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2023-10-19file: convert to SLAB_TYPESAFE_BY_RCUChristian Brauner
In recent discussions around some performance improvements in the file handling area we discussed switching the file cache to rely on SLAB_TYPESAFE_BY_RCU which allows us to get rid of call_rcu() based freeing for files completely. This is a pretty sensitive change overall but it might actually be worth doing. The main downside is the subtlety. The other one is that we should really wait for Jann's patch to land that enables KASAN to handle SLAB_TYPESAFE_BY_RCU UAFs. Currently it doesn't but a patch for this exists. With SLAB_TYPESAFE_BY_RCU objects may be freed and reused multiple times which requires a few changes. So it isn't sufficient anymore to just acquire a reference to the file in question under rcu using atomic_long_inc_not_zero() since the file might have already been recycled and someone else might have bumped the reference. In other words, callers might see reference count bumps from newer users. For this reason it is necessary to verify that the pointer is the same before and after the reference count increment. This pattern can be seen in get_file_rcu() and __files_get_rcu(). In addition, it isn't possible to access or check fields in struct file without first aqcuiring a reference on it. Not doing that was always very dodgy and it was only usable for non-pointer data in struct file. With SLAB_TYPESAFE_BY_RCU it is necessary that callers first acquire a reference under rcu or they must hold the files_lock of the fdtable. Failing to do either one of this is a bug. Thanks to Jann for pointing out that we need to ensure memory ordering between reallocations and pointer check by ensuring that all subsequent loads have a dependency on the second load in get_file_rcu() and providing a fixup that was folded into this patch. Cc: Jann Horn <jannh@google.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-09-01Merge tag 'percpu-for-6.6' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu Pull percpu updates from Dennis Zhou: "One bigger change to percpu_counter's api allowing for init and destroy of multiple counters via percpu_counter_init_many() and percpu_counter_destroy_many(). This is used to help begin remediating a performance regression with percpu rss stats. Additionally, it seems larger core count machines are feeling the burden of the single threaded allocation of percpu. Mateusz is thinking about it and I will spend some time on it too. percpu: - A couple cleanups by Baoquan He and Bibo Mao. The only behavior change is to start printing messages if we're under the warn limit for failed atomic allocations. percpu_counter: - Shakeel introduced percpu counters into mm_struct which caused percpu allocations be on the hot path [1]. Originally I spent some time trying to improve the percpu allocator, but instead preferred what Mateusz Guzik proposed grouping at the allocation site, percpu_counter_init_many(). This allows a single percpu allocation to be shared by the counters. I like this approach because it creates a shared lifetime by the allocations. Additionally, I believe many inits have higher level synchronization requirements, like percpu_counter does against HOTPLUG_CPU. Therefore we can group these optimizations together" Link: https://lore.kernel.org/linux-mm/20221024052841.3291983-1-shakeelb@google.com/ [1] * tag 'percpu-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu: kernel/fork: group allocation/free of per-cpu counters for mm struct pcpcntr: add group allocation/free mm/percpu.c: print error message too if atomic alloc failed mm/percpu.c: optimize the code in pcpu_setup_first_chunk() a little bit mm/percpu.c: remove redundant check mm/percpu: Remove some local variables in pcpu_populate_pte
2023-08-29Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull non-MM updates from Andrew Morton: - An extensive rework of kexec and crash Kconfig from Eric DeVolder ("refactor Kconfig to consolidate KEXEC and CRASH options") - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a couple of macros to args.h") - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper commands") - vsprintf inclusion rationalization from Andy Shevchenko ("lib/vsprintf: Rework header inclusions") - Switch the handling of kdump from a udev scheme to in-kernel handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory hot un/plug") - Many singleton patches to various parts of the tree * tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits) document while_each_thread(), change first_tid() to use for_each_thread() drivers/char/mem.c: shrink character device's devlist[] array x86/crash: optimize CPU changes crash: change crash_prepare_elf64_headers() to for_each_possible_cpu() crash: hotplug support for kexec_load() x86/crash: add x86 crash hotplug support crash: memory and CPU hotplug sysfs attributes kexec: exclude elfcorehdr from the segment digest crash: add generic infrastructure for crash hotplug support crash: move a few code bits to setup support of crash hotplug kstrtox: consistently use _tolower() kill do_each_thread() nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse scripts/bloat-o-meter: count weak symbol sizes treewide: drop CONFIG_EMBEDDED lockdep: fix static memory detection even more lib/vsprintf: declare no_hash_pointers in sprintf.h lib/vsprintf: split out sprintf() and friends kernel/fork: stop playing lockless games for exe_file replacement adfs: delete unused "union adfs_dirtail" definition ...
2023-08-25kernel/fork: group allocation/free of per-cpu counters for mm structMateusz Guzik
A trivial execve scalability test which tries to be very friendly (statically linked binaries, all separate) is predominantly bottlenecked by back-to-back per-cpu counter allocations which serialize on global locks. Ease the pain by allocating and freeing them in one go. Bench can be found here: http://apollo.backplane.com/DFlyMisc/doexec.c $ cc -static -O2 -o static-doexec doexec.c $ ./static-doexec $(nproc) Even at a very modest scale of 26 cores (ops/s): before: 133543.63 after: 186061.81 (+39%) While with the patch these allocations remain a significant problem, the primary bottleneck shifts to page release handling. Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Link: https://lore.kernel.org/r/20230823050609.2228718-3-mjguzik@gmail.com [Dennis: reflowed 1 line] Signed-off-by: Dennis Zhou <dennis@kernel.org>
2023-08-21kernel/fork: stop playing lockless games for exe_file replacementMateusz Guzik
xchg originated in 6e399cd144d8 ("prctl: avoid using mmap_sem for exe_file serialization"). While the commit message does not explain *why* the change, I found the original submission [1] which ultimately claims it cleans things up by removing dependency of exe_file on the semaphore. However, fe69d560b5bd ("kernel/fork: always deny write access to current MM exe_file") added a semaphore up/down cycle to synchronize the state of exe_file against fork, defeating the point of the original change. This is on top of semaphore trips already present both in the replacing function and prctl (the only consumer). Normally replacing exe_file does not happen for busy processes, thus write-locking is not an impediment to performance in the intended use case. If someone keeps invoking the routine for a busy processes they are trying to play dirty and that's another reason to avoid any trickery. As such I think the atomic here only adds complexity for no benefit. Just write-lock around the replacement. I also note that replacement races against the mapping check loop as nothing synchronizes actual assignment with with said checks but I am not addressing it in this patch. (Is the loop of any use to begin with?) Link: https://lore.kernel.org/linux-mm/1424979417.10344.14.camel@stgolabs.net/ [1] Link: https://lkml.kernel.org/r/20230814172140.1777161-1-mjguzik@gmail.com Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: "Christian Brauner (Microsoft)" <brauner@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mateusz Guzik <mjguzik@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-07-13kernel/fork: beware of __put_task_struct() calling contextWander Lairson Costa
