Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
Writing the current state back in hotplug/target calls cpu_down()
which will set cpu dying even when it isn't and then nothing will
ever clear it. A stress test that reads values and writes them back
for all cpu device files in sysfs will trigger the BUG() in
select_fallback_rq once all cpus are marked as dying.
kernel/cpu.c::target_store()
...
if (st->state < target)
ret = cpu_up(dev->id, target);
else
ret = cpu_down(dev->id, target);
cpu_down() -> cpu_set_state()
bool bringup = st->state < target;
...
if (cpu_dying(cpu) != !bringup)
set_cpu_dying(cpu, !bringup);
Fix this by letting state==target fall through in the target_store()
conditional. Also make sure st->target == target in that case.
Fixes: 757c989b99 ("cpu/hotplug: Make target state writeable")
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20221117162329.3164999-2-pauld@redhat.com
Pull Intel TDX support from Borislav Petkov:
"Intel Trust Domain Extensions (TDX) support.
This is the Intel version of a confidential computing solution called
Trust Domain Extensions (TDX). This series adds support to run the
kernel as part of a TDX guest. It provides similar guest protections
to AMD's SEV-SNP like guest memory and register state encryption,
memory integrity protection and a lot more.
Design-wise, it differs from AMD's solution considerably: it uses a
software module which runs in a special CPU mode called (Secure
Arbitration Mode) SEAM. As the name suggests, this module serves as
sort of an arbiter which the confidential guest calls for services it
needs during its lifetime.
Just like AMD's SNP set, this series reworks and streamlines certain
parts of x86 arch code so that this feature can be properly
accomodated"
* tag 'x86_tdx_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
x86/tdx: Fix RETs in TDX asm
x86/tdx: Annotate a noreturn function
x86/mm: Fix spacing within memory encryption features message
x86/kaslr: Fix build warning in KASLR code in boot stub
Documentation/x86: Document TDX kernel architecture
ACPICA: Avoid cache flush inside virtual machines
x86/tdx/ioapic: Add shared bit for IOAPIC base address
x86/mm: Make DMA memory shared for TD guest
x86/mm/cpa: Add support for TDX shared memory
x86/tdx: Make pages shared in ioremap()
x86/topology: Disable CPU online/offline control for TDX guests
x86/boot: Avoid #VE during boot for TDX platforms
x86/boot: Set CR0.NE early and keep it set during the boot
x86/acpi/x86/boot: Add multiprocessor wake-up support
x86/boot: Add a trampoline for booting APs via firmware handoff
x86/tdx: Wire up KVM hypercalls
x86/tdx: Port I/O: Add early boot support
x86/tdx: Port I/O: Add runtime hypercalls
x86/boot: Port I/O: Add decompression-time support for TDX
x86/boot: Port I/O: Allow to hook up alternative helpers
...
Rather than waiting until a CPU is first brought online, do the
initialisation of the cpuhp_cpu_state structure for each CPU during the
__init phase. This saves a (small) amount of non-__init memory and
avoids potential confusion about when the cpuhp_cpu_state struct is
valid.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220411152233.474129-3-steven.price@arm.com
Currently the setting of the 'cpu' member of struct cpuhp_cpu_state in
cpuhp_create() is too late as it is used earlier in _cpu_up().
If kzalloc_node() in __smpboot_create_thread() fails then the rollback will
be done with st->cpu==0 causing CPU0 to be erroneously set to be dying,
causing the scheduler to get mightily confused and throw its toys out of
the pram.
However the cpu number is actually available directly, so simply remove
the 'cpu' member and avoid the problem in the first place.
Fixes: 2ea46c6fc9 ("cpumask/hotplug: Fix cpu_dying() state tracking")
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220411152233.474129-2-steven.price@arm.com
Unlike regular VMs, TDX guests use the firmware hand-off wakeup method
to wake up the APs during the boot process. This wakeup model uses a
mailbox to communicate with firmware to bring up the APs. As per the
design, this mailbox can only be used once for the given AP, which means
after the APs are booted, the same mailbox cannot be used to
offline/online the given AP. More details about this requirement can be
found in Intel TDX Virtual Firmware Design Guide, sec titled "AP
initialization in OS" and in sec titled "Hotplug Device".
