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AArch32 CP1x registers are overlayed on their AArch64 counterparts
in the vcpu struct. This leads to an interesting problem as they
are stored in their CPU-local format, and thus a CP1x register
doesn't "hit" the lower 32bit portion of the AArch64 register on
a BE host.
To workaround this unfortunate situation, introduce a bias trick
in the vcpu_cp1x() accessors which picks the correct half of the
64bit register.
Cc: stable@vger.kernel.org
Reported-by: James Morse <james.morse@arm.com>
Tested-by: James Morse <james.morse@arm.com>
Acked-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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KVM sets HCR_EL2.TACR via HCR_GUEST_FLAGS. This means ACTLR* accesses
from the guest are always trapped, and always return the value in the
sys_regs array.
The guest can't change the value of these registers, so we are
save restoring the reset value, which came from the host.
Stop save/restoring this register. Keep the storage for this register
in sys_regs[] as this is how the value is exposed to user-space,
removing it would break migration.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200529150656.7339-4-james.morse@arm.com
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ACTLR_EL1 is a 64bit register while the 32bit ACTLR is obviously 32bit.
For 32bit software, the extra bits are accessible via ACTLR2... which
KVM doesn't emulate.
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200529150656.7339-3-james.morse@arm.com
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aarch32 has pairs of registers to access the high and low parts of 64bit
registers. KVM has a union of 64bit sys_regs[] and 32bit copro[]. The
32bit accessors read the high or low part of the 64bit sys_reg[] value
through the union.
Both sys_reg_descs[] and cp15_regs[] list access_csselr() as the accessor
for CSSELR{,_EL1}. access_csselr() is only aware of the 64bit sys_regs[],
and expects r->reg to be 'CSSELR_EL1' in the enum, index 2 of the 64bit
array.
cp15_regs[] uses the 32bit copro[] alias of sys_regs[]. Here CSSELR is
c0_CSSELR which is the same location in sys_reg[]. r->reg is 'c0_CSSELR',
index 4 in the 32bit array.
access_csselr() uses the 32bit r->reg value to access the 64bit array,
so reads and write the wrong value. sys_regs[4], is ACTLR_EL1, which
is subsequently save/restored when we enter the guest.
ACTLR_EL1 is supposed to be read-only for the guest. This register
only affects execution at EL1, and the host's value is restored before
we return to host EL1.
Convert the 32bit register index back to the 64bit version.
Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200529150656.7339-2-james.morse@arm.com
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On a system with FWB, we don't need to unmap Stage-2 on reboot,
as even if userspace takes this opportunity to repaint the whole
of memory, FWB ensures that the data side stays consistent even
if the guest uses non-cacheable mappings.
However, the I-side is not necessarily coherent with the D-side
if CTR_EL0.DIC is 0. In this case, invalidate the i-cache to
preserve coherency.
Reported-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Fixes: 892713e97ca1 ("KVM: arm64: Sidestep stage2_unmap_vm() on vcpu reset when S2FWB is supported")
Signed-off-by: Marc Zyngier <maz@kernel.org>
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The general comment about keeping the enum order in sync
with the save/restore code has been obsolete for many years now.
Just drop it.
Note that there are other ordering requirements in the enum,
such as the PtrAuth and PMU registers, which are still valid.
Reported-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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We currently assume that an exception is delivered to EL1, always.
Once we emulate EL2, this no longer will be the case. To prepare
for this, add a target_mode parameter.
While we're at it, merge the computing of the target PC and PSTATE in
a single function that updates both PC and CPSR after saving their
previous values in the corresponding ELR/SPSR. This ensures that they
are updated in the correct order (a pretty common source of bugs...).
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Keeping empty structure as the vcpu state initializer is slightly
wasteful: we only want to set pstate, and zero everything else.
Just do that.
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Our sysreg reset check has become a bit silly, as it only checks whether
a reset callback actually exists for a given sysreg entry, and apply the
method if available. Doing the check at each vcpu reset is pretty dumb,
as the tables never change. It is thus perfectly possible to do the same
checks at boot time.
