Disallows open of FIFOs or regular files not owned by the user in world
writable sticky directories, unless the owner is the same as that of the
directory or the file is opened without the O_CREAT flag. The purpose
is to make data spoofing attacks harder. This protection can be turned
on and off separately for FIFOs and regular files via sysctl, just like
the symlinks/hardlinks protection. This patch is based on Openwall's
"HARDEN_FIFO" feature by Solar Designer.
This is a brief list of old vulnerabilities that could have been prevented
by this feature, some of them even allow for privilege escalation:
CVE-2000-1134
CVE-2007-3852
CVE-2008-0525
CVE-2009-0416
CVE-2011-4834
CVE-2015-1838
CVE-2015-7442
CVE-2016-7489
This list is not meant to be complete. It's difficult to track down all
vulnerabilities of this kind because they were often reported without any
mention of this particular attack vector. In fact, before
hardlinks/symlinks restrictions, fifos/regular files weren't the favorite
vehicle to exploit them.
[s.mesoraca16@gmail.com: fix bug reported by Dan Carpenter]
Link: https://lkml.kernel.org/r/20180426081456.GA7060@mwanda
Link: http://lkml.kernel.org/r/1524829819-11275-1-git-send-email-s.mesoraca16@gmail.com
[keescook@chromium.org: drop pr_warn_ratelimited() in favor of audit changes in the future]
[keescook@chromium.org: adjust commit subjet]
Link: http://lkml.kernel.org/r/20180416175918.GA13494@beast
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Suggested-by: Solar Designer <solar@openwall.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ipc_addid() initializes kern_ipc_perm.seq after having called idr_alloc()
(within ipc_idr_alloc()).
Thus a parallel semop() or msgrcv() that uses ipc_obtain_object_check()
may see an uninitialized value.
The patch moves the initialization of kern_ipc_perm.seq before the calls
of idr_alloc().
Notes:
1) This patch has a user space visible side effect:
If /proc/sys/kernel/*_next_id is used (i.e.: checkpoint/restore) and
if semget()/msgget()/shmget() fails in the final step of adding the id
to the rhash tree, then .._next_id is cleared. Before the patch, is
remained unmodified.
There is no change of the behavior after a successful ..get() call: It
always clears .._next_id, there is no impact to non checkpoint/restore
code as that code does not use .._next_id.
2) The patch correctly documents that after a call to ipc_idr_alloc(),
the full tear-down sequence must be used. The callers of ipc_addid()
do not fullfill that, i.e. more bugfixes are required.
The patch is a squash of a patch from Dmitry and my own changes.
Link: http://lkml.kernel.org/r/20180712185241.4017-3-manfred@colorfullife.com
Reported-by: syzbot+2827ef6b3385deb07eaf@syzkaller.appspotmail.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently task hung checking interval is equal to timeout, as the result
hung is detected anywhere between timeout and 2*timeout. This is fine for
most interactive environments, but this hurts automated testing setups
(syzbot). In an automated setup we need to strictly order CPU lockup <
RCU stall < workqueue lockup < task hung < silent loss, so that RCU stall
is not detected as task hung and task hung is not detected as silent
machine loss. The large variance in task hung detection timeout requires
setting silent machine loss timeout to a very large value (e.g. if task
hung is 3 mins, then silent loss need to be set to ~7 mins). The
additional 3 minutes significantly reduce testing efficiency because
usually we crash kernel within a minute, and this can add hours to bug
localization process as it needs to do dozens of tests.
Allow setting checking interval separately from timeout. This allows to
set timeout to, say, 3 minutes, but checking interval to 10 secs.
The interval is controlled via a new hung_task_check_interval_secs sysctl,
similar to the existing hung_task_timeout_secs sysctl. The default value
of 0 results in the current behavior: checking interval is equal to
timeout.
