From: Al Viro <viro@zeniv.linux.org.uk>
To: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>,
linux-mm@kvack.org, Kent Overstreet <kent.overstreet@gmail.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [RFC] pgflags_t
Date: Wed, 6 Oct 2021 15:28:45 +0000 [thread overview]
Message-ID: <YV3ArQxQ7CFzhBhR@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <106400c5-d3f2-e858-186a-82f9b517917b@redhat.com>
On Wed, Oct 06, 2021 at 05:23:49PM +0200, David Hildenbrand wrote:
> On 06.10.21 17:22, Al Viro wrote:
> > On Wed, Oct 06, 2021 at 03:58:14PM +0100, Matthew Wilcox wrote:
> > > David expressed some unease about the lack of typesafety in patches
> > > 1 & 2 of the page->slab conversion [1], and I'll admit to not being
> > > particularly a fan of passing around an unsigned long. That crystallised
> > > in a discussion with Kent [2] about how to lock a page when you don't know
> > > its type (solution: every memory descriptor type starts with a
> > > pgflags_t)
> >
> > Why bother making it a struct? What's wrong with __bitwise and letting
> > sparse catch conversions?
> >
>
> As I raised in my reply, we store all kinds of different things in
> page->flags ... not sure if that could be worked around somehow.
What of that? Inline helpers with force-casts for accessing those and
that's it...
Use of __bitwise is simply invisible to compiler - it doesn't get past the
preprocessor on non-sparse builds. So it's not like you'd disrupt the
atomic accesses, layout, etc.
next prev parent reply other threads:[~2021-10-06 15:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 14:58 [RFC] pgflags_t Matthew Wilcox
2021-10-06 15:16 ` David Hildenbrand
2021-10-06 15:29 ` Matthew Wilcox
2021-10-06 15:22 ` Al Viro
2021-10-06 15:23 ` David Hildenbrand
2021-10-06 15:28 ` Al Viro [this message]
2021-10-06 15:32 ` David Hildenbrand
2021-10-06 15:46 ` Al Viro
2021-10-06 15:47 ` David Hildenbrand
2021-10-06 15:38 ` Matthew Wilcox
2021-10-06 15:48 ` Al Viro
2021-10-07 14:37 ` Vlastimil Babka
2021-10-07 14:48 ` Matthew Wilcox
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