Messages in this thread | | | Date | Thu, 1 Jun 2023 20:13:59 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v9] kernel/fork: beware of __put_task_struct calling context |
| |
On 06/01, Wander Lairson Costa wrote: > > On Mon, May 29, 2023 at 9:23 AM Oleg Nesterov <oleg@redhat.com> wrote: > > > > On 05/17, Wander Lairson Costa wrote: > > > > > > On Wed, May 17, 2023 at 12:26 PM Oleg Nesterov <oleg@redhat.com> wrote: > > > > > > > > LGTM but we still need to understand the possible problems with CONFIG_PROVE_RAW_LOCK_NESTING ... > > > > > > > > Again, I'll try to investigate when I have time although I am not sure I can really help. > > > > > > > > Perhaps you too can try to do this ? ;) > > > > > > > > > > FWIW, I tested this patch with CONFIG_PROVE_LOCK_NESTING in RT and > > > stock kernels. No splat happened. > > > > Strange... FYI, I am running the kernel with this patch > > > > diff --git a/kernel/sys.c b/kernel/sys.c > > index 339fee3eff6a..3169cceddf3b 100644 > > --- a/kernel/sys.c > > +++ b/kernel/sys.c > > @@ -2412,6 +2412,17 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > > > > error = 0; > > switch (option) { > > + case 666: { > > + static DEFINE_SPINLOCK(l); > > + static DEFINE_RAW_SPINLOCK(r); > > + > > + raw_spin_lock(&r); > > + spin_lock(&l); > > + spin_unlock(&l); > > + raw_spin_unlock(&r); > > + > > + break; > > + } > > case PR_SET_PDEATHSIG: > > if (!valid_signal(arg2)) { > > error = -EINVAL; > > > > applied (because I am too lazy to compile a module ;) and > > > > FWIW, I converted it to a module [1]
where is [1] ? not that I think this matters though...
> > # perl -e 'syscall 157,666' > > > > triggers the lockdep bug > > > > ============================= > > [ BUG: Invalid wait context ] > > 6.4.0-rc2-00018-g4d6d4c7f541d-dirty #1176 Not tainted > > ----------------------------- > > perl/35 is trying to lock: > > ffffffff81c4cc18 (l){....}-{3:3}, at: __do_sys_prctl+0x21b/0x87b > > other info that might help us debug this: > > context-{5:5} > > ... > > > > as expected. > > > > Yeah, I tried it here and I had the same results,
OK,
> but only in the RT kernel
this again suggests that your testing was wrong or I am totally confused (quite possible, I know nothing about RT). I did the testing without CONFIG_PREEMPT_RT.
> But running the reproducer for put_task_struct(), works fine.
which reproducer ?
Oleg.
| |