From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Stephane Marchesin <marcheu@chromium.org>,
Andi Kleen <andi@firstfloor.org>, Dave Airlie <airlied@gmail.com>,
Daniel Vetter <ffwll.ch@google.com>,
Rob Clark <rob.clark@linaro.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/10] shmem: replace page if mapping excludes its zone
Date: Mon, 14 May 2012 18:06:07 +0900 [thread overview]
Message-ID: <4FB0CAFF.6060705@jp.fujitsu.com> (raw)
In-Reply-To: <alpine.LSU.2.00.1205120453210.28861@eggly.anvils>
(2012/05/12 20:59), Hugh Dickins wrote:
> The GMA500 GPU driver uses GEM shmem objects, but with a new twist:
> the backing RAM has to be below 4GB. Not a problem while the boards
> supported only 4GB: but now Intel's D2700MUD boards support 8GB, and
> their GMA3600 is managed by the GMA500 driver.
>
> shmem/tmpfs has never pretended to support hardware restrictions on
> the backing memory, but it might have appeared to do so before v3.1,
> and even now it works fine until a page is swapped out then back in.
> When read_cache_page_gfp() supplied a freshly allocated page for copy,
> that compensated for whatever choice might have been made by earlier
> swapin readahead; but swapoff was likely to destroy the illusion.
>
> We'd like to continue to support GMA500, so now add a new
> shmem_should_replace_page() check on the zone when about to move
> a page from swapcache to filecache (in swapin and swapoff cases),
> with shmem_replace_page() to allocate and substitute a suitable page
> (given gma500/gem.c's mapping_set_gfp_mask GFP_KERNEL | __GFP_DMA32).
>
> This does involve a minor extension to mem_cgroup_replace_page_cache()
> (the page may or may not have already been charged); and I've removed
> a comment and call to mem_cgroup_uncharge_cache_page(), which in fact
> is always a no-op while PageSwapCache.
>
> Also removed optimization of an unlikely path in shmem_getpage_gfp(),
> now that we need to check PageSwapCache more carefully (a racing caller
> might already have made the copy). And at one point shmem_unuse_inode()
> needs to use the hitherto private page_swapcount(), to guard against
> racing with inode eviction.
>
> It would make sense to extend shmem_should_replace_page(), to cover
> cpuset and NUMA mempolicy restrictions too, but set that aside for
> now: needs a cleanup of shmem mempolicy handling, and more testing,
> and ought to handle swap faults in do_swap_page() as well as shmem.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> ---
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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next prev parent reply other threads:[~2012-05-14 9:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-12 11:52 [PATCH 0/10] shmem/tmpfs: misc and fallocate Hugh Dickins
2012-05-12 11:59 ` [PATCH 1/10] shmem: replace page if mapping excludes its zone Hugh Dickins
2012-05-14 8:55 ` Cong Wang
2012-05-14 19:42 ` Hugh Dickins
2012-05-15 9:44 ` Cong Wang
2012-05-14 9:06 ` KAMEZAWA Hiroyuki [this message]
2012-05-14 23:13 ` Andrew Morton
2012-05-15 4:07 ` Hugh Dickins
2012-05-19 1:41 ` Hugh Dickins
2012-05-19 1:44 ` [PATCH v2 1/10] shmem: substitute " Hugh Dickins
2012-05-12 12:02 ` [PATCH 2/10] tmpfs: enable NOSEC optimization Hugh Dickins
2012-05-14 9:35 ` Cong Wang
2012-05-14 19:48 ` Hugh Dickins
2012-05-12 12:04 ` [PATCH 3/10] tmpfs: optimize clearing when writing Hugh Dickins
2012-05-15 8:51 ` Nick Piggin
2012-05-12 12:05 ` [PATCH 4/10] tmpfs: support fallocate FALLOC_FL_PUNCH_HOLE Hugh Dickins
2012-05-12 12:13 ` [PATCH 5/10] mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE Hugh Dickins
2012-05-22 0:08 ` john stultz
2012-05-22 15:11 ` Hugh Dickins
2012-05-12 12:15 ` [PATCH 6/10] mm/fs: remove truncate_range Hugh Dickins
2012-05-12 12:17 ` [PATCH 7/10] tmpfs: support fallocate preallocation Hugh Dickins
2012-05-12 12:19 ` [PATCH 8/10] tmpfs: undo fallocation on failure Hugh Dickins
2012-05-12 12:21 ` [PATCH 9/10] tmpfs: quit when fallocate fills memory Hugh Dickins
2012-05-12 12:27 ` [PATCH 10/10] tmpfs: support SEEK_DATA and SEEK_HOLE Hugh Dickins
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