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Pull kvm updates from Paolo Bonzini:
"The biggest change here is eliminating the awful idea that KVM had of
essentially guessing which pfns are refcounted pages.
The reason to do so was that KVM needs to map both non-refcounted
pages (for example BARs of VFIO devices) and VM_PFNMAP/VM_MIXMEDMAP
VMAs that contain refcounted pages.
However, the result was security issues in the past, and more recently
the inability to map VM_IO and VM_PFNMAP memory that _is_ backed by
struct page but is not refcounted. In particular this broke virtio-gpu
blob resources (which directly map host graphics buffers into the
guest as "vram" for the virtio-gpu device) with the amdgpu driver,
because amdgpu allocates non-compound higher order pages and the tail
pages could not be mapped into KVM.
This requires adjusting all uses of struct page in the
per-architecture code, to always work on the pfn whenever possible.
The large series that did this, from David Stevens and Sean
Christopherson, also cleaned up substantially the set of functions
that provided arch code with the pfn for a host virtual addresses.
The previous maze of twisty little passages, all different, is
replaced by five functions (__gfn_to_page, __kvm_faultin_pfn, the
non-__ versions of these two, and kvm_prefetch_pages) saving almost
200 lines of code.
ARM:
- Support for stage-1 permission indirection (FEAT_S1PIE) and
permission overlays (FEAT_S1POE), including nested virt + the
emulated page table walker
- Introduce PSCI SYSTEM_OFF2 support to KVM + client driver. This
call was introduced in PSCIv1.3 as a mechanism to request
hibernation, similar to the S4 state in ACPI
- Explicitly trap + hide FEAT_MPAM (QoS controls) from KVM guests. As
part of it, introduce trivial initialization of the host's MPAM
context so KVM can use the corresponding traps
- PMU support under nested virtualization, honoring the guest
hypervisor's trap configuration and event filtering when running a
nested guest
- Fixes to vgic ITS serialization where stale device/interrupt table
entries are not zeroed when the mapping is invalidated by the VM
- Avoid emulated MMIO completion if userspace has requested
synchronous external abort injection
- Various fixes and cleanups affecting pKVM, vCPU initialization, and
selftests
LoongArch:
- Add iocsr and mmio bus simulation in kernel.
- Add in-kernel interrupt controller emulation.
- Add support for virtualization extensions to the eiointc irqchip.
PPC:
- Drop lingering and utterly obsolete references to PPC970 KVM, which
was removed 10 years ago.
- Fix incorrect documentation references to non-existing ioctls
RISC-V:
- Accelerate KVM RISC-V when running as a guest
- Perf support to collect KVM guest statistics from host side
s390:
- New selftests: more ucontrol selftests and CPU model sanity checks
- Support for the gen17 CPU model
- List registers supported by KVM_GET/SET_ONE_REG in the
documentation
x86:
- Cleanup KVM's handling of Accessed and Dirty bits to dedup code,
improve documentation, harden against unexpected changes.
Even if the hardware A/D tracking is disabled, it is possible to
use the hardware-defined A/D bits to track if a PFN is Accessed
and/or Dirty, and that removes a lot of special cases.
- Elide TLB flushes when aging secondary PTEs, as has been done in
x86's primary MMU for over 10 years.
- Recover huge pages in-place in the TDP MMU when dirty page logging
is toggled off, instead of zapping them and waiting until the page
is re-accessed to create a huge mapping. This reduces vCPU jitter.
- Batch TLB flushes when dirty page logging is toggled off. This
reduces the time it takes to disable dirty logging by ~3x.
- Remove the shrinker that was (poorly) attempting to reclaim shadow
page tables in low-memory situations.
- Clean up and optimize KVM's handling of writes to
MSR_IA32_APICBASE.
- Advertise CPUIDs for new instructions in Clearwater Forest
- Quirk KVM's misguided behavior of initialized certain feature MSRs
to their maximum supported feature set, which can result in KVM
creating invalid vCPU state. E.g. initializing PERF_CAPABILITIES to
a non-zero value results in the vCPU having invalid state if
userspace hides PDCM from the guest, which in turn can lead to
save/restore failures.
- Fix KVM's handling of non-canonical checks for vCPUs that support
LA57 to better follow the "architecture", in quotes because the
actual behavior is poorly documented. E.g. most MSR writes and
descriptor table loads ignore CR4.LA57 and operate purely on
whether the CPU supports LA57.
- Bypass the register cache when querying CPL from kvm_sched_out(),
as filling the cache from IRQ context is generally unsafe; harden
the cache accessors to try to prevent similar issues from occuring
in the future. The issue that triggered this change was already
fixed in 6.12, but was still kinda latent.
- Advertise AMD_IBPB_RET to userspace, and fix a related bug where
KVM over-advertises SPEC_CTRL when trying to support cross-vendor
VMs.
- Minor cleanups
- Switch hugepage recovery thread to use vhost_task.