This also allows us to introduce a sparse sys_regs[] array, something
that will be required with ARMv8.4-NV.
Signed-off-by: Marc Zyngier <maz@kernel.org>
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As we're about to become a bit more harsh when it comes to the lack of
reset callbacks, let's add the missing PMU reset handlers. Note that
these only cover *CLR registers that were always covered by their *SET
counterpart, so there is no semantic change here.
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Extract the direct HW accessors for later reuse.
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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If we move the used_lrs field to the version-specific cpu interface
structure, the following functions only operate on the struct
vgic_v3_cpu_if and not the full vcpu:
__vgic_v3_save_state
__vgic_v3_restore_state
__vgic_v3_activate_traps
__vgic_v3_deactivate_traps
__vgic_v3_save_aprs
__vgic_v3_restore_aprs
This is going to be very useful for nested virt, so move the used_lrs
field and change the prototypes and implementations of these functions to
take the cpu_if parameter directly.
No functional change.
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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This abstraction was introduced to hide the difference between arm and
arm64 but, with the former no longer supported, this abstraction can be
removed and the canonical kernel API used directly instead.
Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
CC: Marc Zyngier <maz@kernel.org>
CC: James Morse <james.morse@arm.com>
CC: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20200519104036.259917-1-ascull@google.com
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The comment used to say that kvm_get_hyp_vector is only called on VHE systems.
In fact, it is also called from the nVHE init function cpu_init_hyp_mode().
Fix the comment to stop confusing devs.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200515152550.83810-1-dbrazdil@google.com
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Pull bits of code to the only place where it is used. Remove empty function
__cpu_init_stage2(). Remove redundant has_vhe() check since this function is
nVHE-only. No functional changes intended.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200515152056.83158-1-dbrazdil@google.com
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KVM_CAP_MAX_VCPUS always return the maximum possible number of
VCPUs, irrespective of the selected interrupt controller. This
is pretty misleading for userspace that selects a GICv2 on a GICv3
system that supports v2 compat: It always gets a maximum of 512
VCPUs, even if the effective limit is 8. The 9th VCPU will fail
to be created, which is unexpected as far as userspace is concerned.
Fortunately, we already have the right information stashed in the
kvm structure, and we can return it as requested.
Reported-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20200427141507.284985-1-maz@kernel.org
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There is already support of enabling dirty log gradually in small chunks
for x86 in commit 3c9bd4006bfc ("KVM: x86: enable dirty log gradually in
small chunks"). This adds support for arm64.
x86 still writes protect all huge pages when DIRTY_LOG_INITIALLY_ALL_SET
is enabled. However, for arm64, both huge pages and normal pages can be
write protected gradually by userspace.
Under the Huawei Kunpeng 920 2.6GHz platform, I did some tests on 128G
Linux VMs with different page size. The memory pressure is 127G in each
case. The time taken of memory_global_dirty_log_start in QEMU is listed
below:
Page Size Before After Optimization
4K 650ms 1.8ms
2M 4ms 1.8ms
1G 2ms 1.8ms
Besides the time reduction, the biggest improvement is that we will minimize
the performance side effect (because of dissolving huge pages and marking
memslots dirty) on guest after enabling dirty log.
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200413122023.52583-1-zhukeqian1@huawei.com
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We support mapping host memory backed by PMD transparent hugepages
at stage2 as huge pages. However the checks are now spread across
two different places. Let us unify the handling of the THPs to
keep the code cleaner (and future proof for PUD THP support).
This patch moves transparent_hugepage_adjust() closer to the caller
to avoid a forward declaration for fault_supports_stage2_huge_mappings().
Also, since we already handle the case where the host VA and the guest
PA may not be aligned, the explicit VM_BUG_ON() is not required.
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200507123546.1875-3-yuzenghui@huawei.com
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If we are checking whether the stage2 can map PAGE_SIZE,
we don't have to do the boundary checks as both the host
VMA and the guest memslots are page aligned. Bail the case
easily.
While we're at it, fixup a typo in the comment below.
