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Davide Libenzi 7ef9964e6d epoll: introduce resource usage limits 
It has been thought that the per-user file descriptors limit would also
limit the resources that a normal user can request via the epoll
interface.  Vegard Nossum reported a very simple program (a modified
version attached) that can make a normal user to request a pretty large
amount of kernel memory, well within the its maximum number of fds.  To
solve such problem, default limits are now imposed, and /proc based
configuration has been introduced.  A new directory has been created,
named /proc/sys/fs/epoll/ and inside there, there are two configuration
points:

  max_user_instances = Maximum number of devices - per user

  max_user_watches   = Maximum number of "watched" fds - per user

The current default for "max_user_watches" limits the memory used by epoll
to store "watches", to 1/32 of the amount of the low RAM.  As example, a
256MB 32bit machine, will have "max_user_watches" set to roughly 90000.
That should be enough to not break existing heavy epoll users.  The
default value for "max_user_instances" is set to 128, that should be
enough too.

This also changes the userspace, because a new error code can now come out
from EPOLL_CTL_ADD (-ENOSPC).  The EMFILE from epoll_create() was already
listed, so that should be ok.

[akpm@linux-foundation.org: use get_current_user()]
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: <stable@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-12-01 19:55:24 -08:00
..
ABI Add c2 port support 2008-11-12 17:17:18 -08:00
accounting .gitignore updates 2008-10-30 11:38:45 -07:00
acpi ACPI: update debug parameter documentation 2008-11-07 21:45:29 -05:00
aoe aoe: user can ask driver to forget previously detected devices 2008-02-08 09:22:31 -08:00
arm [ARM] 5323/1: Remove outdated empeg documentation. 2008-10-29 22:00:39 +00:00
auxdisplay .gitignore updates 2008-10-30 11:38:45 -07:00
blackfin Blackfin arch: add supporting for kgdb 2008-10-13 14:07:19 +08:00
block Merge branch 'docs' of git://git.lwn.net/linux-2.6 2008-10-16 12:18:16 -07:00
blockdev Create/use more directory structure in the Documentation/ tree. 2008-11-14 17:28:53 +00:00
cdrom doc/cdrom: Trvial documentation error, file not present 2008-10-10 08:22:44 +02:00
cgroups freezer_cg: disable writing freezer.state of root cgroup 2008-11-12 17:17:16 -08:00
connector .gitignore updates 2008-10-30 11:38:45 -07:00
console
controllers memcg: avoid accounting special pages 2008-10-20 08:52:38 -07:00
cpu-freq [CPUFREQ] Documentation: Add Blackfin to list of supported processors 2008-11-25 13:38:29 -05:00
cpuidle cpuidle: Add Documentation 2008-02-14 00:16:13 -05:00
cris fix random typos 2008-10-16 11:21:30 -07:00
crypto [CRYPTO] doc: Update api-intro.txt 2008-01-11 08:16:14 +11:00
development-process Add the development process document 2008-10-16 11:51:30 -06:00
device-mapper dm crypt: add documentation 2008-04-25 13:27:03 +01:00
DocBook Rationalise Randy's address a bit 2008-10-30 11:38:47 -07:00
driver-model Driver core: Update some prototypes in platform.txt 2008-02-02 15:14:49 -08:00
dvb V4L/DVB (7077): bt878: remove handcrafted PCI subsystem ID check 2008-01-25 19:05:22 -02:00
early-userspace Documentation: Remove last references to BitKeeper. 2008-04-21 22:19:05 +00:00
fault-injection
fb uvesafb: document mode to mode_option parameter change 2008-10-16 11:21:44 -07:00
filesystems epoll: introduce resource usage limits 2008-12-01 19:55:24 -08:00
firmware_class firmware_sample_driver.c: fix coding style 2008-04-21 22:23:30 +00:00
frv move frv docs one level up 2008-02-03 15:54:28 +02:00
