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commit 9fc9e278a5c0b708eeffaf47d6eb0c82aa74ed78 upstream.
Like oops_limit, add warn_limit for limiting the number of warnings when
panic_on_warn is not set.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit de92f65719cd672f4b48397540b9f9eff67eca40 upstream.
In preparation for keeping oops_limit logic in sync with warn_limit,
have oops_limit == 0 disable checking the Oops counter.
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit d4ccd54d28d3c8598e2354acc13e28c060961dbb upstream.
Many Linux systems are configured to not panic on oops; but allowing an
attacker to oops the system **really** often can make even bugs that look
completely unexploitable exploitable (like NULL dereferences and such) if
each crash elevates a refcount by one or a lock is taken in read mode, and
this causes a counter to eventually overflow.
The most interesting counters for this are 32 bits wide (like open-coded
refcounts that don't use refcount_t). (The ldsem reader count on 32-bit
platforms is just 16 bits, but probably nobody cares about 32-bit platforms
that much nowadays.)
So let's panic the system if the kernel is constantly oopsing.
The speed of oopsing 2^32 times probably depends on several factors, like
how long the stack trace is and which unwinder you're using; an empirically
important one is whether your console is showing a graphical environment or
a text console that oopses will be printed to.
In a quick single-threaded benchmark, it looks like oopsing in a vfork()
child with a very short stack trace only takes ~510 microseconds per run
when a graphical console is active; but switching to a text console that
oopses are printed to slows it down around 87x, to ~45 milliseconds per
run.
(Adding more threads makes this faster, but the actual oops printing
happens under &die_lock on x86, so you can maybe speed this up by a factor
of around 2 and then any further improvement gets eaten up by lock
contention.)
It looks like it would take around 8-12 days to overflow a 32-bit counter
with repeated oopsing on a multi-core X86 system running a graphical
environment; both me (in an X86 VM) and Seth (with a distro kernel on
normal hardware in a standard configuration) got numbers in that ballpark.
12 days aren't *that* short on a desktop system, and you'd likely need much
longer on a typical server system (assuming that people don't run graphical
desktop environments on their servers), and this is a *very* noisy and
violent approach to exploiting the kernel; and it also seems to take orders
of magnitude longer on some machines, probably because stuff like EFI
pstore will slow it down a ton if that's active.
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20221107201317.324457-1-jannh@google.com
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-2-keescook@chromium.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 069c4ea6871c18bd368f27756e0f91ffb524a788 upstream.
A semicolon was missing, and the almost-alphabetical-but-not ordering
was confusing, so regroup these by category instead.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 95e6060c20a7f5db60163274c5222a725ac118f9 upstream.
With tools like kbench9000 giving more finegrained responses, and this
basically never having been used ever since it was initially added,
let's just get rid of this. There *is* still work to be done on the
interrupt handler, but this really isn't the way it's being developed.
Cc: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 489c7fc44b5740d377e8cfdbf0851036e493af00 upstream.
Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up
entropy writers after every extraction. Therefore there's no point of
write_wakeup_threshold, so we can move it to the dustbin of unused
compatibility sysctls. While we're at it, we can fix a small comparison
where we were waking up after <= min rather than < min.
Cc: Theodore Ts'o <tytso@mit.edu>
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a1ff1de00db21ecb956213f046b79741b64c6b65 upstream.
Patch series "Some improvements on panic_print".
This is a mix of a documentation fix with some additions to the
"panic_print" syscall / parameter. The goal here is being able to collect
all CPUs backtraces during a panic event and also to enable "panic_print"
in a kdump event - details of the reasoning and design choices in the
patches.
This patch (of 3):
Commit de6da1e8bcf0 ("panic: add an option to replay all the printk
message in buffer") added a new bit to the sysctl/kernel parameter
"panic_print", but the documentation was added only in
kernel-parameters.txt, not in the sysctl guide.
Fix it here by adding bit 5 to sysctl admin-guide documentation.
[rdunlap@infradead.org: fix table format warning]
Link: https://lkml.kernel.org/r/20220109055635.6999-1-rdunlap@infradead.org
Link: https://lkml.kernel.org/r/20211109202848.610874-1-gpiccoli@igalia.com
Link: https://lkml.kernel.org/r/20211109202848.610874-2-gpiccoli@igalia.com
Fixes: de6da1e8bcf0 ("panic: add an option to replay all the printk message in buffer")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0f60a29c52b515532e6b11dc6b3c9e5b5f7ff2b4 upstream.