Under PREEMPT_RT, __put_task_struct() indirectly acquires sleeping locks. Therefore, it can't be called from an non-preemptible context. One practical example is splat inside inactive_task_timer(), which is called in a interrupt context: CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W --------- Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012 Call Trace: dump_stack_lvl+0x57/0x7d mark_lock_irq.cold+0x33/0xba mark_lock+0x1e7/0x400 mark_usage+0x11d/0x140 __lock_acquire+0x30d/0x930 lock_acquire.part.0+0x9c/0x210 rt_spin_lock+0x27/0xe0 refill_obj_stock+0x3d/0x3a0 kmem_cache_free+0x357/0x560 inactive_task_timer+0x1ad/0x340 __run_hrtimer+0x8a/0x1a0 __hrtimer_run_queues+0x91/0x130 hrtimer_interrupt+0x10f/0x220 __sysvec_apic_timer_interrupt+0x7b/0xd0 sysvec_apic_timer_interrupt+0x4f/0xd0 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0033:0x7fff196bf6f5 Instead of calling __put_task_struct() directly, we defer it using call_rcu(). A more natural approach would use a workqueue, but since in PREEMPT_RT, we can't allocate dynamic memory from atomic context, the code would become more complex because we would need to put the work_struct instance in the task_struct and initialize it when we allocate a new task_struct. The issue is reproducible with stress-ng: while true; do stress-ng --sched deadline --sched-period 1000000000 \ --sched-runtime 800000000 --sched-deadline \ 1000000000 --mmapfork 23 -t 20 done Reported-by: Hu Chunyu <chuhu@redhat.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> Suggested-by: Valentin Schneider <vschneid@redhat.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Wander Lairson Costa <wander@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230614122323.37957-2-wander@redhat.com
2023-07-08fork: lock VMAs of the parent process when forkingSuren Baghdasaryan
When forking a child process, the parent write-protects anonymous pages and COW-shares them with the child being forked using copy_present_pte(). We must not take any concurrent page faults on the source vma's as they are being processed, as we expect both the vma and the pte's behind it to be stable. For example, the anon_vma_fork() expects the parents vma->anon_vma to not change during the vma copy. A concurrent page fault on a page newly marked read-only by the page copy might trigger wp_page_copy() and a anon_vma_prepare(vma) on the source vma, defeating the anon_vma_clone() that wasn't done because the parent vma originally didn't have an anon_vma, but we now might end up copying a pte entry for a page that has one. Before the per-vma lock based changes, the mmap_lock guaranteed exclusion with concurrent page faults. But now we need to do a vma_start_write() to make sure no concurrent faults happen on this vma while it is being processed. This fix can potentially regress some fork-heavy workloads. Kernel build time did not show noticeable regression on a 56-core machine while a stress test mapping 10000 VMAs and forking 5000 times in a tight loop shows ~5% regression. If such fork time regression is unacceptable, disabling CONFIG_PER_VMA_LOCK should restore its performance. Further optimizations are possible if this regression proves to be problematic. Suggested-by: David Hildenbrand <david@redhat.com> Reported-by: Jiri Slaby <jirislaby@kernel.org> Closes: https://lore.kernel.org/all/dbdef34c-3a07-5951-e1ae-e9c6e3cdf51b@kernel.org/ Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com> Closes: https://lore.kernel.org/all/b198d649-f4bf-b971-31d0-e8433ec2a34c@applied-asynchrony.com/ Reported-by: Jacob Young <jacobly.alt@gmail.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217624 Fixes: 0bff0aaea03e ("x86/mm: try VMA lock-based page fault handling first") Cc: stable@vger.kernel.org Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-06-28Merge tag 'mm-nonmm-stable-2023-06-24-19-23' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull non-mm updates from Andrew Morton: - Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in top-level directories - Douglas Anderson has added a new "buddy" mode to the hardlockup detector. It permits the detector to work on architectures which cannot provide the required interrupts, by having CPUs periodically perform checks on other CPUs - Zhen Lei has enhanced kexec's ability to support two crash regions - Petr Mladek has done a lot of cleanup on the hard lockup detector's Kconfig entries - And the usual bunch of singleton patches in various places * tag 'mm-nonmm-stable-2023-06-24-19-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits) kernel/time/posix-stubs.c: remove duplicated include ocfs2: remove redundant assignment to variable bit_off watchdog/hardlockup: fix typo in config HARDLOCKUP_DETECTOR_PREFER_BUDDY powerpc: move arch_trigger_cpumask_backtrace from nmi.h to irq.h devres: show which resource was invalid in __devm_ioremap_resource() watchdog/hardlockup: define HARDLOCKUP_DETECTOR_ARCH watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64 watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific watchdog/hardlockup: declare arch_touch_nmi_watchdog() only in linux/nmi.h watchdog/hardlockup: make the config checks more straightforward watchdog/hardlockup: sort hardlockup detector related config values a logical way watchdog/hardlockup: move SMP barriers from common code to buddy code watchdog/buddy: simplify the dependency for HARDLOCKUP_DETECTOR_PREFER_BUDDY watchdog/buddy: don't copy the cpumask in watchdog_next_cpu() watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog() watchdog/hardlockup: in watchdog_hardlockup_check() use cpumask_copy() watchdog/hardlockup: don't use raw_cpu_ptr() in watchdog_hardlockup_kick() watchdog/hardlockup: HAVE_NMI_WATCHDOG must implement watchdog_hardlockup_probe() watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails ...
2023-06-09fork: optimize memcg_charge_kernel_stack() a bitHaifeng Xu
Since commit f1c1a9ee00e4 ("fork: Move memcg_charge_kernel_stack() into CONFIG_VMAP_STACK"), memcg_charge_kernel_stack() has been moved into CONFIG_VMAP_STACK block, so the CONFIG_VMAP_STACK check can be removed. Furthermore, memcg_charge_kernel_stack() is only invoked by alloc_thread_stack_node() instead of dup_task_struct(). If memcg_kmem_charge_page() fails, the uncharge process is handled in memcg_charge_kernel_stack() itself instead of free_thread_stack(), so remove the incorrect comments. If memcg_charge_kernel_stack() fails to charge pages used by kernel stack, only charged pages need to be uncharged. It's unnecessary to uncharge those pages which memory cgroup pointer is NULL. [akpm@linux-foundation.org: remove assertion that PAGE_SIZE is a multiple of 1k] Link: https://lkml.kernel.org/r/20230508064458.32855-1-haifeng.xu@shopee.com Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Daniel Bristot de Oliveira <bristot@kernel.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-07Merge tag 'for-netdev' of ↵Jakub Kicinski
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf Daniel Borkmann says: ==================== pull-request: bpf 2023-06-07 We've added 7 non-merge commits during the last 7 day(s) which contain a total of 12 files changed, 112 insertions(+), 7 deletions(-). The main changes are: 1) Fix a use-after-free in BPF's task local storage, from KP Singh. 2) Make struct path handling more robust in bpf_d_path, from Jiri Olsa. 3) Fix a syzbot NULL-pointer dereference in sockmap, from Eric Dumazet. 4) UAPI fix for BPF_NETFILTER before final kernel ships, from Florian Westphal. 5) Fix map-in-map array_map_gen_lookup code generation where elem_size was not being set for inner maps, from Rhys Rustad-Elliott. 6) Fix sockopt_sk selftest's NETLINK_LIST_MEMBERSHIPS assertion, from Yonghong Song. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: bpf: Add extra path pointer check to d_path helper selftests/bpf: Fix sockopt_sk selftest bpf: netfilter: Add BPF_NETFILTER bpf_attach_type selftests/bpf: Add access_inner_map selftest bpf: Fix elem_size not being set for inner maps bpf: Fix UAF in task local storage bpf, sockmap: Avoid potential NULL dereference in sk_psock_verdict_data_ready() ==================== Link: https://lore.kernel.org/r/20230607220514.29698-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-06-02bpf: Fix UAF in task local storageKP Singh
When task local storage was generalized for tracing programs, the bpf_task_local_storage callback was moved from a BPF LSM hook callback for security_task_free LSM hook to it's own callback. But a failure case in bad_fork_cleanup_security was missed which, when triggered, led to a dangling task owner pointer and a subsequent use-after-free. Move the bpf_task_storage_free to the very end of free_task to handle all failure cases. This issue was noticed when a BPF LSM program was attached to the task_alloc hook on a kernel with KASAN enabled. The program used bpf_task_storage_get to copy the task local storage from the current task to the new task being created. Fixes: a10787e6d58c ("bpf: Enable task local storage for tracing programs") Reported-by: Kuba Piecuch <jpiecuch@google.com> Signed-off-by: KP Singh <kpsingh@kernel.org> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20230602002612.1117381-1-kpsingh@kernel.org Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-06-01fork, vhost: Use CLONE_THREAD to fix freezer/ps regressionMike Christie
