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Author SHA1 Message Date
Linus Torvalds
a6dc77254b Merge branch 'dmaengine' of git://git.linaro.org/people/rmk/linux-arm 
Pull ARM DMA engine updates from Russell King:
 "This looks scary at first glance, but what it is is:
   - a rework of the sa11x0 DMA engine driver merged during the previous
     cycle, to extract a common set of helper functions for DMA engine
     implementations.
   - conversion of amba-pl08x.c to use these helper functions.
   - addition of OMAP DMA engine driver (using these helper functions),
     and conversion of some of the OMAP DMA users to use DMA engine.

  Nothing in the helper functions is ARM specific, so I hope that other
  implementations can consolidate some of their code by making use of
  these helpers.

  This has been sitting in linux-next most of the merge cycle, and has
  been tested by several OMAP folk.  I've tested it on sa11x0 platforms,
  and given it my best shot on my broken platforms which have the
  amba-pl08x controller.

  The last point is the addition to feature-removal-schedule.txt, which
  will have a merge conflict.  Between myself and TI, we're planning to
  remove the old TI DMA implementation next year."

Fix up trivial add/add conflicts in Documentation/feature-removal-schedule.txt
and drivers/dma/{Kconfig,Makefile}

* 'dmaengine' of git://git.linaro.org/people/rmk/linux-arm: (53 commits)
  ARM: 7481/1: OMAP2+: omap2plus_defconfig: enable OMAP DMA engine
  ARM: 7464/1: mmc: omap_hsmmc: ensure probe returns error if DMA channel request fails
  Add feature removal of old OMAP private DMA implementation
  mtd: omap2: remove private DMA API implementation
  mtd: omap2: add DMA engine support
  spi: omap2-mcspi: remove private DMA API implementation
  spi: omap2-mcspi: add DMA engine support
  ARM: omap: remove mmc platform data dma_mask and initialization
  mmc: omap: remove private DMA API implementation
  mmc: omap: add DMA engine support
  mmc: omap_hsmmc: remove private DMA API implementation
  mmc: omap_hsmmc: add DMA engine support
  dmaengine: omap: add support for cyclic DMA
  dmaengine: omap: add support for setting fi
  dmaengine: omap: add support for returning residue in tx_state method
  dmaengine: add OMAP DMA engine driver
  dmaengine: sa11x0-dma: add cyclic DMA support
  dmaengine: sa11x0-dma: fix DMA residue support
  dmaengine: PL08x: ensure all descriptors are freed when channel is released
  dmaengine: PL08x: get rid of write only pool_ctr and free_txd locking
  ...
 2012-08-01 16:41:07 -07:00
Linus Torvalds
d4fdc32517 Merge tag 'fbdev-updates-for-3.6' of git://github.com/schandinat/linux-2.6 
Pull fbdev updates from Florian Tobias Schandinat:
 - large updates for OMAP
   - support for LCD3 overlay manager (omap5)
   - omapdss output cleanup
   - removal of passive matrix LCD support as there are no drivers for
     such panels for DSS or DSS2 and nobody complained (cleanup)
 - large updates for SH Mobile
   - overlay support
   - separating MERAM (cache) from framebuffer driver
 - some updates for Exynos and da8xx-fb
 - various other small patches

* tag 'fbdev-updates-for-3.6' of git://github.com/schandinat/linux-2.6: (78 commits)
  da8xx-fb: fix compile issue due to missing include
  fbdev: Make pixel_to_pat() failure mode more friendly
  da8xx-fb: do not turn ON LCD backlight unless LCDC is enabled
  fbdev: sh_mobile_lcdc: Fix vertical panning step
  video: exynos mipi dsi: Fix mipi dsi regulators handling issue
  video: da8xx-fb: do clock reset of revision 2 LCDC before enabling
  arm: da850: configure LCDC fifo threshold
  video: da8xx-fb: configure FIFO threshold to reduce underflow errors
  video: da8xx-fb: fix flicker due to 1 frame delay in updated frame
  video: da8xx-fb rev2: fix disabling of palette completion interrupt
  da8xx-fb: add missing FB_BLANK operations
  video: exynos_dp: use usleep_range instead of delay
  video: exynos_dp: check the only INTERLANE_ALIGN_DONE bit during Link Training
  fb: epson1355fb: Fix section mismatch
  video: exynos_dp: fix wrong DPCD address during Link Training
  video/smscufx: fix line counting in fb_write
  aty128fb: Fix coding style issues
  fbdev: sh_mobile_lcdc: Fix pan offset computation in YUV mode
  fbdev: sh_mobile_lcdc: Fix overlay registers update during pan operation
  fbdev: sh_mobile_lcdc: Support horizontal panning
  ...
 2012-08-01 10:45:12 -07:00
Linus Torvalds
9a51cf28a3 Merge tag 'sound-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound 
Pull sound fixes from Takashi Iwai:
 "A collection of small fixes that have been found recently.  Most of
  the commits are regression fixes in HD-audio and some other random
  drivers."