Since the architecture does not support any method of offlining the
CPUs, disable CPU hotplug support in the kernel.
Since this hotplug disable feature can be re-used by other VM guests,
add a new CC attribute CC_ATTR_HOTPLUG_DISABLED and use it to disable
the hotplug support.
Attempt to offline CPU will fail with -EOPNOTSUPP.
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20220405232939.73860-25-kirill.shutemov@linux.intel.com
Pull scheduler updates from Ingo Molnar:
- Cleanups for SCHED_DEADLINE
- Tracing updates/fixes
- CPU Accounting fixes
- First wave of changes to optimize the overhead of the scheduler
build, from the fast-headers tree - including placeholder *_api.h
headers for later header split-ups.
- Preempt-dynamic using static_branch() for ARM64
- Isolation housekeeping mask rework; preperatory for further changes
- NUMA-balancing: deal with CPU-less nodes
- NUMA-balancing: tune systems that have multiple LLC cache domains per
node (eg. AMD)
- Updates to RSEQ UAPI in preparation for glibc usage
- Lots of RSEQ/selftests, for same
- Add Suren as PSI co-maintainer
* tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits)
sched/headers: ARM needs asm/paravirt_api_clock.h too
sched/numa: Fix boot crash on arm64 systems
headers/prep: Fix header to build standalone: <linux/psi.h>
sched/headers: Only include <linux/entry-common.h> when CONFIG_GENERIC_ENTRY=y
cgroup: Fix suspicious rcu_dereference_check() usage warning
sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers
sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains
sched/deadline,rt: Remove unused parameter from pick_next_[rt|dl]_entity()
sched/deadline,rt: Remove unused functions for !CONFIG_SMP
sched/deadline: Use __node_2_[pdl|dle]() and rb_first_cached() consistently
sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy()
sched/deadline: Move bandwidth mgmt and reclaim functions into sched class source file
sched/deadline: Remove unused def_dl_bandwidth
sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE
sched/tracing: Don't re-read p->state when emitting sched_switch event
sched/rt: Plug rt_mutex_setprio() vs push_rt_task() race
sched/cpuacct: Remove redundant RCU read lock
sched/cpuacct: Optimize away RCU read lock
sched/cpuacct: Fix charge percpu cpuusage
sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies
...
For the irq randomness fast pool, rather than having to use expensive
atomics, which were visibly the most expensive thing in the entire irq
handler, simply take care of the extreme edge case of resetting count to
zero in the cpuhp online handler, just after workqueues have been
reenabled. This simplifies the code a bit and lets us use vanilla
variables rather than atomics, and performance should be improved.
As well, very early on when the CPU comes up, while interrupts are still
disabled, we clear out the per-cpu crng and its batches, so that it
always starts with fresh randomness.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
To hot unplug a CPU, the idle task on that CPU calls a few layers of C
code before finally leaving the kernel. When KASAN is in use, poisoned
shadow is left around for each of the active stack frames, and when
shadow call stacks are in use. When shadow call stacks (SCS) are in use
the task's saved SCS SP is left pointing at an arbitrary point within
the task's shadow call stack.
When a CPU is offlined than onlined back into the kernel, this stale
state can adversely affect execution. Stale KASAN shadow can alias new
stackframes and result in bogus KASAN warnings. A stale SCS SP is
effectively a memory leak, and prevents a portion of the shadow call
stack being used. Across a number of hotplug cycles the idle task's
entire shadow call stack can become unusable.
We previously fixed the KASAN issue in commit:
e1b77c9298 ("sched/kasan: remove stale KASAN poison after hotplug")
... by removing any stale KASAN stack poison immediately prior to
onlining a CPU.
Subsequently in commit:
f1a0a376ca ("sched/core: Initialize the idle task with preemption disabled")
... the refactoring left the KASAN and SCS cleanup in one-time idle
thread initialization code rather than something invoked prior to each
CPU being onlined, breaking both as above.
