This is done using the RCU data structure (io_ev_fd). eventfd_async is
moved from io_ring_ctx to io_ev_fd which is RCU protected hence avoiding
ring quiesce which is much more expensive than an RCU lock. The place
where eventfd_async is read is already under rcu_read_lock so there is no
extra RCU read-side critical section needed.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-4-usama.arif@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is done by creating a new RCU data structure (io_ev_fd) as part of
io_ring_ctx that holds the eventfd_ctx.
The function io_eventfd_signal is executed under rcu_read_lock with a
single rcu_dereference to io_ev_fd so that if another thread unregisters
the eventfd while io_eventfd_signal is still being executed, the
eventfd_signal for which io_eventfd_signal was called completes
successfully.
The process of registering/unregistering eventfd is already done under
uring_lock so multiple threads won't enter a race condition while
registering/unregistering eventfd.
With the above approach ring quiesce can be avoided which is much more
expensive then using RCU lock. On the system tested, io_uring_register
with IORING_REGISTER_EVENTFD takes less than 1ms with RCU lock, compared
to 15ms before with ring quiesce.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Link: https://lore.kernel.org/r/20220204145117.1186568-3-usama.arif@bytedance.com
[axboe: long line fixups]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull btrfs fixes from David Sterba:
"A few more fixes for various problems that have user visible effects
or seem to be urgent:
- fix corruption when combining DIO and non-blocking io_uring over
multiple extents (seen on MariaDB)
- fix relocation crash due to premature return from commit
- fix quota deadlock between rescan and qgroup removal
- fix item data bounds checks in tree-checker (found on a fuzzed
image)
- fix fsync of prealloc extents after EOF
- add missing run of delayed items after unlink during log replay
- don't start relocation until snapshot drop is finished
- fix reversed condition for subpage writers locking
- fix warning on page error"
* tag 'for-5.17-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fallback to blocking mode when doing async dio over multiple extents
btrfs: add missing run of delayed items after unlink during log replay
btrfs: qgroup: fix deadlock between rescan worker and remove qgroup
btrfs: fix relocation crash due to premature return from btrfs_commit_transaction()
btrfs: do not start relocation until in progress drops are done
btrfs: tree-checker: use u64 for item data end to avoid overflow
btrfs: do not WARN_ON() if we have PageError set
btrfs: fix lost prealloc extents beyond eof after full fsync
btrfs: subpage: fix a wrong check on subpage->writers
Pull kvm fixes from Paolo Bonzini:
"x86 guest:
- Tweaks to the paravirtualization code, to avoid using them when
they're pointless or harmful
x86 host:
- Fix for SRCU lockdep splat
- Brown paper bag fix for the propagation of errno"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run
KVM: x86/mmu: Passing up the error state of mmu_alloc_shadow_roots()
KVM: x86: Yield to IPI target vCPU only if it is busy
x86/kvmclock: Fix Hyper-V Isolated VM's boot issue when vCPUs > 64
x86/kvm: Don't waste memory if kvmclock is disabled
x86/kvm: Don't use PV TLB/yield when mwait is advertised
Pull powerpc fix from Michael Ellerman:
"Fix build failure when CONFIG_PPC_64S_HASH_MMU is not set.
Thanks to Murilo Opsfelder Araujo, and Erhard F"
* tag 'powerpc-5.17-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/64s: Fix build failure when CONFIG_PPC_64S_HASH_MMU is not set
Pull tracing fixes from Steven Rostedt:
- Fix sorting on old "cpu" value in histograms
- Fix return value of __setup() boot parameter handlers
* tag 'trace-v5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix return value of __setup handlers
tracing/histogram: Fix sorting on old "cpu" value
Pull input updates from Dmitry Torokhov:
- a fixup for Goodix touchscreen driver allowing it to work on certain
Cherry Trail devices
- a fix for imbalanced enable/disable regulator in Elam touchpad driver
that became apparent when used with Asus TF103C 2-in-1 dock
- a couple new input keycodes used on newer keyboards
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
HID: add mapping for KEY_ALL_APPLICATIONS
HID: add mapping for KEY_DICTATE
Input: elan_i2c - fix regulator enable count imbalance after suspend/resume
Input: elan_i2c - move regulator_[en|dis]able() out of elan_[en|dis]able_power()
Input: goodix - workaround Cherry Trail devices with a bogus ACPI Interrupt() resource
Input: goodix - use the new soc_intel_is_byt() helper
Input: samsung-keypad - properly state IOMEM dependency
Merge misc fixes from Andrew Morton:
"8 patches.
