Mel Gorman 8fb74b9fb2 mm: compaction: partially revert capture of suitable high-order page ... Eric Wong reported on 3.7 and 3.8-rc2 that ppoll() got stuck when waiting for POLLIN on a local TCP socket. It was easier to trigger if there was disk IO and dirty pages at the same time and he bisected it to commit 1fb3f8ca0e ("mm: compaction: capture a suitable high-order page immediately when it is made available"). The intention of that patch was to improve high-order allocations under memory pressure after changes made to reclaim in 3.6 drastically hurt THP allocations but the approach was flawed. For Eric, the problem was that page->pfmemalloc was not being cleared for captured pages leading to a poor interaction with swap-over-NFS support causing the packets to be dropped. However, I identified a few more problems with the patch including the fact that it can increase contention on zone->lock in some cases which could result in async direct compaction being aborted early. In retrospect the capture patch took the wrong approach. What it should have done is mark the pageblock being migrated as MIGRATE_ISOLATE if it was allocating for THP and avoided races that way. While the patch was showing to improve allocation success rates at the time, the benefit is marginal given the relative complexity and it should be revisited from scratch in the context of the other reclaim-related changes that have taken place since the patch was first written and tested. This patch partially reverts commit 1fb3f8ca0e ("mm: compaction: capture a suitable high-order page immediately when it is made available"). Reported-and-tested-by: Eric Wong <normalperson@yhbt.net> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2013-01-11 14:54:56 -08:00
..
acpi	PCI changes for the v3.8 merge window:	2012-12-13 12:14:47 -08:00
asm-generic	mm: limit mmu_gather batching to fix soft lockups on !CONFIG_PREEMPT	2013-01-04 16:11:46 -08:00
clocksource
crypto	crypto: cast5/cast6 - move lookup tables to shared module	2012-12-06 17:16:26 +08:00
drm	drm/exynos: change file license to GPL	2013-01-04 15:54:32 +09:00
keys
linux	mm: compaction: partially revert capture of suitable high-order page	2013-01-11 14:54:56 -08:00
math-emu
media	[media] V4L: Add driver for S3C24XX/S3C64XX SoC series camera interface	2012-11-28 09:43:34 -02:00
memory
misc
net	Merge branch 'master' of git://1984.lsi.us.es/nf	2012-12-28 14:28:17 -08:00
pcmcia
ras
rdma	UAPI: Remove empty Kbuild files	2013-01-02 17:36:10 -08:00
rxrpc
scsi	SCSI misc on 20121212	2012-12-13 19:20:31 -08:00
sound	UAPI: Remove empty Kbuild files	2013-01-02 17:36:10 -08:00
target	target/iscsi_target: Add NodeACL tags for initiator group support	2012-12-13 14:18:09 -08:00
trace	Various bug fixes for ext4. Perhaps the most serious bug fixed is one	2013-01-02 09:57:34 -08:00
uapi	linux/audit.h: move ptrace.h include to kernel header	2013-01-11 14:54:56 -08:00
video	Merge branch 'omap-for-v3.8/fixes-for-merge-window' into omap-for-v3.8/fixes-for-merge-window-v2	2012-12-16 11:28:10 -08:00
xen	Bugfixes:	2012-12-18 12:26:54 -08:00
Kbuild	UAPI: Remove empty Kbuild files	2013-01-02 17:36:10 -08:00