hwmon adt7462: new hwmon driver 2008-11-12 17:17:17 -08:00
i2c i2c: The i2c mailing list is moving 2008-10-30 15:55:47 +01:00
i2o
ia64 .gitignore updates 2008-10-30 11:38:45 -07:00
ide gayle: add "doubler" parameter 2008-04-27 15:38:30 +02:00
infiniband IB/umad: Add P_Key index support 2007-10-09 19:59:15 -07:00
input Input: fix the example of an input device driver 2008-11-11 11:41:49 -05:00
ioctl Create/use more directory structure in the Documentation/ tree. 2008-11-14 17:28:53 +00:00
isdn Rationalise Randy's address a bit 2008-10-30 11:38:47 -07:00
ja_JP HOWTO: Sync patch for jp_JP/HOWTO 2008-10-29 15:03:50 -07:00
kbuild kconfig-language.txt: remove bogus hint 2008-05-04 21:05:56 +02:00
kdump powerpc: Support for relocatable kdump kernel 2008-10-22 15:01:22 +11:00
ko_KR HOWTO: update misspelling and word incorrected 2007-12-17 10:33:19 -08:00
laptops Merge branch 'linus' into test 2008-10-23 00:11:07 -04:00
lguest lguest: fix example launcher compile after moved asm-x86 dir. 2008-10-31 11:24:27 +11:00
m68k [SCSI] 53c7xx: fix removal fallout 2008-01-11 18:22:30 -06:00
make Documentation/make/headers_install.txt 2007-10-17 08:43:05 -07:00
mips au1xxx-ide: fix MWDMA support 2008-04-26 22:25:22 +02:00
mn10300 mn10300: add the MN10300/AM33 architecture to the kernel 2008-02-08 09:22:30 -08:00
mtd [MTD] [NAND] nand_ecc.c: rewrite for improved performance 2008-08-16 10:55:33 +01:00
namespaces The namespaces compatibility list doc 2007-11-29 09:24:53 -08:00
netlabel
networking phylib: fix phy name example in documentation 2008-11-19 15:38:24 -08:00
parisc
PCI Create/use more directory structure in the Documentation/ tree. 2008-11-14 17:28:53 +00:00
pcmcia .gitignore updates 2008-10-30 11:38:45 -07:00
power pm: document use of RTC in pm_trace 2008-10-16 11:21:29 -07:00
powerpc powerpc: Repair device bindings documentation 2008-11-10 15:17:52 -06:00
prctl generic, x86: add tests for prctl PR_GET_TSC and PR_SET_TSC 2008-04-19 19:19:55 +02:00
RCU doc/RCU: fix pseudocode in rcuref.txt 2008-09-10 08:36:07 +02:00
s390 [S390] cio: Exorcise cio_msg= from documentation. 2008-10-10 21:33:49 +02:00
scheduler sched: remove sched-design.txt from 00-INDEX 2008-10-30 11:37:58 +01:00
scsi Rationalise Randy's address a bit 2008-10-30 11:38:47 -07:00
serial Create/use more directory structure in the Documentation/ tree. 2008-11-14 17:28:53 +00:00
sh sh: Kill off long-dead HD64465 cchip support. 2008-10-28 20:07:44 +09:00
sound Merge branch 'topic/fix/hda' into for-linus 2008-11-25 17:21:32 +01:00
sparc sparc: Remove Documentation/sparc/sbus_drivers.txt 2008-08-29 02:15:25 -07:00
spi spi documentation: use __initdata on struct 2008-12-01 19:55:24 -08:00
sysctl Document kernel taint flags properly 2008-10-29 15:03:49 -07:00
telephony remove mention of CONFIG_KMOD from documentation 2008-07-22 19:24:29 +10:00
thermal thermal: update the documentation 2008-04-29 02:49:47 -04:00
timers hpet: /dev/hpet - fixes and cleanup 2008-07-31 18:45:41 +02:00
tracers tracing, doc: update mmiotrace documentation 2008-11-23 20:33:24 +01:00
uml
usb Merge branch 'master' into for-upstream 2008-10-20 16:07:19 +01:00
video4linux V4L/DVB (9482): Documentation, especially regarding audio and informational links 2008-11-11 08:11:24 -02:00
vm .gitignore updates 2008-10-30 11:38:45 -07:00
w1 hdq: documentation for OMAP HDQ 2008-11-12 17:17:18 -08:00
watchdog .gitignore updates 2008-10-30 11:38:45 -07:00
x86 doc/x86: fix doc subdirs 2008-10-28 16:36:42 +01:00
zh_CN Chinese: add translation of Codingstyle 2008-01-24 20:40:04 -08:00
00-INDEX Merge branch 'doc-subdirs' of git://git.kernel.org/pub/scm/linux/kernel/git/rdunlap/linux-docs 2008-11-15 11:51:03 -08:00
applying-patches.txt
