linux/drivers/iommu
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
..
Kconfig IOMMU Updates for Linux v4.4 2015-11-05 16:12:10 -08:00
Makefile IOMMU Updates for Linux v4.4 2015-11-05 16:12:10 -08:00
amd_iommu.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
amd_iommu_init.c IOMMU Updates for Linux v4.4 2015-11-05 16:12:10 -08:00
amd_iommu_proto.h IOMMU Updates for Linux v4.2 2015-06-23 18:27:19 -07:00
amd_iommu_types.h IOMMU Updates for Linux v4.4 2015-11-05 16:12:10 -08:00
amd_iommu_v2.c iommu/amd: Fix BUG when faulting a PROT_NONE VMA 2015-10-15 16:13:07 +02:00
arm-smmu-v3.c Merge branches 'x86/vt-d', 'arm/omap', 'arm/smmu', 's390', 'core' and 'x86/amd' into next 2015-11-02 20:03:34 +09:00
arm-smmu.c Merge branches 'x86/vt-d', 'arm/omap', 'arm/smmu', 's390', 'core' and 'x86/amd' into next 2015-11-02 20:03:34 +09:00
dma-iommu.c iommu: Implement common IOMMU ops for DMA mapping 2015-10-15 16:41:04 +02:00
dmar.c iommu/vt-d: Generalise DMAR MSI setup to allow for page request events 2015-10-15 13:22:41 +01:00
exynos-iommu.c iommu/exynos: Add callback for initializing devices from device tree 2015-05-29 10:50:08 +02:00
fsl_pamu.c powerpc/fsl: Move fsl_guts.h out of arch/powerpc 2015-10-21 18:05:50 -05:00
fsl_pamu.h iommu/fsl: Various cleanups 2015-02-03 18:47:18 +01:00
fsl_pamu_domain.c iommu/fsl: Convert to device_group call-back 2015-10-22 00:00:49 +02:00
fsl_pamu_domain.h iommu/fsl: Make use of domain_alloc and domain_free 2015-03-31 15:32:14 +02:00
intel-iommu.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
intel-svm.c iommu/vt-d: Fix rwxp flags in SVM device fault callback 2015-10-28 15:14:09 +09:00
intel_irq_remapping.c iommu/vt-d: Fix return value check of parse_ioapics_under_ir() 2015-11-02 19:57:31 +09:00
io-pgtable-arm.c iommu/io-pgtable-arm: Don't use dma_to_phys() 2015-09-22 17:35:33 +01:00
io-pgtable.c iommu/io-pgtable-arm: Move init-fn declarations to io-pgtable.h 2015-08-13 19:51:04 +02:00
io-pgtable.h iommu/io-pgtable-arm: Move init-fn declarations to io-pgtable.h 2015-08-13 19:51:04 +02:00
iommu-sysfs.c iommu: Fix compile error in iommu-sysfs.c 2014-07-07 12:01:21 +02:00
iommu-traces.c iommu: Add iommu_error class event to iommu trace 2013-09-25 11:07:04 +02:00
iommu.c iommu: Move default domain allocation to iommu_group_get_for_dev() 2015-10-22 00:00:49 +02:00
iova.c iommu: Make the iova library a module 2015-07-28 15:48:01 +01:00
ipmmu-vmsa.c iommu/ipmmu-vmsa: Clean up DMA API usage 2015-08-06 14:35:39 +01:00
irq_remapping.c iommu/vt-d: Add a command line parameter for VT-d posted-interrupts 2015-10-01 15:06:54 +02:00
irq_remapping.h iommu, x86: Setup Posted-Interrupts capability for Intel iommu 2015-06-12 11:33:52 +02:00
msm_iommu.c iommu/msm: Use BUG_ON instead of if () BUG() 2015-08-13 19:50:51 +02:00
msm_iommu.h iommu/msm: Move mach includes to iommu directory 2013-08-06 11:18:03 -07:00
msm_iommu_dev.c iommu/msm: Use dev_get_platdata() 2014-11-04 15:03:39 +01:00
msm_iommu_hw-8xxx.h iommu/msm: Move mach includes to iommu directory 2013-08-06 11:18:03 -07:00
of_iommu.c of: iommu: Silence misleading warning 2015-08-03 16:07:49 +02:00
omap-iommu-debug.c fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to void 2015-09-11 15:21:34 -07:00
omap-iommu.c iommu/omap: Add support for configuring dsp iommus on DRA7xx 2015-10-14 14:35:47 +02:00
omap-iommu.h iommu/omap: Add support for configuring dsp iommus on DRA7xx 2015-10-14 14:35:47 +02:00
omap-iopgtable.h iommu/omap: Use BIT(x) macros in omap-iopgtable.h 2015-08-03 16:04:42 +02:00
rockchip-iommu.c Merge branches 'arm/rockchip', 'arm/exynos', 'arm/smmu', 'x86/vt-d', 'x86/amd', 'default-domains' and 'core' into next 2015-06-19 17:17:47 +02:00
s390-iommu.c iommu/s390: Add iommu api for s390 pci devices 2015-10-06 12:20:24 +02:00
shmobile-iommu.c iommu/shmobile: Make use of domain_alloc and domain_free 2015-03-31 15:32:13 +02:00
shmobile-ipmmu.c iommu: drop owner assignment from platform_drivers 2014-10-20 16:20:42 +02:00
shmobile-ipmmu.h iommu/shmobile: Turn the flush_lock mutex into a spinlock 2014-01-07 15:35:25 +01:00
tegra-gart.c Merge branches 'iommu/fixes', 'x86/vt-d', 'x86/amd', 'arm/smmu', 'arm/tegra' and 'core' into next 2015-04-02 13:33:19 +02:00
tegra-smmu.c iommu/tegra-smmu: Parameterize number of TLB lines 2015-08-13 17:05:28 +02:00