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From: Ingo Molnar <mingo@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -v2] seqlock, procfs: Match scoped_seqlock_read() critical section vs. RCU ordering in do_task_stat() to do_io_accounting()
Date: Tue, 2 Dec 2025 11:18:30 +0100	[thread overview]
Message-ID: <aS689gFv5gi1qTwF@gmail.com> (raw)
In-Reply-To: <aS6vpLzte-9LqwYQ@redhat.com>


* Oleg Nesterov <oleg@redhat.com> wrote:

> On 12/02, Ingo Molnar wrote:
> >
> > * Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > > On 12/02, Ingo Molnar wrote:
> > > >
> > > > RCU read-lock should not nest inside a read-seqlock
> > > > irqsave ->stats_lock IRQs-off critical section,
> > >
> > > Hmm... I agree with this patch, but is it actually wrong?
> > >
> > > I thought that rcu_read_lock/unlock is safe under spin_lock_irq...
> >
> > Yeah, true - it's allowed and not a bug,
> 
> OK, thanks ;)
> 
> > merely
> > discouraged inside irqs-off sections if it can be
> > avoided, and it's an inconsistency versus
> > do_io_accounting().
> 
> Yes, yes, agreed
> 
> > How about the -v2 phrasing below? I also removed the
> > Fixes tags.
> 
> Acked-by: Oleg Nesterov <oleg@redhat.com>

Thanks Oleg!

	Ingo

  reply	other threads:[~2025-12-02 10:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-02  4:09 [PATCH] seqlock, procfs: Fix scoped_seqlock_read() critical section in do_task_stat() Ingo Molnar
2025-12-02  7:29 ` Oleg Nesterov
2025-12-02  9:05   ` [PATCH -v2] seqlock, procfs: Match scoped_seqlock_read() critical section vs. RCU ordering in do_task_stat() to do_io_accounting() Ingo Molnar
2025-12-02  9:21     ` Oleg Nesterov
2025-12-02 10:18       ` Ingo Molnar [this message]
2025-12-02 10:23     ` [tip: locking/urgent] " tip-bot2 for Ingo Molnar

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