap_lock_do_trace_released

[Tetsuo Handa]

On 2024/07/03 7:35, Axel Rasmussen wrote:
> But, note that stack_map_get_build_id calls mmap_read_trylock, so I
> would expect in the recursive case that call will simply fail, and
> then stack_map_get_build_id_offset appears to deal gracefully with
> that?

Unless that mmap was already held for write (or someone has started waiting
to hold it for write), recursive mmap_read_trylock() will succeed. Thus,
unless there is a guarantee of no infinite recursion, we should implement
a safeguard based on the worst scenario.