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200507123546.1875-2-yuzenghui@huawei.com
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Do cond_resched_lock() in stage2_flush_memslot() like what is done in
unmap_stage2_range() and other places holding mmu_lock while processing
a possibly large range of memory.
Signed-off-by: Jiang Yi <giangyi@amazon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20200415084229.29992-1-giangyi@amazon.com
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stage2_unmap_vm() was introduced to unmap user RAM region in the stage2
page table to make the caches coherent. E.g., a guest reboot with stage1
MMU disabled will access memory using non-cacheable attributes. If the
RAM and caches are not coherent at this stage, some evicted dirty cache
line may go and corrupt guest data in RAM.
Since ARMv8.4, S2FWB feature is mandatory and KVM will take advantage
of it to configure the stage2 page table and the attributes of memory
access. So we ensure that guests always access memory using cacheable
attributes and thus, the caches always be coherent.
So on CPUs that support S2FWB, we can safely reset the vcpu without a
heavy stage2 unmapping.
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200415072835.1164-1-yuzenghui@huawei.com
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Fix spelling and typos (e.g., repeated words) in comments.
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200401140310.29701-1-tabba@google.com
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By the time we start using the has_vhe() helper, we have long
discovered whether we are running VHE or not. It thus makes
sense to use cpus_have_final_cap() instead of cpus_have_const_cap(),
which leads to a small text size reduction.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20200513103828.74580-1-maz@kernel.org
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Now that this function isn't constrained by the 32bit PCS,
let's simplify it by taking a single 64bit offset instead
of two 32bit parameters.
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Consolidate references to the CONFIG_KVM configuration item to encompass
entire folders rather than per line.
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200505154520.194120-5-tabba@google.com
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Changing CONFIG_KVM to be a 'menuconfig' entry in Kconfig mean that we
can straightforwardly enumerate optional features, such as the virtual
PMU device as dependent options.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200505154520.194120-4-tabba@google.com
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arm64 KVM supports 16k pages since 02e0b7600f83
("arm64: kvm: Add support for 16K pages"), so update the Kconfig help
text accordingly.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200505154520.194120-3-tabba@google.com
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CONFIG_KVM_ARM_HOST is just a proxy for CONFIG_KVM, so remove it in favour
of the latter.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200505154520.194120-2-tabba@google.com
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Now that the 32bit KVM/arm host is a distant memory, let's move the
whole of the KVM/arm64 code into the arm64 tree.
As they said in the song: Welcome Home (Sanitarium).
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200513104034.74741-1-maz@kernel.org
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It seems that for whatever reason, gcc-10 ends up not inlining a couple
of functions that used to be inlined before. Even if they only have one
single callsite - it looks like gcc may have decided that the code was
unlikely, and not worth inlining.
The code generation difference is harmless, but caused a few new section
mismatch errors, since the (now no longer inlined) function wasn't in
the __init section, but called other init functions:
Section mismatch in reference from the function kexec_free_initrd() to the function .init.text:free_initrd_mem()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memremap()
Section mismatch in reference from the function tpm2_calc_event_log_size() to the function .init.text:early_memunmap()
So add the appropriate __init annotation to make modpost not complain.
In both cases there were trivially just a single callsite from another
__init function.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.
This results in warnings like:
crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]
because the crypto layer had its local freeing functions called
'free()'.
Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.
But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.
[ Side note: gcc knowing about 'free()' is in itself not the
mis-feature: the semantics of 'free()' are special enough that a
compiler can validly do special things when seeing it.
So the mis-feature here is that gcc thinks that 'free()' is some
restricted name, and you can't shadow it as a local static function.
Making the special 'free()' semantics be a function attribute rather
than tied to the name would be the much better model ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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gcc-10 now warns about passing aliasing pointers to functions that take
restricted pointers.
That's actually a great warning, and if we ever start using 'restrict'
in the kernel, it might be quite useful. But right now we don't, and it
turns out that the only thing this warns about is an idiom where we have
declared a few functions to be "printf-like" (which seems to make gcc
pick up the restricted pointer thing), and then we print to the same
buffer that we also use as an input.
