linux-kernel - Re: [PATCH v6 02/30] mm: Add set/end/wait functions for PG_private

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Message-ID: <14840.1617895534@warthog.procyon.org.uk>
Date:   Thu, 08 Apr 2021 16:25:34 +0100
From:   David Howells <dhowells@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     dhowells@...hat.com, linux-fsdevel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@....de>, linux-mm@...ck.org,
        linux-cachefs@...hat.com, linux-afs@...ts.infradead.org,
        linux-nfs@...r.kernel.org, linux-cifs@...r.kernel.org,
        ceph-devel@...r.kernel.org, v9fs-developer@...ts.sourceforge.net,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Steve French <sfrench@...ba.org>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Jeff Layton <jlayton@...hat.com>,
        David Wysochanski <dwysocha@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 02/30] mm: Add set/end/wait functions for PG_private_2

Matthew Wilcox <willy@...radead.org> wrote:

> > +void end_page_private_2(struct page *page)
> > +{
> > +	page = compound_head(page);
> > +	VM_BUG_ON_PAGE(!PagePrivate2(page), page);
> > +	clear_bit_unlock(PG_private_2, &page->flags);
> > +	wake_up_page_bit(page, PG_private_2);
> 
> ... but when we try to end on a tail, we actually wake up the head ...

Question is, should I remove compound_head() here or add it into the other
functions?

David