When switching from kthreads to vhost_tasks two bugs were added: 1. The vhost worker tasks's now show up as processes so scripts doing ps or ps a would not incorrectly detect the vhost task as another process. 2. kthreads disabled freeze by setting PF_NOFREEZE, but vhost tasks's didn't disable or add support for them. To fix both bugs, this switches the vhost task to be thread in the process that does the VHOST_SET_OWNER ioctl, and has vhost_worker call get_signal to support SIGKILL/SIGSTOP and freeze signals. Note that SIGKILL/STOP support is required because CLONE_THREAD requires CLONE_SIGHAND which requires those 2 signals to be supported. This is a modified version of the patch written by Mike Christie <michael.christie@oracle.com> which was a modified version of patch originally written by Linus. Much of what depended upon PF_IO_WORKER now depends on PF_USER_WORKER. Including ignoring signals, setting up the register state, and having get_signal return instead of calling do_group_exit. Tidied up the vhost_task abstraction so that the definition of vhost_task only needs to be visible inside of vhost_task.c. Making it easier to review the code and tell what needs to be done where. As part of this the main loop has been moved from vhost_worker into vhost_task_fn. vhost_worker now returns true if work was done. The main loop has been updated to call get_signal which handles SIGSTOP, freezing, and collects the message that tells the thread to exit as part of process exit. This collection clears __fatal_signal_pending. This collection is not guaranteed to clear signal_pending() so clear that explicitly so the schedule() sleeps. For now the vhost thread continues to exist and run work until the last file descriptor is closed and the release function is called as part of freeing struct file. To avoid hangs in the coredump rendezvous and when killing threads in a multi-threaded exec. The coredump code and de_thread have been modified to ignore vhost threads. Remvoing the special case for exec appears to require teaching vhost_dev_flush how to directly complete transactions in case the vhost thread is no longer running. Removing the special case for coredump rendezvous requires either the above fix needed for exec or moving the coredump rendezvous into get_signal. Fixes: 6e890c5d5021 ("vhost: use vhost_tasks for worker threads") Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Co-developed-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-04-30Merge tag 'iommu-updates-v6.4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu Pull iommu updates from Joerg Roedel: - Convert to platform remove callback returning void - Extend changing default domain to normal group - Intel VT-d updates: - Remove VT-d virtual command interface and IOASID - Allow the VT-d driver to support non-PRI IOPF - Remove PASID supervisor request support - Various small and misc cleanups - ARM SMMU updates: - Device-tree binding updates: * Allow Qualcomm GPU SMMUs to accept relevant clock properties * Document Qualcomm 8550 SoC as implementing an MMU-500 * Favour new "qcom,smmu-500" binding for Adreno SMMUs - Fix S2CR quirk detection on non-architectural Qualcomm SMMU implementations - Acknowledge SMMUv3 PRI queue overflow when consuming events - Document (in a comment) why ATS is disabled for bypass streams - AMD IOMMU updates: - 5-level page-table support - NUMA awareness for memory allocations - Unisoc driver: Support for reattaching an existing domain - Rockchip driver: Add missing set_platform_dma_ops callback - Mediatek driver: Adjust the dma-ranges - Various other small fixes and cleanups * tag 'iommu-updates-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (82 commits) iommu: Remove iommu_group_get_by_id() iommu: Make iommu_release_device() static iommu/vt-d: Remove BUG_ON in dmar_insert_dev_scope() iommu/vt-d: Remove a useless BUG_ON(dev->is_virtfn) iommu/vt-d: Remove BUG_ON in map/unmap() iommu/vt-d: Remove BUG_ON when domain->pgd is NULL iommu/vt-d: Remove BUG_ON in handling iotlb cache invalidation iommu/vt-d: Remove BUG_ON on checking valid pfn range iommu/vt-d: Make size of operands same in bitwise operations iommu/vt-d: Remove PASID supervisor request support iommu/vt-d: Use non-privileged mode for all PASIDs iommu/vt-d: Remove extern from function prototypes iommu/vt-d: Do not use GFP_ATOMIC when not needed iommu/vt-d: Remove unnecessary checks in iopf disabling path iommu/vt-d: Move PRI handling to IOPF feature path iommu/vt-d: Move pfsid and ats_qdep calculation to device probe path iommu/vt-d: Move iopf code from SVA to IOPF enabling path iommu/vt-d: Allow SVA with device-specific IOPF dmaengine: idxd: Add enable/disable device IOPF feature arm64: dts: mt8186: Add dma-ranges for the parent "soc" node ...
2023-04-28Merge tag 'trace-v6.4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing updates from Steven Rostedt: - User events are finally ready! After lots of collaboration between various parties, we finally locked down on a stable interface for user events that can also work with user space only tracing. This is implemented by telling the kernel (or user space library, but that part is user space only and not part of this patch set), where the variable is that the application uses to know if something is listening to the trace. There's also an interface to tell the kernel about these events, which will show up in the /sys/kernel/tracing/events/user_events/ directory, where it can be enabled. When it's enabled, the kernel will update the variable, to tell the application to start writing to the kernel. See https://lwn.net/Articles/927595/ - Cleaned up the direct trampolines code to simplify arm64 addition of direct trampolines. Direct trampolines use the ftrace interface but instead of jumping to the ftrace trampoline, applications (mostly BPF) can register their own trampoline for performance reasons. - Some updates to the fprobe infrastructure. fprobes are more efficient than kprobes, as it does not need to save all the registers that kprobes on ftrace do. More work needs to be done before the fprobes will be exposed as dynamic events. - More updates to references to the obsolete path of /sys/kernel/debug/tracing for the new /sys/kernel/tracing path. - Add a seq_buf_do_printk() helper to seq_bufs, to print a large buffer line by line instead of all at once. There are users in production kernels that have a large data dump that originally used printk() directly, but the data dump was larger than what printk() allowed as a single print. Using seq_buf() to do the printing fixes that. - Add /sys/kernel/tracing/touched_functions that shows all functions that was every traced by ftrace or a direct trampoline. This is used for debugging issues where a traced function could have caused a crash by a bpf program or live patching. - Add a "fields" option that is similar to "raw" but outputs the fields of the events. It's easier to read by humans. - Some minor fixes and clean ups. * tag 'trace-v6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (41 commits) ring-buffer: Sync IRQ works before buffer destruction tracing: Add missing spaces in trace_print_hex_seq() ring-buffer: Ensure proper resetting of atomic variables in ring_buffer_reset_online_cpus recordmcount: Fix memory leaks in the uwrite function tracing/user_events: Limit max fault-in attempts tracing/user_events: Prevent same address and bit per process tracing/user_events: Ensure bit is cleared on unregister tracing/user_events: Ensure write index cannot be negative seq_buf: Add seq_buf_do_printk() helper tracing: Fix print_fields() for __dyn_loc/__rel_loc tracing/user_events: Set event filter_type from type ring-buffer: Clearly check null ptr returned by rb_set_head_page() tracing: Unbreak user events tracing/user_events: Use print_format_fields() for trace output tracing/user_events: Align structs with tabs for readability tracing/user_events: Limit global user_event count tracing/user_events: Charge event allocs to cgroups tracing/user_events: Update documentation for ABI tracing/user_events: Use write ABI in example tracing/user_events: Add ABI self-test ...