These kthreads can consume significant amounts of CPU time on
behalf of a VM or in response to how the VM behaves (for example
how it accesses its memory); therefore KVM tried to place the
thread in the VM's cgroups and charge the CPU time consumed by that
work to the VM's container.
However the kthreads did not process SIGSTOP/SIGCONT, and therefore
cgroups which had KVM instances inside could not complete freezing.
Fix this by replacing the kthread with a PF_USER_WORKER thread, via
the vhost_task abstraction. Another 100+ lines removed, with
generally better behavior too like having these threads properly
parented in the process tree.
- Revert a workaround for an old CPU erratum (Nehalem/Westmere) that
didn't really work; there was really nothing to work around anyway:
the broken patch was meant to fix nested virtualization, but the
PERF_GLOBAL_CTRL MSR is virtualized and therefore unaffected by the
erratum.
- Fix 6.12 regression where CONFIG_KVM will be built as a module even
if asked to be builtin, as long as neither KVM_INTEL nor KVM_AMD is
'y'.
x86 selftests:
- x86 selftests can now use AVX.
Documentation:
- Use rST internal links
- Reorganize the introduction to the API document
Generic:
- Protect vcpu->pid accesses outside of vcpu->mutex with a rwlock
instead of RCU, so that running a vCPU on a different task doesn't
encounter long due to having to wait for all CPUs become quiescent.
In general both reads and writes are rare, but userspace that
supports confidential computing is introducing the use of "helper"
vCPUs that may jump from one host processor to another. Those will
be very happy to trigger a synchronize_rcu(), and the effect on
performance is quite the disaster"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (298 commits)
KVM: x86: Break CONFIG_KVM_X86's direct dependency on KVM_INTEL || KVM_AMD
KVM: x86: add back X86_LOCAL_APIC dependency
Revert "KVM: VMX: Move LOAD_IA32_PERF_GLOBAL_CTRL errata handling out of setup_vmcs_config()"
KVM: x86: switch hugepage recovery thread to vhost_task
KVM: x86: expose MSR_PLATFORM_INFO as a feature MSR
x86: KVM: Advertise CPUIDs for new instructions in Clearwater Forest
Documentation: KVM: fix malformed table
irqchip/loongson-eiointc: Add virt extension support
LoongArch: KVM: Add irqfd support
LoongArch: KVM: Add PCHPIC user mode read and write functions
LoongArch: KVM: Add PCHPIC read and write functions
LoongArch: KVM: Add PCHPIC device support
LoongArch: KVM: Add EIOINTC user mode read and write functions
LoongArch: KVM: Add EIOINTC read and write functions
LoongArch: KVM: Add EIOINTC device support
LoongArch: KVM: Add IPI user mode read and write function
LoongArch: KVM: Add IPI read and write function
LoongArch: KVM: Add IPI device support
LoongArch: KVM: Add iocsr and mmio bus simulation in kernel
KVM: arm64: Pass on SVE mapping failures
...
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kvm_vm_create_worker_thread() is meant to be used for kthreads that
can consume significant amounts of CPU time on behalf of a VM or in
response to how the VM behaves (for example how it accesses its memory).
Therefore it wants to charge the CPU time consumed by that work to
the VM's container.
However, because of these threads, cgroups which have kvm instances
inside never complete freezing. This can be trivially reproduced:
root@test ~# mkdir /sys/fs/cgroup/test
root@test ~# echo $$ > /sys/fs/cgroup/test/cgroup.procs
root@test ~# qemu-system-x86_64 -nographic -enable-kvm
and in another terminal:
root@test ~# echo 1 > /sys/fs/cgroup/test/cgroup.freeze
root@test ~# cat /sys/fs/cgroup/test/cgroup.events
populated 1
frozen 0
The cgroup freezing happens in the signal delivery path but
kvm_nx_huge_page_recovery_worker, while joining non-root cgroups, never
calls into the signal delivery path and thus never gets frozen. Because
the cgroup freezer determines whether a given cgroup is frozen by
comparing the number of frozen threads to the total number of threads
in the cgroup, the cgroup never becomes frozen and users waiting for
the state transition may hang indefinitely.
Since the worker kthread is tied to a user process, it's better if
it behaves similarly to user tasks as much as possible, including
being able to send SIGSTOP and SIGCONT. In fact, vhost_task is all
that kvm_vm_create_worker_thread() wanted to be and more: not only it
inherits the userspace process's cgroups, it has other niceties like
being parented properly in the process tree. Use it instead of the
homegrown alternative.
Incidentally, the new code is also better behaved when you flip recovery
back and forth to disabled and back to enabled. If your recovery period
is 1 minute, it will run the next recovery after 1 minute independent
of how many times you flipped the parameter.
(Commit message based on emails from Tejun).
