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Re: [RFC v3 05/17] RCU free VMAs

From Matthew Wilcox <willy@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC v3 05/17] RCU free VMAs
Date 2017-04-30 07:10 +0200
Message-ID <tBPhn-7vt-3@gated-at.bofh.it> (permalink)
References <tATZL-2FN-3@gated-at.bofh.it> <tATZM-2FN-21@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Apr 27, 2017 at 05:52:44PM +0200, Laurent Dufour wrote:
> +static inline bool vma_is_dead(struct vm_area_struct *vma, unsigned int sequence)
> +{
> +	int ret = RB_EMPTY_NODE(&vma->vm_rb);
> +	unsigned seq = ACCESS_ONCE(vma->vm_sequence.sequence);
> +
> +	/*
> +	 * Matches both the wmb in write_seqlock_{begin,end}() and
> +	 * the wmb in vma_rb_erase().
> +	 */
> +	smp_rmb();
> +
> +	return ret || seq != sequence;
> +}

Hang on, this isn't vma_is_dead().  This is vma_has_changed() (possibly
from live to dead, but also possibly grown or shrunk; see your earlier
patch).

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Thread

[RFC v3 05/17] RCU free VMAs Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-04-27 18:00 +0200
  Re: [RFC v3 05/17] RCU free VMAs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-27 20:30 +0200
  Re: [RFC v3 05/17] RCU free VMAs Matthew Wilcox <willy@infradead.org> - 2017-04-30 07:00 +0200
  Re: [RFC v3 05/17] RCU free VMAs Matthew Wilcox <willy@infradead.org> - 2017-04-30 07:10 +0200
    Re: [RFC v3 05/17] RCU free VMAs Laurent Dufour <ldufour@linux.vnet.ibm.com> - 2017-05-03 09:30 +0200

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