* tag 'sound-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: snd-usb: fix clock source validity index
  ALSA: hda - Fix mute-LED GPIO initialization for IDT codecs
  ALSA: hda - Add descriptions for missing IDT 92HD83x models
  ALSA: hda - Fix polarity of mute LED on HP Mini 210
  ALSA: es1688 - freeup resources on init failure
  ALSA: hda - Workaround for silent output on VAIO Z with ALC889
  ALSA: hda - Fix WARNING from HDMI/DP parser
  ALSA: hda - Detach from converter at closing in patch_hdmi.c
  ALSA: hda - Fix mute-LED GPIO setup for HP Mini 210
  ALSA: mpu401: Fix missing initialization of irq field
  ALSA: hda - Fix invalid D3 of headphone DAC on VT202x codecs
 2012-08-01 10:42:26 -07:00
Linus Torvalds
a0e881b7c1 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 
Pull second vfs pile from Al Viro:
 "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the
  deadlock reproduced by xfstests 068), symlink and hardlink restriction
  patches, plus assorted cleanups and fixes.

  Note that another fsfreeze deadlock (emergency thaw one) is *not*
  dealt with - the series by Fernando conflicts a lot with Jan's, breaks
  userland ABI (FIFREEZE semantics gets changed) and trades the deadlock
  for massive vfsmount leak; this is going to be handled next cycle.
  There probably will be another pull request, but that stuff won't be
  in it."

Fix up trivial conflicts due to unrelated changes next to each other in
drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c}

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
  delousing target_core_file a bit
  Documentation: Correct s_umount state for freeze_fs/unfreeze_fs
  fs: Remove old freezing mechanism
  ext2: Implement freezing
  btrfs: Convert to new freezing mechanism
  nilfs2: Convert to new freezing mechanism
  ntfs: Convert to new freezing mechanism
  fuse: Convert to new freezing mechanism
  gfs2: Convert to new freezing mechanism
  ocfs2: Convert to new freezing mechanism
  xfs: Convert to new freezing code
  ext4: Convert to new freezing mechanism
  fs: Protect write paths by sb_start_write - sb_end_write
  fs: Skip atime update on frozen filesystem
  fs: Add freezing handling to mnt_want_write() / mnt_drop_write()
  fs: Improve filesystem freezing handling
  switch the protection of percpu_counter list to spinlock
  nfsd: Push mnt_want_write() outside of i_mutex
  btrfs: Push mnt_want_write() outside of i_mutex
  fat: Push mnt_want_write() outside of i_mutex
  ...
 2012-08-01 10:26:23 -07:00
Linus Torvalds
eff0d13f38 Merge branch 'for-3.6/drivers' of git://git.kernel.dk/linux-block 
Pull block driver changes from Jens Axboe:

 - Making the plugging support for drivers a bit more sane from Neil.
   This supersedes the plugging change from Shaohua as well.

 - The usual round of drbd updates.

 - Using a tail add instead of a head add in the request completion for
   ndb, making us find the most completed request more quickly.

 - A few floppy changes, getting rid of a duplicated flag and also
   running the floppy init async (since it takes forever in boot terms)
   from Andi.

* 'for-3.6/drivers' of git://git.kernel.dk/linux-block:
  floppy: remove duplicated flag FD_RAW_NEED_DISK
  blk: pass from_schedule to non-request unplug functions.
  block: stack unplug
  blk: centralize non-request unplug handling.
  md: remove plug_cnt feature of plugging.
  block/nbd: micro-optimization in nbd request completion
  drbd: announce FLUSH/FUA capability to upper layers
  drbd: fix max_bio_size to be unsigned
  drbd: flush drbd work queue before invalidate/invalidate remote
  drbd: fix potential access after free
  drbd: call local-io-error handler early
  drbd: do not reset rs_pending_cnt too early
  drbd: reset congestion information before reporting it in /proc/drbd
  drbd: report congestion if we are waiting for some userland callback
  drbd: differentiate between normal and forced detach
  drbd: cleanup, remove two unused global flags
  floppy: Run floppy initialization asynchronous
 2012-08-01 09:06:47 -07:00
Linus Torvalds
8cf1a3fce0 Merge branch 'for-3.6/core' of git://git.kernel.dk/linux-block 
Pull core block IO bits from Jens Axboe:
 "The most complicated part if this is the request allocation rework by
  Tejun, which has been queued up for a long time and has been in
  for-next ditto as well.

  There are a few commits from yesterday and today, mostly trivial and
  obvious fixes.  So I'm pretty confident that it is sound.  It's also
  smaller than usual."

* 'for-3.6/core' of git://git.kernel.dk/linux-block:
  block: remove dead func declaration
  block: add partition resize function to blkpg ioctl
  block: uninitialized ioc->nr_tasks triggers WARN_ON
  block: do not artificially constrain max_sectors for stacking drivers
  blkcg: implement per-blkg request allocation
  block: prepare for multiple request_lists
  block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv
  blkcg: inline bio_blkcg() and friends
  block: allocate io_context upfront
  block: refactor get_request[_wait]()
  block: drop custom queue draining used by scsi_transport_{iscsi|fc}
  mempool: add @gfp_mask to mempool_create_node()
  blkcg: make root blkcg allocation use %GFP_KERNEL
  blkcg: __blkg_lookup_create() doesn't need radix preload
 2012-08-01 09:02:41 -07:00
J. Bruce Fields
068535f1fe locks: remove unused lm_release_private 
In commit 3b6e2723f3 ("locks: prevent side-effects of
locks_release_private before file_lock is initialized") we removed the
last user of lm_release_private without removing the field itself.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-08-01 09:01:46 -07:00
Vivek Goyal
c83f6bf98d block: add partition resize function to blkpg ioctl 
Add a new operation code (BLKPG_RESIZE_PARTITION) to the BLKPG ioctl that
allows altering the size of an existing partition, even if it is currently
in use.