2023-04-28Merge tag 'sched-core-2023-04-27' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - Allow unprivileged PSI poll()ing - Fix performance regression introduced by mm_cid - Improve livepatch stalls by adding livepatch task switching to cond_resched(). This resolves livepatching busy-loop stalls with certain CPU-bound kthreads - Improve sched_move_task() performance on autogroup configs - On core-scheduling CPUs, avoid selecting throttled tasks to run - Misc cleanups, fixes and improvements * tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/clock: Fix local_clock() before sched_clock_init() sched/rt: Fix bad task migration for rt tasks sched: Fix performance regression introduced by mm_cid sched/core: Make sched_dynamic_mutex static sched/psi: Allow unprivileged polling of N*2s period sched/psi: Extract update_triggers side effect sched/psi: Rename existing poll members in preparation sched/psi: Rearrange polling code in preparation sched/fair: Fix inaccurate tally of ttwu_move_affine vhost: Fix livepatch timeouts in vhost_worker() livepatch,sched: Add livepatch task switching to cond_resched() livepatch: Skip task_call_func() for current task livepatch: Convert stack entries array to percpu sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization sched/core: Reduce cost of sched_move_task when config autogroup sched/core: Avoid selecting the task that is throttled to run when core-sched enable sched/topology: Make sched_energy_mutex,update static
2023-04-27Merge tag 'mm-stable-2023-04-27-15-30' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of switching from a user process to a kernel thread. - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav. - zsmalloc performance improvements from Sergey Senozhatsky. - Yue Zhao has found and fixed some data race issues around the alteration of memcg userspace tunables. - VFS rationalizations from Christoph Hellwig: - removal of most of the callers of write_one_page() - make __filemap_get_folio()'s return value more useful - Luis Chamberlain has changed tmpfs so it no longer requires swap backing. Use `mount -o noswap'. - Qi Zheng has made the slab shrinkers operate locklessly, providing some scalability benefits. - Keith Busch has improved dmapool's performance, making part of its operations O(1) rather than O(n). - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd, permitting userspace to wr-protect anon memory unpopulated ptes. - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather than exclusive, and has fixed a bunch of errors which were caused by its unintuitive meaning. - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature, which causes minor faults to install a write-protected pte. - Vlastimil Babka has done some maintenance work on vma_merge(): cleanups to the kernel code and improvements to our userspace test harness. - Cleanups to do_fault_around() by Lorenzo Stoakes. - Mike Rapoport has moved a lot of initialization code out of various mm/ files and into mm/mm_init.c. - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for DRM, but DRM doesn't use it any more. - Lorenzo has also coverted read_kcore() and vread() to use iterators and has thereby removed the use of bounce buffers in some cases. - Lorenzo has also contributed further cleanups of vma_merge(). - Chaitanya Prakash provides some fixes to the mmap selftesting code. - Matthew Wilcox changes xfs and afs so they no longer take sleeping locks in ->map_page(), a step towards RCUification of pagefaults. - Suren Baghdasaryan has improved mmap_lock scalability by switching to per-VMA locking. - Frederic Weisbecker has reworked the percpu cache draining so that it no longer causes latency glitches on cpu isolated workloads. - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig logic. - Liu Shixin has changed zswap's initialization so we no longer waste a chunk of memory if zswap is not being used. - Yosry Ahmed has improved the performance of memcg statistics flushing. - David Stevens has fixed several issues involving khugepaged, userfaultfd and shmem. - Christoph Hellwig has provided some cleanup work to zram's IO-related code paths. - David Hildenbrand has fixed up some issues in the selftest code's testing of our pte state changing. - Pankaj Raghav has made page_endio() unneeded and has removed it. - Peter Xu contributed some rationalizations of the userfaultfd selftests. - Yosry Ahmed has fixed an issue around memcg's page recalim accounting. - Chaitanya Prakash has fixed some arm-related issues in the selftests/mm code. - Longlong Xia has improved the way in which KSM handles hwpoisoned pages. - Peter Xu fixes a few issues with uffd-wp at fork() time. - Stefan Roesch has changed KSM so that it may now be used on a per-process and per-cgroup basis. * tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits) mm,unmap: avoid flushing TLB in batch if PTE is inaccessible shmem: restrict noswap option to initial user namespace mm/khugepaged: fix conflicting mods to collapse_file() sparse: remove unnecessary 0 values from rc mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area() hugetlb: pte_alloc_huge() to replace huge pte_alloc_map() maple_tree: fix allocation in mas_sparse_area() mm: do not increment pgfault stats when page fault handler retries zsmalloc: allow only one active pool compaction context selftests/mm: add new selftests for KSM mm: add new KSM process and sysfs knobs mm: add new api to enable ksm per process mm: shrinkers: fix debugfs file permissions mm: don't check VMA write permissions if the PTE/PMD indicates write permissions migrate_pages_batch: fix statistics for longterm pin retry userfaultfd: use helper function range_in_vma() lib/show_mem.c: use for_each_populated_zone() simplify code mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list() fs/buffer: convert create_page_buffers to folio_create_buffers fs/buffer: add folio_create_empty_buffers helper ...
2023-04-24Merge tag 'v6.4/pidfd.file' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull pidfd updates from Christian Brauner: "This adds a new pidfd_prepare() helper which allows the caller to reserve a pidfd number and allocates a new pidfd file that stashes the provided struct pid. It should be avoided installing a file descriptor into a task's file descriptor table just to close it again via close_fd() in case an error occurs. The fd has been visible to userspace and might already be in use. Instead, a file descriptor should be reserved but not installed into the caller's file descriptor table. If another failure path is hit then the reserved file descriptor and file can just be put without any userspace visible side-effects. And if all failure paths are cleared the file descriptor and file can be installed into the task's file descriptor table. This helper is now used in all places that open coded this functionality before. For example, this is currently done during copy_process() and fanotify used pidfd_create(), which returns a pidfd that has already been made visibile in the caller's file descriptor table, but then closed it using close_fd(). In one of the next merge windows there is also new functionality coming to unix domain sockets that will have to rely on pidfd_prepare()" * tag 'v6.4/pidfd.file' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: fanotify: use pidfd_prepare() fork: use pidfd_prepare() pid: add pidfd_prepare()
2023-04-24Merge tag 'v6.4/kernel.user_worker' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull user work thread updates from Christian Brauner: "This contains the work generalizing the ability to create a kernel worker from a userspace process. Such user workers will run with the same credentials as the userspace process they were created from providing stronger security and accounting guarantees than the traditional override_creds() approach ever could've hoped for. The original work was heavily based and optimzed for the needs of io_uring which was the first user. However, as it quickly turned out the ability to create user workers inherting properties from a userspace process is generally useful. The vhost subsystem currently creates workers using the kthread api. The consequences of using the kthread api are that RLIMITs don't work correctly as they are inherited from khtreadd. This leads to bugs where more workers are created than would be allowed by the RLIMITs of the userspace process in lieu of which workers are created. Problems like this disappear with user workers created from the userspace processes for which they perform the work. In addition, providing this api allows vhost to remove additional complexity. For example, cgroup and mm sharing will just work out of the box with user workers based on the relevant userspace process instead of manually ensuring the correct cgroup and mm contexts are used. So the vhost subsystem should simply be made to use the same mechanism as io_uring. To this end the original mechanism used for create_io_thread() is generalized into user workers: - Introduce PF_USER_WORKER as a generic indicator that a given task is a user worker, i.e., a kernel task that was created from a userspace process. Now a PF_IO_WORKER thread is just a specialized version of PF_USER_WORKER. So io_uring io workers raise both flags. - Make copy_process() available to core kernel code - Extend struct kernel_clone_args with the following bitfields allowing to indicate to copy_process(): - to create a user worker (raise PF_USER_WORKER) - to not inherit any files from the userspace process - to ignore signals After all generic changes are in place the vhost subsystem implements a new dedicated vhost api based on user workers. Finally, vhost is switched to rely on the new api moving it off of kthreads. Thanks to Mike for sticking it out and making it through this rather arduous journey" * tag 'v6.4/kernel.user_worker' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: vhost: use vhost_tasks for worker threads vhost: move worker thread fields to new struct vhost_task: Allow vhost layer to use copy_process fork: allow kernel code to call copy_process fork: Add kernel_clone_args flag to ignore signals fork: add kernel_clone_args flag to not dup/clone files fork/vm: Move common PF_IO_WORKER behavior to new flag kernel: Make io_thread and kthread bit fields kthread: Pass in the thread's name during creation kernel: Allow a kernel thread's name to be set in copy_process csky: Remove kernel_thread declaration
