On Thu, Oct 10, 2024 at 01:56:42PM -0700, Andrii Nakryiko wrote: > To increase mm->mm_lock_seq robustness, switch it from int to long, so > that it's a 64-bit counter on 64-bit systems and we can stop worrying > about it wrapping around in just ~4 billion iterations. Same goes for > VMA's matching vm_lock_seq, which is derived from mm_lock_seq. > > I didn't use __u64 outright to keep 32-bit architectures unaffected, but > if it seems important enough, I have nothing against using __u64.
(__uXX are the uapi types) > > Suggested-by: Jann Horn <[email protected]> Jann, do you see problems with the normal seqcount being unsigned (int)? I suppose especially for preemptible seqcounts it might already be entirely feasible to wrap them? Doing u64 is tricky but not impossible, it would require something like we do for GUP_GET_PXX_LOW_HIGH. OTOH, I don't think we really care about 32bit enough to bother.