atomic_ops.txt documentation: atomic_add_unless() doesn't imply mb() on failure 2008-02-23 17:52:36 -08:00
basic_profiling.txt
binfmt_misc.txt
braille-console.txt Basic braille screen reader support 2008-04-30 08:29:52 -07:00
bt8xxgpio.txt gpio: add bt8xxgpio driver 2008-07-25 10:53:30 -07:00
BUG-HUNTING Documentation: add hint about call traces & module symbols to BUG-HUNTING 2008-02-06 10:41:09 -08:00
c2port.txt Add c2 port support 2008-11-12 17:17:18 -08:00
cachetlb.txt remove unused flush_tlb_pgtables 2007-10-19 11:53:34 -07:00
Changes [x86 setup] Document grub < 0.93 as broken 2007-08-02 13:50:43 -04:00
CodingStyle documentation: update CodingStyle tips for Emacs users 2008-07-25 10:53:29 -07:00
cpu-hotplug.txt cpu hotplug: s390 doesn't support additional_cpus anymore. 2008-08-12 16:07:28 -07:00
cpu-load.txt
cpusets.txt container freezer: document the cgroup freezer subsystem. 2008-10-20 08:52:34 -07:00
cputopology.txt cpu topology: always define CPU topology information 2008-06-13 10:09:46 +02:00
dcdbas.txt
debugging-modules.txt Documentation: Clarify when module debugging actually works. 2008-02-03 15:27:38 +02:00
debugging-via-ohci1394.txt firewire: fw-ohci: add option for remote debugging 2008-04-18 17:55:33 +02:00
dell_rbu.txt
devices.txt USB: add USB test and measurement class driver 2008-10-17 14:40:51 -07:00
DMA-API.txt fix an example of scatterlists handling in DMA-API.txt 2008-10-09 08:56:18 +02:00
DMA-attributes.txt powerpc/cell: Add DMA_ATTR_WEAK_ORDERING dma attribute and use in Cell IOMMU code 2008-07-22 10:39:36 +10:00
DMA-ISA-LPC.txt
DMA-mapping.txt Documentation/DMA-mapping.txt: update for pci_dma_mapping_error() changes 2008-09-23 08:09:14 -07:00
dontdiff dontdiff: more updates to be closer to gitignore 2008-10-16 11:21:31 -07:00
edac.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
eisa.txt
email-clients.txt Documentation/email-clients.txt: add some info about gmail 2008-11-06 15:41:19 -08:00
exception.txt
feature-removal-schedule.txt V4L/DVB (9337b): remove tuner-3036 and dpc7146 drivers from feature-removal-schedule.txt 2008-11-11 08:09:44 -02:00
ftrace.txt ftrace: ftrace.txt version update 2008-11-04 10:12:24 +01:00
gpio.txt gpiolib: request/free hooks 2008-10-16 11:21:40 -07:00
highuid.txt [SPARC]: Remove SunOS and Solaris binary support. 2008-04-21 15:10:15 -07:00
HOWTO Remove Andrew Morton's http://www.zip.com.au/~akpm/ 2008-10-16 11:21:32 -07:00
hw_random.txt hw_random doc updates 2008-03-24 19:22:19 -07:00
ics932s401 ics932s401: new clock generator chip driver 2008-11-12 17:17:18 -08:00
initrd.txt use the newc archive format as requested by initramfs 2008-02-03 14:54:41 +02:00
Intel-IOMMU.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
io_ordering.txt
io-mapping.txt io mapping: improve documentation 2008-11-03 18:21:44 +01:00
IO-mapping.txt
iostats.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
IPMI.txt IPMI: new NMI handling 2007-10-18 14:37:32 -07:00
IRQ-affinity.txt genirq: Expose default irq affinity mask (take 3) 2008-06-05 15:18:30 +02:00
IRQ.txt
irqflags-tracing.txt
isapnp.txt
java.txt Documentation/java.txt: typo and grammar fixes 2007-10-20 02:37:21 +02:00
kernel-doc-nano-HOWTO.txt sched: add kernel doc for the completion, fix kernel-doc-nano-HOWTO.txt 2008-08-26 10:26:54 +02:00
kernel-docs.txt doc: update to URL and status of kernel-docs.txt entry 2008-06-06 11:29:10 -07:00
kernel-parameters.txt Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-11-19 18:51:56 -08:00
keys-request-key.txt keys: allow the callout data to be passed as a blob rather than a string 2008-04-29 08:06:16 -07:00
keys.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