2023-04-21sched: Fix performance regression introduced by mm_cidMathieu Desnoyers
Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL sysbench regression reported by Aaron Lu. Keep track of the currently allocated mm_cid for each mm/cpu rather than freeing them immediately on context switch. This eliminates most atomic operations when context switching back and forth between threads belonging to different memory spaces in multi-threaded scenarios (many processes, each with many threads). The per-mm/per-cpu mm_cid values are serialized by their respective runqueue locks. Thread migration is handled by introducing invocation to sched_mm_cid_migrate_to() (with destination runqueue lock held) in activate_task() for migrating tasks. If the destination cpu's mm_cid is unset, and if the source runqueue is not actively using its mm_cid, then the source cpu's mm_cid is moved to the destination cpu on migration. Introduce a task-work executed periodically, similarly to NUMA work, which delays reclaim of cid values when they are unused for a period of time. Keep track of the allocation time for each per-cpu cid, and let the task work clear them when they are observed to be older than SCHED_MM_CID_PERIOD_NS and unused. This task work also clears all mm_cids which are greater or equal to the Hamming weight of the mm cidmask to keep concurrency ids compact. Because we want to ensure the mm_cid converges towards the smaller values as migrations happen, the prior optimization that was done when context switching between threads belonging to the same mm is removed, because it could delay the lazy release of the destination runqueue mm_cid after it has been replaced by a migration. Removing this prior optimization is not an issue performance-wise because the introduced per-mm/per-cpu mm_cid tracking also covers this more specific case. Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID") Reported-by: Aaron Lu <aaron.lu@intel.com> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Aaron Lu <aaron.lu@intel.com> Link: https://lore.kernel.org/lkml/20230327080502.GA570847@ziqianlu-desk2/
2023-04-18sync mm-stable with mm-hotfixes-stable to pick up depended-upon upstream changesAndrew Morton
2023-04-18mm: fix memory leak on mm_init error handlingMathieu Desnoyers
commit f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter") introduces a memory leak by missing a call to destroy_context() when a percpu_counter fails to allocate. Before introducing the per-cpu counter allocations, init_new_context() was the last call that could fail in mm_init(), and thus there was no need to ever invoke destroy_context() in the error paths. Adding the following percpu counter allocations adds error paths after init_new_context(), which means its associated destroy_context() needs to be called when percpu counters fail to allocate. Link: https://lkml.kernel.org/r/20230330133822.66271-1-mathieu.desnoyers@efficios.com Fixes: f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-16sync mm-stable with mm-hotfixes-stable to pick up depended-upon upstream changesAndrew Morton
2023-04-14Merge branches 'iommu/fixes', 'arm/allwinner', 'arm/exynos', 'arm/mediatek', ↵Joerg Roedel
'arm/omap', 'arm/renesas', 'arm/rockchip', 'arm/smmu', 'ppc/pamu', 'unisoc', 'x86/vt-d', 'x86/amd', 'core' and 'platform-remove_new' into next
2023-04-05sched/numa: apply the scan delay to every new vmaMel Gorman
Pach series "sched/numa: Enhance vma scanning", v3. The patchset proposes one of the enhancements to numa vma scanning suggested by Mel. This is continuation of [3]. Reposting the rebased patchset to akpm mm-unstable tree (March 1) Existing mechanism of scan period involves, scan period derived from per-thread stats. Process Adaptive autoNUMA [1] proposed to gather NUMA fault stats at per-process level to capture aplication behaviour better. During that course of discussion, Mel proposed several ideas to enhance current numa balancing. One of the suggestion was below Track what threads access a VMA. The suggestion was to use an unsigned long pid_mask and use the lower bits to tag approximately what threads access a VMA. Skip VMAs that did not trap a fault. This would be approximate because of PID collisions but would reduce scanning of areas the thread is not interested in. The above suggestion intends not to penalize threads that has no interest in the vma, thus reduce scanning overhead. V3 changes are mostly based on PeterZ comments (details below in changes) Summary of patchset: Current patchset implements: 1. Delay the vma scanning logic for newly created VMA's so that additional overhead of scanning is not incurred for short lived tasks (implementation by Mel) 2. Store the information of tasks accessing VMA in 2 windows. It is regularly cleared in (4*sysctl_numa_balancing_scan_delay) interval. The above time is derived from experimenting (Suggested by PeterZ) to balance between frequent clearing vs obsolete access data 3. hash_32 used to encode task index accessing VMA information 4. VMA's acess information is used to skip scanning for the tasks which had not accessed VMA Changes since V2: patch1: - Renaming of structure, macro to function, - Add explanation to heuristics - Adding more details from result (PeterZ) Patch2: - Usage of test and set bit (PeterZ) - Move storing access PID info to numa_migrate_prep() - Add a note on fainess among tasks allowed to scan (PeterZ) Patch3: - Maintain two windows of access PID information (PeterZ supported implementation and Gave idea to extend to N if needed) Patch4: - Apply hash_32 function to track VMA accessing PIDs (PeterZ) Changes since RFC V1: - Include Mel's vma scan delay patch - Change the accessing pid store logic (Thanks Mel) - Fencing structure / code to NUMA_BALANCING (David, Mel) - Adding clearing access PID logic (Mel) - Descriptive change log ( Mike Rapoport) Things to ponder over: ========================================== - Improvement to clearing accessing PIDs logic (discussed in-detail in patch3 itself (Done in this patchset by implementing 2 window history) - Current scan period is not changed in the patchset, so we do see frequent tries to scan. Relaxing scan period dynamically could improve results further. [1] sched/numa: Process Adaptive autoNUMA Link: https://lore.kernel.org/lkml/20220128052851.17162-1-bharata@amd.com/T/ [2] RFC V1 Link: https://lore.kernel.org/all/cover.1673610485.git.raghavendra.kt@amd.com/ [3] V2 Link: https://lore.kernel.org/lkml/cover.1675159422.git.raghavendra.kt@amd.com/ Results: Summary: Huge autonuma cost reduction seen in mmtest. Kernbench improvement is more than 5% and huge system time (80%+) improvement from mmtest autonuma. (dbench had huge std deviation to post) kernbench =========== 6.2.0-mmunstable-base 6.2.0-mmunstable-patched Amean user-256 22002.51 ( 0.00%) 22649.95 * -2.94%* Amean syst-256 10162.78 ( 0.00%) 8214.13 * 19.17%* Amean elsp-256 160.74 ( 0.00%) 156.92 * 2.38%* Duration User 66017.43 67959.84 Duration System 30503.15 24657.03 Duration Elapsed 504.61 493.12 6.2.0-mmunstable-base 6.2.0-mmunstable-patched Ops NUMA alloc hit 1738835089.00 1738780310.00 Ops NUMA alloc local 1738834448.00 1738779711.00 Ops NUMA base-page range updates 477310.00 392566.00 Ops NUMA PTE updates 477310.00 392566.00 Ops NUMA hint faults 96817.00 87555.00 Ops NUMA hint local faults % 10150.00 2192.00 Ops NUMA hint local percent 10.48 2.50 Ops NUMA pages migrated 86660.00 85363.00 Ops AutoNUMA cost 489.07 442.14 autonumabench =============== 6.2.0-mmunstable-base 6.2.0-mmunstable-patched Amean syst-NUMA01 399.50 ( 0.00%) 52.05 * 86.97%* Amean syst-NUMA01_THREADLOCAL 0.21 ( 0.00%) 0.22 * -5.41%* Amean syst-NUMA02 0.80 ( 0.00%) 0.78 * 2.68%* Amean syst-NUMA02_SMT 0.65 ( 0.00%) 0.68 * -3.95%* Amean elsp-NUMA01 313.26 ( 0.00%) 313.11 * 0.05%* Amean elsp-NUMA01_THREADLOCAL 1.06 ( 0.00%) 1.08 * -1.76%* Amean elsp-NUMA02 3.19 ( 0.00%) 3.24 * -1.52%* Amean elsp-NUMA02_SMT 3.72 ( 0.00%) 3.61 * 2.92%* Duration User 396433.47 324835.96 Duration System 2808.70 376.66 Duration Elapsed 2258.61 2258.12 6.2.0-mmunstable-base 6.2.0-mmunstable-patched Ops NUMA alloc hit 59921806.00 49623489.00 Ops NUMA alloc miss 0.00 0.00 Ops NUMA interleave hit 0.00 0.00 Ops NUMA alloc local 59920880.00 49622594.00 Ops NUMA base-page range updates 152259275.00 50075.00 Ops NUMA PTE updates 152259275.00 50075.00 Ops NUMA PMD updates 0.00 0.00 Ops NUMA hint faults 154660352.00 39014.00 Ops NUMA hint local faults % 138550501.00 23139.00 Ops NUMA hint local percent 89.58 59.31 Ops NUMA pages migrated 8179067.00 14147.00 Ops AutoNUMA cost 774522.98 195.69 This patch (of 4): Currently whenever a new task is created we wait for sysctl_numa_balancing_scan_delay to avoid unnessary scanning overhead. Extend the same logic to new or very short-lived VMAs. [raghavendra.kt@amd.com: add initialization in vm_area_dup())] Link: https://lkml.kernel.org/r/cover.1677672277.git.raghavendra.kt@amd.com Link: https://lkml.kernel.org/r/7a6fbba87c8b51e67efd3e74285bb4cb311a16ca.1677672277.git.raghavendra.kt@amd.com Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com> Cc: Bharata B Rao <bharata@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Disha Talreja <dishaa.talreja@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm: separate vma->lock from vm_area_structSuren Baghdasaryan
