The existing busy-polling mode, enabled by the SO_BUSY_POLL socket
option or system-wide using the /proc/sys/net/core/busy_read knob, is
an opportunistic. That means that if the NAPI context is not
scheduled, it will poll it. If, after busy-polling, the budget is
exceeded the busy-polling logic will schedule the NAPI onto the
regular softirq handling.
One implication of the behavior above is that a busy/heavy loaded NAPI
context will never enter/allow for busy-polling. Some applications
prefer that most NAPI processing would be done by busy-polling.
This series adds a new socket option, SO_PREFER_BUSY_POLL, that works
in concert with the napi_defer_hard_irqs and gro_flush_timeout
knobs. The napi_defer_hard_irqs and gro_flush_timeout knobs were
introduced in commit 6f8b12d661 ("net: napi: add hard irqs deferral
feature"), and allows for a user to defer interrupts to be enabled and
instead schedule the NAPI context from a watchdog timer. When a user
enables the SO_PREFER_BUSY_POLL, again with the other knobs enabled,
and the NAPI context is being processed by a softirq, the softirq NAPI
processing will exit early to allow the busy-polling to be performed.
If the application stops performing busy-polling via a system call,
the watchdog timer defined by gro_flush_timeout will timeout, and
regular softirq handling will resume.
In summary; Heavy traffic applications that prefer busy-polling over
softirq processing should use this option.
Example usage:
$ echo 2 | sudo tee /sys/class/net/ens785f1/napi_defer_hard_irqs
$ echo 200000 | sudo tee /sys/class/net/ens785f1/gro_flush_timeout
Note that the timeout should be larger than the userspace processing
window, otherwise the watchdog will timeout and fall back to regular
softirq processing.
Enable the SO_BUSY_POLL/SO_PREFER_BUSY_POLL options on your socket.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/bpf/20201130185205.196029-2-bjorn.topel@gmail.com
Randy Dunlap wrote:
> On 11/27/20 10:43 AM, Randy Dunlap wrote:
>
> > on parisc, _SA_SIGGFAULT is undefined and causing build errors.
> >
> > commit 23acdc76f1
> > Author: Peter Collingbourne <pcc@google.com>
> > Date: Thu Nov 12 18:53:34 2020 -0800
> >
> > signal: clear non-uapi flag bits when passing/returning sa_flags
> >
> >
> >
> > _SA_SIGGFAULT is not used or defined anywhere else in the
> > kernel source tree.
>
>
> Here is the build error (although it should be obvious):
>
> ../kernel/signal.c: In function 'do_sigaction':
> ../arch/parisc/include/asm/signal.h:24:30: error: '_SA_SIGGFAULT' undeclared (first use in this function)
> 24 | #define __ARCH_UAPI_SA_FLAGS _SA_SIGGFAULT
> | ^~~~~~~~~~~~~
Stephen Rothwell pointed out:
> _SA_SIGGFAULT was removed by commit
>
> 41f5a81c07 ("parisc: Drop HP-UX specific fcntl and signal flags")
>
> which was added to Linus' tree in v5.10-rc1.
Solve this by removing the the parisc specific definition of
__ARCH_UAPI_SA_FLAGS that was just added.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Fixes: 23acdc76f1 ("signal: clear non-uapi flag bits when passing/returning sa_flags")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Previously we were not clearing non-uapi flag bits in
sigaction.sa_flags when storing the userspace-provided sa_flags or
when returning them via oldact. Start doing so.
This allows userspace to detect missing support for flag bits and
allows the kernel to use non-uapi bits internally, as we are already
doing in arch/x86 for two flag bits. Now that this change is in
place, we no longer need the code in arch/x86 that was hiding these
bits from userspace, so remove it.
This is technically a userspace-visible behavior change for sigaction, as
the unknown bits returned via oldact.sa_flags are no longer set. However,
we are free to define the behavior for unknown bits exactly because
their behavior is currently undefined, so for now we can define the
meaning of each of them to be "clear the bit in oldact.sa_flags unless
the bit becomes known in the future". Furthermore, this behavior is
consistent with OpenBSD [1], illumos [2] and XNU [3] (FreeBSD [4] and
NetBSD [5] fail the syscall if unknown bits are set). So there is some
precedent for this behavior in other kernels, and in particular in XNU,
which is probably the most popular kernel among those that I looked at,
which means that this change is less likely to be a compatibility issue.