The file name: accounting/delay-accounting.rst
should be, instead: Documentation/accounting/delay-accounting.rst.
Also, there's no need to use doc:`foo`, as automarkup.py will
automatically handle plain text mentions to Documentation/
files.
So, update its cross-reference accordingly.
Fixes: fcb501704554 ("delayacct: Document task_delayacct sysctl")
Fixes: c3123552aad3 ("docs: accounting: convert to ReST")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge misc updates from Andrew Morton:
"191 patches.
Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
pagealloc, and memory-failure)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
mm,hwpoison: make get_hwpoison_page() call get_any_page()
mm,hwpoison: send SIGBUS with error virutal address
mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
docs: remove description of DISCONTIGMEM
arch, mm: remove stale mentions of DISCONIGMEM
mm: remove CONFIG_DISCONTIGMEM
m68k: remove support for DISCONTIGMEM
arc: remove support for DISCONTIGMEM
arc: update comment about HIGHMEM implementation
alpha: remove DISCONTIGMEM and NUMA
mm/page_alloc: move free_the_page
mm/page_alloc: fix counting of managed_pages
mm/page_alloc: improve memmap_pages dbg msg
mm: drop SECTION_SHIFT in code comments
mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
mm/page_alloc: scale the number of pages that are batch freed
...
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"watchdog/%u" threads has be replaced by cpu_stop_work. The current
description is extremely misleading.
Link: https://lkml.kernel.org/r/1619687073-24686-5-git-send-email-wangqing@vivo.com
Signed-off-by: Wang Qing <wangqing@vivo.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Qais Yousef <qais.yousef@arm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Santosh Sivaraj <santosh@fossix.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull documentation updates from Jonathan Corbet:
"This was a reasonably active cycle for documentation; this includes:
- Some kernel-doc cleanups. That script is still regex onslaught from
hell, but it has gotten a little better.
- Improvements to the checkpatch docs, which are also used by the
tool itself.
- A major update to the pathname lookup documentation.
- Elimination of :doc: markup, since our automarkup magic can create
references from filenames without all the extra noise.
- The flurry of Chinese translation activity continues.
Plus, of course, the usual collection of updates, typo fixes, and
warning fixes"
* tag 'docs-5.14' of git://git.lwn.net/linux: (115 commits)
docs: path-lookup: use bare function() rather than literals
docs: path-lookup: update symlink description
docs: path-lookup: update get_link() ->follow_link description
docs: path-lookup: update WALK_GET, WALK_PUT desc
docs: path-lookup: no get_link()
docs: path-lookup: update i_op->put_link and cookie description
docs: path-lookup: i_op->follow_link replaced with i_op->get_link
docs: path-lookup: Add macro name to symlink limit description
docs: path-lookup: remove filename_mountpoint
docs: path-lookup: update do_last() part
docs: path-lookup: update path_mountpoint() part
docs: path-lookup: update path_to_nameidata() part
docs: path-lookup: update follow_managed() part
docs: Makefile: Use CONFIG_SHELL not SHELL
docs: Take a little noise out of the build process
docs: x86: avoid using ReST :doc:`foo` markup
docs: virt: kvm: s390-pv-boot.rst: avoid using ReST :doc:`foo` markup
docs: userspace-api: landlock.rst: avoid using ReST :doc:`foo` markup
docs: trace: ftrace.rst: avoid using ReST :doc:`foo` markup
docs: trace: coresight: coresight.rst: avoid using ReST :doc:`foo` markup
...
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The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/12abd2290c7ebc05c89178d2556bea740bd70fac.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
"Networking fixes for 5.13-rc4, including fixes from bpf, netfilter,
can and wireless trees. Notably including fixes for the recently
announced "FragAttacks" WiFi vulnerabilities. Rather large batch,
touching some core parts of the stack, too, but nothing hair-raising.