And people do that as an odd concatenation pattern, with code like this:
#define sysfs_show_gen_prop(buffer, fmt, ...) \
snprintf(buffer, PAGE_SIZE, "%s"fmt, buffer, __VA_ARGS__)
where we have 'buffer' as both the destination of the final result, and
as the initial argument.
Yes, it's a bit questionable. And outside of the kernel, people do have
standard declarations like
int snprintf( char *restrict buffer, size_t bufsz,
const char *restrict format, ... );
where that output buffer is marked as a restrict pointer that cannot
alias with any other arguments.
But in the context of the kernel, that 'use snprintf() to concatenate to
the end result' does work, and the pattern shows up in multiple places.
And we have not marked our own version of snprintf() as taking restrict
pointers, so the warning is incorrect for now, and gcc picks it up on
its own.
If we do start using 'restrict' in the kernel (and it might be a good
idea if people find places where it matters), we'll need to figure out
how to avoid this issue for snprintf and friends. But in the meantime,
this warning is not useful.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is the final array bounds warning removal for gcc-10 for now.
Again, the warning is good, and we should re-enable all these warnings
when we have converted all the legacy array declaration cases to
flexible arrays. But in the meantime, it's just noise.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When the controller is reconnecting, the host fails I/O and admin
commands as the host cannot reach the controller. ns scanning may
revalidate namespaces during that period and it is wrong to remove
namespaces due to these failures as we may hang (see 205da2434301).
One command that may fail is nvme_identify_ns_descs. Since we return
success due to having ns identify descriptor list optional, we continue
to compare ns identifiers in nvme_revalidate_disk, obviously fail and
return -ENODEV to nvme_validate_ns, which will remove the namespace.
Exactly what we don't want to happen.
Fixes: 22802bf742c2 ("nvme: Namepace identification descriptor list is optional")
Tested-by: Anton Eidelman <anton@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pre-incrementing ->cq_head can't be done in memory because OOB value
can be observed by another context.
This devalues space savings compared to original code :-\
$ ./scripts/bloat-o-meter ../vmlinux-000 ../obj/vmlinux
add/remove: 0/0 grow/shrink: 0/4 up/down: 0/-32 (-32)
Function old new delta
nvme_poll_irqdisable 464 456 -8
nvme_poll 455 447 -8
nvme_irq 388 380 -8
nvme_dev_disable 955 947 -8
But the code is minimal now: one read for head, one read for q_depth,
one increment, one comparison, single instruction phase bit update and
one write for new head.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reported-by: John Garry <john.garry@huawei.com>
Tested-by: John Garry <john.garry@huawei.com>
Fixes: e2a366a4b0feaeb ("nvme-pci: slimmer CQ head update")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.
Fixes: 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Use the common interface bdi_dev_name() to get device name.
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Add missing <linux/backing-dev.h> include BFQ
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This is another fine warning, related to the 'zero-length-bounds' one,
but hitting the same historical code in the kernel.
Because C didn't historically support flexible array members, we have
code that instead uses a one-sized array, the same way we have cases of
zero-sized arrays.
The one-sized arrays come from either not wanting to use the gcc
zero-sized array extension, or from a slight convenience-feature, where
particularly for strings, the size of the structure now includes the
allocation for the final NUL character.
So with a "char name[1];" at the end of a structure, you can do things
like
v = my_malloc(sizeof(struct vendor) + strlen(name));
and avoid the "+1" for the terminator.
Yes, the modern way to do that is with a flexible array, and using
'offsetof()' instead of 'sizeof()', and adding the "+1" by hand. That
also technically gets the size "more correct" in that it avoids any
alignment (and thus padding) issues, but this is another long-term
cleanup thing that will not happen for 5.7.
So disable the warning for now, even though it's potentially quite
useful. Having a slew of warnings that then hide more urgent new issues
is not an improvement.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is a fine warning, but we still have a number of zero-length arrays
in the kernel that come from the traditional gcc extension. Yes, they
are getting converted to flexible arrays, but in the meantime the gcc-10
warning about zero-length bounds is very verbose, and is hiding other
issues.