[akpm@linux-foundation.org: update hung_task_timeout_max's comment]
Link: http://lkml.kernel.org/r/20180611111004.203513-1-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull char/misc driver updates from Greg KH:
"Here is the bit set of char/misc drivers for 4.19-rc1
There is a lot here, much more than normal, seems like everyone is
writing new driver subsystems these days... Anyway, major things here
are:
- new FSI driver subsystem, yet-another-powerpc low-level hardware
bus
- gnss, finally an in-kernel GPS subsystem to try to tame all of the
crazy out-of-tree drivers that have been floating around for years,
combined with some really hacky userspace implementations. This is
only for GNSS receivers, but you have to start somewhere, and this
is great to see.
Other than that, there are new slimbus drivers, new coresight drivers,
new fpga drivers, and loads of DT bindings for all of these and
existing drivers.
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (255 commits)
android: binder: Rate-limit debug and userspace triggered err msgs
fsi: sbefifo: Bump max command length
fsi: scom: Fix NULL dereference
misc: mic: SCIF Fix scif_get_new_port() error handling
misc: cxl: changed asterisk position
genwqe: card_base: Use true and false for boolean values
misc: eeprom: assignment outside the if statement
uio: potential double frees if __uio_register_device() fails
eeprom: idt_89hpesx: clean up an error pointer vs NULL inconsistency
misc: ti-st: Fix memory leak in the error path of probe()
android: binder: Show extra_buffers_size in trace
firmware: vpd: Fix section enabled flag on vpd_section_destroy
platform: goldfish: Retire pdev_bus
goldfish: Use dedicated macros instead of manual bit shifting
goldfish: Add missing includes to goldfish.h
mux: adgs1408: new driver for Analog Devices ADGS1408/1409 mux
dt-bindings: mux: add adi,adgs1408
Drivers: hv: vmbus: Cleanup synic memory free path
Drivers: hv: vmbus: Remove use of slow_virt_to_phys()
Drivers: hv: vmbus: Reset the channel callback in vmbus_onoffer_rescind()
...
This patch adds 'nr_hugepages_mempolicy' parameter which is currently missing
in 'vm.txt' file. It also contains a short description of 'nr_hugepages_mempolicy'
parameter.
Signed-off-by: Prashant Dhamdhere <pdhamdhe@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
In the VM mode on Hyper-V, currently, when the kernel panics, an error
code and few register values are populated in an MSR and the Hypervisor
notified. This information is collected on the host. The amount of
information currently collected is found to be limited and not very
actionable. To gather more actionable data, such as stack trace, the
proposal is to write one page worth of kmsg data on an allocated page
and the Hypervisor notified of the page address through the MSR.
- Sysctl option to control the behavior, with ON by default.
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1efff914af ("fs: add
dirtytime_expire_seconds sysctl") introduced dirtytime_expire_seconds
knob, but there is not description about it in
Documentation/sysctl/vm.txt.
Add the description for it.
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Pull networking updates from David Miller:
1) Add Maglev hashing scheduler to IPVS, from Inju Song.
2) Lots of new TC subsystem tests from Roman Mashak.
3) Add TCP zero copy receive and fix delayed acks and autotuning with
SO_RCVLOWAT, from Eric Dumazet.
4) Add XDP_REDIRECT support to mlx5 driver, from Jesper Dangaard
Brouer.
5) Add ttl inherit support to vxlan, from Hangbin Liu.
6) Properly separate ipv6 routes into their logically independant
components. fib6_info for the routing table, and fib6_nh for sets of
nexthops, which thus can be shared. From David Ahern.
7) Add bpf_xdp_adjust_tail helper, which can be used to generate ICMP
messages from XDP programs. From Nikita V. Shirokov.
8) Lots of long overdue cleanups to the r8169 driver, from Heiner
Kallweit.
9) Add BTF ("BPF Type Format"), from Martin KaFai Lau.
10) Add traffic condition monitoring to iwlwifi, from Luca Coelho.
11) Plumb extack down into fib_rules, from Roopa Prabhu.
12) Add Flower classifier offload support to igb, from Vinicius Costa
Gomes.
13) Add UDP GSO support, from Willem de Bruijn.
14) Add documentation for eBPF helpers, from Quentin Monnet.
15) Add TLS tx offload to mlx5, from Ilya Lesokhin.
16) Allow applications to be given the number of bytes available to read
on a socket via a control message returned from recvmsg(), from
Soheil Hassas Yeganeh.