Current release - regressions:
- tipc: make node link identity publish thread safe
- dsa: felix: re-enable TAS guard band mode
- stmmac: correct clocks enabled in stmmac_vlan_rx_kill_vid()
- stmmac: fix system hang if change mac address after interface
ifdown
Current release - new code bugs:
- mptcp: avoid OOB access in setsockopt()
- bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers
- ethtool: stats: fix a copy-paste error - init correct array size
Previous releases - regressions:
- sched: fix packet stuck problem for lockless qdisc
- net: really orphan skbs tied to closing sk
- mlx4: fix EEPROM dump support
- bpf: fix alu32 const subreg bound tracking on bitwise operations
- bpf: fix mask direction swap upon off reg sign change
- bpf, offload: reorder offload callback 'prepare' in verifier
- stmmac: Fix MAC WoL not working if PHY does not support WoL
- packetmmap: fix only tx timestamp on request
- tipc: skb_linearize the head skb when reassembling msgs
Previous releases - always broken:
- mac80211: address recent "FragAttacks" vulnerabilities
- mac80211: do not accept/forward invalid EAPOL frames
- mptcp: avoid potential error message floods
- bpf, ringbuf: deny reserve of buffers larger than ringbuf to
prevent out of buffer writes
- bpf: forbid trampoline attach for functions with variable arguments
- bpf: add deny list of functions to prevent inf recursion of tracing
programs
- tls splice: check SPLICE_F_NONBLOCK instead of MSG_DONTWAIT
- can: isotp: prevent race between isotp_bind() and
isotp_setsockopt()
- netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check,
fallback to non-AVX2 version
Misc:
- bpf: add kconfig knob for disabling unpriv bpf by default"
* tag 'net-5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (172 commits)
net: phy: Document phydev::dev_flags bits allocation
mptcp: validate 'id' when stopping the ADD_ADDR retransmit timer
mptcp: avoid error message on infinite mapping
mptcp: drop unconditional pr_warn on bad opt
mptcp: avoid OOB access in setsockopt()
nfp: update maintainer and mailing list addresses
net: mvpp2: add buffer header handling in RX
bnx2x: Fix missing error code in bnx2x_iov_init_one()
net: zero-initialize tc skb extension on allocation
net: hns: Fix kernel-doc
sctp: fix the proc_handler for sysctl encap_port
sctp: add the missing setting for asoc encap_port
bpf, selftests: Adjust few selftest result_unpriv outcomes
bpf: No need to simulate speculative domain for immediates
bpf: Fix mask direction swap upon off reg sign change
bpf: Wrap aux data inside bpf_sanitize_info container
bpf: Fix BPF_LSM kconfig symbol dependency
selftests/bpf: Add test for l3 use of bpf_redirect_peer
bpftool: Add sock_release help info for cgroup attach/prog load command
net: dsa: microchip: enable phy errata workaround on 9567
...
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Update sysctl/kernel.rst.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210512114035.GH3672@suse.de
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When I added CONFIG_MODPROBE_PATH, I neglected to update Documentation/.
It's still true that this defaults to /sbin/modprobe, but now via a level
of indirection. So document that the kernel might have been built with
something other than /sbin/modprobe as the initial value.
Link: https://lkml.kernel.org/r/20210420125324.1246826-1-linux@rasmusvillemoes.dk
Fixes: 17652f4240f7a ("modules: add CONFIG_MODPROBE_PATH")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It's been a few releases since this defaulted to /sbin/hotplug. Update
the text, and include pointers to the two CONFIG_UEVENT_HELPER{,_PATH}
config knobs whose help text could provide more info, but also hint
that the user probably doesn't need to care at all.
Fixes: 7934779a69f1 ("Driver-Core: disable /sbin/hotplug by default")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20210420120638.1104016-1-linux@rasmusvillemoes.dk
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.
This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.
We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.
Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
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Here's a patch updating the meaning of TAINT_CPU_OUT_OF_SPEC after
Borislav introduced changes in a7e1f67ed29f and upcoming patches in tip.
TAINT_CPU_OUT_OF_SPEC now means a bit more what it implies as the
flag isn't set just because of a CPU misconfiguration or mismatch.
Historically it was for SMP kernel oops on an officially SMP incapable
processor but now it also covers CPUs whose MSRs have been incorrectly
poked at from userspace, drivers being used on non supported
architectures, broken firmware, mismatched CPUs, ...
Update documentation and script to reflect that.
Signed-off-by: Mathieu Chouquet-Stringer <me@mathieu.digital>
Link: https://lore.kernel.org/r/20201202153244.709752-1-me@mathieu.digital
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Fix thirty five typos in dm-integrity.rst, dm-raid.rst, dm-zoned.rst,
verity.rst, writecache.rst, tsx_async_abort.rst, md.rst, bttv.rst,
dvb_references.rst, frontend-cardlist.rst, gspca-cardlist.rst, ipu3.rst,
remote-controller.rst, mm/index.rst, numaperf.rst, userfaultfd.rst,
module-signing.rst, imx-ddr.rst, intel-speed-select.rst,
intel_pstate.rst, ramoops.rst, abi.rst, kernel.rst, vm.rst
Signed-off-by: Andrew Klychkov <andrew.a.klychkov@gmail.com>
Link: https://lore.kernel.org/r/20201204072848.GA49895@spblnx124.lan
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This cleans up a few titles with extra colons, and removes the
reference to kernel 2.2. The docs don't yet cover *all* of 5.10 or
5.11, but I think they're close enough. Most entries are documented,
and have been checked against current kernels.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20201208074922.30359-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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The document reads "%e" should be "executable filename" while actually it
could be changed by things like pr_ctl PR_SET_NAME. People who uses "%e"
in core_pattern get surprised when they find out they get thread name
instead of executable filename.
