From: peterz@infradead.org
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-arch@vger.kernel.org, Alexey Kardashevskiy <aik@ozlabs.ru>,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state
Date: Tue, 18 Aug 2020 17:41:43 +0200 [thread overview]
Message-ID: <20200818154143.GT2674@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1597735273.s0usqkrlsk.astroid@bobo.none>
On Tue, Aug 18, 2020 at 05:22:33PM +1000, Nicholas Piggin wrote:
> Excerpts from peterz@infradead.org's message of August 12, 2020 8:35 pm:
> > On Wed, Aug 12, 2020 at 06:18:28PM +1000, Nicholas Piggin wrote:
> >> Excerpts from peterz@infradead.org's message of August 7, 2020 9:11 pm:
> >> >
> >> > What's wrong with something like this?
> >> >
> >> > AFAICT there's no reason to actually try and add IRQ tracing here, it's
> >> > just a hand full of instructions at the most.
> >>
> >> Because we may want to use that in other places as well, so it would
> >> be nice to have tracing.
> >>
> >> Hmm... also, I thought NMI context was free to call local_irq_save/restore
> >> anyway so the bug would still be there in those cases?
> >
> > NMI code has in_nmi() true, in which case the IRQ tracing is disabled
> > (except for x86 which has CONFIG_TRACE_IRQFLAGS_NMI).
> >
>
> That doesn't help. It doesn't fix the lockdep irq state going out of
> synch with the actual irq state. The code which triggered this with the
> special powerpc irq disable has in_nmi() true as well.
Urgh, you're talking about using lockdep_assert_irqs*() from NMI
context?
If not, I'm afraid I might've lost the plot a little on what exact
failure case we're talking about.
next prev parent reply other threads:[~2020-08-18 16:24 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-23 10:56 [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state Nicholas Piggin
2020-07-23 10:56 ` [PATCH 2/2] lockdep: warn on redundant or incorrect irq state changes Nicholas Piggin
2020-07-24 2:57 ` kernel test robot
2020-08-04 10:00 ` Alexey Kardashevskiy
2020-07-23 11:40 ` [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state Peter Zijlstra
2020-07-23 13:11 ` Nicholas Piggin
2020-07-23 14:59 ` Peter Zijlstra
2020-07-23 16:20 ` Nicholas Piggin
2020-07-24 4:16 ` Alexey Kardashevskiy
2020-07-24 5:59 ` Nicholas Piggin
2020-07-26 7:40 ` Alexey Kardashevskiy
2020-07-24 6:16 ` Athira Rajeev
2020-07-24 2:19 ` kernel test robot
2020-07-24 3:15 ` kernel test robot
2020-07-25 20:26 ` Peter Zijlstra
2020-07-26 4:14 ` Nicholas Piggin
2020-07-26 11:59 ` peterz
2020-07-26 12:11 ` peterz
2020-07-28 11:22 ` Nicholas Piggin
2020-08-07 11:11 ` peterz
2020-08-12 8:18 ` Nicholas Piggin
2020-08-12 10:35 ` peterz
2020-08-18 7:22 ` Nicholas Piggin
2020-08-18 15:41 ` peterz [this message]
2020-08-18 23:54 ` Nicholas Piggin
2020-08-19 10:39 ` Alexey Kardashevskiy
2020-08-19 15:32 ` peterz
2020-08-19 15:39 ` peterz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200818154143.GT2674@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=aik@ozlabs.ru \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mingo@redhat.com \
--cc=npiggin@gmail.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).