10 Jul, 2014
1 commit
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commit 7cd2b0a34ab8e4db971920eef8982f985441adfb upstream.
Oleg reports a division by zero error on zero-length write() to the
percpu_pagelist_fraction sysctl:divide error: 0000 [#1] SMP DEBUG_PAGEALLOC
CPU: 1 PID: 9142 Comm: badarea_io Not tainted 3.15.0-rc2-vm-nfs+ #19
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
task: ffff8800d5aeb6e0 ti: ffff8800d87a2000 task.ti: ffff8800d87a2000
RIP: 0010: percpu_pagelist_fraction_sysctl_handler+0x84/0x120
RSP: 0018:ffff8800d87a3e78 EFLAGS: 00010246
RAX: 0000000000000f89 RBX: ffff88011f7fd000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000010
RBP: ffff8800d87a3e98 R08: ffffffff81d002c8 R09: ffff8800d87a3f50
R10: 000000000000000b R11: 0000000000000246 R12: 0000000000000060
R13: ffffffff81c3c3e0 R14: ffffffff81cfddf8 R15: ffff8801193b0800
FS: 00007f614f1e9740(0000) GS:ffff88011f440000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f614f1fa000 CR3: 00000000d9291000 CR4: 00000000000006e0
Call Trace:
proc_sys_call_handler+0xb3/0xc0
proc_sys_write+0x14/0x20
vfs_write+0xba/0x1e0
SyS_write+0x46/0xb0
tracesys+0xe1/0xe6However, if the percpu_pagelist_fraction sysctl is set by the user, it
is also impossible to restore it to the kernel default since the user
cannot write 0 to the sysctl.This patch allows the user to write 0 to restore the default behavior.
It still requires a fraction equal to or larger than 8, however, as
stated by the documentation for sanity. If a value in the range [1, 7]
is written, the sysctl will return EINVAL.This successfully solves the divide by zero issue at the same time.
Signed-off-by: David Rientjes
Reported-by: Oleg Drokin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
06 May, 2014
1 commit
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commit 80df28476505ed4e6701c3448c63c9229a50c655 upstream.
As sysctl_hung_task_timeout_sec is unsigned long, when this value is
larger then LONG_MAX/HZ, the function schedule_timeout_interruptible in
watchdog will return immediately without sleep and with print :schedule_timeout: wrong timeout value ffffffffffffff83
and then the funtion watchdog will call schedule_timeout_interruptible
again and again. The screen will be filled with"schedule_timeout: wrong timeout value ffffffffffffff83"
This patch does some check and correction in sysctl, to let the function
schedule_timeout_interruptible allways get the valid parameter.Signed-off-by: Liu Hua
Tested-by: Satoru Takeuchi
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
01 Feb, 2014
1 commit
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Pull core debug changes from Ingo Molnar:
"This contains mostly kernel debugging related updates:- make hung_task detection more configurable to distros
- add final bits for x86 UV NMI debugging, with related KGDB changes
- update the mailing-list of MAINTAINERS entries I'm involved with"* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hung_task: Display every hung task warning
sysctl: Add neg_one as a standard constraint
x86/uv/nmi, kgdb/kdb: Fix UV NMI handler when KDB not configured
x86/uv/nmi: Fix Sparse warnings
kgdb/kdb: Fix no KDB config problem
MAINTAINERS: Restore "L: linux-kernel@vger.kernel.org" entries
30 Jan, 2014
1 commit
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Prior to commit fe35004fbf9e ("mm: avoid swapping out with
swappiness==0") setting swappiness to 0, reclaim code could still evict
recently used user anonymous memory to swap even though there is a
significant amount of RAM used for page cache.The behaviour of setting swappiness to 0 has since changed. When set,
the reclaim code does not initiate swap until the amount of free pages
and file-backed pages, is less than the high water mark in a zone.Let's update the documentation to reflect this.
[akpm@linux-foundation.org: remove comma, per Randy]
Signed-off-by: Aaron Tomlin
Acked-by: Rik van Riel
Acked-by: Bryn M. Reeves
Cc: Satoru Moriya
Cc: Randy Dunlap
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Jan, 2014
1 commit
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When khungtaskd detects hung tasks, it prints out
backtraces from a number of those tasks.Limiting the number of backtraces being printed
out can result in the user not seeing the information
necessary to debug the issue. The hung_task_warnings
sysctl controls this feature.This patch makes it possible for hung_task_warnings
to accept a special value to print an unlimited
number of backtraces when khungtaskd detects hung
tasks.The special value is -1. To use this value it is
necessary to change types from ulong to int.Signed-off-by: Aaron Tomlin
Reviewed-by: Rik van Riel
Acked-by: David Rientjes
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1390239253-24030-3-git-send-email-atomlin@redhat.com
[ Build warning fix. ]
Signed-off-by: Ingo Molnar
24 Jan, 2014
1 commit
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For general-purpose (i.e. distro) kernel builds it makes sense to build
with CONFIG_KEXEC to allow end users to choose what kind of things they
want to do with kexec. However, in the face of trying to lock down a
system with such a kernel, there needs to be a way to disable kexec_load
(much like module loading can be disabled). Without this, it is too easy
for the root user to modify kernel memory even when CONFIG_STRICT_DEVMEM
and modules_disabled are set. With this change, it is still possible to
load an image for use later, then disable kexec_load so the image (or lack
of image) can't be altered.The intention is for using this in environments where "perfect"
enforcement is hard. Without a verified boot, along with verified
modules, and along with verified kexec, this is trying to give a system a
better chance to defend itself (or at least grow the window of
discoverability) against attack in the face of a privilege escalation.In my mind, I consider several boot scenarios:
1) Verified boot of read-only verified root fs loading fd-based
verification of kexec images.
