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Date:   Thu, 4 Apr 2019 22:58:10 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     "Tobin C. Harding" <me@tobin.cc>
Cc:     "Tobin C. Harding" <tobin@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <guro@fb.com>,
        Alexander Viro <viro@ftp.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>,
        Pekka Enberg <penberg@cs.helsinki.fi>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Christopher Lameter <cl@linux.com>,
        Matthew Wilcox <willy@infradead.org>,
        Miklos Szeredi <mszeredi@redhat.com>,
        Andreas Dilger <adilger@dilger.ca>,
        Waiman Long <longman@redhat.com>,
        Tycho Andersen <tycho@tycho.ws>, Theodore Ts'o <tytso@mit.edu>,
        Andi Kleen <ak@linux.intel.com>,
        David Chinner <david@fromorbit.com>,
        Nick Piggin <npiggin@gmail.com>,
        Rik van Riel <riel@redhat.com>,
        Hugh Dickins <hughd@google.com>, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC PATCH v2 14/14] dcache: Implement object migration
Message-ID: <20190404215810.GG2217@ZenIV.linux.org.uk>
References: <20190403042127.18755-1-tobin@kernel.org>
 <20190403042127.18755-15-tobin@kernel.org>
 <20190403170811.GR2217@ZenIV.linux.org.uk>
 <20190403171920.GS2217@ZenIV.linux.org.uk>
 <20190403174855.GT2217@ZenIV.linux.org.uk>
 <20190404202914.GA16709@eros.localdomain>
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On Fri, Apr 05, 2019 at 07:29:14AM +1100, Tobin C. Harding wrote:
> > __d_alloc() is not holding ->d_lock, since the object is not visible to
> > anybody else yet; with your changes it *is* visible.
> 
> I don't quite understand this comment.  How is the object visible?  The
> constructor is only called when allocating a new page to the slab and
> this is done with interrupts disabled.

Not to constructor, to your try-to-evict code...