vma->lock being part of the vm_area_struct causes performance regression during page faults because during contention its count and owner fields are constantly updated and having other parts of vm_area_struct used during page fault handling next to them causes constant cache line bouncing. Fix that by moving the lock outside of the vm_area_struct. All attempts to keep vma->lock inside vm_area_struct in a separate cache line still produce performance regression especially on NUMA machines. Smallest regression was achieved when lock is placed in the fourth cache line but that bloats vm_area_struct to 256 bytes. Considering performance and memory impact, separate lock looks like the best option. It increases memory footprint of each VMA but that can be optimized later if the new size causes issues. Note that after this change vma_init() does not allocate or initialize vma->lock anymore. A number of drivers allocate a pseudo VMA on the stack but they never use the VMA's lock, therefore it does not need to be allocated. The future drivers which might need the VMA lock should use vm_area_alloc()/vm_area_free() to allocate the VMA. Link: https://lkml.kernel.org/r/20230227173632.3292573-34-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm/mmap: free vm_area_struct without call_rcu in exit_mmapSuren Baghdasaryan
call_rcu() can take a long time when callback offloading is enabled. Its use in the vm_area_free can cause regressions in the exit path when multiple VMAs are being freed. Because exit_mmap() is called only after the last mm user drops its refcount, the page fault handlers can't be racing with it. Any other possible user like oom-reaper or process_mrelease are already synchronized using mmap_lock. Therefore exit_mmap() can free VMAs directly, without the use of call_rcu(). Expose __vm_area_free() and use it from exit_mmap() to avoid possible call_rcu() floods and performance regressions caused by it. Link: https://lkml.kernel.org/r/20230227173632.3292573-33-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05kernel/fork: assert no VMA readers during its destructionSuren Baghdasaryan
Assert there are no holders of VMA lock for reading when it is about to be destroyed. Link: https://lkml.kernel.org/r/20230227173632.3292573-21-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm: add per-VMA lock and helper functions to control itSuren Baghdasaryan
Introduce per-VMA locking. The lock implementation relies on a per-vma and per-mm sequence counters to note exclusive locking: - read lock - (implemented by vma_start_read) requires the vma (vm_lock_seq) and mm (mm_lock_seq) sequence counters to differ. If they match then there must be a vma exclusive lock held somewhere. - read unlock - (implemented by vma_end_read) is a trivial vma->lock unlock. - write lock - (vma_start_write) requires the mmap_lock to be held exclusively and the current mm counter is assigned to the vma counter. This will allow multiple vmas to be locked under a single mmap_lock write lock (e.g. during vma merging). The vma counter is modified under exclusive vma lock. - write unlock - (vma_end_write_all) is a batch release of all vma locks held. It doesn't pair with a specific vma_start_write! It is done before exclusive mmap_lock is released by incrementing mm sequence counter (mm_lock_seq). - write downgrade - if the mmap_lock is downgraded to the read lock, all vma write locks are released as well (effectivelly same as write unlock). Link: https://lkml.kernel.org/r/20230227173632.3292573-13-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm: rcu safe VMA freeingMichel Lespinasse
This prepares for page faults handling under VMA lock, looking up VMAs under protection of an rcu read lock, instead of the usual mmap read lock. Link: https://lkml.kernel.org/r/20230227173632.3292573-11-surenb@google.com Signed-off-by: Michel Lespinasse <michel@lespinasse.org> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-05mm: enable maple tree RCU mode by defaultLiam R. Howlett
Use the maple tree in RCU mode for VMA tracking. The maple tree tracks the stack and is able to update the pivot (lower/upper boundary) in-place to allow the page fault handler to write to the tree while holding just the mmap read lock. This is safe as the writes to the stack have a guard VMA which ensures there will always be a NULL in the direction of the growth and thus will only update a pivot. It is possible, but not recommended, to have VMAs that grow up/down without guard VMAs. syzbot has constructed a testcase which sets up a VMA to grow and consume the empty space. Overwriting the entire NULL entry causes the tree to be altered in a way that is not safe for concurrent readers; the readers may see a node being rewritten or one that does not match the maple state they are using. Enabling RCU mode allows the concurrent readers to see a stable node and will return the expected result. [Liam.Howlett@Oracle.com: we don't need to free the nodes with RCU[ Link: https://lore.kernel.org/linux-mm/000000000000b0a65805f663ace6@google.com/ Link: https://lkml.kernel.org/r/20230227173632.3292573-9-surenb@google.com Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reported-by: syzbot+8d95422d3537159ca390@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-03fork: use pidfd_prepare()Christian Brauner
Stop open-coding get_unused_fd_flags() and anon_inode_getfile(). That's brittle just for keeping the flags between both calls in sync. Use the dedicated helper. Message-Id: <20230327-pidfd-file-api-v1-2-5c0e9a3158e4@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-04-03pid: add pidfd_prepare()Christian Brauner
Add a new helper that allows to reserve a pidfd and allocates a new pidfd file that stashes the provided struct pid. This will allow us to remove places that either open code this function or that call pidfd_create() but then have to call close_fd() because there are still failure points after pidfd_create() has been called. Reviewed-by: Jan Kara <jack@suse.cz> Message-Id: <20230327-pidfd-file-api-v1-1-5c0e9a3158e4@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-03-31iommu/sva: Move PASID helpers to sva codeJacob Pan
Preparing to remove IOASID infrastructure, PASID management will be under SVA code. Decouple mm code from IOASID. Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Link: https://lore.kernel.org/r/20230322200803.869130-3-jacob.jun.pan@linux.intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
2023-03-29tracing/user_events: Track fork/exec/exit for mm lifetimeBeau Belgrave
During tracefs discussions it was decided instead of requiring a mapping within a user-process to track the lifetime of memory descriptors we should hook the appropriate calls. Do this by adding the minimal stubs required for task fork, exec, and exit. Currently this is just a NOP. Future patches will implement these calls fully. Link: https://lkml.kernel.org/r/20230328235219.203-3-beaub@linux.microsoft.com Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-03-28lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling schemeNicholas Piggin
On big systems, the mm refcount can become highly contented when doing a lot of context switching with threaded applications. user<->idle switch is one of the important cases. Abandoning lazy tlb entirely slows this switching down quite a bit in the common uncontended case, so that is not viable. Implement a scheme where lazy tlb mm references do not contribute to the refcount, instead they get explicitly removed when the refcount reaches zero. The final mmdrop() sends IPIs to all CPUs in the mm_cpumask and they switch away from this mm to init_mm if it was being used as the lazy tlb mm. Enabling the shoot lazies option therefore requires that the arch ensures that mm_cpumask contains all CPUs that could possibly be using mm. A DEBUG_VM option IPIs every CPU in the system after this to ensure there are no references remaining before the mm is freed. Shootdown IPIs cost could be an issue, but they have not been observed to be a serious problem with this scheme, because short-lived processes tend not to migrate CPUs much, therefore they don't get much chance to leave lazy tlb mm references on remote CPUs. There are a lot of options to reduce them if necessary, described in comments. The near-worst-case can be benchmarked with will-it-scale: context_switch1_threads -t $(($(nproc) / 2)) This will create nproc threads (nproc / 2 switching pairs) all sharing the same mm that spread over all CPUs so each CPU does thread->idle->thread switching. [ Rik came up with basically the same idea a few years ago, so credit to him for that. ] Link: https://lore.kernel.org/linux-mm/20230118080011.2258375-1-npiggin@gmail.com/ Link: https://lore.kernel.org/all/20180728215357.3249-11-riel@surriel.com/ Link: https://lkml.kernel.org/r/20230203071837.1136453-5-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-25Merge tag 'xfs-6.3-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds
Pull xfs percpu counter fixes from Darrick Wong: "We discovered a filesystem summary counter corruption problem that was traced to cpu hot-remove racing with the call to percpu_counter_sum that sets the free block count in the superblock when writing it to disk. The root cause is that percpu_counter_sum doesn't cull from dying cpus and hence misses those counter values if the cpu shutdown hooks have not yet run to merge the values. I'm hoping this is a fairly painless fix to the problem, since the dying cpu mask should generally be empty. It's been in for-next for a week without any complaints from the bots. - Fix a race in the percpu counters summation code where the summation failed to add in the values for any CPUs that were dying but not yet dead. This fixes some minor discrepancies and incorrect assertions when running generic/650" * tag 'xfs-6.3-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: pcpcntr: remove percpu_counter_sum_all() fork: remove use of percpu_counter_sum_all pcpcntrs: fix dying cpu summation race cpumask: introduce for_each_cpu_or
2023-03-19fork: remove use of percpu_counter_sum_allDave Chinner
This effectively reverts the change made in commit f689054aace2 ("percpu_counter: add percpu_counter_sum_all interface") as the race condition percpu_counter_sum_all() was invented to avoid is now handled directly in percpu_counter_sum() and nobody needs to care about summing racing with cpu unplug anymore. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
2023-03-12fork: allow kernel code to call copy_processMike Christie
The next patch adds helpers like create_io_thread, but for use by the vhost layer. There are several functions, so they are in their own file instead of cluttering up fork.c. This patch allows that new file to call copy_process. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12fork: Add kernel_clone_args flag to ignore signalsMike Christie
Since: commit 10ab825bdef8 ("change kernel threads to ignore signals instead of blocking them") kthreads have been ignoring signals by default, and the vhost layer has never had a need to change that. This patch adds an option flag, USER_WORKER_SIG_IGN, handled in copy_process() after copy_sighand() and copy_signals() so vhost_tasks added in the next patches can continue to ignore singals. Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12fork: add kernel_clone_args flag to not dup/clone filesMike Christie
Each vhost device gets a thread that is used to perform IO and management operations. Instead of a thread that is accessing a device, the thread is part of the device, so when it creates a thread using a helper based on copy_process we can't dup or clone the parent's files/FDS because it would do an extra increment on ourself. Later, when we do: Qemu process exits: do_exit -> exit_files -> put_files_struct -> close_files we would leak the device's resources because of that extra refcount on the fd or file_struct. This patch adds a no_files option so these worker threads can prevent taking an extra refcount on themselves. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Christian Brauner <brauner@kernel.org> Acked-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12fork/vm: Move common PF_IO_WORKER behavior to new flagMike Christie
This adds a new flag, PF_USER_WORKER, that's used for behavior common to to both PF_IO_WORKER and users like vhost which will use a new helper instead of create_io_thread because they require different behavior for operations like signal handling. The common behavior PF_USER_WORKER covers is the vm reclaim handling. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-12kernel: Allow a kernel thread's name to be set in copy_processMike Christie
This patch allows kernel users to pass in the thread name so it can be set during creation instead of having to use set_task_comm after the thread is created. Signed-off-by: Mike Christie <michael.christie@oracle.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-03-08fork: allow CLONE_NEWTIME in clone3 flagsTobias Klauser
Currently, calling clone3() with CLONE_NEWTIME in clone_args->flags fails with -EINVAL. This is because CLONE_NEWTIME intersects with CSIGNAL. However, CSIGNAL was deprecated when clone3 was introduced in commit 7f192e3cd316 ("fork: add clone3"), allowing re-use of that part of clone flags. Fix this by explicitly allowing CLONE_NEWTIME in clone3_args_valid. This is also in line with the respective check in check_unshare_flags which allow CLONE_NEWTIME for unshare(). Fixes: 769071ac9f20 ("ns: Introduce Time Namespace") Cc: Andrey Vagin <avagin@openvz.org> Cc: Christian Brauner <brauner@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-02-23Merge tag 'mm-stable-2023-02-20-13-37' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Daniel Verkamp has contributed a memfd series ("mm/memfd: add F_SEAL_EXEC") which permits the setting of the memfd execute bit at memfd creation time, with the option of sealing the state of the X bit. - Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare") which addresses a rare race condition related to PMD unsharing. - Several folioification patch serieses from Matthew Wilcox, Vishal Moola, Sidhartha Kumar and Lorenzo Stoakes - Johannes Weiner has a series ("mm: push down lock_page_memcg()") which does perform some memcg maintenance and cleanup work. - SeongJae Park has added DAMOS filtering to DAMON, with the series "mm/damon/core: implement damos filter". These filters provide users with finer-grained control over DAMOS's actions. SeongJae has also done some DAMON cleanup work. - Kairui Song adds a series ("Clean up and fixes for swap"). - Vernon Yang contributed the series "Clean up and refinement for maple tree". - Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It adds to MGLRU an LRU of memcgs, to improve the scalability of global reclaim. - David Hildenbrand has added some userfaultfd cleanup work in the series "mm: uffd-wp + change_protection() cleanups". - Christoph Hellwig has removed the generic_writepages() library function in the series "remove generic_writepages". - Baolin Wang has performed some maintenance on the compaction code in his series "Some small improvements for compaction". - Sidhartha Kumar is doing some maintenance work on struct page in his series "Get rid of tail page fields". - David Hildenbrand contributed some cleanup, bugfixing and generalization of pte management and of pte debugging in his series "mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with swap PTEs". - Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation flag in the series "Discard __GFP_ATOMIC". - Sergey Senozhatsky has improved zsmalloc's memory utilization with his series "zsmalloc: make zspage chain size configurable". - Joey Gouly has added prctl() support for prohibiting the creation of writeable+executable mappings. The previous BPF-based approach had shortcomings. See "mm: In-kernel support for memory-deny-write-execute (MDWE)". - Waiman Long did some kmemleak cleanup and bugfixing in the series "mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF". - T.J. Alumbaugh has contributed some MGLRU cleanup work in his series "mm: multi-gen LRU: improve". - Jiaqi Yan has provided some enhancements to our memory error statistics reporting, mainly by presenting the statistics on a per-node basis. See the series "Introduce per NUMA node memory error statistics". - Mel Gorman has a second and hopefully final shot at fixing a CPU-hog regression in compaction via his series "Fix excessive CPU usage during compaction". - Christoph Hellwig does some vmalloc maintenance work in the series "cleanup vfree and vunmap". - Christoph Hellwig has removed block_device_operations.rw_page() in ths series "remove ->rw_page". - We get some maple_tree improvements and cleanups in Liam Howlett's series "VMA tree type safety and remove __vma_adjust()". - Suren Baghdasaryan has done some work on the maintainability of our vm_flags handling in the series "introduce vm_flags modifier functions". - Some pagemap cleanup and generalization work in Mike Rapoport's series "mm, arch: add generic implementation of pfn_valid() for FLATMEM" and "fixups for generic implementation of pfn_valid()" - Baoquan He has done some work to make /proc/vmallocinfo and /proc/kcore better represent the real state of things in his series "mm/vmalloc.c: allow vread() to read out vm_map_ram areas". - Jason Gunthorpe rationalized the GUP system's interface to the rest of the kernel in the series "Simplify the external interface for GUP". - SeongJae Park wishes to migrate people from DAMON's debugfs interface over to its sysfs interface. To support this, we'll temporarily be printing warnings when people use the debugfs interface. See the series "mm/damon: deprecate DAMON debugfs interface". - Andrey Konovalov provided the accurately named "lib/stackdepot: fixes and clean-ups" series. - Huang Ying has provided a dramatic reduction in migration's TLB flush IPI rates with the series "migrate_pages(): batch TLB flushing". - Arnd Bergmann has some objtool fixups in "objtool warning fixes". * tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits) include/linux/migrate.h: remove unneeded externs mm/memory_hotplug: cleanup return value handing in do_migrate_range() mm/uffd: fix comment in handling pte markers mm: change to return bool for isolate_movable_page() mm: hugetlb: change to return bool for isolate_hugetlb() mm: change to return bool for isolate_lru_page() mm: change to return bool for folio_isolate_lru() objtool: add UACCESS exceptions for __tsan_volatile_read/write kmsan: disable ftrace in kmsan core code kasan: mark addr_has_metadata __always_inline mm: memcontrol: rename memcg_kmem_enabled() sh: initialize max_mapnr m68k/nommu: add missing definition of ARCH_PFN_OFFSET mm: percpu: fix incorrect size in pcpu_obj_full_size() maple_tree: reduce stack usage with gcc-9 and earlier mm: page_alloc: call panic() when memoryless node allocation fails mm: multi-gen LRU: avoid futile retries migrate_pages: move THP/hugetlb migration support check to simplify code migrate_pages: batch flushing TLB migrate_pages: share more code between _unmap and _move ...
