From: Dmitry Vyukov <dvyukov(a)google.com>
POSIX timers using the CLOCK_PROCESS_CPUTIME_ID clock prefer the main
thread of a thread group for signal delivery. However, this has a
significant downside: it requires waking up a potentially idle thread.
Instead, prefer to deliver signals to the current thread (in the same
thread group) if SIGEV_THREAD_ID is not set by the user. This does not
change guaranteed semantics, since POSIX process CPU time timers have
never guaranteed that signal delivery is to a specific thread (without
SIGEV_THREAD_ID set).
The effect is that we no longer wake up potentially idle threads, and
the kernel is no longer biased towards delivering the timer signal to
any particular thread (which better distributes the timer signals esp.
when multiple timers fire concurrently).
Signed-off-by: Dmitry Vyukov <dvyukov(a)google.com>
Suggested-by: Oleg Nesterov <oleg(a)redhat.com>
Reviewed-by: Oleg Nesterov <oleg(a)redhat.com>
Signed-off-by: Marco Elver <elver(a)google.com>
---
v6:
- Split test from this patch.
- Update wording on what this patch aims to improve.
v5:
- Rebased onto v6.2.
v4:
- Restructured checks in send_sigqueue() as suggested.
v3:
- Switched to the completely different implementation (much simpler)
based on the Oleg's idea.
RFC v2:
- Added additional Cc as Thomas asked.
---
kernel/signal.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index 8cb28f1df294..605445fa27d4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1003,8 +1003,7 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
/*
* Now find a thread we can wake up to take the signal off the queue.
*
- * If the main thread wants the signal, it gets first crack.
- * Probably the least surprising to the average bear.
+ * Try the suggested task first (may or may not be the main thread).
*/
if (wants_signal(sig, p))
t = p;
@@ -1970,8 +1969,23 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
ret = -1;
rcu_read_lock();
+ /*
+ * This function is used by POSIX timers to deliver a timer signal.
+ * Where type is PIDTYPE_PID (such as for timers with SIGEV_THREAD_ID
+ * set), the signal must be delivered to the specific thread (queues
+ * into t->pending).
+ *
+ * Where type is not PIDTYPE_PID, signals must just be delivered to the
+ * current process. In this case, prefer to deliver to current if it is
+ * in the same thread group as the target, as it avoids unnecessarily
+ * waking up a potentially idle task.
+ */
t = pid_task(pid, type);
- if (!t || !likely(lock_task_sighand(t, &flags)))
+ if (!t)
+ goto ret;
+ if (type != PIDTYPE_PID && same_thread_group(t, current))
+ t = current;
+ if (!likely(lock_task_sighand(t, &flags)))
goto ret;
ret = 1; /* the signal is ignored */
@@ -1993,6 +2007,11 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type)
q->info.si_overrun = 0;
signalfd_notify(t, sig);
+ /*
+ * If the type is not PIDTYPE_PID, we just use shared_pending, which
+ * won't guarantee that the specified task will receive the signal, but
+ * is sufficient if t==current in the common case.
+ */
pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;
list_add_tail(&q->list, &pending->list);
sigaddset(&pending->signal, sig);
--
2.40.0.rc1.284.g88254d51c5-goog
From: Zi Yan <ziy(a)nvidia.com>
Hi all,
File folio supports any order and people would like to support flexible orders
for anonymous folio[1] too. Currently, split_huge_page() only splits a huge
page to order-0 pages, but splitting to orders higher than 0 is also useful.
This patchset adds support for splitting a huge page to any lower order pages
and uses it during file folio truncate operations.
The patchset is on top of mm-everything-2023-03-27-21-20.
Changelog
===
Since v2
---
1. Fixed an issue in __split_page_owner() introduced during my rebase
Since v1
---
1. Changed split_page_memcg() and split_page_owner() parameter to use order
2. Used folio_test_pmd_mappable() in place of the equivalent code
Details
===
* Patch 1 changes split_page_memcg() to use order instead of nr_pages
* Patch 2 changes split_page_owner() to use order instead of nr_pages
* Patch 3 and 4 add new_order parameter split_page_memcg() and
split_page_owner() and prepare for upcoming changes.
* Patch 5 adds split_huge_page_to_list_to_order() to split a huge page
to any lower order. The original split_huge_page_to_list() calls
split_huge_page_to_list_to_order() with new_order = 0.
* Patch 6 uses split_huge_page_to_list_to_order() in large pagecache folio
truncation instead of split the large folio all the way down to order-0.
* Patch 7 adds a test API to debugfs and test cases in
split_huge_page_test selftests.
Comments and/or suggestions are welcome.