This patch converts hd_struct->nr_sects into sequence counter because
One might extend a partition while IO is happening to it and update of
nr_sects can be non-atomic on 32bit machines with 64bit sector_t. This
can lead to issues like reading inconsistent size of a partition. Sequence
counter have been used so that readers don't have to take bdev mutex lock
as we call sector_in_part() very frequently.

Now all the access to hd_struct->nr_sects should happen using sequence
counter read/update helper functions part_nr_sects_read/part_nr_sects_write.
There is one exception though, set_capacity()/get_capacity(). I think
theoritically race should exist there too but this patch does not
modify set_capacity()/get_capacity() due to sheer number of call sites
and I am afraid that change might break something. I have left that as a
TODO item. We can handle it later if need be. This patch does not introduce
any new races as such w.r.t set_capacity()/get_capacity().

v2: Add CONFIG_LBDAF test to UP preempt case as suggested by Phillip.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Phillip Susi <psusi@ubuntu.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
 2012-08-01 12:24:18 +02:00
Linus Torvalds
2d53492620 Merge tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6 
Pull irqdomain changes from Grant Likely:
 "Round of refactoring and enhancements to irq_domain infrastructure.
  This series starts the process of simplifying irqdomain.  The ultimate
  goal is to merge LEGACY, LINEAR and TREE mappings into a single
  system, but had to back off from that after some last minute bugs.
  Instead it mainly reorganizes the code and ensures that the reverse
  map gets populated when the irq is mapped instead of the first time it
  is looked up.

  Merging of the irq_domain types is deferred to v3.7

  In other news, this series adds helpers for creating static mappings
  on a linear or tree mapping."

* tag 'irqdomain-for-linus' of git://git.secretlab.ca/git/linux-2.6:
  irqdomain: Improve diagnostics when a domain mapping fails
  irqdomain: eliminate slow-path revmap lookups
  irqdomain: Fix irq_create_direct_mapping() to test irq_domain type.
  irqdomain: Eliminate dedicated radix lookup functions
  irqdomain: Support for static IRQ mapping and association.
  irqdomain: Always update revmap when setting up a virq
  irqdomain: Split disassociating code into separate function
  irq_domain: correct a minor wrong comment for linear revmap
  irq_domain: Standardise legacy/linear domain selection
  irqdomain: Make ops->map hook optional
  irqdomain: Remove unnecessary test for IRQ_DOMAIN_MAP_LEGACY
  irqdomain: Simple NUMA awareness.
  devicetree: add helper inline for retrieving a node's full name
 2012-07-31 20:44:03 -07:00
Linus Torvalds
ac694dbdbc Merge branch 'akpm' (Andrew's patch-bomb) 
Merge Andrew's second set of patches:
 - MM
 - a few random fixes
 - a couple of RTC leftovers

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (120 commits)
  rtc/rtc-88pm80x: remove unneed devm_kfree
  rtc/rtc-88pm80x: assign ret only when rtc_register_driver fails
  mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables
  tmpfs: distribute interleave better across nodes
  mm: remove redundant initialization
  mm: warn if pg_data_t isn't initialized with zero
  mips: zero out pg_data_t when it's allocated
  memcg: gix memory accounting scalability in shrink_page_list
  mm/sparse: remove index_init_lock
  mm/sparse: more checks on mem_section number
  mm/sparse: optimize sparse_index_alloc
  memcg: add mem_cgroup_from_css() helper
  memcg: further prevent OOM with too many dirty pages
  memcg: prevent OOM with too many dirty pages
  mm: mmu_notifier: fix freed page still mapped in secondary MMU
  mm: memcg: only check anon swapin page charges for swap cache
  mm: memcg: only check swap cache pages for repeated charging
  mm: memcg: split swapin charge function into private and public part
  mm: memcg: remove needless !mm fixup to init_mm when charging
  mm: memcg: remove unneeded shmem charge type
  ...
 2012-07-31 19:25:39 -07:00
Linus Torvalds
a40a1d3d0a Merge tag 'vfio-for-v3.6' of git://github.com/awilliam/linux-vfio 
Pull VFIO core from Alex Williamson:
 "This series includes the VFIO userspace driver interface for the 3.6
  kernel merge window.  This driver is intended to provide a secure
  interface for device access using IOMMU protection for applications
  like assignment of physical devices to virtual machines.

  Qemu will be the first user of this interface, enabling assignment of
  PCI devices to Qemu guests.  This interface is intended to eventually
  replace the x86-specific assignment mechanism currently available in
  KVM.

  This interface has the advantage of being more secure, by working with
  IOMMU groups to ensure device isolation and providing it's own
  filtered resource access mechanism, and also more flexible, in not
  being x86 or KVM specific (extensions to enable POWER are already
  working).

  This driver is originally the work of Tom Lyon, but has since been
  handed over to me and gone through a complete overhaul thanks to the
  input from David Gibson, Ben Herrenschmidt, Chris Wright, Joerg
  Roedel, and others.  This driver has been available in linux-next for
  the last month."

Paul Mackerras says:
 "I would be glad to see it go in since we want to use it with KVM on
  PowerPC.  If possible we'd like the PowerPC bits for it to go in as
  well."

* tag 'vfio-for-v3.6' of git://github.com/awilliam/linux-vfio:
  vfio: Add PCI device driver
  vfio: Type1 IOMMU implementation
  vfio: Add documentation
  vfio: VFIO core
 2012-07-31 19:17:27 -07:00
Linus Torvalds
3e9a97082f Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random 
Pull random subsystem patches from Ted Ts'o:
 "This patch series contains a major revamp of how we collect entropy
  from interrupts for /dev/random and /dev/urandom.

