linux/drivers/firewire
Mel Gorman d0164adc89 mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-06 17:50:42 -08:00
..
core-card.c IEEE 1394 (FireWire) subsystem updates post v3.4: 2012-05-24 12:57:47 -07:00
core-cdev.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
core-device.c firewire: core: document fw_csr_string's truncation of long strings 2014-12-10 20:53:02 +01:00
core-iso.c firewire: core: fix multichannel IR with buffers larger than 2 GB 2012-06-17 19:35:26 +02:00
core-topology.c Remove all #inclusions of asm/system.h 2012-03-28 18:30:03 +01:00
core-transaction.c firewire: core: use correct vendor/model IDs 2015-02-02 21:56:03 +01:00
core.h sound updates for 3.16-rc1 2014-06-04 09:08:25 -07:00
init_ohci1394_dma.c various: Fix spelling of "asynchronous" in comments. 2012-11-19 14:32:13 +01:00
Kconfig firewire: IEEE 1394 (FireWire) support should depend on HAS_DMA 2014-07-13 20:53:25 +02:00
Makefile ieee1394: move init_ohci1394_dma to drivers/firewire/ 2010-10-11 14:48:03 +02:00
net.c net: Kill dev_rebuild_header 2015-03-02 16:43:41 -05:00
nosy-user.h firewire: nosy: endianess fixes and annotations 2010-07-27 11:04:11 +02:00
nosy.c firewire: remove use of __devinitdata 2012-11-28 12:40:42 -08:00
nosy.h firewire: nosy: misc cleanups 2010-07-27 11:04:10 +02:00
ohci.c firewire: ohci: Remove unused function 2015-01-22 11:08:52 +01:00
ohci.h firewire: ohci: fix TI TSB82AA2 regression since 2.6.35 2010-10-17 14:09:12 +02:00
sbp2.c scsi: Do not set cmd_per_lun to 1 in the host template 2015-05-31 18:06:28 -07:00