Link: [1] f634a6a4b5/sys/kern/kern_sig.c (L278)
Link: [2] 76f19f5fdc/usr/src/uts/common/syscall/sigaction.c (L86)
Link: [3] a449c6a3b8/bsd/kern/kern_sig.c (L480)
Link: [4] eded70c370/sys/kern/kern_sig.c (L699)
Link: [5] 3365779bec/sys/kern/sys_sig.c (L473)
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://linux-review.googlesource.com/id/I35aab6f5be932505d90f3b3450c083b4db1eca86
Link: https://lkml.kernel.org/r/878dbcb5f47bc9b11881c81f745c0bef5c23f97f.1605235762.git.pcc@google.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Most architectures with the exception of alpha, mips, parisc and
sparc use the same values for these flags. Move their definitions into
asm-generic/signal-defs.h and allow the architectures with non-standard
values to override them. Also, document the non-standard flag values
in order to make it easier to add new generic flags in the future.
A consequence of this change is that on powerpc and x86, the constants'
values aside from SA_RESETHAND change signedness from unsigned
to signed. This is not expected to impact realistic use of these
constants. In particular the typical use of the constants where they
are or'ed together and assigned to sa_flags (or another int variable)
would not be affected.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://linux-review.googlesource.com/id/Ia3849f18b8009bf41faca374e701cdca36974528
Link: https://lkml.kernel.org/r/b6d0d1ec34f9ee93e1105f14f288fba5f89d1f24.1605235762.git.pcc@google.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
I believe we can and *should* drop this parisc-specific typedef for
__sighandler_t when compiling a 64-bit kernel. The reasons:
1. We don't have a 64-bit userspace yet, so nothing (on userspace side)
can break.
2. Inside the Linux kernel, this is only used in kernel/signal.c, in
function kernel_sigaction() where the signal handler is compared against
SIG_IGN. SIG_IGN is defined as (__sighandler_t)1), so only the pointers
are compared.
3. Even when a 64-bit userspace gets added at some point, I think
__sighandler_t should be defined what it is: a function pointer struct.
I compiled kernel/signal.c with and without the patch, and the produced code
is identical in both cases.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I21c43f21b264f339e3aa395626af838646f62d97
Link: https://lkml.kernel.org/r/a75b8eb7bb9eac1cf73fb119eb53e5892d6e9656.1605235762.git.pcc@google.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
On parisc we need to initialize the memory layout for the user stack at
process start time to a fixed size, which up until now was limited to
the size as given by CONFIG_MAX_STACK_SIZE_MB at compile time.
This hard limit was too small and showed problems when compiling
ruby2.7, qmlcachegen and some Qt packages.
This patch changes two things:
a) It increases the default maximum stack size to 100MB.
b) Users can modify the stack hard limit size with ulimit and then newly
forked processes will use the given stack size which can even be bigger
than the default 100MB.
Reported-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
We will not allow unitialized anon mmaps, but we need this define
to prevent build errors, e.g. the debian foot package.
Suggested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Use READ_ONCE() to check if spinlock is locked.
The other changes are cleanups.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Increase the number of lws locks to 256 entries (instead of 16) and
choose lock entry based on bits 3-11 (instead of 4-7) of the relevant
address. With this change we archieve more fine-grained locking in
futex syscalls and thus reduce the number of possible stalls.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Let the complier treat the pointers volatile to ensure that they get
accessed atomicly.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
This change allows the sync barrier instruction to be patched to a nop.
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
HPUX has separate NDELAY & NONBLOCK values. In the past we wanted to
be able to run HP-UX binaries natively on parisc Linux which is why
we defined O_NONBLOCK to 000200004 to distinguish NDELAY & NONBLOCK
bits.
But with 2 bits set in this bitmask we often ran into compatibility
issues with other Linux applications which often only test one bit (or
even compare the values).
To avoid such issues in the future, this patch changes O_NONBLOCK to
become 000200000. That way old programs will still be functional, and
for new programs we now have only one bit set.
Update the comment about SOCK_NONBLOCK too.
Signed-off-by: Helge Deller <deller@gmx.de>
Those flags are nowhere used in the Linux kernel and were added when we
still wanted to support HP-UX in a compat mode. Since we never will
support HP-UX, drop those flags.
Signed-off-by: Helge Deller <deller@gmx.de>
Pull compat quotactl cleanups from Al Viro:
"More Christoph's compat cleanups: quotactl(2)"
* 'work.quota-compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
quota: simplify the quotactl compat handling
compat: add a compat_need_64bit_alignment_fixup() helper
compat: lift compat_s64 and compat_u64 to <asm-generic/compat.h>
lift the compat_s64 and compat_u64 definitions into common code using the
COMPAT_FOR_U64_ALIGNMENT symbol for the x86 special case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All callers of these primitives will
* discard anything we might've copied in case of error
* ignore the csum value in case of error
* always pass 0xffffffff as the initial sum, so the
resulting csum value (in case of success, that is) will never be 0.
