Hi Jason,
On Thu, Jun 9, 2022 at 2:17 PM Jason A. Donenfeld <Jason@xxxxxxxxx> wrote:
> The RNG uses vanilla spinlocks, not raw spinlocks, so kfence should pick
> its random numbers before taking its raw spinlocks. This also has the
> nice effect of doing less work inside the lock. It should fix a splat
> that Geert saw with CONFIG_PROVE_RAW_LOCK_NESTING:
>
> dump_backtrace.part.0+0x98/0xc0
> show_stack+0x14/0x28
> dump_stack_lvl+0xac/0xec
> dump_stack+0x14/0x2c
> __lock_acquire+0x388/0x10a0
> lock_acquire+0x190/0x2c0
> _raw_spin_lock_irqsave+0x6c/0x94
> crng_make_state+0x148/0x1e4
> _get_random_bytes.part.0+0x4c/0xe8
> get_random_u32+0x4c/0x140
> __kfence_alloc+0x460/0x5c4
> kmem_cache_alloc_trace+0x194/0x1dc
> __kthread_create_on_node+0x5c/0x1a8
> kthread_create_on_node+0x58/0x7c
> printk_start_kthread.part.0+0x34/0xa8
> printk_activate_kthreads+0x4c/0x54
> do_one_initcall+0xec/0x278
> kernel_init_freeable+0x11c/0x214
> kernel_init+0x24/0x124
> ret_from_fork+0x10/0x20
>
> Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Marco Elver <elver@xxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Thank you, the splat is gone.
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