Reported-by: Tejun Heo <tj@kernel.org>
Reported-by: Luca Boccassi <bluca@debian.org>
Acked-by: Tejun Heo <tj@kernel.org>
Tested-by: Luca Boccassi <bluca@debian.org>
Cc: stable@vger.kernel.org
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson into HEAD
LoongArch KVM changes for v6.13
1. Add iocsr and mmio bus simulation in kernel.
2. Add in-kernel interrupt controller emulation.
3. Add virt extension support for eiointc irqchip.
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Add device model for PCHPIC interrupt controller, implemente basic
create & destroy interface, and register device model to kvm device
table.
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add device model for EIOINTC interrupt controller, implement basic
create & destroy interfaces, and register device model to kvm device
table.
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add device model for IPI interrupt controller, implement basic create &
destroy interfaces, and register device model to kvm device table.
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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Add iocsr and mmio memory read and write simulation to the kernel. When
the VM accesses the device address space through iocsr instructions or
mmio, it does not need to return to the qemu user mode but can directly
completes the access in the kernel mode.
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 changes for 6.13, part #1
- Support for stage-1 permission indirection (FEAT_S1PIE) and
permission overlays (FEAT_S1POE), including nested virt + the
emulated page table walker
- Introduce PSCI SYSTEM_OFF2 support to KVM + client driver. This call
was introduced in PSCIv1.3 as a mechanism to request hibernation,
similar to the S4 state in ACPI
- Explicitly trap + hide FEAT_MPAM (QoS controls) from KVM guests. As
part of it, introduce trivial initialization of the host's MPAM
context so KVM can use the corresponding traps
- PMU support under nested virtualization, honoring the guest
hypervisor's trap configuration and event filtering when running a
nested guest
- Fixes to vgic ITS serialization where stale device/interrupt table
entries are not zeroed when the mapping is invalidated by the VM
- Avoid emulated MMIO completion if userspace has requested synchronous
external abort injection
- Various fixes and cleanups affecting pKVM, vCPU initialization, and
selftests
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* kvm-arm64/nv-pmu:
: Support for vEL2 PMU controls
:
: Align the vEL2 PMU support with the current state of non-nested KVM,
: including:
:
: - Trap routing, with the annoying complication of EL2 traps that apply
: in Host EL0
:
: - PMU emulation, using the correct configuration bits depending on
: whether a counter falls in the hypervisor or guest range of PMCs
:
: - Perf event swizzling across nested boundaries, as the event filtering
: needs to be remapped to cope with vEL2
KVM: arm64: nv: Reprogram PMU events affected by nested transition
KVM: arm64: nv: Apply EL2 event filtering when in hyp context
KVM: arm64: nv: Honor MDCR_EL2.HLP
KVM: arm64: nv: Honor MDCR_EL2.HPME
KVM: arm64: Add helpers to determine if PMC counts at a given EL
KVM: arm64: nv: Adjust range of accessible PMCs according to HPMN
KVM: arm64: Rename kvm_pmu_valid_counter_mask()
KVM: arm64: nv: Advertise support for FEAT_HPMN0
KVM: arm64: nv: Describe trap behaviour of MDCR_EL2.HPMN
KVM: arm64: nv: Honor MDCR_EL2.{TPM, TPMCR} in Host EL0
KVM: arm64: nv: Reinject traps that take effect in Host EL0
KVM: arm64: nv: Rename BEHAVE_FORWARD_ANY
KVM: arm64: nv: Allow coarse-grained trap combos to use complex traps
KVM: arm64: Describe RES0/RES1 bits of MDCR_EL2
arm64: sysreg: Add new definitions for ID_AA64DFR0_EL1
arm64: sysreg: Migrate MDCR_EL2 definition to table
arm64: sysreg: Describe ID_AA64DFR2_EL1 fields
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Start reprogramming PMU events at nested boundaries now that everything
is in place to handle the EL2 event filter. Only repaint events where
the filter differs between EL1 and EL2 as a slight optimization.
PMU now 'works' for nested VMs, albeit slow.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025182559.3364829-1-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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The value of MDCR_EL2.HPMN controls the number of event counters made
visible to EL0 and EL1. This means it is possible for the guest
hypervisor to allow direct access to event counters to the L2.
Rework KVM's PMU register emulation to take the effects of HPMN into
account when handling a trap. For bitmask-style registers, writes only
affect accessible registers.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025182354.3364124-14-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Nested PMU support requires dynamically changing the visible range of
PMU counters based on the exception level and value of MDCR_EL2.HPMN. At
the same time, the PMU emulation code needs to know the absolute number
of implemented counters, regardless of context.
Rename the existing helper to make it obvious that it returns the number
of implemented counters and not anything else.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025182354.3364124-13-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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MDCR_EL2.HPMN splits the PMU event counters into two ranges: the first
range is accessible from all ELs, and the second range is accessible
only to EL2/3. Supposing the guest hypervisor allows direct access to
the PMU counters from the L2, KVM needs to locally handle those
accesses.