2) Secure boot of writable root fs loading signed kexec images.
3) Regular boot loading kexec (e.g. kcrash) image early and locking it.
4) Regular boot with no control of kexec image at all.1 and 2 don't exist yet, but will soon once the verified kexec series has
landed. 4 is the state of things now. The gap between 2 and 4 is too
large, so this change creates scenario 3, a middle-ground above 4 when 2
and 1 are not possible for a system.Signed-off-by: Kees Cook
Acked-by: Rik van Riel
Cc: Vivek Goyal
Cc: Eric Biederman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Jan, 2014
1 commit
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Some applications that run on HPC clusters are designed around the
availability of RAM and the overcommit ratio is fine tuned to get the
maximum usage of memory without swapping. With growing memory, the
1%-of-all-RAM grain provided by overcommit_ratio has become too coarse
for these workload (on a 2TB machine it represents no less than 20GB).This patch adds the new overcommit_kbytes sysctl variable that allow a
much finer grain.[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Jerome Marchand
Cc: Dave Hansen
Cc: Alan Cox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Dec, 2013
1 commit
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commit 887c290e (sched/numa: Decide whether to favour task or group weights
based on swap candidate relationships) drop the check against
sysctl_numa_balancing_settle_count, this patch remove the sysctl.Signed-off-by: Wanpeng Li
Acked-by: Mel Gorman
Reviewed-by: Rik van Riel
Acked-by: David Rientjes
Signed-off-by: Peter Zijlstra
Cc: Andrew Morton
Cc: Naoya Horiguchi
Link: http://lkml.kernel.org/r/1386833006-6600-1-git-send-email-liwanp@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
13 Nov, 2013
2 commits
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Some setuid binaries will allow reading of files which have read
permission by the real user id. This is problematic with files which
use %pK because the file access permission is checked at open() time,
but the kptr_restrict setting is checked at read() time. If a setuid
binary opens a %pK file as an unprivileged user, and then elevates
permissions before reading the file, then kernel pointer values may be
leaked.This happens for example with the setuid pppd application on Ubuntu 12.04:
$ head -1 /proc/kallsyms
00000000 T startup_32$ pppd file /proc/kallsyms
pppd: In file /proc/kallsyms: unrecognized option 'c1000000'This will only leak the pointer value from the first line, but other
setuid binaries may leak more information.Fix this by adding a check that in addition to the current process having
CAP_SYSLOG, that effective user and group ids are equal to the real ids.
If a setuid binary reads the contents of a file which uses %pK then the
pointer values will be printed as NULL if the real user is unprivileged.Update the sysctl documentation to reflect the changes, and also correct
the documentation to state the kptr_restrict=0 is the default.This is a only temporary solution to the issue. The correct solution is
to do the permission check at open() time on files, and to replace %pK
with a function which checks the open() time permission. %pK uses in
printk should be removed since no sane permission check can be done, and
instead protected by using dmesg_restrict.Signed-off-by: Ryan Mallon
Cc: Kees Cook
Cc: Alexander Viro
Cc: Joe Perches
Cc: "Eric W. Biederman"
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now dirty_background_ratio/dirty_ratio contains a percentage of total
avaiable memory, which contains free pages and reclaimable pages. The
number of these pages is not equal to the number of total system memory.
