Pull printk updates from Petr Mladek:
"The big new thing is the fully lockless ringbuffer implementation,
including the support for continuous lines. It will allow to store and
read messages in any situation wihtout the risk of deadlocks and
without the need of temporary per-CPU buffers.
The access is still serialized by logbuf_lock. It synchronizes few
more operations, for example, temporary buffer for formatting the
message, syslog and kmsg_dump operations. The lock removal is being
discussed and should be ready for the next release.
The continuous lines are handled exactly the same way as before to
avoid regressions in user space. It means that they are appended to
the last message when the caller is the same. Only the last message
can be extended.
The data ring includes plain text of the messages. Except for an
integer at the beginning of each message that points back to the
descriptor ring with other metadata.
The dictionary has to stay. journalctl uses it to filter the log. It
allows to show messages related to a given device. The dictionary
values are stored in the descriptor ring with the other metadata.
This is the first part of the printk rework as discussed at Plumbers
2019, see https://lore.kernel.org/r/87k1acz5rx.fsf@linutronix.de. The
next big step will be handling consoles by kthreads during the normal
system operation. It will require special handling of situations when
the kthreads could not get scheduled, for example, early boot,
suspend, panic.
Other changes:
- Add John Ogness as a reviewer for printk subsystem. He is author of
the rework and is familiar with the code and history.
- Fix locking in serial8250_do_startup() to prevent lockdep report.
- Few code cleanups"
* tag 'printk-for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (27 commits)
printk: Use fallthrough pseudo-keyword
printk: reduce setup_text_buf size to LOG_LINE_MAX
printk: avoid and/or handle record truncation
printk: remove dict ring
printk: move dictionary keys to dev_printk_info
printk: move printk_info into separate array
printk: reimplement log_cont using record extension
printk: ringbuffer: add finalization/extension support
printk: ringbuffer: change representation of states
printk: ringbuffer: clear initial reserved fields
printk: ringbuffer: add BLK_DATALESS() macro
printk: ringbuffer: relocate get_data()
printk: ringbuffer: avoid memcpy() on state_var
printk: ringbuffer: fix setting state in desc_read()
kernel.h: Move oops_in_progress to printk.h
scripts/gdb: update for lockless printk ringbuffer
scripts/gdb: add utils.read_ulong()
docs: vmcoreinfo: add lockless printk ringbuffer vmcoreinfo
printk: reduce LOG_BUF_SHIFT range for H8300
printk: ringbuffer: support dataless records
...
I keep getting sparse warnings in crypto such as:
CHECK drivers/crypto/ccree/cc_hash.c
drivers/crypto/ccree/cc_hash.c:49:9: warning: cast truncates bits from constant value (47b5481dbefa4fa4 becomes befa4fa4)
drivers/crypto/ccree/cc_hash.c:49:26: warning: cast truncates bits from constant value (db0c2e0d64f98fa7 becomes 64f98fa7)
[.. many more ..]
This patch removes the warning by adding a mask to keep sparse
happy.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The documentation of the kstrto*() functions reference the simple_strtoull
function by "used as a replacement for [the obsolete] simple_strtoull".
All these functions describes themselves as replacements for the function
simple_strtoull, even though a function like kstrtol() would be more aptly
described as a replacement of simple_strtol().
Fix these references by making the documentation of kstrto*() reference
the closest simple_strto*() equivalent available. The functions
kstrto[u]int() do not have direct simple_strto[u]int() equivalences, so
these are made to refer to simple_strto[u]l() instead.
Furthermore, add parentheses after function names, as is standard in
kernel documentation.
Fixes: 4c925d6031 ("kstrto*: add documentation")
Signed-off-by: Kars Mulder <kerneldev@karsmulder.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Eldad Zack <eldad@fogrefinery.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Mans Rullgard <mans@mansr.com>
Cc: Petr Mladek <pmladek@suse.com>
Link: http://lkml.kernel.org/r/1ee1-5f234c00-f3-165a6440@234394593
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
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>
Some code pathes rely on preempt_disable() to prevent migration on a non RT
enabled kernel. These preempt_disable/enable() pairs are substituted by
migrate_disable/enable() pairs or other forms of RT specific protection. On
RT these protections prevent migration but not preemption. Obviously a
cant_sleep() check in such a section will trigger on RT because preemption
is not disabled.
Provide a cant_migrate() macro which maps to cant_sleep() on a non RT
kernel and an empty placeholder for RT for now. The placeholder will be
changed to a proper debug check along with the RT specific migration
protection mechanism.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200214161503.070487511@linutronix.de
Now that all callers of FIELD_SIZEOF() have been converted to
sizeof_field(), remove the unused prior macro.
Signed-off-by: Kees Cook <keescook@chromium.org>
In some special cases we must not block, but there's not a spinlock,
preempt-off, irqs-off or similar critical section already that arms the
might_sleep() debug checks. Add a non_block_start/end() pair to annotate
these.
This will be used in the oom paths of mmu-notifiers, where blocking is not
allowed to make sure there's forward progress. Quoting Michal:
"The notifier is called from quite a restricted context - oom_reaper -
which shouldn't depend on any locks or sleepable conditionals. The code
should be swift as well but we mostly do care about it to make a forward
progress. Checking for sleepable context is the best thing we could come
up with that would describe these demands at least partially."
Peter also asked whether we want to catch spinlocks on top, but Michal
said those are less of a problem because spinlocks can't have an indirect
dependency upon the page allocator and hence close the loop with the oom
reaper.
Suggested by Michal Hocko.
Link: https://lore.kernel.org/r/20190826201425.17547-4-daniel.vetter@ffwll.ch
Acked-by: Christian König <christian.koenig@amd.com> (v1)
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Pull in v5.1-rc6 to resolve two conflicts. One is in BFQ, in just a
comment, and is trivial. The other one is a conflict due to a later fix
in the bio multi-page work, and needs a bit more care.
* tag 'v5.1-rc6': (770 commits)
Linux 5.1-rc6
block: make sure that bvec length can't be overflow
block: kill all_q_node in request_queue
x86/cpu/intel: Lower the "ENERGY_PERF_BIAS: Set to normal" message's log priority
coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping
mm/kmemleak.c: fix unused-function warning
init: initialize jump labels before command line option parsing
kernel/watchdog_hld.c: hard lockup message should end with a newline
kcov: improve CONFIG_ARCH_HAS_KCOV help text
mm: fix inactive list balancing between NUMA nodes and cgroups
mm/hotplug: treat CMA pages as unmovable
proc: fixup proc-pid-vm test
proc: fix map_files test on F29
mm/vmstat.c: fix /proc/vmstat format for CONFIG_DEBUG_TLBFLUSH=y CONFIG_SMP=n
mm/memory_hotplug: do not unlock after failing to take the device_hotplug_lock
mm: swapoff: shmem_unuse() stop eviction without igrab()
mm: swapoff: take notice of completion sooner
mm: swapoff: remove too limiting SWAP_UNUSE_MAX_TRIES
mm: swapoff: shmem_find_swap_entries() filter out other types
slab: store tagged freelist for off-slab slabmgmt
...
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently support for 64-bit sector_t and blkcnt_t is optional on 32-bit
architectures. These types are required to support block device and/or
file sizes larger than 2 TiB, and have generally defaulted to on for
a long time. Enabling the option only increases the i386 tinyconfig
size by 145 bytes, and many data structures already always use
64-bit values for their in-core and on-disk data structures anyway,
so there should not be a large change in dynamic memory usage either.
Dropping this option removes a somewhat weird non-default config that
has cause various bugs or compiler warnings when actually used.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