Add a new complex trap configuration for HPMN that checks if the counter
index is accessible to the current context. As written, the architecture
suggests HPMN only causes PMEVCNTR<n>_EL0 to trap, though intuition (and
the pseudocode) suggest that the trap applies to PMEVTYPER<n>_EL0 as
well.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025182354.3364124-11-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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* kvm-arm64/psci-1.3:
: PSCI v1.3 support, courtesy of David Woodhouse
:
: Bump KVM's PSCI implementation up to v1.3, with the added bonus of
: implementing the SYSTEM_OFF2 call. Like other system-scoped PSCI calls,
: this gets relayed to userspace for further processing with a new
: KVM_SYSTEM_EVENT_SHUTDOWN flag.
:
: As an added bonus, implement client-side support for hibernation with
: the SYSTEM_OFF2 call.
arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate
KVM: arm64: nvhe: Pass through PSCI v1.3 SYSTEM_OFF2 call
KVM: selftests: Add test for PSCI SYSTEM_OFF2
KVM: arm64: Add support for PSCI v1.2 and v1.3
KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function for hibernation
firmware/psci: Add definitions for PSCI v1.3 specification
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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As with PSCI v1.1 in commit 512865d83fd9 ("KVM: arm64: Bump guest PSCI
version to 1.1"), expose v1.3 to the guest by default. The SYSTEM_OFF2
call which is exposed by doing so is compatible for userspace because
it's just a new flag in the event that KVM raises, in precisely the same
way that SYSTEM_RESET2 was compatible when v1.1 was enabled by default.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Link: https://lore.kernel.org/r/20241019172459.2241939-4-dwmw2@infradead.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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The v1.3 PSCI spec (https://developer.arm.com/documentation/den0022) adds
the SYSTEM_OFF2 function. Add definitions for it and its hibernation type
parameter.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Link: https://lore.kernel.org/r/20241019172459.2241939-2-dwmw2@infradead.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Accessing CNTHCTL_EL2 is fraught with danger if running with
HCR_EL2.E2H=1: half of the bits are held in CNTKCTL_EL1, and
thus can be changed behind our back, while the rest lives
in the CNTHCTL_EL2 shadow copy that is memory-based.
Yes, this is a lot of fun!
Make sure that we merge the two on read access, while we can
write to CNTKCTL_EL1 in a more straightforward manner.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-7-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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- Drop obsolete references to PPC970 KVM, which was removed 10 years ago.
- Fix incorrect references to non-existing ioctls
- List registers supported by KVM_GET/SET_ONE_REG on s390
- Use rST internal links
- Reorganize the introduction to the API document
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KVM generic changes for 6.13
- Rework kvm_vcpu_on_spin() to use a single for-loop instead of making two
partial poasses over "all" vCPUs. Opportunistically expand the comment
to better explain the motivation and logic.
- Protect vcpu->pid accesses outside of vcpu->mutex with a rwlock instead
of RCU, so that running a vCPU on a different task doesn't encounter
long stalls due to having to wait for all CPUs become quiescent.
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To avoid jitter on KVM_RUN due to synchronize_rcu(), use a rwlock instead
of RCU to protect vcpu->pid, a.k.a. the pid of the task last used to a
vCPU. When userspace is doing M:N scheduling of tasks to vCPUs, e.g. to
run SEV migration helper vCPUs during post-copy, the synchronize_rcu()
needed to change the PID associated with the vCPU can stall for hundreds
of milliseconds, which is problematic for latency sensitive post-copy
operations.
In the directed yield path, do not acquire the lock if it's contended,
i.e. if the associated PID is changing, as that means the vCPU's task is
already running.
Reported-by: Steve Rutherford <srutherford@google.com>
Reviewed-by: Steve Rutherford <srutherford@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240802200136.329973-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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KVM/riscv changes for 6.13
- Accelerate KVM RISC-V when running as a guest
- Perf support to collect KVM guest statistics from host side
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Now that KVM no longer relies on an ugly heuristic to find its struct page
references, i.e. now that KVM can't get false positives on VM_MIXEDMAP
pfns, remove KVM's hack to elevate the refcount for pfns that happen to
have a valid struct page. In addition to removing a long-standing wart
in KVM, this allows KVM to map non-refcounted struct page memory into the
guest, e.g. for exposing GPU TTM buffers to KVM guests.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-86-seanjc@google.com>
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Remove all kvm_{release,set}_pfn_*() APIs now that all users are gone.
No functional change intended.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-85-seanjc@google.com>
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Drop gfn_to_pfn() and all its variants now that all users are gone.
No functional change intended.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-80-seanjc@google.com>
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Rework gfn_to_page() to support read-only accesses so that it can be used
by arm64 to get MTE tags out of guest memory.
Opportunistically rewrite the comment to be even more stern about using
gfn_to_page(), as there are very few scenarios where requiring a struct
page is actually the right thing to do (though there are such scenarios).
Add a FIXME to call out that KVM probably should be pinning pages, not
just getting pages.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-77-seanjc@google.com>
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Move KVM x86's helper that "finishes" the faultin process to common KVM
so that the logic can be shared across all architectures. Note, not all
architectures implement a fast page fault path, but the gist of the
comment applies to all architectures.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-50-seanjc@google.com>
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Provide the "struct page" associated with a guest_memfd pfn as an output
from __kvm_gmem_get_pfn() so that KVM guest page fault handlers can
directly put the page instead of having to rely on
kvm_pfn_to_refcounted_page().
