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
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
Pull md updates from NeilBrown.
* 'for-next' of git://neil.brown.name/md:
DM RAID: Add support for MD RAID10
md/RAID1: Add missing case for attempting to repair known bad blocks.
md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE.
md/raid1: don't abort a resync on the first badblock.
md: remove duplicated test on ->openers when calling do_md_stop()
raid5: Add R5_ReadNoMerge flag which prevent bio from merging at block layer
md/raid1: prevent merging too large request
md/raid1: read balance chooses idlest disk for SSD
md/raid1: make sequential read detection per disk based
MD RAID10: Export md_raid10_congested
MD: Move macros from raid1*.h to raid1*.c
MD RAID1: rename mirror_info structure
MD RAID10: rename mirror_info structure
MD RAID10: Fix compiler warning.
raid5: add a per-stripe lock
raid5: remove unnecessary bitmap write optimization
raid5: lockless access raid5 overrided bi_phys_segments
raid5: reduce chance release_stripe() taking device_lock
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>
__generic_unplug_device() function is removed with commit
7eaceaccab, which forgot to
remove the declaration at meantime. Here remove it.
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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>
Hi,
I'm using the old-fashioned 'dump' backup tool, and I noticed that it spews the
below warning as of 3.5-rc1 and later (3.4 is fine):
[ 10.886893] ------------[ cut here ]------------
[ 10.886904] WARNING: at include/linux/iocontext.h:140 copy_process+0x1488/0x1560()
[ 10.886905] Hardware name: Bochs
[ 10.886906] Modules linked in:
[ 10.886908] Pid: 2430, comm: dump Not tainted 3.5.0-rc7+ #27
[ 10.886908] Call Trace:
[ 10.886911] [<ffffffff8107ce8a>] warn_slowpath_common+0x7a/0xb0
[ 10.886912] [<ffffffff8107ced5>] warn_slowpath_null+0x15/0x20
[ 10.886913] [<ffffffff8107c088>] copy_process+0x1488/0x1560
[ 10.886914] [<ffffffff8107c244>] do_fork+0xb4/0x340
[ 10.886918] [<ffffffff8108effa>] ? recalc_sigpending+0x1a/0x50
[ 10.886919] [<ffffffff8108f6b2>] ? __set_task_blocked+0x32/0x80
[ 10.886920] [<ffffffff81091afa>] ? __set_current_blocked+0x3a/0x60
[ 10.886923] [<ffffffff81051db3>] sys_clone+0x23/0x30
[ 10.886925] [<ffffffff8179bd73>] stub_clone+0x13/0x20
[ 10.886927] [<ffffffff8179baa2>] ? system_call_fastpath+0x16/0x1b
[ 10.886928] ---[ end trace 32a14af7ee6a590b ]---
Reproducing is easy, I can hit it on a KVM system with a very basic
config (x86_64 make defconfig + enable the drivers needed). To hit it,
just install dump (on debian/ubuntu, not sure what the package might be
called on Fedora), and:
dump -o -f /tmp/foo /
You'll see the warning in dmesg once it forks off the I/O process and
starts dumping filesystem contents.
I bisected it down to the following commit:
commit f6e8d01bee
Author: Tejun Heo <tj@kernel.org>
Date: Mon Mar 5 13:15:26 2012 -0800
block: add io_context->active_ref
Currently ioc->nr_tasks is used to decide two things - whether an ioc
is done issuing IOs and whether it's shared by multiple tasks. This
patch separate out the first into ioc->active_ref, which is acquired
and released using {get|put}_io_context_active() respectively.
This will be used to associate bio's with a given task. This patch
doesn't introduce any visible behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It seems like the init of ioc->nr_tasks was removed in that patch,
so it starts out at 0 instead of 1.
Tejun, is the right thing here to add back the init, or should something else
be done?
The below patch removes the warning, but I haven't done any more extensive
testing on it.
Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk_set_stacking_limits is intended to allow stacking drivers to build
up the limits of the stacked device based on the underlying devices'
limits. But defaulting 'max_sectors' to BLK_DEF_MAX_SECTORS (1024)
doesn't allow the stacking driver to inherit a max_sectors larger than
1024 -- due to blk_stack_limits' use of min_not_zero.
It is now clear that this artificial limit is getting in the way so
change blk_set_stacking_limits's max_sectors to UINT_MAX (which allows
stacking drivers like dm-multipath to inherit 'max_sectors' from the
underlying paths).
Reported-by: Vijay Chauhan <vijay.chauhan@netapp.com>
Tested-by: Vijay Chauhan <vijay.chauhan@netapp.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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
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
...
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
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
...
Pull final RDMA changes from Roland Dreier:
- Fix IPoIB to stop using unsafe linkage between networking neighbour
layer and private path database.
- Small fixes for bugs found by Fengguang Wu's automated builds.
* tag 'rdma-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
IPoIB: Use a private hash table for path lookup in xmit path
IB/qib: Fix size of cc_supported_table_entries
RDMA/ucma: Convert open-coded equivalent to memdup_user()
RDMA/ocrdma: Fix check of GSI CQs
RDMA/cma: Use PTR_RET rather than if (IS_ERR(...)) + PTR_ERR
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
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
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
...
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>
Warn if memory-hotplug/boot code doesn't initialize pg_data_t with zero
when it is allocated. Arch code and memory hotplug already initiailize
pg_data_t. So this warning should never happen. I select fields randomly
near the beginning, middle and end of pg_data_t for checking.
This patch isn't for performance but for removing initialization code
which is necessary to add whenever we adds new field to pg_data_t or zone.
Firstly, Andrew suggested clearing out of pg_data_t in MM core part but
Tejun doesn't like it because in the future, some archs can initialize
some fields in arch code and pass them into general MM part so blindly
clearing it out in mm core part would be very annoying.
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>
Linus Torvalds
J. Bruce Fields
Jonathan Brassow
NeilBrown
Yuanhan Liu
Vivek Goyal
Olof Johansson
Mike Snitzer
Devendra Naga
Mel Gorman
Nathan Zimmer
Minchan Kim