17) Add x86_32 eBPF JIT compiler, from Wang YanQing.
18) Add AF_XDP sockets, with zerocopy support infrastructure as well.
From Björn Töpel.
19) Remove indirect load support from all of the BPF JITs and handle
these operations in the verifier by translating them into native BPF
instead. From Daniel Borkmann.
20) Add GRO support to ipv6 gre tunnels, from Eran Ben Elisha.
21) Allow XDP programs to do lookups in the main kernel routing tables
for forwarding. From David Ahern.
22) Allow drivers to store hardware state into an ELF section of kernel
dump vmcore files, and use it in cxgb4. From Rahul Lakkireddy.
23) Various RACK and loss detection improvements in TCP, from Yuchung
Cheng.
24) Add TCP SACK compression, from Eric Dumazet.
25) Add User Mode Helper support and basic bpfilter infrastructure, from
Alexei Starovoitov.
26) Support ports and protocol values in RTM_GETROUTE, from Roopa
Prabhu.
27) Support bulking in ->ndo_xdp_xmit() API, from Jesper Dangaard
Brouer.
28) Add lots of forwarding selftests, from Petr Machata.
29) Add generic network device failover driver, from Sridhar Samudrala.
* ra.kernel.org:/pub/scm/linux/kernel/git/davem/net-next: (1959 commits)
strparser: Add __strp_unpause and use it in ktls.
rxrpc: Fix terminal retransmission connection ID to include the channel
net: hns3: Optimize PF CMDQ interrupt switching process
net: hns3: Fix for VF mailbox receiving unknown message
net: hns3: Fix for VF mailbox cannot receiving PF response
bnx2x: use the right constant
Revert "net: sched: cls: Fix offloading when ingress dev is vxlan"
net: dsa: b53: Fix for brcm tag issue in Cygnus SoC
enic: fix UDP rss bits
netdev-FAQ: clarify DaveM's position for stable backports
rtnetlink: validate attributes in do_setlink()
mlxsw: Add extack messages for port_{un, }split failures
netdevsim: Add extack error message for devlink reload
devlink: Add extack to reload and port_{un, }split operations
net: metrics: add proper netlink validation
ipmr: fix error path when ipmr_new_table fails
ip6mr: only set ip6mr_table from setsockopt when ip6mr_new_table succeeds
net: hns3: remove unused hclgevf_cfg_func_mta_filter
netfilter: provide udp*_lib_lookup for nf_tproxy
qed*: Utilize FW 8.37.2.0
...
The JIT compiler emits ia32 bit instructions. Currently, It supports eBPF
only. Classic BPF is supported because of the conversion by BPF core.
Almost all instructions from eBPF ISA supported except the following:
BPF_ALU64 | BPF_DIV | BPF_K
BPF_ALU64 | BPF_DIV | BPF_X
BPF_ALU64 | BPF_MOD | BPF_K
BPF_ALU64 | BPF_MOD | BPF_X
BPF_STX | BPF_XADD | BPF_W
BPF_STX | BPF_XADD | BPF_DW
It doesn't support BPF_JMP|BPF_CALL with BPF_PSEUDO_CALL at the moment.
IA32 has few general purpose registers, EAX|EDX|ECX|EBX|ESI|EDI. I use
EAX|EDX|ECX|EBX as temporary registers to simulate instructions in eBPF
ISA, and allocate ESI|EDI to BPF_REG_AX for constant blinding, all others
eBPF registers, R0-R10, are simulated through scratch space on stack.
The reasons behind the hardware registers allocation policy are:
1:MUL need EAX:EDX, shift operation need ECX, so they aren't fit
for general eBPF 64bit register simulation.
2:We need at least 4 registers to simulate most eBPF ISA operations
on registers operands instead of on register&memory operands.
3:We need to put BPF_REG_AX on hardware registers, or constant blinding
will degrade jit performance heavily.
Tested on PC (Intel(R) Core(TM) i5-5200U CPU).
Testing results on i5-5200U:
1) test_bpf: Summary: 349 PASSED, 0 FAILED, [319/341 JIT'ed]
2) test_progs: Summary: 83 PASSED, 0 FAILED.
