On 2024-07-10, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > console_lock is the outermost subsystem lock for a lot of subsystems, > which means get/put_user must nest within. Which means it cannot be > acquired somewhere deeply nested in other locks, and most definitely > not while holding fs locks potentially needed to resolve faults. > > console_trylock is the best we can do here. But John pointed out on a > previous version that this is futile: > > "Using the console lock here at all is wrong. The console lock does not > prevent other CPUs from calling printk() and inserting lines in between. > > "There is no way to guarantee a contiguous ringbuffer block using > multiple printk() calls. > > "The console_lock usage should be removed." > > https://lore.kernel.org/lkml/87frsh33xp.fsf@xxxxxxxxxxxxxxxxxxxxx/ > > Do that. > > Reported-by: syzbot+6cebc1af246fe020a2f0@xxxxxxxxxxxxxxxxxxxxxxxxx > References: https://lore.kernel.org/dri-devel/00000000000026c1ff061cd0de12@xxxxxxxxxx/ > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > Fixes: a8f354284304 ("bcachefs: bch2_print_string_as_lines()") Reviewed-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