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-47-seanjc@google.com>
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Add a new dedicated API, kvm_faultin_pfn(), for servicing guest page
faults, i.e. for getting pages/pfns that will be mapped into the guest via
an mmu_notifier-protected KVM MMU. Keep struct kvm_follow_pfn buried in
internal code, as having __kvm_faultin_pfn() take "out" params is actually
cleaner for several architectures, e.g. it allows the caller to have its
own "page fault" structure without having to marshal data to/from
kvm_follow_pfn.
Long term, common KVM would ideally provide a kvm_page_fault structure, a
la x86's struct of the same name. But all architectures need to be
converted to a common API before that can happen.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-44-seanjc@google.com>
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Move the memslot lookup helpers further up in kvm_host.h so that they can
be used by inlined "to pfn" wrappers.
No functional change intended.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-43-seanjc@google.com>
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Now that all kvm_vcpu_{,un}map() users pass "true" for @dirty, have them
pass "true" as a @writable param to kvm_vcpu_map(), and thus create a
read-only mapping when possible.
Note, creating read-only mappings can be theoretically slower, as they
don't play nice with fast GUP due to the need to break CoW before mapping
the underlying PFN. But practically speaking, creating a mapping isn't
a super hot path, and getting a writable mapping for reading is weird and
confusing.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-34-seanjc@google.com>
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Pin, as in FOLL_PIN, pages when mapping them for direct access by KVM.
As per Documentation/core-api/pin_user_pages.rst, writing to a page that
was gotten via FOLL_GET is explicitly disallowed.
Correct (uses FOLL_PIN calls):
pin_user_pages()
write to the data within the pages
unpin_user_pages()
INCORRECT (uses FOLL_GET calls):
get_user_pages()
write to the data within the pages
put_page()
Unfortunately, FOLL_PIN is a "private" flag, and so kvm_follow_pfn must
use a one-off bool instead of being able to piggyback the "flags" field.
Link: https://lwn.net/Articles/930667
Link: https://lore.kernel.org/all/cover.1683044162.git.lstoakes@gmail.com
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-32-seanjc@google.com>
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Migrate kvm_vcpu_map() to kvm_follow_pfn(), and have it track whether or
not the map holds a refcounted struct page. Precisely tracking struct
page references will eventually allow removing kvm_pfn_to_refcounted_page()
and its various wrappers.
Signed-off-by: David Stevens <stevensd@chromium.org>
[sean: use a pointer instead of a boolean]
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-31-seanjc@google.com>
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Drop yet another unnecessary magic page value from KVM, as there's zero
reason to use a poisoned pointer to indicate "no page". If KVM uses a
NULL page pointer, the kernel will explode just as quickly as if KVM uses
a poisoned pointer. Never mind the fact that such usage would be a
blatant and egregious KVM bug.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-23-seanjc@google.com>
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Drop @hva from __gfn_to_pfn_memslot() now that all callers pass NULL.
No functional change intended.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-19-seanjc@google.com>
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Add a pfn error code to communicate that hva_to_pfn() failed because I/O
was needed and disallowed, and convert @async to a constant @no_wait
boolean. This will allow eliminating the @no_wait param by having callers
pass in FOLL_NOWAIT along with other FOLL_* flags.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: David Stevens <stevensd@chromium.org>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-17-seanjc@google.com>
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Drop @atomic from the myriad "to_pfn" APIs now that all callers pass
"false", and remove a comment blurb about KVM running only the "GUP fast"
part in atomic context.
No functional change intended.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-13-seanjc@google.com>
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Rename gfn_to_page_many_atomic() to kvm_prefetch_pages() to try and
communicate its true purpose, as the "atomic" aspect is essentially a
side effect of the fact that x86 uses the API while holding mmu_lock.
E.g. even if mmu_lock weren't held, KVM wouldn't want to fault-in pages,
as the goal is to opportunistically grab surrounding pages that have
already been accessed and/or dirtied by the host, and to do so quickly.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-12-seanjc@google.com>
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Add an API to release an unused page, i.e. to put a page without marking
it accessed or dirty. The API will be used when KVM faults-in a page but
bails before installing the guest mapping (and other similar flows).
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-4-seanjc@google.com>
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Remove KVM_ERR_PTR_BAD_PAGE and instead return NULL, as "bad page" is just
a leftover bit of weirdness from days of old when KVM stuffed a "bad" page
into the guest instead of actually handling missing pages. See commit
cea7bb21280e ("KVM: MMU: Make gfn_to_page() always safe").
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-2-seanjc@google.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection
algorithm. This leads to improved memory savings.
- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"
- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.
- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping
code.
- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of
shadow entries.
- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.
- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in
the hugetlb code.
- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page
into small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.
- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.
- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to
do.
- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio
size rather than as individual pages. A 20% speedup was observed.
- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
splitting.
- The series "memcg-v1: fully deprecate charge moving" from Shakeel
Butt removes the long-deprecated memcgv2 charge moving feature.
- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.
- The series "x86/module: use large ROX pages for text allocations"
from Mike Rapoport teaches x86 to use large pages for
read-only-execute module text.
- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.
- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.
- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.
- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.
- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
tests over to the KUnit framework.
- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a
single VMA, rather than requiring that multiple VMAs be created for
this. Improved efficiencies for userspace memory allocators are
expected.
- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.
- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.
- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP
from the kernel boot command line.
- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.
- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep
is enabled.
* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
mm/kfence: add a new kunit test test_use_after_free_read_nofault()
zram: fix NULL pointer in comp_algorithm_show()
memcg/hugetlb: add hugeTLB counters to memcg
vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
zram: ZRAM_DEF_COMP should depend on ZRAM
MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
Docs/mm/damon: recommend academic papers to read and/or cite
mm: define general function pXd_init()
kmemleak: iommu/iova: fix transient kmemleak false positive
mm/list_lru: simplify the list_lru walk callback function
mm/list_lru: split the lock to per-cgroup scope
mm/list_lru: simplify reparenting and initial allocation
mm/list_lru: code clean up for reparenting
mm/list_lru: don't export list_lru_add
mm/list_lru: don't pass unnecessary key parameters
kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
...
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This patch introduces a new counter to memory.stat that tracks hugeTLB
usage, only if hugeTLB accounting is done to memory.current. This feature
is enabled the same way hugeTLB accounting is enabled, via the
memory_hugetlb_accounting mount flag for cgroupsv2.
1. Why is this patch necessary?
Currently, memcg hugeTLB accounting is an opt-in feature [1] that adds
hugeTLB usage to memory.current. However, the metric is not reported in
memory.stat. Given that users often interpret memory.stat as a breakdown
of the value reported in memory.current, the disparity between the two
reports can be confusing. This patch solves this problem by including the
metric in memory.stat as well, but only if it is also reported in
memory.current (it would also be confusing if the value was reported in
memory.stat, but not in memory.current)
Aside from the consistency between the two files, we also see benefits in
observability. Userspace might be interested in the hugeTLB footprint of
cgroups for many reasons. For instance, system admins might want to
verify that hugeTLB usage is distributed as expected across tasks: i.e.
memory-intensive tasks are using more hugeTLB pages than tasks that don't
consume a lot of memory, or are seen to fault frequently. Note that this
is separate from wanting to inspect the distribution for limiting purposes
(in which case, hugeTLB controller makes more sense).
2. We already have a hugeTLB controller. Why not use that?
It is true that hugeTLB tracks the exact value that we want. In fact, by
enabling the hugeTLB controller, we get all of the observability benefits
that I mentioned above, and users can check the total hugeTLB usage,
verify if it is distributed as expected, etc.
With this said, there are 2 problems:
(a) They are still not reported in memory.stat, which means the
disparity between the memcg reports are still there.
(b) We cannot reasonably expect users to enable the hugeTLB controller
just for the sake of hugeTLB usage reporting, especially since
they don't have any use for hugeTLB usage enforcing [2].
3. Implementation Details:
In the alloc / free hugetlb functions, we call lruvec_stat_mod_folio
regardless of whether memcg accounts hugetlb. mem_cgroup_commit_charge
which is called from alloc_hugetlb_folio will set memcg for the folio only
if the CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING cgroup mount option is used, so
lruvec_stat_mod_folio accounts per-memcg hugetlb counters only if the
feature is enabled. Regardless of whether memcg accounts for hugetlb, the
newly added global counter is updated and shown in /proc/vmstat.
The global counter is added because vmstats is the preferred framework for
cgroup stats. It makes stat items consistent between global and cgroups.
It also provides a per-node breakdown, which is useful. Because it does
not use cgroup-specific hooks, we also keep generic MM code separate from
memcg code.
[1] https://lore.kernel.org/all/20231006184629.155543-1-nphamcs@gmail.com/
[2] Of course, we can't make a new patch for every feature that can be
duplicated. However, since the existing solution of enabling the
hugeTLB controller is an imperfect solution that still leaves a
discrepancy between memory.stat and memory.curent, I think that it
is reasonable to isolate the feature in this case.
Link: https://lkml.kernel.org/r/20241101204402.1885383-1-joshua.hahnjy@gmail.com
Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Suggested-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Shakeel Butt <shakeel.butt@linux.dev>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Since 7d6be67cfdd4 ("mm: mmap_lock: replace get_memcg_path_buf() with
on-stack buffer") we use trace_mmap_lock_reg()/unreg() only to maintain an
atomic reg_refcount which is checked to avoid performing
get_mm_memcg_path() in case none of the tracepoints using it is enabled.