We fixed SCS (but not KASAN) in commit:
63acd42c0d ("sched/scs: Reset the shadow stack when idle_task_exit")
... but as this runs in the context of the idle task being offlined it's
potentially fragile.
To fix these consistently and more robustly, reset the SCS SP and KASAN
shadow of a CPU's idle task immediately before we online that CPU in
bringup_cpu(). This ensures the idle task always has a consistent state
when it is running, and removes the need to so so when exiting an idle
task.
Whenever any thread is created, dup_task_struct() will give the task a
stack which is free of KASAN shadow, and initialize the task's SCS SP,
so there's no need to specially initialize either for idle thread within
init_idle(), as this was only necessary to handle hotplug cycles.
I've tested this on arm64 with:
* gcc 11.1.0, defconfig +KASAN_INLINE, KASAN_STACK
* clang 12.0.0, defconfig +KASAN_INLINE, KASAN_STACK, SHADOW_CALL_STACK
... offlining and onlining CPUS with:
| while true; do
| for C in /sys/devices/system/cpu/cpu*/online; do
| echo 0 > $C;
| echo 1 > $C;
| done
| done
Fixes: f1a0a376ca ("sched/core: Initialize the idle task with preemption disabled")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Qian Cai <quic_qiancai@quicinc.com>
Link: https://lore.kernel.org/lkml/20211115113310.35693-1-mark.rutland@arm.com/
CPU hotplug callbacks can fail and cause a rollback to the previous
state. These failures are silent and therefore hard to debug.
Add pr_debug() to the up and down paths which provide information about the
error code, the CPU and the failed state. The debug printks can be enabled
via kernel command line or sysfs.
[ tglx: Adopt to current mainline, massage printk and changelog ]
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
Link: https://lore.kernel.org/r/20210409055316.1709-1-dongli.zhang@oracle.com
kernel/cpu.c:57: warning: cannot understand function prototype: 'struct cpuhp_cpu_state '
kernel/cpu.c:115: warning: cannot understand function prototype: 'struct cpuhp_step '
kernel/cpu.c:146: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* cpuhp_invoke_callback _ Invoke the callbacks for a given state
kernel/cpu.c:75: warning: Function parameter or member 'fail' not described in 'cpuhp_cpu_state'
kernel/cpu.c:75: warning: Function parameter or member 'cpu' not described in 'cpuhp_cpu_state'
kernel/cpu.c:75: warning: Function parameter or member 'node' not described in 'cpuhp_cpu_state'
kernel/cpu.c:75: warning: Function parameter or member 'last' not described in 'cpuhp_cpu_state'
kernel/cpu.c:130: warning: Function parameter or member 'list' not described in 'cpuhp_step'
kernel/cpu.c:130: warning: Function parameter or member 'multi_instance' not described in 'cpuhp_step'
kernel/cpu.c:158: warning: No description found for return value of 'cpuhp_invoke_callback'
kernel/cpu.c:1188: warning: No description found for return value of 'cpu_device_down'
kernel/cpu.c:1400: warning: No description found for return value of 'cpu_device_up'
kernel/cpu.c:1425: warning: No description found for return value of 'bringup_hibernate_cpu'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210809223825.24512-1-rdunlap@infradead.org
Pull CPU hotplug fix from Thomas Gleixner:
"A fix for the CPU hotplug and cpusets interaction:
cpusets delegate the hotplug work to a workqueue to prevent a lock
order inversion vs. the CPU hotplug lock. The work is not flushed
before the hotplug operation returns which creates user visible
inconsistent state. Prevent this by flushing the work after dropping
CPU hotplug lock and before releasing the outer mutex which serializes
the CPU hotplug related sysfs interface operations"
* tag 'smp-urgent-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu/hotplug: Cure the cpusets trainwreck
Alexey and Joshua tried to solve a cpusets related hotplug problem which is
user space visible and results in unexpected behaviour for some time after
a CPU has been plugged in and the corresponding uevent was delivered.
cpusets delegate the hotplug work (rebuilding cpumasks etc.) to a
workqueue. This is done because the cpusets code has already a lock
nesting of cgroups_mutex -> cpu_hotplug_lock. A synchronous callback or
waiting for the work to finish with cpu_hotplug_lock held can and will
deadlock because that results in the reverse lock order.