  The goal is to addresses weaknesses discussed in the paper "Mining
  your Ps and Qs: Detection of Widespread Weak Keys in Network Devices",
  by Nadia Heninger, Zakir Durumeric, Eric Wustrow, J.  Alex Halderman,
  which will be published in the Proceedings of the 21st Usenix Security
  Symposium, August 2012.  (See https://factorable.net for more
  information and an extended version of the paper.)"

Fix up trivial conflicts due to nearby changes in
drivers/{mfd/ab3100-core.c, usb/gadget/omap_udc.c}

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random: (33 commits)
  random: mix in architectural randomness in extract_buf()
  dmi: Feed DMI table to /dev/random driver
  random: Add comment to random_initialize()
  random: final removal of IRQF_SAMPLE_RANDOM
  um: remove IRQF_SAMPLE_RANDOM which is now a no-op
  sparc/ldc: remove IRQF_SAMPLE_RANDOM which is now a no-op
  [ARM] pxa: remove IRQF_SAMPLE_RANDOM which is now a no-op
  board-palmz71: remove IRQF_SAMPLE_RANDOM which is now a no-op
  isp1301_omap: remove IRQF_SAMPLE_RANDOM which is now a no-op
  pxa25x_udc: remove IRQF_SAMPLE_RANDOM which is now a no-op
  omap_udc: remove IRQF_SAMPLE_RANDOM which is now a no-op
  goku_udc: remove IRQF_SAMPLE_RANDOM which was commented out
  uartlite: remove IRQF_SAMPLE_RANDOM which is now a no-op
  drivers: hv: remove IRQF_SAMPLE_RANDOM which is now a no-op
  xen-blkfront: remove IRQF_SAMPLE_RANDOM which is now a no-op
  n2_crypto: remove IRQF_SAMPLE_RANDOM which is now a no-op
  pda_power: remove IRQF_SAMPLE_RANDOM which is now a no-op
  i2c-pmcmsp: remove IRQF_SAMPLE_RANDOM which is now a no-op
  input/serio/hp_sdc.c: remove IRQF_SAMPLE_RANDOM which is now a no-op
  mfd: remove IRQF_SAMPLE_RANDOM which is now a no-op
  ...
 2012-07-31 19:07:42 -07:00
Linus Torvalds
8762541f06 Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 
Pull second set of media updates from Mauro Carvalho Chehab:

 - radio API: add support to work with radio frequency bands

 - new AM/FM radio drivers: radio-shark, radio-shark2

 - new Remote Controller USB driver: iguanair

 - conversion of several drivers to the v4l2 core control framework

 - new board additions at existing drivers

 - the remaining (and vast majority of the patches) are due to
   drivers/DocBook fixes/cleanups.

* 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (154 commits)
  [media] radio-tea5777: use library for 64bits div
  [media] tlg2300: Declare MODULE_FIRMWARE usage
  [media] lgs8gxx: Declare MODULE_FIRMWARE usage
  [media] xc5000: Add MODULE_FIRMWARE statements
  [media] s2255drv: Add MODULE_FIRMWARE statement
  [media] dib8000: move dereference after check for NULL
  [media] Documentation: Update cardlists
  [media] bttv: add support for Aposonic W-DVR
  [media] cx25821: Remove bad strcpy to read-only char*
  [media] pms.c: remove duplicated include
  [media] smiapp-core.c: remove duplicated include
  [media] via-camera: pass correct format settings to sensor
  [media] rtl2832.c: minor cleanup
  [media] Add support for the IguanaWorks USB IR Transceiver
  [media] Minor cleanups for MCE USB
  [media] drivers/media/dvb/siano/smscoreapi.c: use list_for_each_entry
  [media] Use a named union in struct v4l2_ioctl_info
  [media] mceusb: Add Twisted Melon USB IDs
  [media] staging/media/solo6x10: use module_pci_driver macro
  [media] staging/media/dt3155v4l: use module_pci_driver macro
  ...

Conflicts:
	Documentation/feature-removal-schedule.txt
 2012-07-31 18:47:44 -07:00
Linus Torvalds
6dbb35b0a7 Merge tag 'nfs-for-3.6-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs 
Pull second wave of NFS client updates from Trond Myklebust:

 - Patches from Bryan to allow splitting of the NFSv2/v3/v4 code into
   separate modules.

 - Fix Oopses in the NFSv4 idmapper

 - Fix a deadlock whereby rpciod tries to allocate a new socket and ends
   up recursing into the NFS code due to memory reclaim.

 - Increase the number of permitted callback connections.

* tag 'nfs-for-3.6-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: explicitly reject LOCK_MAND flock() requests
  nfs: increase number of permitted callback connections.
  SUNRPC: return negative value in case rpcbind client creation error
  NFS: Convert v4 into a module
  NFS: Convert v3 into a module
  NFS: Convert v2 into a module
  NFS: Keep module parameters in the generic NFS client
  NFS: Split out remaining NFS v4 inode functions
  NFS: Pass super operations and xattr handlers in the nfs_subversion
  NFS: Only initialize the ACL client in the v3 case
  NFS: Create a try_mount rpc op
  NFS: Remove the NFS v4 xdev mount function
  NFS: Add version registering framework
  NFS: Fix a number of bugs in the idmapper
  nfs: skip commit in releasepage if we're freeing memory for fs-related reasons
  sunrpc: clarify comments on rpc_make_runnable
  pnfsblock: bail out partial page IO
 2012-07-31 18:45:44 -07:00
Linus Torvalds
fd37ce34bd Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 
Pull networking update from David S. Miller:
 "I think Eric Dumazet and I have dealt with all of the known routing
  cache removal fallout.  Some other minor fixes all around.

