Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Thu, 9 Jun 2022 14:31:18 +0200 | Subject | Re: [PATCH] mm/kfence: select random number before taking raw lock |
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Hi Jason,
On Thu, Jun 9, 2022 at 2:17 PM Jason A. Donenfeld <Jason@zx2c4.com> 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@linutronix.de> > Cc: Alexander Potapenko <glider@google.com> > Cc: Marco Elver <elver@google.com> > Cc: Dmitry Vyukov <dvyukov@google.com> > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Thank you, the splat is gone.
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
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
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