3) test_lpm: OK
4) test_lru_map: OK
5) test_verifier: Summary: 828 PASSED, 0 FAILED.
Above tests are all done in following two conditions separately:
1:bpf_jit_enable=1 and bpf_jit_harden=0
2:bpf_jit_enable=1 and bpf_jit_harden=2
Below are some numbers for this jit implementation:
Note:
I run test_progs in kselftest 100 times continuously for every condition,
the numbers are in format: total/times=avg.
The numbers that test_bpf reports show almost the same relation.
a:jit_enable=0 and jit_harden=0 b:jit_enable=1 and jit_harden=0
test_pkt_access:PASS:ipv4:15622/100=156 test_pkt_access:PASS:ipv4:10674/100=106
test_pkt_access:PASS:ipv6:9130/100=91 test_pkt_access:PASS:ipv6:4855/100=48
test_xdp:PASS:ipv4:240198/100=2401 test_xdp:PASS:ipv4:138912/100=1389
test_xdp:PASS:ipv6:137326/100=1373 test_xdp:PASS:ipv6:68542/100=685
test_l4lb:PASS:ipv4:61100/100=611 test_l4lb:PASS:ipv4:37302/100=373
test_l4lb:PASS:ipv6:101000/100=1010 test_l4lb:PASS:ipv6:55030/100=550
c:jit_enable=1 and jit_harden=2
test_pkt_access:PASS:ipv4:10558/100=105
test_pkt_access:PASS:ipv6:5092/100=50
test_xdp:PASS:ipv4:131902/100=1319
test_xdp:PASS:ipv6:77932/100=779
test_l4lb:PASS:ipv4:38924/100=389
test_l4lb:PASS:ipv6:57520/100=575
The numbers show we get 30%~50% improvement.
See Documentation/networking/filter.txt for more information.
Changelog:
Changes v5-v6:
1:Add do {} while (0) to RETPOLINE_RAX_BPF_JIT for
consistence reason.
2:Clean up non-standard comments, reported by Daniel Borkmann.
3:Fix a memory leak issue, repoted by Daniel Borkmann.
Changes v4-v5:
1:Delete is_on_stack, BPF_REG_AX is the only one
on real hardware registers, so just check with
it.
2:Apply commit 1612a981b7 ("bpf, x64: fix JIT emission
for dead code"), suggested by Daniel Borkmann.
Changes v3-v4:
1:Fix changelog in commit.
I install llvm-6.0, then test_progs willn't report errors.
I submit another patch:
"bpf: fix misaligned access for BPF_PROG_TYPE_PERF_EVENT program type on x86_32 platform"
to fix another problem, after that patch, test_verifier willn't report errors too.
2:Fix clear r0[1] twice unnecessarily in *BPF_IND|BPF_ABS* simulation.
Changes v2-v3:
1:Move BPF_REG_AX to real hardware registers for performance reason.
3:Using bpf_load_pointer instead of bpf_jit32.S, suggested by Daniel Borkmann.
4:Delete partial codes in 1c2a088a66, suggested by Daniel Borkmann.
5:Some bug fixes and comments improvement.
Changes v1-v2:
1:Fix bug in emit_ia32_neg64.
2:Fix bug in emit_ia32_arsh_r64.
3:Delete filename in top level comment, suggested by Thomas Gleixner.
4:Delete unnecessary boiler plate text, suggested by Thomas Gleixner.
5:Rewrite some words in changelog.
6:CodingSytle improvement and a little more comments.
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Several documents in Documentation/vm fit quite well into the "admin/user
guide" category. The documents that don't overload the reader with lots of
implementation details and provide coherent description of certain feature
can be moved to Documentation/admin-guide/mm.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Mike Rapoport says:
These patches convert files in Documentation/vm to ReST format, add an
initial index and link it to the top level documentation.
There are no contents changes in the documentation, except few spelling
fixes. The relatively large diffstat stems from the indentation and
paragraph wrapping changes.
I've tried to keep the formatting as consistent as possible, but I could
miss some places that needed markup and add some markup where it was not
necessary.
[jc: significant conflicts in vm/hmm.rst]
fallback tunnels (like tunl0, gre0, gretap0, erspan0, sit0,
ip6tnl0, ip6gre0) are automatically created when the corresponding
module is loaded.