But they are described as a percentage of total system memory in
Documentation/sysctl/vm.txt. So we need to fix them to avoid
misunderstanding.Signed-off-by: Zheng Liu
Cc: Rob Landley
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Oct, 2013
5 commits
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Shared faults can lead to lots of unnecessary page migrations,
slowing down the system, and causing private faults to hit the
per-pgdat migration ratelimit.This patch adds sysctl numa_balancing_migrate_deferred, which specifies
how many shared page migrations to skip unconditionally, after each page
migration that is skipped because it is a shared fault.This reduces the number of page migrations back and forth in
shared fault situations. It also gives a strong preference to
the tasks that are already running where most of the memory is,
and to moving the other tasks to near the memory.Testing this with a much higher scan rate than the default
still seems to result in fewer page migrations than before.Memory seems to be somewhat better consolidated than previously,
with multi-instance specjbb runs on a 4 node system.Signed-off-by: Rik van Riel
Signed-off-by: Mel Gorman
Cc: Andrea Arcangeli
Cc: Johannes Weiner
Cc: Srikar Dronamraju
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1381141781-10992-62-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar -
With scan rate adaptions based on whether the workload has properly
converged or not there should be no need for the scan period reset
hammer. Get rid of it.Signed-off-by: Mel Gorman
Reviewed-by: Rik van Riel
Cc: Andrea Arcangeli
Cc: Johannes Weiner
Cc: Srikar Dronamraju
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1381141781-10992-60-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar -
This patch favours moving tasks towards NUMA node that recorded a higher
number of NUMA faults during active load balancing. Ideally this is
self-reinforcing as the longer the task runs on that node, the more faults
it should incur causing task_numa_placement to keep the task running on that
node. In reality a big weakness is that the nodes CPUs can be overloaded
and it would be more efficient to queue tasks on an idle node and migrate
to the new node. This would require additional smarts in the balancer so
for now the balancer will simply prefer to place the task on the preferred
node for a PTE scans which is controlled by the numa_balancing_settle_count
sysctl. Once the settle_count number of scans has complete the schedule
is free to place the task on an alternative node if the load is imbalanced.[srikar@linux.vnet.ibm.com: Fixed statistics]
Signed-off-by: Mel Gorman
Reviewed-by: Rik van Riel
Cc: Andrea Arcangeli
Cc: Johannes Weiner
Cc: Srikar Dronamraju
[ Tunable and use higher faults instead of preferred. ]
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1381141781-10992-23-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar -
The NUMA PTE scan rate is controlled with a combination of the
numa_balancing_scan_period_min, numa_balancing_scan_period_max and
numa_balancing_scan_size. This scan rate is independent of the size
of the task and as an aside it is further complicated by the fact that
numa_balancing_scan_size controls how many pages are marked pte_numa and
not how much virtual memory is scanned.In combination, it is almost impossible to meaningfully tune the min and
max scan periods and reasoning about performance is complex when the time
to complete a full scan is is partially a function of the tasks memory
size. This patch alters the semantic of the min and max tunables to be
about tuning the length time it takes to complete a scan of a tasks occupied
virtual address space. Conceptually this is a lot easier to understand. There
is a "sanity" check to ensure the scan rate is never extremely fast based on
the amount of virtual memory that should be scanned in a second. The default
of 2.5G seems arbitrary but it is to have the maximum scan rate after the
patch roughly match the maximum scan rate before the patch was applied.On a similar note, numa_scan_period is in milliseconds and not
jiffies. Properly placed pages slow the scanning rate but adding 10 jiffies
to numa_scan_period means that the rate scanning slows depends on HZ which
is confusing. Get rid of the jiffies_to_msec conversion and treat it as ms.Signed-off-by: Mel Gorman
Reviewed-by: Rik van Riel
Cc: Andrea Arcangeli
Cc: Johannes Weiner
Cc: Srikar Dronamraju
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1381141781-10992-18-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar -
Signed-off-by: Mel Gorman
Reviewed-by: Rik van Riel
Cc: Andrea Arcangeli
Cc: Johannes Weiner
Cc: Srikar Dronamraju
Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/r/1381141781-10992-3-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar
12 Sep, 2013
2 commits
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Add a new %P variable to be used in core_pattern. This variable contains
the global PID (PID in the init namespace) as %p contains the PID in the
current namespace which isn't always what we want.The main use for this is to make it easier to handle crashes that happened
within a container. With that new variables it's possible to have the
crashes dumped into the container or forwarded to the host with the right
PID (from the host's point of view).Signed-off-by: Stéphane Graber
Reported-by: Hans Feldt
Cc: Alexander Viro
Cc: Eric W. Biederman
Cc: Andy Whitcroft
Acked-by: Serge E. Hallyn
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Now hugepage migration is enabled, although restricted on pmd-based
hugepages for now (due to lack of testing.) So we should allocate
migratable hugepages from ZONE_MOVABLE if possible.This patch makes GFP flags in hugepage allocation dependent on migration
support, not only the value of hugepages_treat_as_movable. It provides no
change on the behavior for architectures which do not support hugepage
migration,Signed-off-by: Naoya Horiguchi
Acked-by: Andi Kleen
Reviewed-by: Wanpeng Li
Cc: Hillf Danton
Cc: Mel Gorman
Cc: Hugh Dickins
Cc: KOSAKI Motohiro
Cc: Michal Hocko
Cc: Rik van Riel
Cc: "Aneesh Kumar K.V"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Aug, 2013
1 commit
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By default, the pfifo_fast queue discipline has been used by default
for all devices. But we have better choices now.This patch allow setting the default queueing discipline with sysctl.
This allows easy use of better queueing disciplines on all devices
without having to use tc qdisc scripts. It is intended to allow
an easy path for distributions to make fq_codel or sfq the default
qdisc.This patch also makes pfifo_fast more of a first class qdisc, since
it is now possible to manually override the default and explicitly
use pfifo_fast. The behavior for systems who do not use the sysctl
is unchanged, they still get pfifo_fastAlso removes leftover random # in sysctl net core.