That suggest the following calling conventions:
* don't pass err_ptr - just return 0 on error.
* don't bother with zeroing destination, etc. in case of error
* don't pass the initial sum - just use 0xffffffff.
This commit does the minimal conversion in the instances of csum_and_copy_...();
the changes of actual asm code behind them are done later in the series.
Note that this asm code is often shared with csum_partial_copy_nocheck();
the difference is that csum_partial_copy_nocheck() passes 0 for initial
sum while csum_and_copy_..._user() pass 0xffffffff. Fortunately, we are
free to pass 0xffffffff in all cases and subsequent patches will use that
freedom without any special comments.
A part that could be split off: parisc and uml/i386 claimed to have
csum_and_copy_to_user() instances of their own, but those were identical
to the generic one, so we simply drop them. Not sure if it's worth
a separate commit...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
quite a few architectures have the same csum_partial_copy_nocheck() -
simply memcpy() the data and then return the csum of the copy.
hexagon, parisc, ia64, s390, um: explicitly spelled out that way.
arc, arm64, csky, h8300, m68k/nommu, microblaze, mips/GENERIC_CSUM, nds32,
nios2, openrisc, riscv, unicore32: end up picking the same thing spelled
out in lib/checksum.h (with varying amounts of perversions along the way).
everybody else (alpha, arm, c6x, m68k/mmu, mips/!GENERIC_CSUM, powerpc,
sh, sparc, x86, xtensa) have non-generic variants. For all except c6x
the declaration is in their asm/checksum.h. c6x uses the wrapper
from asm-generic/checksum.h that would normally lead to the lib/checksum.h
instance, but in case of c6x we end up using an asm function from arch/c6x
instead.
Screw that mess - have architectures with private instances define
_HAVE_ARCH_CSUM_AND_COPY in their asm/checksum.h and have the default
one right in net/checksum.h conditional on _HAVE_ARCH_CSUM_AND_COPY
*not* defined.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 1355c31eeb ("asm-generic: pgalloc: provide generic pmd_alloc_one()
and pmd_free_one()") converted parisc to use generic version of
pmd_alloc_one() but it missed the fact that parisc uses order-1 pages for
PMD.
Restore the original version of pmd_alloc_one() for parisc, just use
GFP_PGTABLE_KERNEL that implies __GFP_ZERO instead of GFP_KERNEL and
memset.
Fixes: 1355c31eeb ("asm-generic: pgalloc: provide generic pmd_alloc_one() and pmd_free_one()")
Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Tested-by: Meelis Roos <mroos@linux.ee>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lkml.kernel.org/r/9f2b5ebd-e4a4-0fa1-6cd3-4b9f6892d1ad@linux.ee
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull more parisc updates from Helge Deller:
- Oscar Carter contributed a patch which fixes parisc's usage of
dereference_function_descriptor() and thus will allow using the
-Wcast-function-type compiler option in the top-level Makefile
- Sven Schnelle fixed a bug in the SBA code to prevent crashes during
kexec
- John David Anglin provided implementations for __smp_store_release()
and __smp_load_acquire barriers() which avoids using the sync
assembler instruction and thus speeds up barrier paths
- Some whitespace cleanups in parisc's atomic.h header file
* 'parisc-5.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: Implement __smp_store_release and __smp_load_acquire barriers
parisc: mask out enable and reserved bits from sba imask
parisc: Whitespace cleanups in atomic.h
parisc/kernel/ftrace: Remove function callback casts
sections.h: dereference_function_descriptor() returns void pointer
This patch implements the __smp_store_release and __smp_load_acquire barriers
using ordered stores and loads. This avoids the sync instruction present in
the generic implementation.
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Dave Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Pull locking updates from Thomas Gleixner:
"A set of locking fixes and updates:
- Untangle the header spaghetti which causes build failures in
various situations caused by the lockdep additions to seqcount to
validate that the write side critical sections are non-preemptible.
- The seqcount associated lock debug addons which were blocked by the
above fallout.
seqcount writers contrary to seqlock writers must be externally
serialized, which usually happens via locking - except for strict
per CPU seqcounts. As the lock is not part of the seqcount, lockdep
cannot validate that the lock is held.
This new debug mechanism adds the concept of associated locks.
sequence count has now lock type variants and corresponding
initializers which take a pointer to the associated lock used for
writer serialization. If lockdep is enabled the pointer is stored
and write_seqcount_begin() has a lockdep assertion to validate that
the lock is held.