Subsystems affected by this patch series: mm (hugetlb, pagemap, and
userfaultfd), memfd, selftests, and kconfig"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
configs/debug: set CONFIG_DEBUG_INFO=y properly
proc: fix documentation and description of pagemap
kselftest/vm: fix tests build with old libc
memfd: fix F_SEAL_WRITE after shmem huge page allocated
mm: fix use-after-free when anon vma name is used after vma is freed
mm: prevent vm_area_struct::anon_name refcount saturation
mm: refactor vm_area_struct::anon_vma_name usage code
selftests/vm: cleanup hugetlb file after mremap test
Pull s390 fixes from Vasily Gorbik:
- Fix HAVE_DYNAMIC_FTRACE_WITH_ARGS implementation by providing correct
switching between ftrace_caller/ftrace_regs_caller and supplying
pt_regs only when ftrace_regs_caller is activated.
- Fix exception table sorting.
- Fix breakage of kdump tooling by preserving metadata it cannot
function without.
* tag 's390-5.17-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/extable: fix exception table sorting
s390/ftrace: fix arch_ftrace_get_regs implementation
s390/ftrace: fix ftrace_caller/ftrace_regs_caller generation
s390/setup: preserve memory at OLDMEM_BASE and OLDMEM_SIZE
The error message when I build vm tests on debian10 (GLIBC 2.28):
userfaultfd.c: In function `userfaultfd_pagemap_test':
userfaultfd.c:1393:37: error: `MADV_PAGEOUT' undeclared (first use
in this function); did you mean `MADV_RANDOM'?
if (madvise(area_dst, test_pgsize, MADV_PAGEOUT))
^~~~~~~~~~~~
MADV_RANDOM
This patch includes these newer definitions from UAPI linux/mman.h, is
useful to fix tests build on systems without these definitions in glibc
sys/mman.h.
Link: https://lkml.kernel.org/r/20220227055330.43087-2-zhouchengming@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Wangyong reports: after enabling tmpfs filesystem to support transparent
hugepage with the following command:
echo always > /sys/kernel/mm/transparent_hugepage/shmem_enabled
the docker program tries to add F_SEAL_WRITE through the following
command, but it fails unexpectedly with errno EBUSY:
fcntl(5, F_ADD_SEALS, F_SEAL_WRITE) = -1.
That is because memfd_tag_pins() and memfd_wait_for_pins() were never
updated for shmem huge pages: checking page_mapcount() against
page_count() is hopeless on THP subpages - they need to check
total_mapcount() against page_count() on THP heads only.
Make memfd_tag_pins() (compared > 1) as strict as memfd_wait_for_pins()
(compared != 1): either can be justified, but given the non-atomic
total_mapcount() calculation, it is better now to be strict. Bear in
mind that total_mapcount() itself scans all of the THP subpages, when
choosing to take an XA_CHECK_SCHED latency break.
Also fix the unlikely xa_is_value() case in memfd_wait_for_pins(): if a
page has been swapped out since memfd_tag_pins(), then its refcount must
have fallen, and so it can safely be untagged.
Link: https://lkml.kernel.org/r/a4f79248-df75-2c8c-3df-ba3317ccb5da@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Reported-by: wangyong <wang.yong12@zte.com.cn>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: CGEL ZTE <cgel.zte@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A deep process chain with many vmas could grow really high. With
default sysctl_max_map_count (64k) and default pid_max (32k) the max
number of vmas in the system is 2147450880 and the refcounter has
headroom of 1073774592 before it reaches REFCOUNT_SATURATED
(3221225472).