Signed-off-by: Stephen Hemminger
Acked-by: Eric Dumazet
Signed-off-by: David S. Miller
02 Aug, 2013
1 commit
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Eliezer renames several *ll_poll to *busy_poll, but forgets
CONFIG_NET_LL_RX_POLL, so in case of confusion, rename it too.Cc: Eliezer Tamir
Cc: David S. Miller
Signed-off-by: Cong Wang
Signed-off-by: David S. Miller
11 Jul, 2013
1 commit
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Rename LL_SO to BUSY_POLL_SO
Rename sysctl_net_ll_{read,poll} to sysctl_busy_{read,poll}
Fix up users of these variables.
Fix documentation for sysctl.a patch for the socket.7 man page will follow separately,
because of limitations of my mail setup.Signed-off-by: Eliezer Tamir
Signed-off-by: David S. Miller
10 Jul, 2013
2 commits
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Pull networking updates from David Miller:
"This is a re-do of the net-next pull request for the current merge
window. The only difference from the one I made the other day is that
this has Eliezer's interface renames and the timeout handling changes
made based upon your feedback, as well as a few bug fixes that have
trickeled in.Highlights:
1) Low latency device polling, eliminating the cost of interrupt
handling and context switches. Allows direct polling of a network
device from socket operations, such as recvmsg() and poll().Currently ixgbe, mlx4, and bnx2x support this feature.
Full high level description, performance numbers, and design in
commit 0a4db187a999 ("Merge branch 'll_poll'")From Eliezer Tamir.
2) With the routing cache removed, ip_check_mc_rcu() gets exercised
more than ever before in the case where we have lots of multicast
addresses. Use a hash table instead of a simple linked list, from
Eric Dumazet.3) Add driver for Atheros CQA98xx 802.11ac wireless devices, from
Bartosz Markowski, Janusz Dziedzic, Kalle Valo, Marek Kwaczynski,
Marek Puzyniak, Michal Kazior, and Sujith Manoharan.4) Support reporting the TUN device persist flag to userspace, from
Pavel Emelyanov.5) Allow controlling network device VF link state using netlink, from
Rony Efraim.6) Support GRE tunneling in openvswitch, from Pravin B Shelar.
7) Adjust SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF for modern times, from
Daniel Borkmann and Eric Dumazet.8) Allow controlling of TCP quickack behavior on a per-route basis,
from Cong Wang.9) Several bug fixes and improvements to vxlan from Stephen
Hemminger, Pravin B Shelar, and Mike Rapoport. In particular,
support receiving on multiple UDP ports.10) Major cleanups, particular in the area of debugging and cookie
lifetime handline, to the SCTP protocol code. From Daniel
Borkmann.11) Allow packets to cross network namespaces when traversing tunnel
devices. From Nicolas Dichtel.12) Allow monitoring netlink traffic via AF_PACKET sockets, in a
manner akin to how we monitor real network traffic via ptype_all.
From Daniel Borkmann.13) Several bug fixes and improvements for the new alx device driver,
from Johannes Berg.14) Fix scalability issues in the netem packet scheduler's time queue,
by using an rbtree. From Eric Dumazet.15) Several bug fixes in TCP loss recovery handling, from Yuchung
Cheng.16) Add support for GSO segmentation of MPLS packets, from Simon
Horman.17) Make network notifiers have a real data type for the opaque
pointer that's passed into them. Use this to properly handle
network device flag changes in arp_netdev_event(). From Jiri
Pirko and Timo Teräs.18) Convert several drivers over to module_pci_driver(), from Peter
Huewe.19) tcp_fixup_rcvbuf() can loop 500 times over loopback, just use a
O(1) calculation instead. From Eric Dumazet.20) Support setting of explicit tunnel peer addresses in ipv6, just
like ipv4. From Nicolas Dichtel.21) Protect x86 BPF JIT against spraying attacks, from Eric Dumazet.
22) Prevent a single high rate flow from overruning an individual cpu
during RX packet processing via selective flow shedding. From
Willem de Bruijn.23) Don't use spinlocks in TCP md5 signing fast paths, from Eric
Dumazet.24) Don't just drop GSO packets which are above the TBF scheduler's
burst limit, chop them up so they are in-bounds instead. Also
from Eric Dumazet.25) VLAN offloads are missed when configured on top of a bridge, fix
from Vlad Yasevich.26) Support IPV6 in ping sockets. From Lorenzo Colitti.
27) Receive flow steering targets should be updated at poll() time
too, from David Majnemer.28) Fix several corner case regressions in PMTU/redirect handling due
to the routing cache removal, from Timo Teräs.29) We have to be mindful of ipv4 mapped ipv6 sockets in
upd_v6_push_pending_frames(). From Hannes Frederic Sowa.30) Fix L2TP sequence number handling bugs, from James Chapman."