kobject.txt kobject: Fix kobject_rename and !CONFIG_SYSFS 2008-10-16 09:24:52 -07:00
kprobes.txt powerpc/booke: Add kprobes support for booke style processors 2008-06-26 03:35:46 -05:00
kref.txt docs: convert kref semaphore to mutex 2008-02-06 10:41:09 -08:00
ldm.txt
leds-class.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
local_ops.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
lockdep-design.txt
lockstat.txt lockstat: documentation 2007-10-07 16:28:43 -07:00
logo.gif
logo.txt
magic-number.txt [SPARC]: Remove SunOS and Solaris binary support. 2008-04-21 15:10:15 -07:00
Makefile docsrc: build Documentation/ sources 2008-08-12 16:07:30 -07:00
ManagementStyle docs: fix ManagementStyle book name 2008-10-30 11:38:46 -07:00
markers.txt markers: documentation fix for teardown 2008-10-14 10:38:33 +02:00
mca.txt The ps2esdi driver was marked as BROKEN more than two years ago due to being 2008-03-17 09:03:05 +01:00
md.txt md: Tidy up rdev_size_store a bit: 2008-07-21 14:22:18 +10:00
memory-barriers.txt read_barrier_depends arch fixlets 2008-05-14 10:05:18 -07:00
memory-hotplug.txt memory hotplug: document the memory hotplug notifier 2007-10-22 08:13:17 -07:00
memory.txt
mono.txt
mutex-design.txt Documentation: Add nested versions of mutex locks to docs 2007-10-20 00:15:26 +02:00
nmi_watchdog.txt x86: nmi_watchdog - documentation fix - v2 2008-07-08 13:16:10 +02:00
nommu-mmap.txt
numastat.txt
oops-tracing.txt Taint kernel after WARN_ON(condition) 2008-04-29 08:05:59 -07:00
parport-lowlevel.txt plip: fix parport_register_device name parameter 2007-11-26 19:39:01 -08:00
parport.txt
pi-futex.txt
pnp.txt Documentation: Replace obsolete "driverfs" with "sysfs". 2008-01-24 20:40:04 -08:00
preempt-locking.txt
printk-formats.txt DOC: add printk-formats.txt 2008-11-12 17:17:17 -08:00
prio_tree.txt
rbtree.txt
rfkill.txt rfkill: remove transmitter blocking on suspend 2008-09-15 16:48:25 -04:00
robust-futex-ABI.txt
robust-futexes.txt
rt-mutex-design.txt
rt-mutex.txt
rtc.txt rtc: cleanup example code 2008-02-06 10:41:14 -08:00
SAK.txt Remove Andrew Morton's old email accounts 2008-10-16 11:21:32 -07:00
SecurityBugs
SELinux.txt selinux: add support for installing a dummy policy (v2) 2008-08-27 08:54:08 +10:00
serial-console.txt
sgi-ioc4.txt
sgi-visws.txt
SM501.txt Tweak Documentation/SM501.txt 2007-10-17 08:43:06 -07:00
Smack.txt Smack: Simplified Mandatory Access Control Kernel 2008-02-05 09:44:20 -08:00
sparse.txt kbuild: sparse needs CF not CHECKFLAGS 2008-07-25 22:12:39 +02:00
spinlocks.txt Add additional examples in Documentation/spinlocks.txt 2008-04-11 13:21:14 -06:00
stable_api_nonsense.txt stable_api_nonsense.txt: Disambiguate the use of "this" by using "that" to refer to the syscall interface 2007-07-30 14:25:12 -07:00
stable_kernel_rules.txt Update stable tree documentation 2008-10-29 15:03:49 -07:00
SubmitChecklist documentation: explain memory barriers 2008-10-16 11:21:32 -07:00
SubmittingDrivers Remove Andrew Morton's old email accounts 2008-10-16 11:21:32 -07:00
SubmittingPatches Merge branch 'docs' of git://git.lwn.net/linux-2.6 2008-10-16 12:18:16 -07:00
svga.txt
sysfs-rules.txt sysfs-rules.txt: reword API stability statement 2008-07-21 21:54:59 -07:00
sysrq.txt Merge branch 'v28-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-10-20 13:19:56 -07:00
tracepoints.txt tracing: tracepoints, documentation 2008-10-14 10:28:47 +02:00
unaligned-memory-access.txt introduce HAVE_EFFICIENT_UNALIGNED_ACCESS Kconfig symbol 2008-07-25 10:53:27 -07:00
unicode.txt
unshare.txt
VGA-softcursor.txt
video-output.txt
volatile-considered-harmful.txt Documentation cleanup: trivial misspelling, punctuation, and grammar corrections. 2008-07-26 12:00:06 -07:00
voyager.txt
zorro.txt