This is either a bug of document or a bug of code. Since the behavior of
"%e" is there for long time, it could bring another surprise for users if
we "fix" the code.
So we just "fix" the document. And more, for users who really need the
"executable filename" in core_pattern, we introduce a new "%f" for the
real executable filename. We already have "%E" for executable path in
kernel, so just reuse most of its code for the new added "%f" format.
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200701031432.2978761-1-ytht.net@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull documentation updates from Jonathan Corbet:
"It's been a busy cycle for documentation - hopefully the busiest for a
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS
URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again
for a while. Unless we decide to switch to asciidoc or
something...:)
- Lots of typo fixes, warning fixes, and more"
* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
scripts/kernel-doc: optionally treat warnings as errors
docs: ia64: correct typo
mailmap: add entry for <alobakin@marvell.com>
doc/zh_CN: add cpu-load Chinese version
Documentation/admin-guide: tainted-kernels: fix spelling mistake
MAINTAINERS: adjust kprobes.rst entry to new location
devices.txt: document rfkill allocation
PCI: correct flag name
docs: filesystems: vfs: correct flag name
docs: filesystems: vfs: correct sync_mode flag names
docs: path-lookup: markup fixes for emphasis
docs: path-lookup: more markup fixes
docs: path-lookup: fix HTML entity mojibake
CREDITS: Replace HTTP links with HTTPS ones
docs: process: Add an example for creating a fixes tag
doc/zh_CN: add Chinese translation prefer section
doc/zh_CN: add clearing-warn-once Chinese version
doc/zh_CN: add admin-guide index
doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
futex: MAINTAINERS: Re-add selftests directory
...
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Uclamp exposes 3 sysctl knobs:
* sched_util_clamp_min
* sched_util_clamp_max
* sched_util_clamp_min_rt_default
Document them in sysctl/kernel.rst.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200716110347.19553-3-qais.yousef@arm.com
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Drop the doubled word "set".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/20200704032020.21923-12-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This documents the random directory, based on the behaviour seen in
drivers/char/random.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200623112514.10650-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Fix heading format warnings in admin-guide/sysctl/kernel.rst:
Documentation/admin-guide/sysctl/kernel.rst:339: WARNING: Title underline too short.
hung_task_all_cpu_backtrace:
================
Documentation/admin-guide/sysctl/kernel.rst:650: WARNING: Title underline too short.
oops_all_cpu_backtrace:
================
Fixes: 0ec9dc9bcba0 ("kernel/hung_task.c: introduce sysctl to print all traces when a hung task is detected")
Fixes: 60c958d8df9c ("panic: add sysctl to dump all CPUs backtraces on oops event")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/8af1cb77-4b5a-64b9-da5d-f6a95e537f99@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Usually when the kernel reaches an oops condition, it's a point of no
return; in case not enough debug information is available in the kernel
splat, one of the last resorts would be to collect a kernel crash dump
and analyze it. The problem with this approach is that in order to
collect the dump, a panic is required (to kexec-load the crash kernel).
When in an environment of multiple virtual machines, users may prefer to
try living with the oops, at least until being able to properly shutdown
their VMs / finish their important tasks.
This patch implements a way to collect a bit more debug details when an
oops event is reached, by printing all the CPUs backtraces through the
usage of NMIs (on architectures that support that). The sysctl added
(and documented) here was called "oops_all_cpu_backtrace", and when set
will (as the name suggests) dump all CPUs backtraces.
Far from ideal, this may be the last option though for users that for
some reason cannot panic on oops. Most of times oopses are clear enough
to indicate the kernel portion that must be investigated, but in virtual
environments it's possible to observe hypervisor/KVM issues that could
lead to oopses shown in other guests CPUs (like virtual APIC crashes).