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1214 commits)
drivers/net: caif: fix wrong rtnl_is_locked() usage
drivers/net: enic: release rtnl_lock on error-path
vhost-net: fix use-after-free in vhost_net_flush
net: mv643xx_eth: do not use port number as platform device id
net: sctp: confirm route during forward progress
virtio_net: fix race in RX VQ processing
virtio: support unlocked queue poll
net/cadence/macb: fix bug/typo in extracting gem_irq_read_clear bit
Documentation: Fix references to defunct linux-net@vger.kernel.org
net/fs: change busy poll time accounting
net: rename low latency sockets functions to busy poll
bridge: fix some kernel warning in multicast timer
sfc: Fix memory leak when discarding scattered packets
sit: fix tunnel update via netlink
dt:net:stmmac: Add dt specific phy reset callback support.
dt:net:stmmac: Add support to dwmac version 3.610 and 3.710
dt:net:stmmac: Allocate platform data only if its NULL.
net:stmmac: fix memleak in the open method
ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available
net: ipv6: fix wrong ping_v6_sendmsg return value
... -
The default zonelist order selecter will select "node" order if any nodes
DMA zone comprises greater than 70% of its local memory instead of 60%,
according to default_zonelist_order::low_kmem_size > total * 70/100.Signed-off-by: Wanpeng Li
Reviewed-by: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Jul, 2013
1 commit
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Rename functions in include/net/ll_poll.h to busy wait.
Clarify documentation about expected power use increase.
Rename POLL_LL to POLL_BUSY_LOOP.
Add need_resched() testing to poll/select busy loops.Note, that in select and poll can_busy_poll is dynamic and is
updated continuously to reflect the existence of supported
sockets with valid queue information.Signed-off-by: Eliezer Tamir
Signed-off-by: David S. Miller
05 Jul, 2013
1 commit
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Pull trivial tree updates from Jiri Kosina:
"The usual stuff from trivial tree"* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (34 commits)
treewide: relase -> release
Documentation/cgroups/memory.txt: fix stat file documentation
sysctl/net.txt: delete reference to obsolete 2.4.x kernel
spinlock_api_smp.h: fix preprocessor comments
treewide: Fix typo in printk
doc: device tree: clarify stuff in usage-model.txt.
open firmware: "/aliasas" -> "/aliases"
md: bcache: Fixed a typo with the word 'arithmetic'
irq/generic-chip: fix a few kernel-doc entries
frv: Convert use of typedef ctl_table to struct ctl_table
sgi: xpc: Convert use of typedef ctl_table to struct ctl_table
doc: clk: Fix incorrect wording
Documentation/arm/IXP4xx fix a typo
Documentation/networking/ieee802154 fix a typo
Documentation/DocBook/media/v4l fix a typo
Documentation/video4linux/si476x.txt fix a typo
Documentation/virtual/kvm/api.txt fix a typo
Documentation/early-userspace/README fix a typo
Documentation/video4linux/soc-camera.txt fix a typo
lguest: fix CONFIG_PAE -> CONFIG_x86_PAE in comment
...
26 Jun, 2013
1 commit
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select/poll busy-poll support.
Split sysctl value into two separate ones, one for read and one for poll.
updated Documentation/sysctl/net.txtAdd a new poll flag POLL_LL. When this flag is set, sock_poll will call
sk_poll_ll if possible. sock_poll sets this flag in its return value
to indicate to select/poll when a socket that can busy poll is found.When poll/select have nothing to report, call the low-level
sock_poll again until we are out of time or we find something.Once the system call finds something, it stops setting POLL_LL, so it can
return the result to the user ASAP.Signed-off-by: Eliezer Tamir
Signed-off-by: David S. Miller
24 Jun, 2013
1 commit
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This random old kernel version has no bearing on the actual
file contents, and has not had for a long time. Delete it.Signed-off-by: Paul Gortmaker
Signed-off-by: Jiri Kosina
23 Jun, 2013
1 commit
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This patch keeps track of how long perf's NMI handler is taking,
and also calculates how many samples perf can take a second. If
the sample length times the expected max number of samples
exceeds a configurable threshold, it drops the sample rate.This way, we don't have a runaway sampling process eating up the
CPU.This patch can tend to drop the sample rate down to level where
perf doesn't work very well. *BUT* the alternative is that my
system hangs because it spends all of its time handling NMIs.I'll take a busted performance tool over an entire system that's
busted and undebuggable any day.BTW, my suspicion is that there's still an underlying bug here.
Using the HPET instead of the TSC is definitely a contributing
factor, but I suspect there are some other things going on.
But, I can't go dig down on a bug like that with my machine
hanging all the time.Signed-off-by: Dave Hansen
Acked-by: Peter Zijlstra
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen
[ Prettified it a bit. ]
Signed-off-by: Ingo Molnar
18 Jun, 2013
1 commit
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As per feedback from the netdev community, we change the buffer
overflow protection algorithm in receiving sockets so that it
always respects the nominal upper limit set in sk_rcvbuf.Instead of scaling up from a small sk_rcvbuf value, which leads to
violation of the configured sk_rcvbuf limit, we now calculate the
weighted per-message limit by scaling down from a much bigger value,
still in the same field, according to the importance priority of the
received message.To allow for administrative tunability of the socket receive buffer
size, we create a tipc_rmem sysctl variable to allow the user to
configure an even bigger value via sysctl command. It is a size of
three (min/default/max) to be consistent with things like tcp_rmem.By default, the value initialized in tipc_rmem[1] is equal to the
receive socket size needed by a TIPC_CRITICAL_IMPORTANCE message.