  1) Fix RCU of cached routes, particular of output routes which require
     liberation via call_rcu() instead of call_rcu_bh().  From Eric
     Dumazet.

  2) Make sure we purge net device references in cached routes properly.

  3) TG3 driver bug fixes from Michael Chan.

  4) Fix reported 'expires' value in ipv6 routes, from Li Wei.

  5) TUN driver ioctl leaks kernel bytes to userspace, from Mathias
     Krause."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (22 commits)
  ipv4: Properly purge netdev references on uncached routes.
  ipv4: Cache routes in nexthop exception entries.
  ipv4: percpu nh_rth_output cache
  ipv4: Restore old dst_free() behavior.
  bridge: make port attributes const
  ipv4: remove rt_cache_rebuild_count
  net: ipv4: fix RCU races on dst refcounts
  net: TCP early demux cleanup
  tun: Fix formatting.
  net/tun: fix ioctl() based info leaks
  tg3: Update version to 3.124
  tg3: Fix race condition in tg3_get_stats64()
  tg3: Add New 5719 Read DMA workaround
  tg3: Fix Read DMA workaround for 5719 A0.
  tg3: Request APE_LOCK_PHY before PHY access
  ipv6: fix incorrect route 'expires' value passed to userspace
  mISDN: Bugfix only few bytes are transfered on a connection
  seeq: use PTR_RET at init_module of driver
  bnx2x: remove cast around the kmalloc in bnx2x_prev_mark_path
  ipv4: clean up put_child
  ...
 2012-07-31 18:43:13 -07:00
Mel Gorman
d833352a43 mm: hugetlbfs: close race during teardown of hugetlbfs shared page tables 
If a process creates a large hugetlbfs mapping that is eligible for page
table sharing and forks heavily with children some of whom fault and
others which destroy the mapping then it is possible for page tables to
get corrupted.  Some teardowns of the mapping encounter a "bad pmd" and
output a message to the kernel log.  The final teardown will trigger a
BUG_ON in mm/filemap.c.

This was reproduced in 3.4 but is known to have existed for a long time
and goes back at least as far as 2.6.37.  It was probably was introduced
in 2.6.20 by [39dde65c: shared page table for hugetlb page].  The messages
look like this;

[  ..........] Lots of bad pmd messages followed by this
[  127.164256] mm/memory.c:391: bad pmd ffff880412e04fe8(80000003de4000e7).
[  127.164257] mm/memory.c:391: bad pmd ffff880412e04ff0(80000003de6000e7).
[  127.164258] mm/memory.c:391: bad pmd ffff880412e04ff8(80000003de0000e7).
[  127.186778] ------------[ cut here ]------------
[  127.186781] kernel BUG at mm/filemap.c:134!
[  127.186782] invalid opcode: 0000 [#1] SMP
[  127.186783] CPU 7
[  127.186784] Modules linked in: af_packet cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd dm_mod coretemp crc32c_intel usb_storage ghash_clmulni_intel aesni_intel i2c_i801 r8169 mii uas sr_mod cdrom sg iTCO_wdt iTCO_vendor_support shpchp serio_raw cryptd aes_x86_64 e1000e pci_hotplug dcdbas aes_generic container microcode ext4 mbcache jbd2 crc16 sd_mod crc_t10dif i915 drm_kms_helper drm i2c_algo_bit ehci_hcd ahci libahci usbcore rtc_cmos usb_common button i2c_core intel_agp video intel_gtt fan processor thermal thermal_sys hwmon ata_generic pata_atiixp libata scsi_mod
[  127.186801]
[  127.186802] Pid: 9017, comm: hugetlbfs-test Not tainted 3.4.0-autobuild #53 Dell Inc. OptiPlex 990/06D7TR
[  127.186804] RIP: 0010:[<ffffffff810ed6ce>]  [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160
[  127.186809] RSP: 0000:ffff8804144b5c08  EFLAGS: 00010002
[  127.186810] RAX: 0000000000000001 RBX: ffffea000a5c9000 RCX: 00000000ffffffc0
[  127.186811] RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffff88042dfdad00
[  127.186812] RBP: ffff8804144b5c18 R08: 0000000000000009 R09: 0000000000000003
[  127.186813] R10: 0000000000000000 R11: 000000000000002d R12: ffff880412ff83d8
[  127.186814] R13: ffff880412ff83d8 R14: 0000000000000000 R15: ffff880412ff83d8
[  127.186815] FS:  00007fe18ed2c700(0000) GS:ffff88042dce0000(0000) knlGS:0000000000000000
[  127.186816] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  127.186817] CR2: 00007fe340000503 CR3: 0000000417a14000 CR4: 00000000000407e0
[  127.186818] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  127.186819] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  127.186820] Process hugetlbfs-test (pid: 9017, threadinfo ffff8804144b4000, task ffff880417f803c0)
[  127.186821] Stack:
[  127.186822]  ffffea000a5c9000 0000000000000000 ffff8804144b5c48 ffffffff810ed83b
[  127.186824]  ffff8804144b5c48 000000000000138a 0000000000001387 ffff8804144b5c98
[  127.186825]  ffff8804144b5d48 ffffffff811bc925 ffff8804144b5cb8 0000000000000000
[  127.186827] Call Trace:
[  127.186829]  [<ffffffff810ed83b>] delete_from_page_cache+0x3b/0x80
[  127.186832]  [<ffffffff811bc925>] truncate_hugepages+0x115/0x220
[  127.186834]  [<ffffffff811bca43>] hugetlbfs_evict_inode+0x13/0x30
[  127.186837]  [<ffffffff811655c7>] evict+0xa7/0x1b0
[  127.186839]  [<ffffffff811657a3>] iput_final+0xd3/0x1f0
[  127.186840]  [<ffffffff811658f9>] iput+0x39/0x50
[  127.186842]  [<ffffffff81162708>] d_kill+0xf8/0x130
[  127.186843]  [<ffffffff81162812>] dput+0xd2/0x1a0
[  127.186845]  [<ffffffff8114e2d0>] __fput+0x170/0x230
[  127.186848]  [<ffffffff81236e0e>] ? rb_erase+0xce/0x150
[  127.186849]  [<ffffffff8114e3ad>] fput+0x1d/0x30
[  127.186851]  [<ffffffff81117db7>] remove_vma+0x37/0x80
[  127.186853]  [<ffffffff81119182>] do_munmap+0x2d2/0x360
[  127.186855]  [<ffffffff811cc639>] sys_shmdt+0xc9/0x170
[  127.186857]  [<ffffffff81410a39>] system_call_fastpath+0x16/0x1b
[  127.186858] Code: 0f 1f 44 00 00 48 8b 43 08 48 8b 00 48 8b 40 28 8b b0 40 03 00 00 85 f6 0f 88 df fe ff ff 48 89 df e8 e7 cb 05 00 e9 d2 fe ff ff <0f> 0b 55 83 e2 fd 48 89 e5 48 83 ec 30 48 89 5d d8 4c 89 65 e0
[  127.186868] RIP  [<ffffffff810ed6ce>] __delete_from_page_cache+0x15e/0x160
[  127.186870]  RSP <ffff8804144b5c08>
[  127.186871] ---[ end trace 7cbac5d1db69f426 ]---