This patch hence aims to help debug such complex issues without
resorting to kdump.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Link: http://lkml.kernel.org/r/20200327224116.21030-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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detected
Commit 401c636a0eeb ("kernel/hung_task.c: show all hung tasks before
panic") introduced a change in that we started to show all CPUs
backtraces when a hung task is detected _and_ the sysctl/kernel
parameter "hung_task_panic" is set. The idea is good, because usually
when observing deadlocks (that may lead to hung tasks), the culprit is
another task holding a lock and not necessarily the task detected as
hung.
The problem with this approach is that dumping backtraces is a slightly
expensive task, specially printing that on console (and specially in
many CPU machines, as servers commonly found nowadays). So, users that
plan to collect a kdump to investigate the hung tasks and narrow down
the deadlock definitely don't need the CPUs backtrace on dmesg/console,
which will delay the panic and pollute the log (crash tool would easily
grab all CPUs traces with 'bt -a' command).
Also, there's the reciprocal scenario: some users may be interested in
seeing the CPUs backtraces but not have the system panic when a hung
task is detected. The current approach hence is almost as embedding a
policy in the kernel, by forcing the CPUs backtraces' dump (only) on
hung_task_panic.
This patch decouples the panic event on hung task from the CPUs
backtraces dump, by creating (and documenting) a new sysctl called
"hung_task_all_cpu_backtrace", analog to the approach taken on soft/hard
lockups, that have both a panic and an "all_cpu_backtrace" sysctl to
allow individual control. The new mechanism for dumping the CPUs
backtraces on hung task detection respects "hung_task_warnings" by not
dumping the traces in case there's no warnings left.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200327223646.20779-1-gpiccoli@canonical.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Analogously to the introduction of panic_on_warn, this patch introduces
a kernel option named panic_on_taint in order to provide a simple and
generic way to stop execution and catch a coredump when the kernel gets
tainted by any given flag.
This is useful for debugging sessions as it avoids having to rebuild the
kernel to explicitly add calls to panic() into the code sites that
introduce the taint flags of interest.
For instance, if one is interested in proceeding with a post-mortem
analysis at the point a given code path is hitting a bad page (i.e.
unaccount_page_cache_page(), or slab_bug()), a coredump can be collected
by rebooting the kernel with 'panic_on_taint=0x20' amended to the
command line.
Another, perhaps less frequent, use for this option would be as a means
for assuring a security policy case where only a subset of taints, or no
single taint (in paranoid mode), is allowed for the running system. The
optional switch 'nousertaint' is handy in this particular scenario, as
it will avoid userspace induced crashes by writes to sysctl interface
/proc/sys/kernel/tainted causing false positive hits for such policies.
[akpm@linux-foundation.org: tweak kernel-parameters.txt wording]
Suggested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull documentation updates from Jonathan Corbet:
"A fair amount of stuff this time around, dominated by yet another
massive set from Mauro toward the completion of the RST conversion. I
*really* hope we are getting close to the end of this. Meanwhile,
those patches reach pretty far afield to update document references
around the tree; there should be no actual code changes there. There
will be, alas, more of the usual trivial merge conflicts.
Beyond that we have more translations, improvements to the sphinx
scripting, a number of additions to the sysctl documentation, and lots
of fixes"
* tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits)
Documentation: fixes to the maintainer-entry-profile template
zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst
tracing: Fix events.rst section numbering
docs: acpi: fix old http link and improve document format
docs: filesystems: add info about efivars content
Documentation: LSM: Correct the basic LSM description
mailmap: change email for Ricardo Ribalda
docs: sysctl/kernel: document unaligned controls
Documentation: admin-guide: update bug-hunting.rst
docs: sysctl/kernel: document ngroups_max
nvdimm: fixes to maintainter-entry-profile
Documentation/features: Correct RISC-V kprobes support entry
Documentation/features: Refresh the arch support status files
Revert "docs: sysctl/kernel: document ngroups_max"
docs: move locking-specific documents to locking/
docs: move digsig docs to the security book
docs: move the kref doc into the core-api book
docs: add IRQ documentation at the core-api book
docs: debugging-via-ohci1394.txt: add it to the core-api book
docs: fix references for ipmi.rst file
...
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This documents ignore-unaligned-usertrap, unaligned-dump-stack, and
unaligned-trap, based on arch/arc/kernel/unaligned.c,
arch/ia64/kernel/unaligned.c, and arch/parisc/kernel/unaligned.c.
While we're at it, integrate unaligned-memory-access.txt into the docs
tree.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200515212443.5012-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This is a read-only export of NGROUPS_MAX.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200518145836.15816-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This reverts commit 2f4c33063ad713e3a5b63002cf8362846e78bd71.