This value is also set as the default value of sk_rcvbuf.Originally-by: Jon Maloy
Cc: Neil Horman
Cc: Jon Maloy
[Ying: added sysctl variation to Jon's original patch]
Signed-off-by: Ying Xue
[PG: don't compile sysctl.c if not config'd; add Documentation]
Signed-off-by: Paul Gortmaker
Signed-off-by: David S. Miller
11 Jun, 2013
1 commit
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Adds an ndo_ll_poll method and the code that supports it.
This method can be used by low latency applications to busy-poll
Ethernet device queues directly from the socket code.
sysctl_net_ll_poll controls how many microseconds to poll.
Default is zero (disabled).
Individual protocol support will be added by subsequent patches.Signed-off-by: Alexander Duyck
Signed-off-by: Jesse Brandeburg
Signed-off-by: Eliezer Tamir
Acked-by: Eric Dumazet
Tested-by: Willem de Bruijn
Signed-off-by: David S. Miller
28 May, 2013
2 commits
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The old softlockup detector has been replaced with new lockup
detector long ago.Signed-off-by: Li Zefan
Acked-by: Don Zickus
Link: http://lkml.kernel.org/r/51959687.9090305@huawei.com
Signed-off-by: Ingo Molnar -
Signed-off-by: Li Zefan
Acked-by: Don Zickus
Link: http://lkml.kernel.org/r/51959678.6000802@huawei.com
Signed-off-by: Ingo Molnar
20 May, 2013
1 commit
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This patch removes mentioning the sysfsf net_device weight attribute
(class/net//weight)
in Documentation/sysctl/net.txt, since the net sysfs weight attribute
was removed by the following patch:[NET]: Make NAPI polling independent of struct net_device objects
bea3348eef27e6044b6161fd04c3152215f96411Signed-off-by: Rami Rosen
Signed-off-by: David S. Miller
30 Apr, 2013
2 commits
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Add an admin_reserve_kbytes knob to allow admins to change the hardcoded
memory reserve to something other than 3%, which may be multiple
gigabytes on large memory systems. Only about 8MB is necessary to
enable recovery in the default mode, and only a few hundred MB are
required even when overcommit is disabled.This affects OVERCOMMIT_GUESS and OVERCOMMIT_NEVER.
admin_reserve_kbytes is initialized to min(3% free pages, 8MB)
I arrived at 8MB by summing the RSS of sshd or login, bash, and top.
Please see first patch in this series for full background, motivation,
testing, and full changelog.[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make init_admin_reserve() static]
Signed-off-by: Andrew Shewmaker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add user_reserve_kbytes knob.
Limit the growth of the memory reserved for other user processes to
min(3% current process size, user_reserve_pages). Only about 8MB is
necessary to enable recovery in the default mode, and only a few hundred
MB are required even when overcommit is disabled.user_reserve_pages defaults to min(3% free pages, 128MB)
I arrived at 128MB by taking the max VSZ of sshd, login, bash, and top ...
then adding the RSS of each.This only affects OVERCOMMIT_NEVER mode.
Background
1. user reserve
__vm_enough_memory reserves a hardcoded 3% of the current process size for
other applications when overcommit is disabled. This was done so that a
user could recover if they launched a memory hogging process. Without the
reserve, a user would easily run into a message such as:bash: fork: Cannot allocate memory
2. admin reserve
Additionally, a hardcoded 3% of free memory is reserved for root in both
overcommit 'guess' and 'never' modes. This was intended to prevent a
scenario where root-cant-log-in and perform recovery operations.Note that this reserve shrinks, and doesn't guarantee a useful reserve.
Motivation
The two hardcoded memory reserves should be updated to account for current
memory sizes.Also, the admin reserve would be more useful if it didn't shrink too much.
When the current code was originally written, 1GB was considered
"enterprise". Now the 3% reserve can grow to multiple GB on large memory
systems, and it only needs to be a few hundred MB at most to enable a user
or admin to recover a system with an unwanted memory hogging process.I've found that reducing these reserves is especially beneficial for a
specific type of application load:* single application system
* one or few processes (e.g. one per core)
* allocating all available memory
* not initializing every page immediately
* long runningI've run scientific clusters with this sort of load. A long running job
sometimes failed many hours (weeks of CPU time) into a calculation. They
weren't initializing all of their memory immediately, and they weren't
using calloc, so I put systems into overcommit 'never' mode. These
clusters run diskless and have no swap.However, with the current reserves, a user wishing to allocate as much
memory as possible to one process may be prevented from using, for
example, almost 2GB out of 32GB.The effect is less, but still significant when a user starts a job with
one process per core. I have repeatedly seen a set of processes
requesting the same amount of memory fail because one of them could not
allocate the amount of memory a user would expect to be able to allocate.