Aside of the type and the initializer no other code changes are
required at the seqcount usage sites. The rest of the seqcount API
is unchanged and determines the type at compile time with the help
of _Generic which is possible now that the minimal GCC version has
been moved up.
Adding this lockdep coverage unearthed a handful of seqcount bugs
which have been addressed already independent of this.
While generally useful this comes with a Trojan Horse twist: On RT
kernels the write side critical section can become preemtible if
the writers are serialized by an associated lock, which leads to
the well known reader preempts writer livelock. RT prevents this by
storing the associated lock pointer independent of lockdep in the
seqcount and changing the reader side to block on the lock when a
reader detects that a writer is in the write side critical section.
- Conversion of seqcount usage sites to associated types and
initializers"
* tag 'locking-urgent-2020-08-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits)
locking/seqlock, headers: Untangle the spaghetti monster
locking, arch/ia64: Reduce <asm/smp.h> header dependencies by moving XTP bits into the new <asm/xtp.h> header
x86/headers: Remove APIC headers from <asm/smp.h>
seqcount: More consistent seqprop names
seqcount: Compress SEQCNT_LOCKNAME_ZERO()
seqlock: Fold seqcount_LOCKNAME_init() definition
seqlock: Fold seqcount_LOCKNAME_t definition
seqlock: s/__SEQ_LOCKDEP/__SEQ_LOCK/g
hrtimer: Use sequence counter with associated raw spinlock
kvm/eventfd: Use sequence counter with associated spinlock
userfaultfd: Use sequence counter with associated spinlock
NFSv4: Use sequence counter with associated spinlock
iocost: Use sequence counter with associated spinlock
raid5: Use sequence counter with associated spinlock
vfs: Use sequence counter with associated spinlock
timekeeping: Use sequence counter with associated raw spinlock
xfrm: policy: Use sequence counters with associated lock
netfilter: nft_set_rbtree: Use sequence counter with associated rwlock
netfilter: conntrack: Use sequence counter with associated spinlock
sched: tasks: Use sequence counter with associated spinlock
...
Pull regset conversion fix from Al Viro:
"Fix a regression from an unnoticed bisect hazard in the regset series.
A bunch of old (aout, originally) primitives used by coredumps became
dead code after fdpic conversion to regsets. Removal of that dead code
had been the first commit in the followups to regset series;
unfortunately, it happened to hide the bisect hazard on sh (extern for
fpregs_get() had not been updated in the main series when it should
have been; followup simply made fpregs_get() static). And without that
followup commit this bisect hazard became breakage in the mainline"
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
kill unused dump_fpu() instances
Patch series "mm: cleanup usage of <asm/pgalloc.h>"
Most architectures have very similar versions of pXd_alloc_one() and
pXd_free_one() for intermediate levels of page table. These patches add
generic versions of these functions in <asm-generic/pgalloc.h> and enable
use of the generic functions where appropriate.
In addition, functions declared and defined in <asm/pgalloc.h> headers are
used mostly by core mm and early mm initialization in arch and there is no
actual reason to have the <asm/pgalloc.h> included all over the place.
The first patch in this series removes unneeded includes of
<asm/pgalloc.h>
In the end it didn't work out as neatly as I hoped and moving
pXd_alloc_track() definitions to <asm-generic/pgalloc.h> would require
unnecessary changes to arches that have custom page table allocations, so
I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local
to mm/.
This patch (of 8):
In most cases <asm/pgalloc.h> header is required only for allocations of
page table memory. Most of the .c files that include that header do not
use symbols declared in <asm/pgalloc.h> and do not require that header.
As for the other header files that used to include <asm/pgalloc.h>, it is
possible to move that include into the .c file that actually uses symbols
from <asm/pgalloc.h> and drop the include from the header file.
The process was somewhat automated using
sed -i -E '/[<"]asm\/pgalloc\.h/d' \
$(grep -L -w -f /tmp/xx \
$(git grep -E -l '[<"]asm/pgalloc\.h'))
where /tmp/xx contains all the symbols defined in
arch/*/include/asm/pgalloc.h.
[rppt@linux.ibm.com: fix powerpc warning]
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We want to remove the #include <asm/io.h> from <asm/smp.h>, but for this
we have to move the XTP bits into a separate header first (as these bits
rely on <asm/io.h> definitions), and include them in the .c files that rely
on those APIs.
Co-developed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull parisc updates from Helge Deller:
"The majority of the patches are reverts of previous commits regarding
the parisc-specific low level spinlocking code and barrier handling,
with which we tried to fix CPU stalls on our build servers. In the end
John David Anglin found the culprit: We missed a define for
atomic64_set_release(). This seems to have fixed our issues, so now
it's good to remove the unnecessary code again.
