From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dave Hansen <dave.hansen@intel.com>, Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>,
Christoph Lameter <cl@gentwo.org>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Steve Capper <steve.capper@linaro.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>,
Jerome Marchand <jmarchan@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>,
alsa-devel@alsa-project.org
Subject: Re: [PATCH 05/16] page-flags: define behavior of FS/IO-related flags on compound pages
Date: Thu, 19 Mar 2015 22:02:52 +0200 [thread overview]
Message-ID: <20150319200252.GA13348@node.dhcp.inet.fi> (raw)
In-Reply-To: <550B15A0.9090308@intel.com>
On Thu, Mar 19, 2015 at 11:29:52AM -0700, Dave Hansen wrote:
> On 03/19/2015 10:08 AM, Kirill A. Shutemov wrote:
> > The odd exception is PG_dirty: sound uses compound pages and maps them
> > with PTEs. NO_COMPOUND triggers VM_BUG_ON() in set_page_dirty() on
> > handling shared fault. Let's use HEAD for PG_dirty.
>
> Can we get the sound guys to look at this, btw? It seems like an odd
> thing that we probably don't want to keep around, right?
CC: +sound guys
I'm not sure what is right fix here. At the time adding __GFP_COMP was a
fix: see f3d48f0373c1.
Other odd part about __GFP_COMP here is that we have ->_mapcount in tail
pages to be used for both: mapcount of the individual page and for gup
pins. __compound_tail_refcounted() doesn't recognize that we don't need
tail page accounting for these pages.
Hugh, I tried to ask you about the situation several times (last time on
the summit). Any comments?
--
Kirill A. Shutemov
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next parent reply other threads:[~2015-03-19 20:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1426784902-125149-1-git-send-email-kirill.shutemov@linux.intel.com>
[not found] ` <1426784902-125149-6-git-send-email-kirill.shutemov@linux.intel.com>
[not found] ` <550B15A0.9090308@intel.com>
2015-03-19 20:02 ` Kirill A. Shutemov [this message]
2015-03-23 0:02 ` [PATCH 05/16] page-flags: define behavior of FS/IO-related flags on compound pages Hugh Dickins
2015-03-23 12:17 ` Kirill A. Shutemov
2015-03-24 22:54 ` Hugh Dickins
2015-03-25 10:23 ` Kirill A. Shutemov
2015-03-25 18:56 ` Hugh Dickins
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