The bug is a race and not always easy to reproduce.  To reproduce it I was
doing the following on a single socket I7-based machine with 16G of RAM.

$ hugeadm --pool-pages-max DEFAULT:13G
$ echo $((18*1048576*1024)) > /proc/sys/kernel/shmmax
$ echo $((18*1048576*1024)) > /proc/sys/kernel/shmall
$ for i in `seq 1 9000`; do ./hugetlbfs-test; done

On my particular machine, it usually triggers within 10 minutes but
enabling debug options can change the timing such that it never hits.
Once the bug is triggered, the machine is in trouble and needs to be
rebooted.  The machine will respond but processes accessing proc like "ps
aux" will hang due to the BUG_ON.  shutdown will also hang and needs a
hard reset or a sysrq-b.

The basic problem is a race between page table sharing and teardown.  For
the most part page table sharing depends on i_mmap_mutex.  In some cases,
it is also taking the mm->page_table_lock for the PTE updates but with
shared page tables, it is the i_mmap_mutex that is more important.

Unfortunately it appears to be also insufficient. Consider the following
situation

Process A					Process B
---------					---------
hugetlb_fault					shmdt
  						LockWrite(mmap_sem)
    						  do_munmap
						    unmap_region
						      unmap_vmas
						        unmap_single_vma
						          unmap_hugepage_range
      						            Lock(i_mmap_mutex)
							    Lock(mm->page_table_lock)
							    huge_pmd_unshare/unmap tables <--- (1)
							    Unlock(mm->page_table_lock)
      						            Unlock(i_mmap_mutex)
  huge_pte_alloc				      ...
    Lock(i_mmap_mutex)				      ...
    vma_prio_walk, find svma, spte		      ...
    Lock(mm->page_table_lock)			      ...
    share spte					      ...
    Unlock(mm->page_table_lock)			      ...
    Unlock(i_mmap_mutex)			      ...
  hugetlb_no_page									  <--- (2)
						      free_pgtables
						        unlink_file_vma
							hugetlb_free_pgd_range
						    remove_vma_list

In this scenario, it is possible for Process A to share page tables with
Process B that is trying to tear them down.  The i_mmap_mutex on its own
does not prevent Process A walking Process B's page tables.  At (1) above,
the page tables are not shared yet so it unmaps the PMDs.  Process A sets
up page table sharing and at (2) faults a new entry.  Process B then trips
up on it in free_pgtables.

This patch fixes the problem by adding a new function
__unmap_hugepage_range_final that is only called when the VMA is about to
be destroyed.  This function clears VM_MAYSHARE during
unmap_hugepage_range() under the i_mmap_mutex.  This makes the VMA
ineligible for sharing and avoids the race.  Superficially this looks like
it would then be vunerable to truncate and madvise issues but hugetlbfs
has its own truncate handlers so does not use unmap_mapping_range() and
does not support madvise(DONTNEED).

This should be treated as a -stable candidate if it is merged.

Test program is as follows. The test case was mostly written by Michal
Hocko with a few minor changes to reproduce this bug.