Other than that it's trivial stuff: Spelling fixes, constifications
and such"
* 'parisc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: make the log level string for register dumps const
parisc: Do not use an ordered store in pa_tlb_lock()
Revert "parisc: Revert "Release spinlocks using ordered store""
Revert "parisc: Use ldcw instruction for SMP spinlock release barrier"
Revert "parisc: Drop LDCW barrier in CAS code when running UP"
Revert "parisc: Improve interrupt handling in arch_spin_lock_flags()"
parisc: Replace HTTP links with HTTPS ones
parisc: elf.h: delete a duplicated word
parisc: Report bad pages as HardwareCorrupted
parisc: Convert to BIT_MASK() and BIT_WORD()
Conflicts:
arch/arm/include/asm/percpu.h
As Stephen Rothwell noted, there's a conflict between this commit
in locking/core:
a21ee6055c ("lockdep: Change hardirq{s_enabled,_context} to per-cpu variables")
and this fresh upstream commit:
aa54ea903a ("ARM: percpu.h: fix build error")
a21ee6055c is a simpler solution to the dependency problem and doesn't
further increase header hell - so this conflict resolution effectively
reverts aa54ea903a and uses the a21ee6055c solution.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This reverts commit 9e5c602186.
No need to use the ldcw instruction as SMP spinlock release barrier.
Revert it to gain back speed again.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.2+
This reverts commit 2772f0efd5.
It turns out that we want to implement the spinlock code differently.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.7+
dump_fpu() is used only on the architectures that support elf
and have neither CORE_DUMP_USE_REGSET nor ELF_CORE_COPY_FPREGS
defined.
Currently that's csky, m68k, microblaze, nds32 and unicore32. The rest
of the instances are dead code.
NB: THIS MUST GO AFTER ELF_FDPIC CONVERSION
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Stalls are quite frequent with recent kernels. I enabled
CONFIG_SOFTLOCKUP_DETECTOR and I caught the following stall:
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [cc1:22803]
CPU: 0 PID: 22803 Comm: cc1 Not tainted 5.6.17+ #3
Hardware name: 9000/800/rp3440
IAOQ[0]: d_alloc_parallel+0x384/0x688
IAOQ[1]: d_alloc_parallel+0x388/0x688
RP(r2): d_alloc_parallel+0x134/0x688
Backtrace:
[<000000004036974c>] __lookup_slow+0xa4/0x200
[<0000000040369fc8>] walk_component+0x288/0x458
[<000000004036a9a0>] path_lookupat+0x88/0x198
[<000000004036e748>] filename_lookup+0xa0/0x168
[<000000004036e95c>] user_path_at_empty+0x64/0x80
[<000000004035d93c>] vfs_statx+0x104/0x158
[<000000004035dfcc>] __do_sys_lstat64+0x44/0x80
[<000000004035e5a0>] sys_lstat64+0x20/0x38
[<0000000040180054>] syscall_exit+0x0/0x14
The code was stuck in this loop in d_alloc_parallel:
4037d414: 0e 00 10 dc ldd 0(r16),ret0
4037d418: c7 fc 5f ed bb,< ret0,1f,4037d414 <d_alloc_parallel+0x384>
4037d41c: 08 00 02 40 nop
This is the inner loop of bit_spin_lock which is called by hlist_bl_unlock in
d_alloc_parallel:
static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
/*
* Assuming the lock is uncontended, this never enters
* the body of the outer loop. If it is contended, then
* within the inner loop a non-atomic test is used to
* busywait with less bus contention for a good time to
* attempt to acquire the lock bit.
*/
preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
preempt_enable();
do {
cpu_relax();
} while (test_bit(bitnum, addr));
preempt_disable();
}
#endif
__acquire(bitlock);
}
After consideration, I realized that we must be losing bit unlocks.
Then, I noticed that we missed defining atomic64_set_release().
Adding this define fixes the stalls in bit operations.
Signed-off-by: Dave Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
The kernel test bot reported[1] that using set_mask_bits on a u8 causes
the following issue on parisc:
hppa-linux-ld: drivers/phy/ti/phy-tusb1210.o: in function `tusb1210_probe':
>> (.text+0x2f4): undefined reference to `__cmpxchg_called_with_bad_pointer'
>> hppa-linux-ld: (.text+0x324): undefined reference to `__cmpxchg_called_with_bad_pointer'
hppa-linux-ld: (.text+0x354): undefined reference to `__cmpxchg_called_with_bad_pointer'
Add support for cmpxchg on u8 pointers.
[1] https://lore.kernel.org/patchwork/patch/1272617/#1468946
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Tested-by: Dave Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