Therefore it's unlikely that an anonymous name refcounter will overflow
with these defaults. Currently the max for pid_max is PID_MAX_LIMIT
(4194304) and for sysctl_max_map_count it's INT_MAX (2147483647). In
this configuration anon_vma_name refcount overflow becomes theoretically
possible (that still require heavy sharing of that anon_vma_name between
processes).
kref refcounting interface used in anon_vma_name structure will detect a
counter overflow when it reaches REFCOUNT_SATURATED value but will only
generate a warning and freeze the ref counter. This would lead to the
refcounted object never being freed. A determined attacker could leak
memory like that but it would be rather expensive and inefficient way to
do so.
To ensure anon_vma_name refcount does not overflow, stop anon_vma_name
sharing when the refcount reaches REFCOUNT_MAX (2147483647), which still
leaves INT_MAX/2 (1073741823) values before the counter reaches
REFCOUNT_SATURATED. This should provide enough headroom for raising the
refcounts temporarily.
Link: https://lkml.kernel.org/r/20220223153613.835563-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Chris Hyser <chris.hyser@oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Colin Cross <ccross@google.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xiaofeng Cao <caoxiaofeng@yulong.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following build failure occurs when CONFIG_PPC_64S_HASH_MMU is not
set:
arch/powerpc/kernel/setup_64.c: In function ‘setup_per_cpu_areas’:
arch/powerpc/kernel/setup_64.c:811:21: error: ‘mmu_linear_psize’ undeclared (first use in this function); did you mean ‘mmu_virtual_psize’?
811 | if (mmu_linear_psize == MMU_PAGE_4K)
| ^~~~~~~~~~~~~~~~
| mmu_virtual_psize
arch/powerpc/kernel/setup_64.c:811:21: note: each undeclared identifier is reported only once for each function it appears in
Move the declaration of mmu_linear_psize outside of
CONFIG_PPC_64S_HASH_MMU ifdef.
After the above is fixed, it fails later with the following error:
ld: arch/powerpc/kexec/file_load_64.o: in function `.arch_kexec_kernel_image_probe':
file_load_64.c:(.text+0x1c1c): undefined reference to `.add_htab_mem_range'
Fix that, too, by conditioning add_htab_mem_range() symbol to
CONFIG_PPC_64S_HASH_MMU.
Fixes: 387e220a2e ("powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMU")
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215567
Link: https://lore.kernel.org/r/20220301204743.45133-1-muriloo@linux.ibm.com
Pull block fix from Jens Axboe:
"Just a small UAF fix for blktrace"
* tag 'block-5.17-2022-03-04' of git://git.kernel.dk/linux-block:
blktrace: fix use after free for struct blk_trace
Pull RISC-V fixes from Palmer Dabbelt:
- Fixes for a handful of KASAN-related crashes.
- A fix to avoid a crash during boot for SPARSEMEM &&
!SPARSEMEM_VMEMMAP configurations.
- A fix to stop reporting some incorrect errors under DEBUG_VIRTUAL.
- A fix for the K210's device tree to properly populate the interrupt
map, so hart1 will get interrupts again.
* tag 'riscv-for-linus-5.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
riscv: dts: k210: fix broken IRQs on hart1
riscv: Fix kasan pud population
riscv: Move high_memory initialization to setup_bootmem
riscv: Fix config KASAN && DEBUG_VIRTUAL
riscv: Fix DEBUG_VIRTUAL false warnings
riscv: Fix config KASAN && SPARSEMEM && !SPARSE_VMEMMAP
riscv: Fix is_linear_mapping with recent move of KASAN region
Pull thermal control fix from Rafael Wysocki:
"Fix NULL pointer dereference in the thermal netlink interface (Nicolas
Cavallari)"
* tag 'thermal-5.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
thermal: core: Fix TZ_GET_TRIP NULL pointer dereference
Usama Arif
Linus Torvalds
Qian Cai
Yun Zhou
Chengming Zhou
Hugh Dickins
Suren Baghdasaryan
Mike Kravetz
Murilo Opsfelder Araujo