On Mon, Aug 26, 2024 at 11:43:39AM +0200, Thomas Gleixner wrote: > As explained before, there is no problem with store or load tearing on > 32bit systems because the generation counter is only 32bit wide. So the > obvious solution is to only update 32 bits on a 32bit kernel: > > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -282,7 +282,7 @@ static void crng_reseed(struct work_stru > * is ordered with the write above to base_crng.generation. Pairs with > * the smp_rmb() before the syscall in the vDSO code. > */ > - smp_store_release(&_vdso_rng_data.generation, next_gen + 1); > + smp_store_release((unsigned long *)&_vdso_rng_data.generation, next_gen + 1); > #endif > if (!static_branch_likely(&crng_is_ready)) > crng_init = CRNG_READY; That seems like a pretty clean fix. > But that's a trivial fix compared to making VM_DROPPABLE work on 32-bit > correclty. :) My initial response too, and then I noticed he posted this: https://lore.kernel.org/all/315e3a268b165b6edad7dcb723b0d8a506a56c4e.1724309198.git.christophe.leroy@xxxxxxxxxx/ If that's correct, maybe it's not so bad, at least here. I haven't yet looked into the details of it. Jason