I missed one actual build failure because it was hidden among hundreds
of lines of warning. Thankfully I caught it on the second go before
pushing things out, but it convinced me that I really need to disable
the new warnings for now.
We'll hopefully be all done with our conversion to flexible arrays in
the not too distant future, and we can then re-enable this warning.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.
For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size. And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).
And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.
At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.
So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".
Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would. In a perfect world, the compilers would be smarter, and
our source code would be simpler.
That's currently not the world we live in, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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A misconfigured cephx can easily result in having the kernel client
flooding the logs with:
ceph: Can't lookup inode 1 (err: -13)
Change this message to debug level.
Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/44546
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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Elsewhere in the file, there is a list_for_each_entry with
&vdev->resv_regions as the second argument, suggesting that
&vdev->resv_regions is the list head. So exchange the
arguments on the list_add call to put the list head in the
second argument.
Fixes: 2a5a31487445 ("iommu/virtio: Add probe request")
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/1588704467-13431-1-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Commit 1c30844d2dfe ("mm: reclaim small amounts of memory when an
external fragmentation event occurs") adds a boost_watermark() function
which increases the min watermark in a zone by at least
pageblock_nr_pages or the number of pages in a page block.
On Arm64, with 64K pages and 512M huge pages, this is 8192 pages or
512M. It does this regardless of the number of managed pages managed in
the zone or the likelihood of success.
This can put the zone immediately under water in terms of allocating
pages from the zone, and can cause a small machine to fail immediately
due to OoM. Unlike set_recommended_min_free_kbytes(), which
substantially increases min_free_kbytes and is tied to THP,
boost_watermark() can be called even if THP is not active.
The problem is most likely to appear on architectures such as Arm64
where pageblock_nr_pages is very large.
It is desirable to run the kdump capture kernel in as small a space as
possible to avoid wasting memory. In some architectures, such as Arm64,
there are restrictions on where the capture kernel can run, and
therefore, the space available. A capture kernel running in 768M can
fail due to OoM immediately after boost_watermark() sets the min in zone
DMA32, where most of the memory is, to 512M. It fails even though there
is over 500M of free memory. With boost_watermark() suppressed, the
capture kernel can run successfully in 448M.
This patch limits boost_watermark() to boosting a zone's min watermark
only when there are enough pages that the boost will produce positive
results. In this case that is estimated to be four times as many pages
as pageblock_nr_pages.
Mel said:
: There is no harm in marking it stable. Clearly it does not happen very
: often but it's not impossible. 32-bit x86 is a lot less common now
: which would previously have been vulnerable to triggering this easily.
: ppc64 has a larger base page size but typically only has one zone.
: arm64 is likely the most vulnerable, particularly when CMA is
: configured with a small movable zone.
Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs")
Signed-off-by: Henry Willard <henry.willard@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1588294148-6586-1-git-send-email-henry.willard@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The documentation for UBSAN_ALIGNMENT already mentions that it should
not be used on all*config builds (and for efficient-unaligned-access
architectures), so just refactor the Kconfig to correctly implement this
so randconfigs will stop creating insane images that freak out objtool
under CONFIG_UBSAN_TRAP (due to the false positives producing functions
that never return, etc).
Link: http://lkml.kernel.org/r/202005011433.C42EA3E2D@keescook
Fixes: 0887a7ebc977 ("ubsan: add trap instrumentation option")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/linux-next/202004231224.D6B3B650@keescook/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since commit a9e7c39fa9fd9 ("mm/vmscan.c: remove 7th argument of
isolate_lru_pages()"), the explanation of 'mode' argument has been
unnecessary. Let's remove it.
Signed-off-by: Qiwu Chen <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200501090346.2894-1-chenqiwu@xiaomi.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch does two things:
- fixes a lost wakeup introduced by commit 339ddb53d373 ("fs/epoll:
remove unnecessary wakeups of nested epoll")
- improves performance for events delivery.