The changes here were fine, but there's a non-documentation change to
sysctl.c that makes messes elsewhere; those changes should have been done
independently.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This is a read-only export of NGROUPS_MAX, so this patch also changes
the declarations in kernel/sysctl.c to const.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200515160222.7994-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Based on the firmware fallback mechanisms documentation and the
implementation in drivers/base/firmware_loader/fallback.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200429205757.8677-2-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Based on the ftrace documentation, the tp_printk boot parameter
documentation, and the implementation in kernel/trace/trace.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200429205757.8677-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/4ac8f3a7edd4d817acf0d173ead7ef74fe010c6c.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Based on the implementation in kernel/sysctl.c (the proc_do_cad_pid()
function), kernel/reboot.c, and include/linux/sched/signal.h.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200423183651.15365-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Pull perf/core fixes and improvements from Arnaldo Carvalho de Melo:
kernel + tools/perf:
Alexey Budankov:
- Introduce CAP_PERFMON to kernel and user space.
callchains:
Adrian Hunter:
- Allow using Intel PT to synthesize callchains for regular events.
Kan Liang:
- Stitch LBR records from multiple samples to get deeper backtraces,
there are caveats, see the csets for details.
perf script:
Andreas Gerstmayr:
- Add flamegraph.py script
BPF:
Jiri Olsa:
- Synthesize bpf_trampoline/dispatcher ksymbol events.
perf stat:
Arnaldo Carvalho de Melo:
- Honour --timeout for forked workloads.
Stephane Eranian:
- Force error in fallback on :k events, to avoid counting nothing when
the user asks for kernel events but is not allowed to.
perf bench:
Ian Rogers:
- Add event synthesis benchmark.
tools api fs:
Stephane Eranian:
- Make xxx__mountpoint() more scalable
libtraceevent:
He Zhe:
- Handle return value of asprintf.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Based on the implementation in kernel/bpf/syscall.c,
kernel/bpf/trampoline.c, include/linux/filter.h, and the documentation
in bpftool-prog.rst.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200315122648.20558-1-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Update the kernel.rst documentation file with the information related to
usage of CAP_PERFMON capability to secure performance monitoring and
observability operations in system.
Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Igor Lubashev <ilubashe@akamai.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: intel-gfx@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org
Cc: linux-man@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: selinux@vger.kernel.org
Link: http://lore.kernel.org/lkml/84c32383-14a2-fa35-16b6-f9e59bd37240@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Documentation for the kernel.modprobe sysctl was added both by
commit 0317c5371e6a ("docs: merge debugging-modules.txt into
sysctl/kernel.rst") and by commit 6e7158250625 ("docs: admin-guide:
document the kernel.modprobe sysctl"), resulting in the same sysctl
being documented in two places. Merge these into one place.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20200414172430.230293-1-ebiggers@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Document the kernel.modprobe sysctl in the same place that all the other
kernel.* sysctls are documented. Make sure to mention how to use this
sysctl to completely disable module autoloading, and how this sysctl
relates to CONFIG_STATIC_USERMODEHELPER.
[ebiggers@google.com: v5]
Link: http://lkml.kernel.org/r/20200318230515.171692-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: NeilBrown <neilb@suse.com>
Link: http://lkml.kernel.org/r/20200312202552.241885-4-ebiggers@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the
softlockup_panic sysctl, but didn't add information about it to the file
Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly
wasn't rst and had other name!).
This patch just adds the respective documentation and references it from
the corresponding entry in Documentation/admin-guide/kernel-parameters.txt.
This patch was strongly based on Scott Wood's commit d22881dc13b6
("Documentation: Better document the hardlockup_panic sysctl").
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Link: https://lore.kernel.org/r/20200310183649.23163-1-gpiccoli@canonical.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This script allows sysctl documentation to be checked against the
kernel source code, to identify missing or obsolete entries. Running
it against 5.5 shows for example that sysctl/kernel.rst has two
obsolete entries and is missing 52 entries.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Based on the implementation in arch/x86/kernel/acpi/sleep.c, in
particular the acpi_sleep_setup() function.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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These have no corresponding code in the kernel.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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The description of panic doesn’t cover all the supported scenarios;
this patch fixes that, describing the three possibilities (no reboot,
immediate reboot, reboot after a delay).
Based on the implementation in kernel/panic.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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This describes the SPARC-specific stop-a sysctl entry, which was
previously listed in kernel.rst but not documented.
Base on the implementation in arch/sparc/kernel/setup_{32,64}.c and
kernel/panic.c.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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