As a consequence the uevent can be delivered before cpusets have consistent
state which means that a user space invocation of sched_setaffinity() to
move a task to the plugged CPU fails up to the point where the scheduled
work has been processed.
The same is true for CPU unplug, but that does not create user observable
failure (yet).
It's still inconsistent to claim that an operation is finished before it
actually is and that's the real issue at hand. uevents just make it
reliably observable.
Obviously the problem should be fixed in cpusets/cgroups, but untangling
that is pretty much impossible because according to the changelog of the
commit which introduced this 8 years ago:
3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside get_online_cpus()")
the lock order cgroups_mutex -> cpu_hotplug_lock is a design decision and
the whole code is built around that.
So bite the bullet and invoke the relevant cpuset function, which waits for
the work to finish, in _cpu_up/down() after dropping cpu_hotplug_lock and
only when tasks are not frozen by suspend/hibernate because that would
obviously wait forever.
Waiting there with cpu_add_remove_lock, which is protecting the present
and possible CPU maps, held is not a problem at all because neither work
queues nor cpusets/cgroups have any lockchains related to that lock.
Waiting in the hotplug machinery is not problematic either because there
are already state callbacks which wait for hardware queues to drain. It
makes the operations slightly slower, but hotplug is slow anyway.
This ensures that state is consistent before returning from a hotplug
up/down operation. It's still inconsistent during the operation, but that's
a different story.
Add a large comment which explains why this is done and why this is not a
dump ground for the hack of the day to work around half thought out locking
schemes. Document also the implications vs. hotplug operations and
serialization or the lack of it.
Thanks to Alexy and Joshua for analyzing why this temporary
sched_setaffinity() failure happened.
Fixes: 3a5a6d0c2b03("cpuset: don't nest cgroup_mutex inside get_online_cpus()")
Reported-by: Alexey Klimov <aklimov@redhat.com>
Reported-by: Joshua Baker <jobaker@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexey Klimov <aklimov@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87tuowcnv3.ffs@nanos.tec.linutronix.de
Vincent reported that for states with a NULL startup/teardown function
we do not call cpuhp_invoke_callback() (because there is none) and as
such we'll not update the cpu_dying() state.
The stale cpu_dying() can eventually lead to triggering BUG().
Rectify this by updating cpu_dying() in the exact same places the
hotplug machinery tracks its directional state, namely
cpuhp_set_state() and cpuhp_reset_state().
Reported-by: Vincent Donnefort <vincent.donnefort@arm.com>
Suggested-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Donnefort <vincent.donnefort@arm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/YH7r+AoQEReSvxBI@hirez.programming.kicks-ass.net
Factorizing and unifying cpuhp callback range invocations, especially for
the hotunplug path, where two different ways of decrementing were used. The
first one, decrements before the callback is called:
cpuhp_thread_fun()
state = st->state;
st->state--;
cpuhp_invoke_callback(state);
The second one, after:
take_down_cpu()|cpuhp_down_callbacks()
cpuhp_invoke_callback(st->state);
st->state--;
This is problematic for rolling back the steps in case of error, as
depending on the decrement, the rollback will start from N or N-1. It also
makes tracing inconsistent, between steps run in the cpuhp thread and
the others.
Additionally, avoid useless cpuhp_thread_fun() loops by skipping empty
steps.
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210216103506.416286-4-vincent.donnefort@arm.com
The atomic states (between CPUHP_AP_IDLE_DEAD and CPUHP_AP_ONLINE) are
triggered by the CPUHP_BRINGUP_CPU step. If the latter fails, no atomic
state can be rolled back.
DEAD callbacks too can't fail and disallow recovery. As a consequence,
during hotunplug, the fail injection interface should prohibit all states
from CPUHP_BRINGUP_CPU to CPUHP_ONLINE.
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210216103506.416286-3-vincent.donnefort@arm.com