The description of the problem is the following: if N (>1) threads are
waiting on ep->wq for new events and M (>1) events come, it is quite
likely that >1 wakeups hit the same wait queue entry, because there is
quite a big window between __add_wait_queue_exclusive() and the
following __remove_wait_queue() calls in ep_poll() function.
This can lead to lost wakeups, because thread, which was woken up, can
handle not all the events in ->rdllist. (in better words the problem is
described here: https://lkml.org/lkml/2019/10/7/905)
The idea of the current patch is to use init_wait() instead of
init_waitqueue_entry().
Internally init_wait() sets autoremove_wake_function as a callback,
which removes the wait entry atomically (under the wq locks) from the
list, thus the next coming wakeup hits the next wait entry in the wait
queue, thus preventing lost wakeups.
Problem is very well reproduced by the epoll60 test case [1].
Wait entry removal on wakeup has also performance benefits, because
there is no need to take a ep->lock and remove wait entry from the queue
after the successful wakeup. Here is the timing output of the epoll60
test case:
With explicit wakeup from ep_scan_ready_list() (the state of the
code prior 339ddb53d373):
real 0m6.970s
user 0m49.786s
sys 0m0.113s
After this patch:
real 0m5.220s
user 0m36.879s
sys 0m0.019s
The other testcase is the stress-epoll [2], where one thread consumes
all the events and other threads produce many events:
With explicit wakeup from ep_scan_ready_list() (the state of the
code prior 339ddb53d373):
threads events/ms run-time ms
8 5427 1474
16 6163 2596
32 6824 4689
64 7060 9064
128 6991 18309
After this patch:
threads events/ms run-time ms
8 5598 1429
16 7073 2262
32 7502 4265
64 7640 8376
128 7634 16767
(number of "events/ms" represents event bandwidth, thus higher is
better; number of "run-time ms" represents overall time spent
doing the benchmark, thus lower is better)
[1] tools/testing/selftests/filesystems/epoll/epoll_wakeup_test.c
[2] https://github.com/rouming/test-tools/blob/master/stress-epoll.c
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jason Baron <jbaron@akamai.com>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Heiher <r@hev.cc>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200430130326.1368509-2-rpenyaev@suse.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This test case catches lost wake up introduced by commit 339ddb53d373
("fs/epoll: remove unnecessary wakeups of nested epoll")
The test is simple: we have 10 threads and 10 event fds. Each thread
can harvest only 1 event. 1 producer fires all 10 events at once and
waits that all 10 events will be observed by 10 threads.
In case of lost wakeup epoll_wait() will timeout and 0 will be returned.
Test case catches two sort of problems: forgotten wakeup on event, which
hits the ->ovflist list, this problem was fixed by:
5a2513239750 ("eventpoll: fix missing wakeup for ovflist in ep_poll_callback")
the other problem is when several sequential events hit the same waiting
thread, thus other waiters get no wakeups. Problem is fixed in the
following patch.
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Heiher <r@hev.cc>
Cc: Jason Baron <jbaron@akamai.com>
Link: http://lkml.kernel.org/r/20200430130326.1368509-1-rpenyaev@suse.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Since 5.7-rc1, on btrfs we have a percpu counter initialization for
which we always pass a GFP_KERNEL gfp_t argument (this happens since
commit 2992df73268f78 ("btrfs: Implement DREW lock")).
That is safe in some contextes but not on others where allowing fs
reclaim could lead to a deadlock because we are either holding some
btrfs lock needed for a transaction commit or holding a btrfs
transaction handle open. Because of that we surround the call to the
function that initializes the percpu counter with a NOFS context using
memalloc_nofs_save() (this is done at btrfs_init_fs_root()).
However it turns out that this is not enough to prevent a possible
deadlock because percpu_alloc() determines if it is in an atomic context
by looking exclusively at the gfp flags passed to it (GFP_KERNEL in this
case) and it is not aware that a NOFS context is set.
Because percpu_alloc() thinks it is in a non atomic context it locks the
pcpu_alloc_mutex. This can result in a btrfs deadlock when
pcpu_balance_workfn() is running, has acquired that mutex and is waiting
for reclaim, while the btrfs task that called percpu_counter_init() (and
therefore percpu_alloc()) is holding either the btrfs commit_root
semaphore or a transaction handle (done fs/btrfs/backref.c:
iterate_extent_inodes()), which prevents reclaim from finishing as an
attempt to commit the current btrfs transaction will deadlock.