==== CUT HERE ====

static size_t huge_page_size = (2UL << 20);
static size_t nr_huge_page_A = 512;
static size_t nr_huge_page_B = 5632;

unsigned int get_random(unsigned int max)
{
	struct timeval tv;

	gettimeofday(&tv, NULL);
	srandom(tv.tv_usec);
	return random() % max;
}

static void play(void *addr, size_t size)
{
	unsigned char *start = addr,
		      *end = start + size,
		      *a;
	start += get_random(size/2);

	/* we could itterate on huge pages but let's give it more time. */
	for (a = start; a < end; a += 4096)
		*a = 0;
}

int main(int argc, char **argv)
{
	key_t key = IPC_PRIVATE;
	size_t sizeA = nr_huge_page_A * huge_page_size;
	size_t sizeB = nr_huge_page_B * huge_page_size;
	int shmidA, shmidB;
	void *addrA = NULL, *addrB = NULL;
	int nr_children = 300, n = 0;

	if ((shmidA = shmget(key, sizeA, IPC_CREAT|SHM_HUGETLB|0660)) == -1) {
		perror("shmget:");
		return 1;
	}

	if ((addrA = shmat(shmidA, addrA, SHM_R|SHM_W)) == (void *)-1UL) {
		perror("shmat");
		return 1;
	}
	if ((shmidB = shmget(key, sizeB, IPC_CREAT|SHM_HUGETLB|0660)) == -1) {
		perror("shmget:");
		return 1;
	}

	if ((addrB = shmat(shmidB, addrB, SHM_R|SHM_W)) == (void *)-1UL) {
		perror("shmat");
		return 1;
	}

fork_child:
	switch(fork()) {
		case 0:
			switch (n%3) {
			case 0:
				play(addrA, sizeA);
				break;
			case 1:
				play(addrB, sizeB);
				break;
			case 2:
				break;
			}
			break;
		case -1:
			perror("fork:");
			break;
		default:
			if (++n < nr_children)
				goto fork_child;
			play(addrA, sizeA);
			break;
	}
	shmdt(addrA);
	shmdt(addrB);
	do {
		wait(NULL);
	} while (--n > 0);
	shmctl(shmidA, IPC_RMID, NULL);
	shmctl(shmidB, IPC_RMID, NULL);
	return 0;
}

[akpm@linux-foundation.org: name the declaration's args, fix CONFIG_HUGETLBFS=n build]
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:50 -07:00
Minchan Kim
6527af5d1b mm: remove redundant initialization 
pg_data_t is zeroed before reaching free_area_init_core(), so remove the
now unnecessary initializations.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:50 -07:00
Johannes Weiner
0030f535a5 mm: memcg: fix compaction/migration failing due to memcg limits 
Compaction (and page migration in general) can currently be hindered
through pages being owned by memory cgroups that are at their limits and
unreclaimable.

The reason is that the replacement page is being charged against the limit
while the page being replaced is also still charged.  But this seems
unnecessary, given that only one of the two pages will still be in use
after migration finishes.

This patch changes the memcg migration sequence so that the replacement
page is not charged.  Whatever page is still in use after successful or
failed migration gets to keep the charge of the page that was going to be
replaced.

The replacement page will still show up temporarily in the rss/cache
statistics, this can be fixed in a later patch as it's less urgent.

Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wanpeng Li <liwp.linux@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:48 -07:00
Mel Gorman
a564b8f039 nfs: enable swap on NFS 
Implement the new swapfile a_ops for NFS and hook up ->direct_IO.  This
will set the NFS socket to SOCK_MEMALLOC and run socket reconnect under
PF_MEMALLOC as well as reset SOCK_MEMALLOC before engaging the protocol
->connect() method.

PF_MEMALLOC should allow the allocation of struct socket and related
objects and the early (re)setting of SOCK_MEMALLOC should allow us to
receive the packets required for the TCP connection buildup.

[jlayton@redhat.com: Restore PF_MEMALLOC task flags in all cases]
[dfeng@redhat.com: Fix handling of multiple swap files]
[a.p.zijlstra@chello.nl: Original patch]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:48 -07:00
Mel Gorman
5a178119b0 mm: add support for direct_IO to highmem pages 
The patch "mm: add support for a filesystem to activate swap files and use
direct_IO for writing swap pages" added support for using direct_IO to
write swap pages but it is insufficient for highmem pages.

To support highmem pages, this patch kmaps() the page before calling the
direct_IO() handler.  As direct_IO deals with virtual addresses an
additional helper is necessary for get_kernel_pages() to lookup the struct
page for a kmap virtual address.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00
Mel Gorman
a509bc1a9e mm: swap: implement generic handler for swap_activate 
The version of swap_activate introduced is sufficient for swap-over-NFS
but would not provide enough information to implement a generic handler.
This patch shuffles things slightly to ensure the same information is
available for aops->swap_activate() as is available to the core.

No functionality change.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00
Mel Gorman
62c230bc17 mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages 
Currently swapfiles are managed entirely by the core VM by using ->bmap to
allocate space and write to the blocks directly.  This effectively ensures
that the underlying blocks are allocated and avoids the need for the swap
subsystem to locate what physical blocks store offsets within a file.

If the swap subsystem is to use the filesystem information to locate the
blocks, it is critical that information such as block groups, block
bitmaps and the block descriptor table that map the swap file were
resident in memory.  This patch adds address_space_operations that the VM
can call when activating or deactivating swap backed by a file.

  int swap_activate(struct file *);
  int swap_deactivate(struct file *);

The ->swap_activate() method is used to communicate to the file that the
VM relies on it, and the address_space should take adequate measures such
as reserving space in the underlying device, reserving memory for mempools
and pinning information such as the block descriptor table in memory.  The
->swap_deactivate() method is called on sys_swapoff() if ->swap_activate()
returned success.