[1] https://lore.kernel.org/linux-mm/Y%2FblF0GIunm+pRIC@casper.infradead.org/
Zi Yan (7):
mm/memcg: use order instead of nr in split_page_memcg()
mm/page_owner: use order instead of nr in split_page_owner()
mm: memcg: make memcg huge page split support any order split.
mm: page_owner: add support for splitting to any order in split
page_owner.
mm: thp: split huge page to any lower order pages.
mm: truncate: split huge page cache page to a non-zero order if
possible.
mm: huge_memory: enable debugfs to split huge pages to any order.
include/linux/huge_mm.h | 10 +-
include/linux/memcontrol.h | 4 +-
include/linux/page_owner.h | 10 +-
mm/huge_memory.c | 137 ++++++++---
mm/memcontrol.c | 10 +-
mm/page_alloc.c | 8 +-
mm/page_owner.c | 8 +-
mm/truncate.c | 21 +-
.../selftests/mm/split_huge_page_test.c | 225 +++++++++++++++++-
9 files changed, 365 insertions(+), 68 deletions(-)
--
2.39.2
Here's a follow-up from my RFC series last year:
https://lore.kernel.org/lkml/20221004093131.40392-1-thuth@redhat.com/T/
and from v1 earlier this year:
https://lore.kernel.org/kvm/20230712075910.22480-1-thuth@redhat.com/
Basic idea of this series is now to use the kselftest_harness.h
framework to get TAP output in the tests, so that it is easier
for the user to see what is going on, and e.g. to be able to
detect whether a certain test is part of the test binary or not
(which is useful when tests get extended in the course of time).
v2:
- Dropped the "Rename the ASSERT_EQ macro" patch (already merged)
- Split the fixes in the sync_regs_test into separate patches
(see the first two patches)
- Introduce the KVM_ONE_VCPU_TEST_SUITE() macro as suggested
by Sean (see third patch) and use it in the following patches
- Add a new patch to convert vmx_pmu_caps_test.c, too
Thomas Huth (7):
KVM: selftests: x86: sync_regs_test: Use vcpu_run() where appropriate
KVM: selftests: x86: sync_regs_test: Get regs structure before
modifying it
KVM: selftests: Add a macro to define a test with one vcpu
KVM: selftests: x86: Use TAP interface in the sync_regs test
KVM: selftests: x86: Use TAP interface in the fix_hypercall test
KVM: selftests: x86: Use TAP interface in the vmx_pmu_caps test
KVM: selftests: x86: Use TAP interface in the userspace_msr_exit test
.../selftests/kvm/include/kvm_test_harness.h | 35 +++++
.../selftests/kvm/x86_64/fix_hypercall_test.c | 27 ++--
.../selftests/kvm/x86_64/sync_regs_test.c | 121 +++++++++++++-----
.../kvm/x86_64/userspace_msr_exit_test.c | 19 +--
.../selftests/kvm/x86_64/vmx_pmu_caps_test.c | 50 ++------
5 files changed, 160 insertions(+), 92 deletions(-)
create mode 100644 tools/testing/selftests/kvm/include/kvm_test_harness.h
--
2.41.0
Make sv48 the default address space for mmap as some applications
currently depend on this assumption. Users can now select a
desired address space using a non-zero hint address to mmap. Previously,
requesting the default address space from mmap by passing zero as the hint
address would result in using the largest address space possible. Some
applications depend on empty bits in the virtual address space, like Go and
Java, so this patch provides more flexibility for application developers.
-Charlie
---
v10:
- Move pgtable.h defintions into a no __ASSEMBLY__ region to resolve compilation
conflicts (pointed out by Conor)
- Will now compile with allmodconfig
v9:
- Raise the mmap_end default to STACK_TOP_MAX to allow the address space to grow
beyond the default of sv48 on sv57 machines as suggested by Alexandre
- Some of the mmap macros had unnecessary conditionals that I have removed
v8:
- Fix RV32 and the RV32 compat mode of RV64 (suggested by Conor)
- Extract out addr and base from the mmap macros (suggested by Alexandre)
v7:
- Changing RLIMIT_STACK inside of an executing program does not trigger
arch_pick_mmap_layout(), so rewrite tests to change RLIMIT_STACK from a
script before executing tests. RLIMIT_STACK of infinity forces bottomup
mmap allocation.
- Make arch_get_mmap_base macro more readible by extracting out the rnd
calculation.
- Use MMAP_MIN_VA_BITS in TASK_UNMAPPED_BASE to support case when mmap
attempts to allocate address smaller than DEFAULT_MAP_WINDOW.
- Fix incorrect wording in documentation.
v6:
- Rebase onto the correct base
v5:
- Minor wording change in documentation
- Change some parenthesis in arch_get_mmap_ macros
- Added case for addr==0 in arch_get_mmap_ because without this, programs would
crash if RLIMIT_STACK was modified before executing the program. This was
tested using the libhugetlbfs tests.