These tunnels are also automatically created when a new network
namespace is created, at a great cost.
In many cases, netns are used for isolation purposes, and these
extra network devices are a waste of resources. We are using
thousands of netns per host, and hit the netns creation/delete
bottleneck a lot. (Many thanks to Kirill for recent work on this)
Add a new sysctl so that we can opt-out from this automatic creation.
Note that these tunnels are still created for the initial namespace,
to be the least intrusive for typical setups.
Tested:
lpk43:~# cat add_del_unshare.sh
for i in `seq 1 40`
do
(for j in `seq 1 100` ; do unshare -n /bin/true >/dev/null ; done) &
done
wait
lpk43:~# echo 0 >/proc/sys/net/core/fb_tunnels_only_for_init_net
lpk43:~# time ./add_del_unshare.sh
real 0m37.521s
user 0m0.886s
sys 7m7.084s
lpk43:~# echo 1 >/proc/sys/net/core/fb_tunnels_only_for_init_net
lpk43:~# time ./add_del_unshare.sh
real 0m4.761s
user 0m0.851s
sys 1m8.343s
lpk43:~#
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull documentation updates from Jonathan Corbet:
"Documentation updates for 4.16.
New stuff includes refcount_t documentation, errseq documentation,
kernel-doc support for nested structure definitions, the removal of
lots of crufty kernel-doc support for unused formats, SPDX tag
documentation, the beginnings of a manual for subsystem maintainers,
and lots of fixes and updates.
As usual, some of the changesets reach outside of Documentation/ to
effect kerneldoc comment fixes. It also adds the new LICENSES
directory, of which Thomas promises I do not need to be the
maintainer"
* tag 'docs-4.16' of git://git.lwn.net/linux: (65 commits)
linux-next: docs-rst: Fix typos in kfigure.py
linux-next: DOC: HWPOISON: Fix path to debugfs in hwpoison.txt
Documentation: Fix misconversion of #if
docs: add index entry for networking/msg_zerocopy
Documentation: security/credentials.rst: explain need to sort group_list
LICENSES: Add MPL-1.1 license
LICENSES: Add the GPL 1.0 license
LICENSES: Add Linux syscall note exception
LICENSES: Add the MIT license
LICENSES: Add the BSD-3-clause "Clear" license
LICENSES: Add the BSD 3-clause "New" or "Revised" License
LICENSES: Add the BSD 2-clause "Simplified" license
LICENSES: Add the LGPL-2.1 license
LICENSES: Add the LGPL 2.0 license
LICENSES: Add the GPL 2.0 license
Documentation: Add license-rules.rst to describe how to properly identify file licenses
scripts: kernel_doc: better handle show warnings logic
fs/*/Kconfig: drop links to 404-compliant http://acl.bestbits.at
doc: md: Fix a file name to md-fault.c in fault-injection.txt
errseq: Add to documentation tree
...
Merge updates from Andrew Morton:
- misc fixes
- ocfs2 updates
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (118 commits)
mm: remove PG_highmem description
tools, vm: new option to specify kpageflags file
mm/swap.c: make functions and their kernel-doc agree
mm, memory_hotplug: fix memmap initialization
mm: correct comments regarding do_fault_around()
mm: numa: do not trap faults on shared data section pages.
hugetlb, mbind: fall back to default policy if vma is NULL
hugetlb, mempolicy: fix the mbind hugetlb migration
mm, hugetlb: further simplify hugetlb allocation API
mm, hugetlb: get rid of surplus page accounting tricks
mm, hugetlb: do not rely on overcommit limit during migration
mm, hugetlb: integrate giga hugetlb more naturally to the allocation path
mm, hugetlb: unify core page allocation accounting and initialization
mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes
mm/memcontrol.c: make local symbol static
mm/hmm: fix uninitialized use of 'entry' in hmm_vma_walk_pmd()
include/linux/mmzone.h: fix explanation of lower bits in the SPARSEMEM mem_map pointer
mm/compaction.c: fix comment for try_to_compact_pages()
mm/page_ext.c: make page_ext_init a noop when CONFIG_PAGE_EXTENSION but nothing uses it
zsmalloc: use U suffix for negative literals being shifted
...
hugepages_treat_as_movable has been introduced by 396faf0303 ("Allow
huge page allocations to use GFP_HIGH_MOVABLE") to allow hugetlb
allocations from ZONE_MOVABLE even when hugetlb pages were not
migrateable. The purpose of the movable zone was different at the time.