For example, Message Passing Interfce (MPI) processes, one per core. And
it is similar for other parallel programming frameworks.Changing this reserve code will make the overcommit never mode more useful
by allowing applications to allocate nearly all of the available memory.Also, the new admin_reserve_kbytes will be safer than the current behavior
since the hardcoded 3% of available memory reserve can shrink to something
useless in the case where applications have grabbed all available memory.Risks
* "bash: fork: Cannot allocate memory"
The downside of the first patch-- which creates a tunable user reserve
that is only used in overcommit 'never' mode--is that an admin can set
it so low that a user may not be able to kill their process, even if
they already have a shell prompt.Of course, a user can get in the same predicament with the current 3%
reserve--they just have to launch processes until 3% becomes negligible.* root-cant-log-in problem
The second patch, adding the tunable rootuser_reserve_pages, allows
the admin to shoot themselves in the foot by setting it too small. They
can easily get the system into a state where root-can't-log-in.However, the new admin_reserve_kbytes will be safer than the current
behavior since the hardcoded 3% of available memory reserve can shrink
to something useless in the case where applications have grabbed all
available memory.Alternatives
* Memory cgroups provide a more flexible way to limit application memory.
Not everyone wants to set up cgroups or deal with their overhead.
* We could create a fourth overcommit mode which provides smaller reserves.
The size of useful reserves may be drastically different depending
on the whether the system is embedded or enterprise.* Force users to initialize all of their memory or use calloc.
Some users don't want/expect the system to overcommit when they malloc.
Overcommit 'never' mode is for this scenario, and it should work well.The new user and admin reserve tunables are simple to use, with low
overhead compared to cgroups. The patches preserve current behavior where
3% of memory is less than 128MB, except that the admin reserve doesn't
shrink to an unusable size under pressure. The code allows admins to tune
for embedded and enterprise usage.FAQ
* How is the root-cant-login problem addressed?
What happens if admin_reserve_pages is set to 0?Root is free to shoot themselves in the foot by setting
admin_reserve_kbytes too low.On x86_64, the minimum useful reserve is:
8MB for overcommit 'guess'
128MB for overcommit 'never'admin_reserve_pages defaults to min(3% free memory, 8MB)
So, anyone switching to 'never' mode needs to adjust
admin_reserve_pages.* How do you calculate a minimum useful reserve?
A user or the admin needs enough memory to login and perform
recovery operations, which includes, at a minimum:sshd or login + bash (or some other shell) + top (or ps, kill, etc.)
For overcommit 'guess', we can sum resident set sizes (RSS)
because we only need enough memory to handle what the recovery
programs will typically use. On x86_64 this is about 8MB.For overcommit 'never', we can take the max of their virtual sizes (VSZ)
and add the sum of their RSS. We use VSZ instead of RSS because mode
forces us to ensure we can fulfill all of the requested memory allocations--
even if the programs only use a fraction of what they ask for.
On x86_64 this is about 128MB.When swap is enabled, reserves are useful even when they are as
small as 10MB, regardless of overcommit mode.When both swap and overcommit are disabled, then the admin should
tune the reserves higher to be absolutley safe. Over 230MB each
was safest in my testing.* What happens if user_reserve_pages is set to 0?
Note, this only affects overcomitt 'never' mode.
Then a user will be able to allocate all available memory minus
admin_reserve_kbytes.However, they will easily see a message such as:
"bash: fork: Cannot allocate memory"
And they won't be able to recover/kill their application.
The admin should be able to recover the system if
admin_reserve_kbytes is set appropriately.* What's the difference between overcommit 'guess' and 'never'?
"Guess" allows an allocation if there are enough free + reclaimable
pages. It has a hardcoded 3% of free pages reserved for root."Never" allows an allocation if there is enough swap + a configurable
percentage (default is 50) of physical RAM. It has a hardcoded 3% of
free pages reserved for root, like "Guess" mode. It also has a
hardcoded 3% of the current process size reserved for additional
applications.* Why is overcommit 'guess' not suitable even when an app eventually
writes to every page? It takes free pages, file pages, available
swap pages, reclaimable slab pages into consideration. In other words,
these are all pages available, then why isn't overcommit suitable?Because it only looks at the present state of the system. It
does not take into account the memory that other applications have
malloced, but haven't initialized yet. It overcommits the system.Test Summary
There was little change in behavior in the default overcommit 'guess'
mode with swap enabled before and after the patch. This was expected.Systems run most predictably (i.e. no oom kills) in overcommit 'never'
mode with swap enabled. This also allowed the most memory to be allocated
to a user application.Overcommit 'guess' mode without swap is a bad idea. It is easy to
crash the system. None of the other tested combinations crashed.