This can be achieved directly by putting all the work needed for the
tracepoint behind the trace_mmap_lock_##type##_enabled(), as suggested by
Documentation/trace/tracepoints.rst and with the following advantages:
- uses the tracepoint's static key instead of evaluating a branch
- the check tracepoint specific, not shared by all of them
- we can get rid of trace_mmap_lock_reg()/unreg() completely
Thus use the trace_..._enabled() check and remove unnecessary code.
Link: https://lkml.kernel.org/r/20241105113456.95066-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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pud_init(), pmd_init() and kernel_pte_init() are duplicated defined in
file kasan.c and sparse-vmemmap.c as weak functions. Move them to generic
header file pgtable.h, architecture can redefine them.
Link: https://lkml.kernel.org/r/20241104070712.52902-1-maobibo@loongson.cn
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The introduction of iova_depot_pop() in 911aa1245da8 ("iommu/iova: Make
the rcache depot scale better") confused kmemleak by moving a struct
iova_magazine object from a singly linked list to rcache->depot and
resetting the 'next' pointer referencing it. Unlike doubly linked lists,
the content of the object being referred is never changed on removal from
a singly linked list and the kmemleak checksum heuristics do not detect
such scenario. This leads to false positives like:
unreferenced object 0xffff8881a5301000 (size 1024):
comm "softirq", pid 0, jiffies 4306297099 (age 462.991s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 e7 7d 05 00 00 00 00 00 .........}......
0f b4 05 00 00 00 00 00 b4 96 05 00 00 00 00 00 ................
backtrace:
[<ffffffff819f5f08>] __kmem_cache_alloc_node+0x1e8/0x320
[<ffffffff818a239a>] kmalloc_trace+0x2a/0x60
[<ffffffff8231d31e>] free_iova_fast+0x28e/0x4e0
[<ffffffff82310860>] fq_ring_free_locked+0x1b0/0x310
[<ffffffff8231225d>] fq_flush_timeout+0x19d/0x2e0
[<ffffffff813e95ba>] call_timer_fn+0x19a/0x5c0
[<ffffffff813ea16b>] __run_timers+0x78b/0xb80
[<ffffffff813ea5bd>] run_timer_softirq+0x5d/0xd0
[<ffffffff82f1d915>] __do_softirq+0x205/0x8b5
Introduce kmemleak_transient_leak() which resets the object checksum
requiring another scan pass before it is reported (if still unreferenced).
Call this new API in iova_depot_pop().
Link: https://lkml.kernel.org/r/20241104111944.2207155-1-catalin.marinas@arm.com
Link: https://lore.kernel.org/r/ZY1osaGLyT-sdKE8@shredder/
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Ido Schimmel <idosch@idosch.org>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Now isolation no longer takes the list_lru global node lock, only use the
per-cgroup lock instead. And this lock is inside the list_lru_one being
walked, no longer needed to pass the lock explicitly.
Link: https://lkml.kernel.org/r/20241104175257.60853-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently, every list_lru has a per-node lock that protects adding,
deletion, isolation, and reparenting of all list_lru_one instances
belonging to this list_lru on this node. This lock contention is heavy
when multiple cgroups modify the same list_lru.
This lock can be split into per-cgroup scope to reduce contention.
To achieve this, we need a stable list_lru_one for every cgroup. This
commit adds a lock to each list_lru_one and introduced a helper function
lock_list_lru_of_memcg, making it possible to pin the list_lru of a memcg.
Then reworked the reparenting process.
Reparenting will switch the list_lru_one instances one by one. By locking
each instance and marking it dead using the nr_items counter, reparenting
ensures that all items in the corresponding cgroup (on-list or not,
because items have a stable cgroup, see below) will see the list_lru_one
switch synchronously.
Objcg reparent is also moved after list_lru reparent so items will have a
stable mem cgroup until all list_lru_one instances are drained.
The only caller that doesn't work the *_obj interfaces are direct calls to
list_lru_{add,del}. But it's only used by zswap and that's also based on
objcg, so it's fine.
This also changes the bahaviour of the isolation function when LRU_RETRY
or LRU_REMOVED_RETRY is returned, because now releasing the lock could
unblock reparenting and free the list_lru_one, isolation function will
have to return withoug re-lock the lru.
