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c6ea41fbbe
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Mikulas Patocka c6ea41fbbe dm kcopyd: preallocate sub jobs to avoid deadlock 
There's a possible theoretical deadlock in dm-kcopyd because multiple
allocations from the same mempool are required to finish a request.
Avoid this by preallocating sub jobs.

There is a mempool of 512 entries. Each request requires up to 9
entries from the mempool. If we have at least 57 concurrent requests
running, the mempool may overflow and mempool allocations may start
blocking until another entry is freed to the mempool. Because the same
thread is used to free entries to the mempool and allocate entries from
the mempool, this may result in a deadlock.

This patch changes it so that one mempool entry contains all 9 "struct
kcopyd_job" required to fulfill the whole request. The allocation is
done only once in dm_kcopyd_copy and no further mempool allocations are
done during request processing.

If dm_kcopyd_copy is not run in the completion thread, this
implementation is deadlock-free.

MIN_JOBS needs reducing accordingly and we've chosen to reduce it
further to 8.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-05-29 13:03:00 +01:00
..
accessibility
acpi Merge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging 2011-05-25 16:52:50 -07:00
amba ARM: 6829/1: amba: make hardcoded periphid override hardware 2011-05-26 10:33:34 +01:00
ata Merge branch 'for-2.6.40/core' of git://git.kernel.dk/linux-2.6-block 2011-05-25 09:14:07 -07:00
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2011-05-20 13:43:21 -07:00
auxdisplay
base mm: per-node vmstat: show proper vmstats 2011-05-25 08:39:07 -07:00
bcma drivers/bcma/host_pci.c needs slab.h 2011-05-26 17:12:32 -07:00
block loop: export module parameters 2011-05-27 07:59:25 +02:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6 2011-05-24 13:28:35 -07:00
cdrom Merge commit 'v2.6.39' into for-2.6.40/core 2011-05-20 20:33:15 +02:00
char drivers/char/ppdev.c: put gotten port value 2011-05-26 17:12:37 -07:00
clk
clocksource Merge branch 'sh-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2011-05-23 21:24:07 -07:00
connector
cpufreq cpufreq: make DB8500 cpufreq driver compile 2011-05-24 22:20:14 +02:00
cpuidle
crypto [S390] ap: skip device registration on type probe failure 2011-05-23 10:24:29 +02:00
dca
dio
dma Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2011-05-28 12:35:15 -07:00
edac edac,rcu: use synchronize_rcu() instead of call_rcu()+rcu_barrier() 2011-05-26 17:12:37 -07:00
eisa
firewire
firmware Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-05-23 09:12:26 -07:00
gpio Merge branch 'gpio/next' of git://git.secretlab.ca/git/linux-2.6 2011-05-28 10:56:34 -07:00
gpu vmscan: change shrinker API by passing shrink_control struct 2011-05-25 08:39:26 -07:00
hid Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6 2011-05-23 12:33:02 -07:00
hwmon hwmon: (coretemp) Fix section mismatch 2011-05-27 02:24:54 -07:00
hwspinlock
i2c mfd: Use mfd cell platform_data for timberdale cells platform bits 2011-05-26 19:45:05 +02:00
ide Merge branch 'for-2.6.40/core' of git://git.kernel.dk/linux-2.6-block 2011-05-25 09:14:07 -07:00
idle
ieee802154
infiniband Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband 2011-05-26 12:13:57 -07:00
input input: Add support for Qualcomm PMIC8XXX power key 2011-05-26 19:45:54 +02:00
isdn Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
leds leds: Add ASIC3 LED support 2011-05-26 19:45:46 +02:00
lguest
macintosh Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-05-23 09:12:26 -07:00
mca
md dm kcopyd: preallocate sub jobs to avoid deadlock 2011-05-29 13:03:00 +01:00
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2011-05-27 10:14:22 -07:00
memstick
message Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2011-05-23 09:12:26 -07:00
mfd mfd: Fix build breakage caused by tps65910 gpio directory move 2011-05-28 08:38:55 +02:00
misc kgdbts: unify/generalize gdb breakpoint adjustment 2011-05-26 17:12:36 -07:00
mmc Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-05-27 19:51:32 -07:00
mtd Merge git://git.infradead.org/mtd-2.6 2011-05-27 20:06:53 -07:00
net Merge git://git.infradead.org/mtd-2.6 2011-05-27 20:06:53 -07:00
nfc
nubus
of Merge branch 'devicetree/arm-next' of git://git.secretlab.ca/git/linux-2.6 into devel-stable 2011-05-25 00:08:17 +01:00
oprofile oprofile: Use linux/mutex.h 2011-05-24 12:45:59 +02:00
parisc
parport Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
pci Merge branch 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2011-05-24 12:06:40 -07:00
pcmcia
platform x86: remove 32-bit versions of readq()/writeq() 2011-05-25 08:39:44 -07:00
pnp
power Merge git://git.infradead.org/battery-2.6 2011-05-27 10:12:35 -07:00
pps
ps3
ptp ptp: Added a clock driver for the National Semiconductor PHYTER. 2011-05-23 13:10:23 -07:00
rapidio
regulator regulator: Fix _regulator_get_voltage if get_voltage callback is NULL 2011-05-27 10:49:30 +01:00
rtc drivers/rtc/rtc-mxc.c: remove defines already included in rtc.h 2011-05-26 17:12:33 -07:00
s390 [S390] irq: merge irq.c and s390_ext.c 2011-05-26 09:48:24 +02:00
sbus
scsi scsi: fix scsi_proc new kernel-doc warning 2011-05-28 23:12:11 -07:00
sfi
sh Merge branch 'sh/genirq-threading' into sh-latest 2011-05-23 11:36:14 +09:00
sn
spi spi/spi_bfin_sport: new driver for a SPI bus via the Blackfin SPORT peripheral 2011-05-27 01:23:54 -06:00
ssb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6 2011-05-20 13:43:21 -07:00
staging Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
target [SCSI] target: Convert TASK_ATTR to scsi_tcq.h definitions 2011-05-24 13:03:56 -04:00
tc
telephony
thermal
tty Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-05-27 19:51:32 -07:00
uio
usb Merge branch 'for-usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sarah/xhci 2011-05-28 12:36:15 -07:00
uwb
vhost
video drivers/video/mb862xx/mb862xxfbdrv.c needs uaccess.h 2011-05-26 17:12:32 -07:00
virtio
vlynq
w1 w1: add Maxim/Dallas DS2780 Stand-Alone Fuel Gauge IC support 2011-05-26 17:12:38 -07:00
watchdog mfd: Use mfd cell platform_data for rdc321x cells platform bits 2011-05-26 19:45:06 +02:00
xen Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/djm/tmem 2011-05-26 10:50:56 -07:00
zorro
Kconfig ptp: Added a brand new class driver for ptp clocks. 2011-05-23 13:01:00 -07:00
Makefile Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx 2011-05-28 12:35:15 -07:00