Messages in this thread | | | From | Wander Lairson Costa <> | Date | Thu, 1 Jun 2023 15:23:32 -0300 | Subject | Re: [PATCH v9] kernel/fork: beware of __put_task_struct calling context |
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On Thu, Jun 1, 2023 at 3:14 PM Oleg Nesterov <oleg@redhat.com> wrote: > > 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. >
Hrm, could you please share your .config?
> > But running the reproducer for put_task_struct(), works fine. > > which reproducer ? >
Only now I noticed I didn't add the reproducer to the commit message:
while true; do stress-ng --sched deadline --sched-period 1000000000 --sched-runtime 800000000 --sched-deadline 1000000000 --mmapfork 23 -t 20 done
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