Lockdep reports this issue with the following trace:
======================================================
WARNING: possible circular locking dependency detected
5.6.0-rc7-btrfs-next-77 #1 Not tainted
------------------------------------------------------
kswapd0/91 is trying to acquire lock:
ffff8938a3b3fdc8 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs]
but task is already holding lock:
ffffffffb4f0dbc0 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #4 (fs_reclaim){+.+.}:
fs_reclaim_acquire.part.0+0x25/0x30
__kmalloc+0x5f/0x3a0
pcpu_create_chunk+0x19/0x230
pcpu_balance_workfn+0x56a/0x680
process_one_work+0x235/0x5f0
worker_thread+0x50/0x3b0
kthread+0x120/0x140
ret_from_fork+0x3a/0x50
-> #3 (pcpu_alloc_mutex){+.+.}:
__mutex_lock+0xa9/0xaf0
pcpu_alloc+0x480/0x7c0
__percpu_counter_init+0x50/0xd0
btrfs_drew_lock_init+0x22/0x70 [btrfs]
btrfs_get_fs_root+0x29c/0x5c0 [btrfs]
resolve_indirect_refs+0x120/0xa30 [btrfs]
find_parent_nodes+0x50b/0xf30 [btrfs]
btrfs_find_all_leafs+0x60/0xb0 [btrfs]
iterate_extent_inodes+0x139/0x2f0 [btrfs]
iterate_inodes_from_logical+0xa1/0xe0 [btrfs]
btrfs_ioctl_logical_to_ino+0xb4/0x190 [btrfs]
btrfs_ioctl+0x165a/0x3130 [btrfs]
ksys_ioctl+0x87/0xc0
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x5c/0x260
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #2 (&fs_info->commit_root_sem){++++}:
down_write+0x38/0x70
btrfs_cache_block_group+0x2ec/0x500 [btrfs]
find_free_extent+0xc6a/0x1600 [btrfs]
btrfs_reserve_extent+0x9b/0x180 [btrfs]
btrfs_alloc_tree_block+0xc1/0x350 [btrfs]
alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs]
__btrfs_cow_block+0x122/0x5a0 [btrfs]
btrfs_cow_block+0x106/0x240 [btrfs]
commit_cowonly_roots+0x55/0x310 [btrfs]
btrfs_commit_transaction+0x509/0xb20 [btrfs]
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20 [btrfs]
deactivate_locked_super+0x31/0x70
cleanup_mnt+0x100/0x160
task_work_run+0x93/0xc0
exit_to_usermode_loop+0xf9/0x100
do_syscall_64+0x20d/0x260
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #1 (&space_info->groups_sem){++++}:
down_read+0x3c/0x140
find_free_extent+0xef6/0x1600 [btrfs]
btrfs_reserve_extent+0x9b/0x180 [btrfs]
btrfs_alloc_tree_block+0xc1/0x350 [btrfs]
alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs]
__btrfs_cow_block+0x122/0x5a0 [btrfs]
btrfs_cow_block+0x106/0x240 [btrfs]
btrfs_search_slot+0x50c/0xd60 [btrfs]
btrfs_lookup_inode+0x3a/0xc0 [btrfs]
__btrfs_update_delayed_inode+0x90/0x280 [btrfs]
__btrfs_commit_inode_delayed_items+0x81f/0x870 [btrfs]
__btrfs_run_delayed_items+0x8e/0x180 [btrfs]
btrfs_commit_transaction+0x31b/0xb20 [btrfs]
iterate_supers+0x87/0xf0
ksys_sync+0x60/0xb0
__ia32_sys_sync+0xa/0x10
do_syscall_64+0x5c/0x260
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&delayed_node->mutex){+.+.}:
__lock_acquire+0xef0/0x1c80
lock_acquire+0xa2/0x1d0
__mutex_lock+0xa9/0xaf0
__btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs]
btrfs_evict_inode+0x40d/0x560 [btrfs]
evict+0xd9/0x1c0
dispose_list+0x48/0x70
prune_icache_sb+0x54/0x80
super_cache_scan+0x124/0x1a0
do_shrink_slab+0x176/0x440
shrink_slab+0x23a/0x2c0
shrink_node+0x188/0x6e0
balance_pgdat+0x31d/0x7f0
kswapd+0x238/0x550
kthread+0x120/0x140
ret_from_fork+0x3a/0x50
other info that might help us debug this:
Chain exists of:
&delayed_node->mutex --> pcpu_alloc_mutex --> fs_reclaim
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(pcpu_alloc_mutex);
lock(fs_reclaim);
lock(&delayed_node->mutex);
*** DEADLOCK ***
3 locks held by kswapd0/91:
#0: (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30
#1: (shrinker_rwsem){++++}, at: shrink_slab+0x12f/0x2c0
#2: (&type->s_umount_key#43){++++}, at: trylock_super+0x16/0x50
stack backtrace:
CPU: 1 PID: 91 Comm: kswapd0 Not tainted 5.6.0-rc7-btrfs-next-77 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8f/0xd0
check_noncircular+0x170/0x190
__lock_acquire+0xef0/0x1c80
lock_acquire+0xa2/0x1d0
__mutex_lock+0xa9/0xaf0
__btrfs_release_delayed_node.part.0+0x3f/0x320 [btrfs]
btrfs_evict_inode+0x40d/0x560 [btrfs]
evict+0xd9/0x1c0
dispose_list+0x48/0x70
prune_icache_sb+0x54/0x80
super_cache_scan+0x124/0x1a0
do_shrink_slab+0x176/0x440
shrink_slab+0x23a/0x2c0
shrink_node+0x188/0x6e0
balance_pgdat+0x31d/0x7f0
kswapd+0x238/0x550
kthread+0x120/0x140
ret_from_fork+0x3a/0x50
This could be fixed by making btrfs pass GFP_NOFS instead of GFP_KERNEL
to percpu_counter_init() in contextes where it is not reclaim safe,
however that type of approach is discouraged since
memalloc_[nofs|noio]_save() were introduced. Therefore this change
makes pcpu_alloc() look up into an existing nofs/noio context before
deciding whether it is in an atomic context or not.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Link: http://lkml.kernel.org/r/20200430164356.15543-1-fdmanana@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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In a couple of places in the slub memory allocator, the code uses
"s->offset" as a check to see if the free pointer is put right after the
object. That check is no longer true with commit 3202fa62fb43 ("slub:
relocate freelist pointer to middle of object").
As a result, echoing "1" into the validate sysfs file, e.g. of dentry,
may cause a bunch of "Freepointer corrupt" error reports like the
following to appear with the system in panic afterwards.
=============================================================================
BUG dentry(666:pmcd.service) (Tainted: G B): Freepointer corrupt
-----------------------------------------------------------------------------
To fix it, use the check "s->offset == s->inuse" in the new helper
function freeptr_outside_object() instead. Also add another helper
function get_info_end() to return the end of info block (inuse + free
pointer if not overlapping with object).
Fixes: 3202fa62fb43 ("slub: relocate freelist pointer to middle of object")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Vitaly Nikolenko <vnik@duasynt.com>
Cc: Silvio Cesare <silvio.cesare@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: Changbin Du <changbin.du@gmail.com>
Link: http://lkml.kernel.org/r/20200429135328.26976-1-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Marc Zyngier
James Morse
Christoffer Dall
Andrew Scull
David Brazdil
Keqian Zhu
Suzuki K Poulose
Jiang Yi
Zenghui Yu
Fuad Tabba
Will Deacon
Linus Torvalds
Sagi Grimberg
Alexey Dobriyan
Christoph Hellwig
Yufen Yu
Luis Henriques
Julia Lawall
Henry Willard
Kees Cook
Qiwu Chen
Roman Penyaev
Filipe Manana
Waiman Long