v4:
- Split testcases/document patch into test cases, in-code documentation, and
formal documentation patches
- Modified the mmap_base macro to be more legible and better represent memory
layout
- Fixed documentation to better reflect the implmentation
- Renamed DEFAULT_VA_BITS to MMAP_VA_BITS
- Added additional test case for rlimit changes
---
Charlie Jenkins (4):
RISC-V: mm: Restrict address space for sv39,sv48,sv57
RISC-V: mm: Add tests for RISC-V mm
RISC-V: mm: Update pgtable comment documentation
RISC-V: mm: Document mmap changes
Documentation/riscv/vm-layout.rst | 22 +++++++
arch/riscv/include/asm/elf.h | 2 +-
arch/riscv/include/asm/pgtable.h | 33 ++++++++--
arch/riscv/include/asm/processor.h | 52 +++++++++++++--
tools/testing/selftests/riscv/Makefile | 2 +-
tools/testing/selftests/riscv/mm/.gitignore | 2 +
tools/testing/selftests/riscv/mm/Makefile | 15 +++++
.../riscv/mm/testcases/mmap_bottomup.c | 35 ++++++++++
.../riscv/mm/testcases/mmap_default.c | 35 ++++++++++
.../selftests/riscv/mm/testcases/mmap_test.h | 64 +++++++++++++++++++
.../selftests/riscv/mm/testcases/run_mmap.sh | 12 ++++
11 files changed, 261 insertions(+), 13 deletions(-)
create mode 100644 tools/testing/selftests/riscv/mm/.gitignore
create mode 100644 tools/testing/selftests/riscv/mm/Makefile
create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_bottomup.c
create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_default.c
create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_test.h
create mode 100755 tools/testing/selftests/riscv/mm/testcases/run_mmap.sh
--
2.34.1
Hi folks,
This series implements the functionality of delivering IO page faults to
user space through the IOMMUFD framework for nested translation. Nested
translation is a hardware feature that supports two-stage translation
tables for IOMMU. The second-stage translation table is managed by the
host VMM, while the first-stage translation table is owned by user
space. This allows user space to control the IOMMU mappings for its
devices.
When an IO page fault occurs on the first-stage translation table, the
IOMMU hardware can deliver the page fault to user space through the
IOMMUFD framework. User space can then handle the page fault and respond
to the device top-down through the IOMMUFD. This allows user space to
implement its own IO page fault handling policies.
User space indicates its capability of handling IO page faults by
setting the IOMMU_HWPT_ALLOC_IOPF_CAPABLE flag when allocating a
hardware page table (HWPT). IOMMUFD will then set up its infrastructure
for page fault delivery. On a successful return of HWPT allocation, the
user can retrieve and respond to page faults by reading and writing to
the file descriptor (FD) returned in out_fault_fd.
The iommu selftest framework has been updated to test the IO page fault
delivery and response functionality.
This series is based on the latest implementation of nested translation
under discussion [1] and the page fault handling framework refactoring in
the IOMMU core [2].
The series and related patches are available on GitHub: [3]
[1] https://lore.kernel.org/linux-iommu/20230921075138.124099-1-yi.l.liu@intel.…
[2] https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@linux.i…
[3] https://github.com/LuBaolu/intel-iommu/commits/iommufd-io-pgfault-delivery-…
Best regards,
baolu
Change log:
v2:
- Move all iommu refactoring patches into a sparated series and discuss
it in a different thread. The latest patch series [v6] is available at
https://lore.kernel.org/linux-iommu/20230928042734.16134-1-baolu.lu@linux.i…
- We discussed the timeout of the pending page fault messages. We
agreed that we shouldn't apply any timeout policy for the page fault
handling in user space.
https://lore.kernel.org/linux-iommu/20230616113232.GA84678@myrica/
- Jason suggested that we adopt a simple file descriptor interface for
reading and responding to I/O page requests, so that user space
applications can improve performance using io_uring.
https://lore.kernel.org/linux-iommu/ZJWjD1ajeem6pK3I@ziepe.ca/
v1: https://lore.kernel.org/linux-iommu/20230530053724.232765-1-baolu.lu@linux.…
Lu Baolu (6):
iommu: Add iommu page fault cookie helpers
iommufd: Add iommu page fault uapi data
iommufd: Initializing and releasing IO page fault data
iommufd: Deliver fault messages to user space
iommufd/selftest: Add IOMMU_TEST_OP_TRIGGER_IOPF test support
iommufd/selftest: Add coverage for IOMMU_TEST_OP_TRIGGER_IOPF
include/linux/iommu.h | 9 +
drivers/iommu/iommu-priv.h | 15 +
drivers/iommu/iommufd/iommufd_private.h | 12 +
drivers/iommu/iommufd/iommufd_test.h | 8 +
include/uapi/linux/iommufd.h | 65 +++++
tools/testing/selftests/iommu/iommufd_utils.h | 66 ++++-
drivers/iommu/io-pgfault.c | 50 ++++
drivers/iommu/iommufd/device.c | 69 ++++-
drivers/iommu/iommufd/hw_pagetable.c | 260 +++++++++++++++++-
drivers/iommu/iommufd/selftest.c | 56 ++++
tools/testing/selftests/iommu/iommufd.c | 24 +-
.../selftests/iommu/iommufd_fail_nth.c | 2 +-
12 files changed, 620 insertions(+), 16 deletions(-)
--
2.34.1