2023-02-20Merge tag 'sched-core-2023-02-20' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - Improve the scalability of the CFS bandwidth unthrottling logic with large number of CPUs. - Fix & rework various cpuidle routines, simplify interaction with the generic scheduler code. Add __cpuidle methods as noinstr to objtool's noinstr detection and fix boatloads of cpuidle bugs & quirks. - Add new ABI: introduce MEMBARRIER_CMD_GET_REGISTRATIONS, to query previously issued registrations. - Limit scheduler slice duration to the sysctl_sched_latency period, to improve scheduling granularity with a large number of SCHED_IDLE tasks. - Debuggability enhancement on sys_exit(): warn about disabled IRQs, but also enable them to prevent a cascade of followup problems and repeat warnings. - Fix the rescheduling logic in prio_changed_dl(). - Micro-optimize cpufreq and sched-util methods. - Micro-optimize ttwu_runnable() - Micro-optimize the idle-scanning in update_numa_stats(), select_idle_capacity() and steal_cookie_task(). - Update the RSEQ code & self-tests - Constify various scheduler methods - Remove unused methods - Refine __init tags - Documentation updates - Misc other cleanups, fixes * tag 'sched-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (110 commits) sched/rt: pick_next_rt_entity(): check list_entry sched/deadline: Add more reschedule cases to prio_changed_dl() sched/fair: sanitize vruntime of entity being placed sched/fair: Remove capacity inversion detection sched/fair: unlink misfit task from cpu overutilized objtool: mem*() are not uaccess safe cpuidle: Fix poll_idle() noinstr annotation sched/clock: Make local_clock() noinstr sched/clock/x86: Mark sched_clock() noinstr x86/pvclock: Improve atomic update of last_value in pvclock_clocksource_read() x86/atomics: Always inline arch_atomic64*() cpuidle: tracing, preempt: Squash _rcuidle tracing cpuidle: tracing: Warn about !rcu_is_watching() cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG cpuidle: drivers: firmware: psci: Dont instrument suspend code KVM: selftests: Fix build of rseq test exit: Detect and fix irq disabled state in oops cpuidle, arm64: Fix the ARM64 cpuidle logic cpuidle: mvebu: Fix duplicate flags assignment sched/fair: Limit sched slice duration ...
2023-02-09mm: replace VM_LOCKED_CLEAR_MASK with VM_LOCKED_MASKSuren Baghdasaryan
To simplify the usage of VM_LOCKED_CLEAR_MASK in vm_flags_clear(), replace it with VM_LOCKED_MASK bitmask and convert all users. Link: https://lkml.kernel.org/r/20230126193752.297968-4-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjun Roy <arjunroy@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Oskolkov <posk@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Sebastian Reichel <sebastian.reichel@collabora.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Song Liu <songliubraving@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09kernel/fork: convert vma assignment to a memcpySuren Baghdasaryan
Patch series "introduce vm_flags modifier functions", v4. This patchset was originally published as a part of per-VMA locking [1] and was split after suggestion that it's viable on its own and to facilitate the review process. It is now a preprequisite for the next version of per-VMA lock patchset, which reuses vm_flags modifier functions to lock the VMA when vm_flags are being updated. VMA vm_flags modifications are usually done under exclusive mmap_lock protection because this attrubute affects other decisions like VMA merging or splitting and races should be prevented. Introduce vm_flags modifier functions to enforce correct locking. This patch (of 7): Convert vma assignment in vm_area_dup() to a memcpy() to prevent compiler errors when we add a const modifier to vma->vm_flags. Link: https://lkml.kernel.org/r/20230126193752.297968-1-surenb@google.com Link: https://lkml.kernel.org/r/20230126193752.297968-2-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjun Roy <arjunroy@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Oskolkov <posk@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Song Liu <songliubraving@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Sebastian Reichel <sebastian.reichel@collabora.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-09kernel/fork: convert forking to using the vmi iteratorLiam R. Howlett
Avoid using the maple tree interface directly. This gains type safety. Link: https://lkml.kernel.org/r/20230120162650.984577-10-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-03blk-cgroup: store a gendisk to throttle in struct task_structChristoph Hellwig
Switch from a request_queue pointer and reference to a gendisk once for the throttle information in struct task_struct. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Andreas Herrmann <aherrmann@suse.de> Link: https://lore.kernel.org/r/20230203150400.3199230-8-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-12-27sched: Introduce per-memory-map concurrency IDMathieu Desnoyers
This feature allows the scheduler to expose a per-memory map concurrency ID to user-space. This concurrency ID is within the possible cpus range, and is temporarily (and uniquely) assigned while threads are actively running within a memory map. If a memory map has fewer threads than cores, or is limited to run on few cores concurrently through sched affinity or cgroup cpusets, the concurrency IDs will be values close to 0, thus allowing efficient use of user-space memory for per-cpu data structures. This feature is meant to be exposed by a new rseq thread area field. The primary purpose of this feature is to do the heavy-lifting needed by memory allocators to allow them to use per-cpu data structures efficiently in the following situations: - Single-threaded applications, - Multi-threaded applications on large systems (many cores) with limited cpu affinity mask, - Multi-threaded applications on large systems (many cores) with restricted cgroup cpuset per container. One of the key concern from scheduler maintainers is the overhead associated with additional spin locks or atomic operations in the scheduler fast-path. This is why the following optimization is implemented. On context switch between threads belonging to the same memory map, transfer the mm_cid from prev to next without any atomic ops. This takes care of use-cases involving frequent context switch between threads belonging to the same memory map. Additional optimizations can be done if the spin locks added when context switching between threads belonging to different memory maps end up being a performance bottleneck. Those are left out of this patch though. A performance impact would have to be clearly demonstrated to justify the added complexity. The credit goes to Paul Turner (Google) for the original virtual cpu id idea. This feature is implemented based on the discussions with Paul Turner and Peter Oskolkov (Google), but I took the liberty to implement scheduler fast-path optimizations and my own NUMA-awareness scheme. The rumor has it that Google have been running a rseq vcpu_id extension internally in production for a year. The tcmalloc source code indeed has comments hinting at a vcpu_id prototype extension to the rseq system call [1]. The following benchmarks do not show any significant overhead added to the scheduler context switch by this feature: * perf bench sched messaging (process) Baseline: 86.5±0.3 ms With mm_cid: 86.7±2.6 ms * perf bench sched messaging (threaded) Baseline: 84.3±3.0 ms With mm_cid: 84.7±2.6 ms * hackbench (process) Baseline: 82.9±2.7 ms With mm_cid: 82.9±2.9 ms * hackbench (threaded) Baseline: 85.2±2.6 ms With mm_cid: 84.4±2.9 ms [1] https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L26 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20221122203932.231377-8-mathieu.desnoyers@efficios.com
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