It aimed at reducing memory fragmentation and hugetlb pages being long
lived and large werre not contributing to the fragmentation so it was
acceptable to use the zone back then.
Things have changed though and the primary purpose of the zone became
migratability guarantee. If we allow non migrateable hugetlb pages to
be in ZONE_MOVABLE memory hotplug might fail to offline the memory.
Remove the knob and only rely on hugepage_migration_supported to allow
movable zones.
Mel said:
: Primarily it was aimed at allowing the hugetlb pool to safely shrink with
: the ability to grow it again. The use case was for batched jobs, some of
: which needed huge pages and others that did not but didn't want the memory
: useless pinned in the huge pages pool.
:
: I suspect that more users rely on THP than hugetlbfs for flexible use of
: huge pages with fallback options so I think that removing the option
: should be ok.
Link: http://lkml.kernel.org/r/20171003072619.8654-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Alexandru Moise <00moses.alexander00@gmail.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Alexandru Moise <00moses.alexander00@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently the behaviour of printk specifier %pK was changed. The
documentation does not currently mirror this.
Update documentation for sysctl kptr_restrict.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit ac1f591249 ("kernel/watchdog.c: add sysctl knob
hardlockup_panic") added the hardlockup_panic sysctl, but did not add it
to Documentation/sysctl/kernel.txt. Add this, and reference it from the
corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
Signed-off-by: Scott Wood <swood@redhat.com>
Acked-by: Christoph von Recklinghausen <crecklin@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This reverts commit 0f6d24f878 ("mm/page-writeback.c: print a warning
if the vm dirtiness settings are illogical") because it causes false
positive warnings during OOM situations as noticed by Tetsuo Handa:
Node 0 active_anon:3525940kB inactive_anon:8372kB active_file:216kB inactive_file:1872kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:2504kB dirty:52kB writeback:0kB shmem:8660kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 636928kB writeback_tmp:0kB unstable:0kB all_unreclaimable? yes
Node 0 DMA free:14848kB min:284kB low:352kB high:420kB active_anon:992kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15988kB managed:15904kB mlocked:0kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 2687 3645 3645
Node 0 DMA32 free:53004kB min:49608kB low:62008kB high:74408kB active_anon:2712648kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:3129216kB managed:2773132kB mlocked:0kB kernel_stack:96kB pagetables:5096kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
lowmem_reserve[]: 0 0 958 958
Node 0 Normal free:17140kB min:17684kB low:22104kB high:26524kB active_anon:812300kB inactive_anon:8372kB active_file:1228kB inactive_file:1868kB unevictable:0kB writepending:52kB present:1048576kB managed:981224kB mlocked:0kB kernel_stack:3520kB pagetables:8552kB bounce:0kB free_pcp:120kB local_pcp:120kB free_cma:0kB
lowmem_reserve[]: 0 0 0 0
[...]
Out of memory: Kill process 8459 (a.out) score 999 or sacrifice child
Killed process 8459 (a.out) total-vm:4180kB, anon-rss:88kB, file-rss:0kB, shmem-rss:0kB
oom_reaper: reaped process 8459 (a.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
vm direct limit must be set greater than background limit.
The problem is that both thresh and bg_thresh will be 0 if
available_memory is less than 4 pages when evaluating
global_dirtyable_memory.
While this might be worked around the whole point of the warning is
dubious at best. We do rely on admins to do sensible things when
changing tunable knobs. Dirty memory writeback knobs are not any
special in that regards so revert the warning rather than adding more
hacks to work this around.
Debugged by Yafang Shao.
Link: http://lkml.kernel.org/r/20171127091939.tahb77nznytcxw55@dhcp22.suse.cz
Fixes: 0f6d24f878 ("mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