prepare() {
mkdir /tmp/test-fs
modprobe brd rd_nr=1 rd_size=33554432
mkfs.xfs -f /dev/ram0
mount -t xfs /dev/ram0 /tmp/test-fs
for i in $(seq 1 512); do
mkdir "/tmp/test-fs/$i"
for j in $(seq 1 10240); do
echo TEST-CONTENT > "/tmp/test-fs/$i/$j"
done &
done; wait
}
do_test() {
read_worker() {
sleep 1
tar -cv "$1" &>/dev/null
}
read_in_all() {
cd "/tmp/test-fs" && ls
for i in $(seq 1 512); do
(exec sh -c 'echo "$PPID"') > "/sys/fs/cgroup/benchmark/$i/cgroup.procs"
read_worker "$i" &
done; wait
}
for i in $(seq 1 512); do
mkdir -p "/sys/fs/cgroup/benchmark/$i"
done
echo +memory > /sys/fs/cgroup/benchmark/cgroup.subtree_control
echo 512M > /sys/fs/cgroup/benchmark/memory.max
echo 3 > /proc/sys/vm/drop_caches
time read_in_all
}
Above script simulates compression of small files in multiple cgroups
with memory pressure. Run prepare() then do_test for 6 times:
Before:
real 0m7.762s user 0m11.340s sys 3m11.224s
real 0m8.123s user 0m11.548s sys 3m2.549s
real 0m7.736s user 0m11.515s sys 3m11.171s
real 0m8.539s user 0m11.508s sys 3m7.618s
real 0m7.928s user 0m11.349s sys 3m13.063s
real 0m8.105s user 0m11.128s sys 3m14.313s
After this commit (about ~15% faster):
real 0m6.953s user 0m11.327s sys 2m42.912s
real 0m7.453s user 0m11.343s sys 2m51.942s
real 0m6.916s user 0m11.269s sys 2m43.957s
real 0m6.894s user 0m11.528s sys 2m45.346s
real 0m6.911s user 0m11.095s sys 2m43.168s
real 0m6.773s user 0m11.518s sys 2m40.774s
Link: https://lkml.kernel.org/r/20241104175257.60853-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/list_lru: Split list_lru lock into per-cgroup scope".
When LOCKDEP is not enabled, lock_class_key is an empty struct that is
never used. But the list_lru initialization function still takes a
placeholder pointer as parameter, and the compiler cannot optimize it
because the function is not static and exported.
Remove this parameter and move it inside the list_lru struct. Only use it
when LOCKDEP is enabled. Kernel builds with LOCKDEP will be slightly
larger, while !LOCKDEP builds without it will be slightly smaller (the
common case).
Link: https://lkml.kernel.org/r/20241104175257.60853-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20241104175257.60853-2-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This tracepoint gives visibility on how often the flushing of memcg stats
occurs and contains info on whether it was forced, skipped, and the value
of stats updated. It can help with understanding how readers are affected
by having to perform the flush, and the effectiveness of the flush by
inspecting the number of stats updated. Paired with the recently added
tracepoints for tracing rstat updates, it can also help show correlation
where stats exceed thresholds frequently.
Link: https://lkml.kernel.org/r/20241029021106.25587-3-inwardvessel@gmail.com
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The last user of put_pages_list() converted away from it in 6.10 commit
06c375053cef ("iommu/vt-d: add wrapper functions for page allocations"):
delete put_pages_list().
Link: https://lkml.kernel.org/r/d9985d6a-293e-176b-e63d-82fdfd28c139@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Implement a new lightweight guard page feature, that is regions of
userland virtual memory that, when accessed, cause a fatal signal to
arise.
Currently users must establish PROT_NONE ranges to achieve this.
However this is very costly memory-wise - we need a VMA for each and every
one of these regions AND they become unmergeable with surrounding VMAs.
In addition repeated mmap() calls require repeated kernel context switches
and contention of the mmap lock to install these ranges, potentially also
having to unmap memory if installed over existing ranges.
The lightweight guard approach eliminates the VMA cost altogether - rather
than establishing a PROT_NONE VMA, it operates at the level of page table
entries - establishing PTE markers such that accesses to them cause a
fault followed by a SIGSGEV signal being raised.
This is achieved through the PTE marker mechanism, which we have already
extended to provide PTE_MARKER_GUARD, which we installed via the generic
page walking logic which we have extended for this purpose.
These guard ranges are established with MADV_GUARD_INSTALL. If the range
in which they are installed contain any existing mappings, they will be
zapped, i.e. free the range and unmap memory (thus mimicking the
behaviour of MADV_DONTNEED in this respect).
Any existing guard entries will be left untouched. There is therefore no
nesting of guarded pages.
Guarded ranges are NOT cleared by MADV_DONTNEED nor MADV_FREE (in both
instances the memory range may be reused at which point a user would
expect guards to still be in place), but they are cleared via
MADV_GUARD_REMOVE, process teardown or unmapping of memory ranges.
The guard property can be removed from ranges via MADV_GUARD_REMOVE. The
ranges over which this is applied, should they contain non-guard entries,
will be untouched, with only guard entries being cleared.
We permit this operation on anonymous memory only, and only VMAs which are
non-special, non-huge and not mlock()'d (if we permitted this we'd have to
drop locked pages which would be rather counterintuitive).
Racing page faults can cause repeated attempts to install guard pages that
are interrupted, result in a zap, and this process can end up being
repeated. If this happens more than would be expected in normal
operation, we rescind locks and retry the whole thing, which avoids lock
contention in this scenario.
Link: https://lkml.kernel.org/r/6aafb5821bf209f277dfae0787abb2ef87a37542.1730123433.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Suggested-by: Jann Horn <jannh@google.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Suggested-by: Jann Horn <jannh@google.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Helge Deller <deller@gmx.de>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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