After a successful swapfile ->swap_activate, the swapfile is marked
SWP_FILE and swapper_space.a_ops will proxy to
sis->swap_file->f_mappings->a_ops using ->direct_io to write swapcache
pages and ->readpage to read.

It is perfectly possible that direct_IO be used to read the swap pages but
it is an unnecessary complication.  Similarly, it is possible that
->writepage be used instead of direct_io to write the pages but filesystem
developers have stated that calling writepage from the VM is undesirable
for a variety of reasons and using direct_IO opens up the possibility of
writing back batches of swap pages in the future.

[a.p.zijlstra@chello.nl: Original patch]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00
Mel Gorman
18022c5d86 mm: add get_kernel_page[s] for pinning of kernel addresses for I/O 
This patch adds two new APIs get_kernel_pages() and get_kernel_page() that
may be used to pin a vector of kernel addresses for IO.  The initial user
is expected to be NFS for allowing pages to be written to swap using
aops->direct_IO().  Strictly speaking, swap-over-NFS only needs to pin one
page for IO but it makes sense to express the API in terms of a vector and
add a helper for pinning single pages.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Cc: Mark Salter <msalter@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00
Mel Gorman
f981c5950f mm: methods for teaching filesystems about PG_swapcache pages 
In order to teach filesystems to handle swap cache pages, three new page
functions are introduced:

  pgoff_t page_file_index(struct page *);
  loff_t page_file_offset(struct page *);
  struct address_space *page_file_mapping(struct page *);

page_file_index() - gives the offset of this page in the file in
PAGE_CACHE_SIZE blocks.  Like page->index is for mapped pages, this
function also gives the correct index for PG_swapcache pages.

page_file_offset() - uses page_file_index(), so that it will give the
expected result, even for PG_swapcache pages.

page_file_mapping() - gives the mapping backing the actual page; that is
for swap cache pages it will give swap_file->f_mapping.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Neil Brown <neilb@suse.de>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00
Mel Gorman
c76562b670 netvm: prevent a stream-specific deadlock 
This patch series is based on top of "Swap-over-NBD without deadlocking
v15" as it depends on the same reservation of PF_MEMALLOC reserves logic.

When a user or administrator requires swap for their application, they
create a swap partition and file, format it with mkswap and activate it
with swapon.  In diskless systems this is not an option so if swap if
required then swapping over the network is considered.  The two likely
scenarios are when blade servers are used as part of a cluster where the
form factor or maintenance costs do not allow the use of disks and thin
clients.

The Linux Terminal Server Project recommends the use of the Network Block
Device (NBD) for swap but this is not always an option.  There is no
guarantee that the network attached storage (NAS) device is running Linux
or supports NBD.  However, it is likely that it supports NFS so there are
users that want support for swapping over NFS despite any performance
concern.  Some distributions currently carry patches that support swapping
over NFS but it would be preferable to support it in the mainline kernel.

Patch 1 avoids a stream-specific deadlock that potentially affects TCP.

Patch 2 is a small modification to SELinux to avoid using PFMEMALLOC
	reserves.

Patch 3 adds three helpers for filesystems to handle swap cache pages.
	For example, page_file_mapping() returns page->mapping for
	file-backed pages and the address_space of the underlying
	swap file for swap cache pages.

Patch 4 adds two address_space_operations to allow a filesystem
	to pin all metadata relevant to a swapfile in memory. Upon
	successful activation, the swapfile is marked SWP_FILE and
	the address space operation ->direct_IO is used for writing
	and ->readpage for reading in swap pages.

Patch 5 notes that patch 3 is bolting
	filesystem-specific-swapfile-support onto the side and that
	the default handlers have different information to what
	is available to the filesystem. This patch refactors the
	code so that there are generic handlers for each of the new
	address_space operations.

Patch 6 adds an API to allow a vector of kernel addresses to be
	translated to struct pages and pinned for IO.

Patch 7 adds support for using highmem pages for swap by kmapping
	the pages before calling the direct_IO handler.

Patch 8 updates NFS to use the helpers from patch 3 where necessary.

Patch 9 avoids setting PF_private on PG_swapcache pages within NFS.

Patch 10 implements the new swapfile-related address_space operations
	for NFS and teaches the direct IO handler how to manage
	kernel addresses.

Patch 11 prevents page allocator recursions in NFS by using GFP_NOIO
	where appropriate.

Patch 12 fixes a NULL pointer dereference that occurs when using
	swap-over-NFS.

With the patches applied, it is possible to mount a swapfile that is on an
NFS filesystem.  Swap performance is not great with a swap stress test
taking roughly twice as long to complete than if the swap device was
backed by NBD.

This patch: netvm: prevent a stream-specific deadlock

It could happen that all !SOCK_MEMALLOC sockets have buffered so much data
that we're over the global rmem limit.  This will prevent SOCK_MEMALLOC
buffers from receiving data, which will prevent userspace from running,
which is needed to reduce the buffered data.

Fix this by exempting the SOCK_MEMALLOC sockets from the rmem limit.  Once
this change it applied, it is important that sockets that set
SOCK_MEMALLOC do not clear the flag until the socket is being torn down.
If this happens, a warning is generated and the tokens reclaimed to avoid
accounting errors until the bug is fixed.

[davem@davemloft.net: Warning about clearing SOCK_MEMALLOC]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2012-07-31 18:42:47 -07:00