This matches my experience on the Roadrunner supercomputer.Without the tunable user reserve, a system in overcommit 'never' mode
and without swap does not allow the admin to recover, although the
admin can.With the new tunable reserves, a system in overcommit 'never' mode
and without swap can be configured to:1. maximize user-allocatable memory, running close to the edge of
recoverability2. maximize recoverability, sacrificing allocatable memory to
ensure that a user cannot take down a systemTest Description
Fedora 18 VM - 4 x86_64 cores, 5725MB RAM, 4GB Swap
System is booted into multiuser console mode, with unnecessary services
turned off. Caches were dropped before each test.Hogs are user memtester processes that attempt to allocate all free memory
as reported by /proc/meminfoIn overcommit 'never' mode, memory_ratio=100
Test Results
3.9.0-rc1-mm1
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5432/5432 no yes yes
guess yes 4 5444/5444 1 yes yes
guess no 1 5302/5449 no yes yes
guess no 4 - crash no nonever yes 1 5460/5460 1 yes yes
never yes 4 5460/5460 1 yes yes
never no 1 5218/5432 no no yes
never no 4 5203/5448 no no yes3.9.0-rc1-mm1-tunablereserves
User and Admin Recovery show their respective reserves, if applicable.
Overcommit | Swap | Hogs | MB Got/Wanted | OOMs | User Recovery | Admin Recovery
---------- ---- ---- ------------- ---- ------------- --------------
guess yes 1 5419/5419 no - yes 8MB yes
guess yes 4 5436/5436 1 - yes 8MB yes
guess no 1 5440/5440 * - yes 8MB yes
guess no 4 - crash - no 8MB no* process would successfully mlock, then the oom killer would pick it
never yes 1 5446/5446 no 10MB yes 20MB yes
never yes 4 5456/5456 no 10MB yes 20MB yes
never no 1 5387/5429 no 128MB no 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barely
never no 1 5323/5428 no 226MB barely 8MB barelynever no 1 5359/5448 no 10MB no 10MB barely
never no 1 5323/5428 no 0MB no 10MB barely
never no 1 5332/5428 no 0MB no 50MB yes
never no 1 5293/5429 no 0MB no 90MB yesnever no 1 5001/5427 no 230MB yes 338MB yes
never no 4* 4998/5424 no 230MB yes 338MB yes* more memtesters were launched, able to allocate approximately another 100MB
Future Work
- Test larger memory systems.
- Test an embedded image.
- Test other architectures.
- Time malloc microbenchmarks.
- Would it be useful to be able to set overcommit policy for
each memory cgroup?- Some lines are slightly above 80 chars.
Perhaps define a macro to convert between pages and kb?
Other places in the kernel do this.[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make init_user_reserve() static]
Signed-off-by: Andrew Shewmaker
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Jan, 2013
2 commits
-
Signed-off-by: Carlos Alberto Lopez Perez
Cc: Rob Landley
Cc: Larry Finger
Cc: Neil Horman
Cc: Mitsuo Hayasaka
Cc: Tejun Heo
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add 3 new variables and sysctls to tune them (by one "next_id" variable
for messages, semaphores and shared memory respectively). This variable
can be used to set desired id for next allocated IPC object. By default
it's equal to -1 and old behaviour is preserved. If this variable is
non-negative, then desired idr will be extracted from it and used as a
start value to search for free IDR slot.Notes:
1) this patch doesn't guarantee that the new object will have desired
id. So it's up to user space how to handle new object with wrong id.2) After a sucessful id allocation attempt, "next_id" will be set back
to -1 (if it was non-negative).[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stanislav Kinsbursky
Cc: Serge Hallyn
Cc: "Eric W. Biederman"
Cc: Pavel Emelyanov
Cc: Al Viro
Cc: KOSAKI Motohiro
Cc: Michael Kerrisk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Oct, 2012
1 commit
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Some coredump handlers want to create a core file in a way compatible with
standard behavior. Standard behavior with fs.suid_dumpable = 2 is to
create core file with uid=gid=0. However, there was no way for coredump
handler to know that the process being dumped was suid'ed.This patch adds the new %d specifier for format_corename() which simply
reports __get_dumpable(mm->flags), this is compatible with
/proc/sys/fs/suid_dumpable we already have.Addresses https://bugzilla.redhat.com/show_bug.cgi?id=787135
Developed during a discussion with Denys Vlasenko.
Signed-off-by: Oleg Nesterov
Cc: Denys Vlasenko
Cc: Alex Kelly
Cc: Andi Kleen
Cc: Cong Wang
Cc: Jiri Moskovcak
Acked-by: Neil Horman
Cc: Alan Cox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Aug, 2012
1 commit
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The pdflush thread is long gone, however we still mention it incorrectly in the
kernel documentation. This patch fixes the situation.Cc: Randy Dunlap
Signed-off-by: Artem Bityutskiy
Signed-off-by: Al Viro
02 Aug, 2012
1 commit
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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
...
01 Aug, 2012
1 commit
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The number of ptes and swap entries are used in the oom killer's badness
heuristic, so they should be shown in the tasklist dump.This patch adds those fields and replaces cpu and oom_adj values that are
currently emitted. Cpu isn't interesting and oom_adj is deprecated and
will be removed later this year, the same information is already displayed
as oom_score_adj which is used internally.At the same time, make the documentation a little more clear to state this
information is helpful to determine why the oom killer chose the task it
did to kill.Signed-off-by: David Rientjes
Cc: KAMEZAWA Hiroyuki
Cc: KOSAKI Motohiro
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds