summaryrefslogtreecommitdiff
path: root/include/linux/sched.h
AgeCommit message (Collapse)Author
2024-07-16Merge tag 'net-next-6.11' of ↵HEADmasterLinus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Not much excitement - a handful of large patchsets (devmem among them) did not make it in time. Core & protocols: - Use local_lock in addition to local_bh_disable() to protect per-CPU resources in networking, a step closer for local_bh_disable() not to act as a big lock on PREEMPT_RT - Use flex array for netdevice priv area, ensure its cache alignment - Add a sysctl knob to allow user to specify a default rto_min at socket init time. Bit of a big hammer but multiple companies were independently carrying such patch downstream so clearly it's useful - Support scheduling transmission of packets based on CLOCK_TAI - Un-pin TCP TIMEWAIT timer to avoid it firing on CPUs later cordoned off using cpusets - Support multiple L2TPv3 UDP tunnels using the same 5-tuple address - Allow configuration of multipath hash seed, to both allow synchronizing hashing of two routers, and preventing partial accidental sync - Improve TCP compliance with RFC 9293 for simultaneous connect() - Support sending NAT keepalives in IPsec ESP in UDP states. Userspace IKE daemon had to do this before, but the kernel can better keep track of it - Support sending supervision HSR frames with MAC addresses stored in ProxyNodeTable when RedBox (i.e. HSR-SAN) is enabled - Introduce IPPROTO_SMC for selecting SMC when socket is created - Allow UDP GSO transmit from devices with no checksum offload - openvswitch: add packet sampling via psample, separating the sampled traffic from "upcall" packets sent to user space for forwarding - nf_tables: shrink memory consumption for transaction objects Things we sprinkled into general kernel code: - Power Sequencing subsystem (used by Qualcomm Bluetooth driver for QCA6390) [ Already merged separately - Linus ] - Add IRQ information in sysfs for auxiliary bus - Introduce guard definition for local_lock - Add aligned flavor of __cacheline_group_{begin, end}() markings for grouping fields in structures BPF: - Notify user space (via epoll) when a struct_ops object is getting detached/unregistered - Add new kfuncs for a generic, open-coded bits iterator - Enable BPF programs to declare arrays of kptr, bpf_rb_root, and bpf_list_head - Support resilient split BTF which cuts down on duplication and makes BTF as compact as possible WRT BTF from modules - Add support for dumping kfunc prototypes from BTF which enables both detecting as well as dumping compilable prototypes for kfuncs - riscv64 BPF JIT improvements in particular to add 12-argument support for BPF trampolines and to utilize bpf_prog_pack for the latter - Add the capability to offload the netfilter flowtable in XDP layer through kfuncs Driver API: - Allow users to configure IRQ tresholds between which automatic IRQ moderation can choose - Expand Power Sourcing (PoE) status with power, class and failure reason. Support setting power limits - Track additional RSS contexts in the core, make sure configuration changes don't break them - Support IPsec crypto offload for IPv6 ESP and IPv4 UDP-encapsulated ESP data paths - Support updating firmware on SFP modules Tests and tooling: - mptcp: use net/lib.sh to manage netns - TCP-AO and TCP-MD5: replace debug prints used by tests with tracepoints - openvswitch: make test self-contained (don't depend on OvS CLI tools) Drivers: - Ethernet high-speed NICs: - Broadcom (bnxt): - increase the max total outstanding PTP TX packets to 4 - add timestamping statistics support - implement netdev_queue_mgmt_ops - support new RSS context API - Intel (100G, ice, idpf): - implement FEC statistics and dumping signal quality indicators - support E825C products (with 56Gbps PHYs) - nVidia/Mellanox: - support HW-GRO - mlx4/mlx5: support per-queue statistics via netlink - obey the max number of EQs setting in sub-functions - AMD/Solarflare: - support new RSS context API - AMD/Pensando: - ionic: rework fix for doorbell miss to lower overhead and skip it on new HW - Wangxun: - txgbe: support Flow Director perfect filters - Ethernet NICs consumer, embedded and virtual: - Add driver for Tehuti Networks TN40xx chips - Add driver for Meta's internal NIC chips - Add driver for Ethernet MAC on Airoha EN7581 SoCs - Add driver for Renesas Ethernet-TSN devices - Google cloud vNIC: - flow steering support - Microsoft vNIC: - support page sizes other than 4KB on ARM64 - vmware vNIC: - support latency measurement (update to version 9) - VirtIO net: - support for Byte Queue Limits - support configuring thresholds for automatic IRQ moderation - support for AF_XDP Rx zero-copy - Synopsys (stmmac): - support for STM32MP13 SoC - let platforms select the right PCS implementation - TI: - icssg-prueth: add multicast filtering support - icssg-prueth: enable PTP timestamping and PPS - Renesas: - ravb: improve Rx performance 30-400% by using page pool, theaded NAPI and timer-based IRQ coalescing - ravb: add MII support for R-Car V4M - Cadence (macb): - macb: add ARP support to Wake-On-LAN - Cortina: - use phylib for RX and TX pause configuration - Ethernet switches: - nVidia/Mellanox: - support configuration of multipath hash seed - report more accurate max MTU - use page_pool to improve Rx performance - MediaTek: - mt7530: add support for bridge port isolation - Qualcomm: - qca8k: add support for bridge port isolation - Microchip: - lan9371/2: add 100BaseTX PHY support - NXP: - vsc73xx: implement VLAN operations - Ethernet PHYs: - aquantia: enable support for aqr115c - aquantia: add support for PHY LEDs - realtek: add support for rtl8224 2.5Gbps PHY - xpcs: add memory-mapped device support - add BroadR-Reach link mode and support in Broadcom's PHY driver - CAN: - add document for ISO 15765-2 protocol support - mcp251xfd: workaround for erratum DS80000789E, use timestamps to catch when device returns incorrect FIFO status - WiFi: - mac80211/cfg80211: - parse Transmit Power Envelope (TPE) data in mac80211 instead of in drivers - improvements for 6 GHz regulatory flexibility - multi-link improvements - support multiple radios per wiphy - remove DEAUTH_NEED_MGD_TX_PREP flag - Intel (iwlwifi): - bump FW API to 91 for BZ/SC devices - report 64-bit radiotap timestamp - enable P2P low latency by default - handle Transmit Power Envelope (TPE) advertised by AP - remove support for older FW for new devices - fast resume (keeping the device configured) - mvm: re-enable Multi-Link Operation (MLO) - aggregation (A-MSDU) optimizations - MediaTek (mt76): - mt7925 Multi-Link Operation (MLO) support - Qualcomm (ath10k): - LED support for various chipsets - Qualcomm (ath12k): - remove unsupported Tx monitor handling - support channel 2 in 6 GHz band - support Spatial Multiplexing Power Save (SMPS) in 6 GHz band - supprt multiple BSSID (MBSSID) and Enhanced Multi-BSSID Advertisements (EMA) - support dynamic VLAN - add panic handler for resetting the firmware state - DebugFS support for datapath statistics - WCN7850: support for Wake on WLAN - Microchip (wilc1000): - read MAC address during probe to make it visible to user space - suspend/resume improvements - TI (wl18xx): - support newer firmware versions - RealTek (rtw89): - preparation for RTL8852BE-VT support - Wake on WLAN support for WiFi 6 chips - 36-bit PCI DMA support - RealTek (rtlwifi): - RTL8192DU support - Broadcom (brcmfmac): - Management Frame Protection support (to enable WPA3) - Bluetooth: - qualcomm: use the power sequencer for QCA6390 - btusb: mediatek: add ISO data transmission functions - hci_bcm4377: add BCM4388 support - btintel: add support for BlazarU core - btintel: add support for Whale Peak2 - btnxpuart: add support for AW693 A1 chipset - btnxpuart: add support for IW615 chipset - btusb: add Realtek RTL8852BE support ID 0x13d3:0x3591" * tag 'net-next-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1589 commits) eth: fbnic: Fix spelling mistake "tiggerring" -> "triggering" tcp: Replace strncpy() with strscpy() wifi: ath12k: fix build vs old compiler tcp: Don't access uninit tcp_rsk(req)->ao_keyid in tcp_create_openreq_child(). eth: fbnic: Write the TCAM tables used for RSS control and Rx to host eth: fbnic: Add L2 address programming eth: fbnic: Add basic Rx handling eth: fbnic: Add basic Tx handling eth: fbnic: Add link detection eth: fbnic: Add initial messaging to notify FW of our presence eth: fbnic: Implement Rx queue alloc/start/stop/free eth: fbnic: Implement Tx queue alloc/start/stop/free eth: fbnic: Allocate a netdevice and napi vectors with queues eth: fbnic: Add FW communication mechanism eth: fbnic: Add message parsing for FW messages eth: fbnic: Add register init to set PCIe/Ethernet device config eth: fbnic: Allocate core device specific structures and devlink interface eth: fbnic: Add scaffolding for Meta's NIC driver PCI: Add Meta Platforms vendor ID net/sched: cls_flower: propagate tca[TCA_OPTIONS] to NL_REQ_ATTR_CHECK ...
2024-07-16Merge tag 'perf-core-2024-07-16' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull performance events updates from Ingo Molnar: - Intel PT support enhancements & fixes - Fix leaked SIGTRAP events - Improve and fix the Intel uncore driver - Add support for Intel HBM and CXL uncore counters - Add Intel Lake and Arrow Lake support - AMD uncore driver fixes - Make SIGTRAP and __perf_pending_irq() work on RT - Micro-optimizations - Misc cleanups and fixes * tag 'perf-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) perf/x86/intel: Add a distinct name for Granite Rapids perf/x86/intel/ds: Fix non 0 retire latency on Raptorlake perf/x86/intel: Hide Topdown metrics events if the feature is not enumerated perf/x86/intel/uncore: Fix the bits of the CHA extended umask for SPR perf: Split __perf_pending_irq() out of perf_pending_irq() perf: Don't disable preemption in perf_pending_task(). perf: Move swevent_htable::recursion into task_struct. perf: Shrink the size of the recursion counter. perf: Enqueue SIGTRAP always via task_work. task_work: Add TWA_NMI_CURRENT as an additional notify mode. perf: Move irq_work_queue() where the event is prepared. perf: Fix event leak upon exec and file release perf: Fix event leak upon exit task_work: Introduce task_work_cancel() again task_work: s/task_work_cancel()/task_work_cancel_func()/ perf/x86/amd/uncore: Fix DF and UMC domain identification perf/x86/amd/uncore: Avoid PMU registration if counters are unavailable perf/x86/intel: Support Perfmon MSRs aliasing perf/x86/intel: Support PERFEVTSEL extension perf/x86: Add config_mask to represent EVENTSEL bitmask ...
2024-07-16Merge tag 'sched-core-2024-07-16' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - Update Daniel Bristot de Oliveira's entry in MAINTAINERS, and credit him in CREDITS - Harmonize the lock-yielding behavior on dynamically selected preemption models with static ones - Reorganize the code a bit: split out sched/syscalls.c to reduce the size of sched/core.c - Micro-optimize psi_group_change() - Fix set_load_weight() for SCHED_IDLE tasks - Misc cleanups & fixes * tag 'sched-core-2024-07-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Update MAINTAINERS and CREDITS sched/fair: set_load_weight() must also call reweight_task() for SCHED_IDLE tasks sched/psi: Optimise psi_group_change a bit sched/core: Drop spinlocks on contention iff kernel is preemptible sched/core: Move preempt_model_*() helpers from sched.h to preempt.h sched/balance: Skip unnecessary updates to idle load balancer's flags idle: Remove stale RCU comment sched/headers: Move struct pre-declarations to the beginning of the header sched/core: Clean up kernel/sched/sched.h a bit sched/core: Simplify prefetch_curr_exec_start() sched: Fix spelling in comments sched/syscalls: Split out kernel/sched/syscalls.c from kernel/sched/core.c
2024-07-11Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR. Conflicts: net/sched/act_ct.c 26488172b029 ("net/sched: Fix UAF when resolving a clash") 3abbd7ed8b76 ("act_ct: prepare for stolen verdict coming from conntrack and nat engine") No adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-07-09sched.h: always_inline alloc_tag_{save|restore} to fix modpost warningsSuren Baghdasaryan
Mark alloc_tag_{save|restore} as always_inline to fix the following modpost warnings: WARNING: modpost: vmlinux: section mismatch in reference: alloc_tag_save+0x1c (section: .text.unlikely) -> initcall_level_names (section: .init.data) WARNING: modpost: vmlinux: section mismatch in reference: alloc_tag_restore+0x3c (section: .text.unlikely) -> initcall_level_names (section: .init.data) The warnings happen when these functions are called from an __init function and they don't get inlined (remain in the .text section) while the value returned by get_current() points into .init.data section. Assuming get_current() always returns a valid address, this situation can happen only during init stage and accessing .init.data from .text section during that stage should pose no issues. Link: https://lkml.kernel.org/r/20240704132506.1011978-1-surenb@google.com Fixes: 22d407b164ff ("lib: add allocation tagging support for memory allocation profiling") Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202407032306.gi9nZsBi-lkp@intel.com/ Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Chris Zankel <chris@zankel.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-07-09perf: Move swevent_htable::recursion into task_struct.Sebastian Andrzej Siewior
The swevent_htable::recursion counter is used to avoid creating an swevent while an event is processed to avoid recursion. The counter is per-CPU and preemption must be disabled to have a stable counter. perf_pending_task() disables preemption to access the counter and then signal. This is problematic on PREEMPT_RT because sending a signal uses a spinlock_t which must not be acquired in atomic on PREEMPT_RT because it becomes a sleeping lock. The atomic context can be avoided by moving the counter into the task_struct. There is a 4 byte hole between futex_state (usually always on) and the following perf pointer (perf_event_ctxp). After the recursion lost some weight it fits perfectly. Move swevent_htable::recursion into task_struct. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20240704170424.1466941-6-bigeasy@linutronix.de
2024-06-24net: Reference bpf_redirect_info via task_struct on PREEMPT_RT.Sebastian Andrzej Siewior
The XDP redirect process is two staged: - bpf_prog_run_xdp() is invoked to run a eBPF program which inspects the packet and makes decisions. While doing that, the per-CPU variable bpf_redirect_info is used. - Afterwards xdp_do_redirect() is invoked and accesses bpf_redirect_info and it may also access other per-CPU variables like xskmap_flush_list. At the very end of the NAPI callback, xdp_do_flush() is invoked which does not access bpf_redirect_info but will touch the individual per-CPU lists. The per-CPU variables are only used in the NAPI callback hence disabling bottom halves is the only protection mechanism. Users from preemptible context (like cpu_map_kthread_run()) explicitly disable bottom halves for protections reasons. Without locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. PREEMPT_RT has forced-threaded interrupts enabled and every NAPI-callback runs in a thread. If each thread has its own data structure then locking can be avoided. Create a struct bpf_net_context which contains struct bpf_redirect_info. Define the variable on stack, use bpf_net_ctx_set() to save a pointer to it, bpf_net_ctx_clear() removes it again. The bpf_net_ctx_set() may nest. For instance a function can be used from within NET_RX_SOFTIRQ/ net_rx_action which uses bpf_net_ctx_set() and NET_TX_SOFTIRQ which does not. Therefore only the first invocations updates the pointer. Use bpf_net_ctx_get_ri() as a wrapper to retrieve the current struct bpf_redirect_info. The returned data structure is zero initialized to ensure nothing is leaked from stack. This is done on first usage of the struct. bpf_net_ctx_set() sets bpf_redirect_info::kern_flags to 0 to note that initialisation is required. First invocation of bpf_net_ctx_get_ri() will memset() the data structure and update bpf_redirect_info::kern_flags. bpf_redirect_info::nh is excluded from memset because it is only used once BPF_F_NEIGH is set which also sets the nh member. The kern_flags is moved past nh to exclude it from memset. The pointer to bpf_net_context is saved task's task_struct. Using always the bpf_net_context approach has the advantage that there is almost zero differences between PREEMPT_RT and non-PREEMPT_RT builds. Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Stanislav Fomichev <sdf@google.com> Cc: Yonghong Song <yonghong.song@linux.dev> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Jesper Dangaard Brouer <hawk@kernel.org> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://patch.msgid.link/20240620132727.660738-15-bigeasy@linutronix.de Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-24net: softnet_data: Make xmit per task.Sebastian Andrzej Siewior
Softirq is preemptible on PREEMPT_RT. Without a per-CPU lock in local_bh_disable() there is no guarantee that only one device is transmitting at a time. With preemption and multiple senders it is possible that the per-CPU `recursion' counter gets incremented by different threads and exceeds XMIT_RECURSION_LIMIT leading to a false positive recursion alert. The `more' member is subject to similar problems if set by one thread for one driver and wrongly used by another driver within another thread. Instead of adding a lock to protect the per-CPU variable it is simpler to make xmit per-task. Sending and receiving skbs happens always in thread context anyway. Having a lock to protected the per-CPU counter would block/ serialize two sending threads needlessly. It would also require a recursive lock to ensure that the owner can increment the counter further. Make the softnet_data.xmit a task_struct member on PREEMPT_RT. Add needed wrapper. Cc: Ben Segall <bsegall@google.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Valentin Schneider <vschneid@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://patch.msgid.link/20240620132727.660738-9-bigeasy@linutronix.de Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-06-05sched/core: Move preempt_model_*() helpers from sched.h to preempt.hSean Christopherson
Move the declarations and inlined implementations of the preempt_model_*() helpers to preempt.h so that they can be referenced in spinlock.h without creating a potential circular dependency between spinlock.h and sched.h. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ankur Arora <ankur.a.arora@oracle.com> Link: https://lkml.kernel.org/r/20240528003521.979836-2-ankur.a.arora@oracle.com
2024-05-19Merge tag 'mm-stable-2024-05-17-19-19' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull mm updates from Andrew Morton: "The usual shower of singleton fixes and minor series all over MM, documented (hopefully adequately) in the respective changelogs. Notable series include: - Lucas Stach has provided some page-mapping cleanup/consolidation/ maintainability work in the series "mm/treewide: Remove pXd_huge() API". - In the series "Allow migrate on protnone reference with MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's MPOL_PREFERRED_MANY mode, yielding almost doubled performance in one test. - In their series "Memory allocation profiling" Kent Overstreet and Suren Baghdasaryan have contributed a means of determining (via /proc/allocinfo) whereabouts in the kernel memory is being allocated: number of calls and amount of memory. - Matthew Wilcox has provided the series "Various significant MM patches" which does a number of rather unrelated things, but in largely similar code sites. - In his series "mm: page_alloc: freelist migratetype hygiene" Johannes Weiner has fixed the page allocator's handling of migratetype requests, with resulting improvements in compaction efficiency. - In the series "make the hugetlb migration strategy consistent" Baolin Wang has fixed a hugetlb migration issue, which should improve hugetlb allocation reliability. - Liu Shixin has hit an I/O meltdown caused by readahead in a memory-tight memcg. Addressed in the series "Fix I/O high when memory almost met memcg limit". - In the series "mm/filemap: optimize folio adding and splitting" Kairui Song has optimized pagecache insertion, yielding ~10% performance improvement in one test. - Baoquan He has cleaned up and consolidated the early zone initialization code in the series "mm/mm_init.c: refactor free_area_init_core()". - Baoquan has also redone some MM initializatio code in the series "mm/init: minor clean up and improvement". - MM helper cleanups from Christoph Hellwig in his series "remove follow_pfn". - More cleanups from Matthew Wilcox in the series "Various page->flags cleanups". - Vlastimil Babka has contributed maintainability improvements in the series "memcg_kmem hooks refactoring". - More folio conversions and cleanups in Matthew Wilcox's series: "Convert huge_zero_page to huge_zero_folio" "khugepaged folio conversions" "Remove page_idle and page_young wrappers" "Use folio APIs in procfs" "Clean up __folio_put()" "Some cleanups for memory-failure" "Remove page_mapping()" "More folio compat code removal" - David Hildenbrand chipped in with "fs/proc/task_mmu: convert hugetlb functions to work on folis". - Code consolidation and cleanup work related to GUP's handling of hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2". - Rick Edgecombe has developed some fixes to stack guard gaps in the series "Cover a guard gap corner case". - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the series "mm/ksm: fix ksm exec support for prctl". - Baolin Wang has implemented NUMA balancing for multi-size THPs. This is a simple first-cut implementation for now. The series is "support multi-size THP numa balancing". - Cleanups to vma handling helper functions from Matthew Wilcox in the series "Unify vma_address and vma_pgoff_address". - Some selftests maintenance work from Dev Jain in the series "selftests/mm: mremap_test: Optimizations and style fixes". - Improvements to the swapping of multi-size THPs from Ryan Roberts in the series "Swap-out mTHP without splitting". - Kefeng Wang has significantly optimized the handling of arm64's permission page faults in the series "arch/mm/fault: accelerate pagefault when badaccess" "mm: remove arch's private VM_FAULT_BADMAP/BADACCESS" - GUP cleanups from David Hildenbrand in "mm/gup: consistently call it GUP-fast". - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault path to use struct vm_fault". - selftests build fixes from John Hubbard in the series "Fix selftests/mm build without requiring "make headers"". - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the series "Improved Memory Tier Creation for CPUless NUMA Nodes". Fixes the initialization code so that migration between different memory types works as intended. - David Hildenbrand has improved follow_pte() and fixed an errant driver in the series "mm: follow_pte() improvements and acrn follow_pte() fixes". - David also did some cleanup work on large folio mapcounts in his series "mm: mapcount for large folios + page_mapcount() cleanups". - Folio conversions in KSM in Alex Shi's series "transfer page to folio in KSM". - Barry Song has added some sysfs stats for monitoring multi-size THP's in the series "mm: add per-order mTHP alloc and swpout counters". - Some zswap cleanups from Yosry Ahmed in the series "zswap same-filled and limit checking cleanups". - Matthew Wilcox has been looking at buffer_head code and found the documentation to be lacking. The series is "Improve buffer head documentation". - Multi-size THPs get more work, this time from Lance Yang. His series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free" optimizes the freeing of these things. - Kemeng Shi has added more userspace-visible writeback instrumentation in the series "Improve visibility of writeback". - Kemeng Shi then sent some maintenance work on top in the series "Fix and cleanups to page-writeback". - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in the series "Improve anon_vma scalability for anon VMAs". Intel's test bot reported an improbable 3x improvement in one test. - SeongJae Park adds some DAMON feature work in the series "mm/damon: add a DAMOS filter type for page granularity access recheck" "selftests/damon: add DAMOS quota goal test" - Also some maintenance work in the series "mm/damon/paddr: simplify page level access re-check for pageout" "mm/damon: misc fixes and improvements" - David Hildenbrand has disabled some known-to-fail selftests ni the series "selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL". - memcg metadata storage optimizations from Shakeel Butt in "memcg: reduce memory consumption by memcg stats". - DAX fixes and maintenance work from Vishal Verma in the series "dax/bus.c: Fixups for dax-bus locking"" * tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits) memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault selftests: cgroup: add tests to verify the zswap writeback path mm: memcg: make alloc_mem_cgroup_per_node_info() return bool mm/damon/core: fix return value from damos_wmark_metric_value mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED selftests: cgroup: remove redundant enabling of memory controller Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT Docs/mm/damon/design: use a list for supported filters Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file selftests/damon: classify tests for functionalities and regressions selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None' selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts selftests/damon/_damon_sysfs: check errors from nr_schemes file reads mm/damon/core: initialize ->esz_bp from damos_quota_init_priv() selftests/damon: add a test for DAMOS quota goal ...
2024-05-11memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_orderXiu Jianfeng
Since commit 857f21397f71 ("memcg, oom: remove unnecessary check in mem_cgroup_oom_synchronize()"), memcg_oom_gfp_mask and memcg_oom_order are no longer used any more. Link: https://lkml.kernel.org/r/20240509032628.1217652-1-xiujianfeng@huawei.com Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Benjamin Segall <bsegall@google.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Valentin Schneider <vschneid@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25lib: add allocation tagging support for memory allocation profilingSuren Baghdasaryan
Introduce CONFIG_MEM_ALLOC_PROFILING which provides definitions to easily instrument memory allocators. It registers an "alloc_tags" codetag type with /proc/allocinfo interface to output allocation tag information when the feature is enabled. CONFIG_MEM_ALLOC_PROFILING_DEBUG is provided for debugging the memory allocation profiling instrumentation. Memory allocation profiling can be enabled or disabled at runtime using /proc/sys/vm/mem_profiling sysctl when CONFIG_MEM_ALLOC_PROFILING_DEBUG=n. CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT enables memory allocation profiling by default. [surenb@google.com: Documentation/filesystems/proc.rst: fix allocinfo title] Link: https://lkml.kernel.org/r/20240326073813.727090-1-surenb@google.com [surenb@google.com: do limited memory accounting for modules with ARCH_NEEDS_WEAK_PER_CPU] Link: https://lkml.kernel.org/r/20240402180933.1663992-2-surenb@google.com [klarasmodin@gmail.com: explicitly include irqflags.h in alloc_tag.h] Link: https://lkml.kernel.org/r/20240407133252.173636-1-klarasmodin@gmail.com [surenb@google.com: fix alloc_tag_init() to prevent passing NULL to PTR_ERR()] Link: https://lkml.kernel.org/r/20240417003349.2520094-1-surenb@google.com Link: https://lkml.kernel.org/r/20240321163705.3067592-14-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Klara Modin <klarasmodin@gmail.com> Tested-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Andreas Hindborg <a.hindborg@samsung.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Gary Guo <gary@garyguo.net> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wedson Almeida Filho <wedsonaf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-03-25sched/fair: Check if a task has a fitting CPU when updating misfitQais Yousef
If a misfit task is affined to a subset of the possible CPUs, we need to verify that one of these CPUs can fit it. Otherwise the load balancer code will continuously trigger needlessly leading the balance_interval to increase in return and eventually end up with a situation where real imbalances take a long time to address because of this impossible imbalance situation. This can happen in Android world where it's common for background tasks to be restricted to little cores. Similarly if we can't fit the biggest core, triggering misfit is pointless as it is the best we can ever get on this system. To be able to detect that; we use asym_cap_list to iterate through capacities in the system to see if the task is able to run at a higher capacity level based on its p->cpus_ptr. We do that when the affinity change, a fair task is forked, or when a task switched to fair policy. We store the max_allowed_capacity in task_struct to allow for cheap comparison in the fast path. Improve check_misfit_status() function by removing redundant checks. misfit_task_load will be 0 if the task can't move to a bigger CPU. And nohz_balancer_kick() already checks for cpu_check_capacity() before calling check_misfit_status(). Test: ===== Add trace_printk("balance_interval = %lu\n", interval) in get_sd_balance_interval(). run if [ "$MASK" != "0" ]; then adb shell "taskset -a $MASK cat /dev/zero > /dev/null" fi sleep 10 // parse ftrace buffer counting the occurrence of each valaue Where MASK is either: * 0: no busy task running * 1: busy task is pinned to 1 cpu; handled today to not cause misfit * f: busy task pinned to little cores, simulates busy background task, demonstrates the problem to be fixed Results: ======== Note how occurrence of balance_interval = 128 overshoots for MASK = f. BEFORE ------ MASK=0 1 balance_interval = 175 120 balance_interval = 128 846 balance_interval = 64 55 balance_interval = 63 215 balance_interval = 32 2 balance_interval = 31 2 balance_interval = 16 4 balance_interval = 8 1870 balance_interval = 4 65 balance_interval = 2 MASK=1 27 balance_interval = 175 37 balance_interval = 127 840 balance_interval = 64 167 balance_interval = 63 449 balance_interval = 32 84 balance_interval = 31 304 balance_interval = 16 1156 balance_interval = 8 2781 balance_interval = 4 428 balance_interval = 2 MASK=f 1 balance_interval = 175 1328 balance_interval = 128 44 balance_interval = 64 101 balance_interval = 63 25 balance_interval = 32 5 balance_interval = 31 23 balance_interval = 16 23 balance_interval = 8 4306 balance_interval = 4 177 balance_interval = 2 AFTER ----- Note how the high values almost disappear for all MASK values. The system has background tasks that could trigger the problem without simulate it even with MASK=0. MASK=0 103 balance_interval = 63 19 balance_interval = 31 194 balance_interval = 8 4827 balance_interval = 4 179 balance_interval = 2 MASK=1 131 balance_interval = 63 1 balance_interval = 31 87 balance_interval = 8 3600 balance_interval = 4 7 balance_interval = 2 MASK=f 8 balance_interval = 127 182 balance_interval = 63 3 balance_interval = 31 9 balance_interval = 16 415 balance_interval = 8 3415 balance_interval = 4 21 balance_interval = 2 Signed-off-by: Qais Yousef <qyousef@layalina.io> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lore.kernel.org/r/20240324004552.999936-3-qyousef@layalina.io
2024-03-25Merge tag 'v6.9-rc1' into sched/core, to pick up fixes and to refresh the branchIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-03-15Merge tag 'bcachefs-2024-03-13' of https://evilpiepirate.org/git/bcachefsLinus Torvalds
Pull bcachefs updates from Kent Overstreet: - Subvolume children btree; this is needed for providing a userspace interface for walking subvolumes, which will come later - Lots of improvements to directory structure checking - Improved journal pipelining, significantly improving performance on high iodepth write workloads - Discard path improvements: the discard path is more efficient, and no longer flushes the journal unnecessarily - Buffered write path can now avoid taking the inode lock - new mm helper: memalloc_flags_{save|restore} - mempool now does kvmalloc mempools * tag 'bcachefs-2024-03-13' of https://evilpiepirate.org/git/bcachefs: (128 commits) bcachefs: time_stats: shrink time_stat_buffer for better alignment bcachefs: time_stats: split stats-with-quantiles into a separate structure bcachefs: mean_and_variance: put struct mean_and_variance_weighted on a diet bcachefs: time_stats: add larger units bcachefs: pull out time_stats.[ch] bcachefs: reconstruct_alloc cleanup bcachefs: fix bch_folio_sector padding bcachefs: Fix btree key cache coherency during replay bcachefs: Always flush write buffer in delete_dead_inodes() bcachefs: Fix order of gc_done passes bcachefs: fix deletion of indirect extents in btree_gc bcachefs: Prefer struct_size over open coded arithmetic bcachefs: Kill unused flags argument to btree_split() bcachefs: Check for writing superblocks with nonsense member seq fields bcachefs: fix bch2_journal_buf_to_text() lib/generic-radix-tree.c: Make nodes more reasonably sized bcachefs: copy_(to|from)_user_errcode() bcachefs: Split out bkey_types.h bcachefs: fix lost journal buf wakeup due to improved pipelining bcachefs: intercept mountoption value for bool type ...
2024-03-14Merge tag 'mm-stable-2024-03-13-20-04' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames from hotplugged memory rather than only from main memory. Series "implement "memmap on memory" feature on s390". - More folio conversions from Matthew Wilcox in the series "Convert memcontrol charge moving to use folios" "mm: convert mm counter to take a folio" - Chengming Zhou has optimized zswap's rbtree locking, providing significant reductions in system time and modest but measurable reductions in overall runtimes. The series is "mm/zswap: optimize the scalability of zswap rb-tree". - Chengming Zhou has also provided the series "mm/zswap: optimize zswap lru list" which provides measurable runtime benefits in some swap-intensive situations. - And Chengming Zhou further optimizes zswap in the series "mm/zswap: optimize for dynamic zswap_pools". Measured improvements are modest. - zswap cleanups and simplifications from Yosry Ahmed in the series "mm: zswap: simplify zswap_swapoff()". - In the series "Add DAX ABI for memmap_on_memory", Vishal Verma has contributed several DAX cleanups as well as adding a sysfs tunable to control the memmap_on_memory setting when the dax device is hotplugged as system memory. - Johannes Weiner has added the large series "mm: zswap: cleanups", which does that. - More DAMON work from SeongJae Park in the series "mm/damon: make DAMON debugfs interface deprecation unignorable" "selftests/damon: add more tests for core functionalities and corner cases" "Docs/mm/damon: misc readability improvements" "mm/damon: let DAMOS feeds and tame/auto-tune itself" - In the series "mm/mempolicy: weighted interleave mempolicy and sysfs extension" Rakie Kim has developed a new mempolicy interleaving policy wherein we allocate memory across nodes in a weighted fashion rather than uniformly. This is beneficial in heterogeneous memory environments appearing with CXL. - Christophe Leroy has contributed some cleanup and consolidation work against the ARM pagetable dumping code in the series "mm: ptdump: Refactor CONFIG_DEBUG_WX and check_wx_pages debugfs attribute". - Luis Chamberlain has added some additional xarray selftesting in the series "test_xarray: advanced API multi-index tests". - Muhammad Usama Anjum has reworked the selftest code to make its human-readable output conform to the TAP ("Test Anything Protocol") format. Amongst other things, this opens up the use of third-party tools to parse and process out selftesting results. - Ryan Roberts has added fork()-time PTE batching of THP ptes in the series "mm/memory: optimize fork() with PTE-mapped THP". Mainly targeted at arm64, this significantly speeds up fork() when the process has a large number of pte-mapped folios. - David Hildenbrand also gets in on the THP pte batching game in his series "mm/memory: optimize unmap/zap with PTE-mapped THP". It implements batching during munmap() and other pte teardown situations. The microbenchmark improvements are nice. - And in the series "Transparent Contiguous PTEs for User Mappings" Ryan Roberts further utilizes arm's pte's contiguous bit ("contpte mappings"). Kernel build times on arm64 improved nicely. Ryan's series "Address some contpte nits" provides some followup work. - In the series "mm/hugetlb: Restore the reservation" Breno Leitao has fixed an obscure hugetlb race which was causing unnecessary page faults. He has also added a reproducer under the selftest code. - In the series "selftests/mm: Output cleanups for the compaction test", Mark Brown did what the title claims. - Kinsey Ho has added the series "mm/mglru: code cleanup and refactoring". - Even more zswap material from Nhat Pham. The series "fix and extend zswap kselftests" does as claimed. - In the series "Introduce cpu_dcache_is_aliasing() to fix DAX regression" Mathieu Desnoyers has cleaned up and fixed rather a mess in our handling of DAX on archiecctures which have virtually aliasing data caches. The arm architecture is the main beneficiary. - Lokesh Gidra's series "per-vma locks in userfaultfd" provides dramatic improvements in worst-case mmap_lock hold times during certain userfaultfd operations. - Some page_owner enhancements and maintenance work from Oscar Salvador in his series "page_owner: print stacks and their outstanding allocations" "page_owner: Fixup and cleanup" - Uladzislau Rezki has contributed some vmalloc scalability improvements in his series "Mitigate a vmap lock contention". It realizes a 12x improvement for a certain microbenchmark. - Some kexec/crash cleanup work from Baoquan He in the series "Split crash out from kexec and clean up related config items". - Some zsmalloc maintenance work from Chengming Zhou in the series "mm/zsmalloc: fix and optimize objects/page migration" "mm/zsmalloc: some cleanup for get/set_zspage_mapping()" - Zi Yan has taught the MM to perform compaction on folios larger than order=0. This a step along the path to implementaton of the merging of large anonymous folios. The series is named "Enable >0 order folio memory compaction". - Christoph Hellwig has done quite a lot of cleanup work in the pagecache writeback code in his series "convert write_cache_pages() to an iterator". - Some modest hugetlb cleanups and speedups in Vishal Moola's series "Handle hugetlb faults under the VMA lock". - Zi Yan has changed the page splitting code so we can split huge pages into sizes other than order-0 to better utilize large folios. The series is named "Split a folio to any lower order folios". - David Hildenbrand has contributed the series "mm: remove total_mapcount()", a cleanup. - Matthew Wilcox has sought to improve the performance of bulk memory freeing in his series "Rearrange batched folio freeing". - Gang Li's series "hugetlb: parallelize hugetlb page init on boot" provides large improvements in bootup times on large machines which are configured to use large numbers of hugetlb pages. - Matthew Wilcox's series "PageFlags cleanups" does that. - Qi Zheng's series "minor fixes and supplement for ptdesc" does that also. S390 is affected. - Cleanups to our pagemap utility functions from Peter Xu in his series "mm/treewide: Replace pXd_large() with pXd_leaf()". - Nico Pache has fixed a few things with our hugepage selftests in his series "selftests/mm: Improve Hugepage Test Handling in MM Selftests". - Also, of course, many singleton patches to many things. Please see the individual changelogs for details. * tag 'mm-stable-2024-03-13-20-04' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (435 commits) mm/zswap: remove the memcpy if acomp is not sleepable crypto: introduce: acomp_is_async to expose if comp drivers might sleep memtest: use {READ,WRITE}_ONCE in memory scanning mm: prohibit the last subpage from reusing the entire large folio mm: recover pud_leaf() definitions in nopmd case selftests/mm: skip the hugetlb-madvise tests on unmet hugepage requirements selftests/mm: skip uffd hugetlb tests with insufficient hugepages selftests/mm: dont fail testsuite due to a lack of hugepages mm/huge_memory: skip invalid debugfs new_order input for folio split mm/huge_memory: check new folio order when split a folio mm, vmscan: retry kswapd's priority loop with cache_trim_mode off on failure mm: add an explicit smp_wmb() to UFFDIO_CONTINUE mm: fix list corruption in put_pages_list mm: remove folio from deferred split list before uncharging it filemap: avoid unnecessary major faults in filemap_fault() mm,page_owner: drop unnecessary check mm,page_owner: check for null stack_record before bumping its refcount mm: swap: fix race between free_swap_and_cache() and swapoff() mm/treewide: align up pXd_leaf() retval across archs mm/treewide: drop pXd_large() ...
2024-03-12sched/balancing: Rename scheduler_tick() => sched_tick()Ingo Molnar
- Standardize on prefixing scheduler-internal functions defined in <linux/sched.h> with sched_*() prefix. scheduler_tick() was the only function using the scheduler_ prefix. Harmonize it. - The other reason to rename it is the NOHZ scheduler tick handling functions are already named sched_tick_*(). Make the 'git grep sched_tick' more meaningful. Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Valentin Schneider <vschneid@redhat.com> Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com> Link: https://lore.kernel.org/r/20240308111819.1101550-3-mingo@kernel.org
2024-03-11Merge tag 'rcu.next.v6.9' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux Pull RCU updates from Boqun Feng: - Eliminate deadlocks involving do_exit() and RCU tasks, by Paul: Instead of SRCU read side critical sections, now a percpu list is used in do_exit() for scaning yet-to-exit tasks - Fix a deadlock due to the dependency between workqueue and RCU expedited grace period, reported by Anna-Maria Behnsen and Thomas Gleixner and fixed by Frederic: Now RCU expedited always uses its own kthread worker instead of a workqueue - RCU NOCB updates, code cleanups, unnecessary barrier removals and minor bug fixes - Maintain real-time response in rcu_tasks_postscan() and a minor fix for tasks trace quiescence check - Misc updates, comments and readibility improvement, boot time parameter for lazy RCU and rcutorture improvement - Documentation updates * tag 'rcu.next.v6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/boqun/linux: (34 commits) rcu-tasks: Maintain real-time response in rcu_tasks_postscan() rcu-tasks: Eliminate deadlocks involving do_exit() and RCU tasks rcu-tasks: Maintain lists to eliminate RCU-tasks/do_exit() deadlocks rcu-tasks: Initialize data to eliminate RCU-tasks/do_exit() deadlocks rcu-tasks: Initialize callback lists at rcu_init() time rcu-tasks: Add data to eliminate RCU-tasks/do_exit() deadlocks rcu-tasks: Repair RCU Tasks Trace quiescence check rcu/sync: remove un-used rcu_sync_enter_start function rcutorture: Suppress rtort_pipe_count warnings until after stalls srcu: Improve comments about acceleration leak rcu: Provide a boot time parameter to control lazy RCU rcu: Rename jiffies_till_flush to jiffies_lazy_flush doc: Update checklist.rst discussion of callback execution doc: Clarify use of slab constructors and SLAB_TYPESAFE_BY_RCU context_tracking: Fix kerneldoc headers for __ct_user_{enter,exit}() doc: Add EARLY flag to early-parsed kernel boot parameters doc: Add CONFIG_RCU_STRICT_GRACE_PERIOD to checklist.rst doc: Make checklist.rst note that spinlocks are implied RCU readers doc: Make whatisRCU.rst note that spinlocks are RCU readers doc: Spinlocks are implied RCU readers ...
2024-03-10mm: introduce PF_MEMALLOC_NORECLAIM, PF_MEMALLOC_NOWARNKent Overstreet
Introduce PF_MEMALLOC_* equivalents of some GFP_ flags: PF_MEMALLOC_NORECLAIM -> GFP_NOWAIT PF_MEMALLOC_NOWARN -> __GFP_NOWARN Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Darrick J. Wong <djwong@kernel.org> Cc: linux-mm@kvack.org Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-02-25rcu-tasks: Add data to eliminate RCU-tasks/do_exit() deadlocksPaul E. McKenney
Holding a mutex across synchronize_rcu_tasks() and acquiring that same mutex in code called from do_exit() after its call to exit_tasks_rcu_start() but before its call to exit_tasks_rcu_stop() results in deadlock. This is by design, because tasks that are far enough into do_exit() are no longer present on the tasks list, making it a bit difficult for RCU Tasks to find them, let alone wait on them to do a voluntary context switch. However, such deadlocks are becoming more frequent. In addition, lockdep currently does not detect such deadlocks and they can be difficult to reproduce. In addition, if a task voluntarily context switches during that time (for example, if it blocks acquiring a mutex), then this task is in an RCU Tasks quiescent state. And with some adjustments, RCU Tasks could just as well take advantage of that fact. This commit therefore adds the data structures that will be needed to rely on these quiescent states and to eliminate these deadlocks. Link: https://lore.kernel.org/all/20240118021842.290665-1-chenzhongjin@huawei.com/ Reported-by: Chen Zhongjin <chenzhongjin@huawei.com> Reported-by: Yang Jihong <yangjihong1@huawei.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Yang Jihong <yangjihong1@huawei.com> Tested-by: Chen Zhongjin <chenzhongjin@huawei.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2024-02-22mm: document memalloc_noreclaim_save() and memalloc_pin_save()Vlastimil Babka
The memalloc_noreclaim_save() function currently has no documentation comment, so the implications of its usage are not obvious. Namely that it not only prevents entering reclaim (as the name suggests), but also allows using all memory reserves and thus should be only used in contexts that are allocating memory to free memory. This may lead to new improper usages being added. Thus add a documenting comment, based on the description of __GFP_MEMALLOC. While at it, also document memalloc_pin_save() so that all the memalloc_ scopes are documented. For those already documented, add missing Return: descriptions, and mark Context: description per kernel-docs style guide. In the comments describing the relevant PF_MEMALLOC flags, refer to their scope setting functions. [vbabka@suse.cz: fix issues that Mike pointed out] Link: https://lkml.kernel.org/r/20240215095827.13756-2-vbabka@suse.cz Link: https://lkml.kernel.org/r/20240212182950.32730-2-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22mm/mempolicy: introduce MPOL_WEIGHTED_INTERLEAVE for weighted interleavingGregory Price
When a system has multiple NUMA nodes and it becomes bandwidth hungry, using the current MPOL_INTERLEAVE could be an wise option. However, if those NUMA nodes consist of different types of memory such as socket-attached DRAM and CXL/PCIe attached DRAM, the round-robin based interleave policy does not optimally distribute data to make use of their different bandwidth characteristics. Instead, interleave is more effective when the allocation policy follows each NUMA nodes' bandwidth weight rather than a simple 1:1 distribution. This patch introduces a new memory policy, MPOL_WEIGHTED_INTERLEAVE, enabling weighted interleave between NUMA nodes. Weighted interleave allows for proportional distribution of memory across multiple numa nodes, preferably apportioned to match the bandwidth of each node. For example, if a system has 1 CPU node (0), and 2 memory nodes (0,1), with bandwidth of (100GB/s, 50GB/s) respectively, the appropriate weight distribution is (2:1). Weights for each node can be assigned via the new sysfs extension: /sys/kernel/mm/mempolicy/weighted_interleave/ For now, the default value of all nodes will be `1`, which matches the behavior of standard 1:1 round-robin interleave. An extension will be added in the future to allow default values to be registered at kernel and device bringup time. The policy allocates a number of pages equal to the set weights. For example, if the weights are (2,1), then 2 pages will be allocated on node0 for every 1 page allocated on node1. The new flag MPOL_WEIGHTED_INTERLEAVE can be used in set_mempolicy(2) and mbind(2). Some high level notes about the pieces of weighted interleave: current->il_prev: Tracks the node previously allocated from. current->il_weight: The active weight of the current node (current->il_prev) When this reaches 0, current->il_prev is set to the next node and current->il_weight is set to the next weight. weighted_interleave_nodes: Counts the number of allocations as they occur, and applies the weight for the current node. When the weight reaches 0, switch to the next node. Operates only on task->mempolicy. weighted_interleave_nid: Gets the total weight of the nodemask as well as each individual node weight, then calculates the node based on the given index. Operates on VMA policies. bulk_array_weighted_interleave: Gets the total weight of the nodemask as well as each individual node weight, then calculates the number of "interleave rounds" as well as any delta ("partial round"). Calculates the number of pages for each node and allocates them. If a node was scheduled for interleave via interleave_nodes, the current weight will be allocated first. Operates only on the task->mempolicy. One piece of complexity is the interaction between a recent refactor which split the logic to acquire the "ilx" (interleave index) of an allocation and the actually application of the interleave. If a call to alloc_pages_mpol() were made with a weighted-interleave policy and ilx set to NO_INTERLEAVE_INDEX, weighted_interleave_nodes() would operate on a VMA policy - violating the description above. An inspection of all callers of alloc_pages_mpol() shows that all external callers set ilx to `0`, an index value, or will call get_vma_policy() to acquire the ilx. For example, mm/shmem.c may call into alloc_pages_mpol. The call stacks all set (pgoff_t ilx) or end up in `get_vma_policy()`. This enforces the `weighted_interleave_nodes()` and `weighted_interleave_nid()` policy requirements (task/vma respectively). Link: https://lkml.kernel.org/r/20240202170238.90004-4-gregory.price@memverge.com Suggested-by: Hasan Al Maruf <Hasan.Maruf@amd.com> Signed-off-by: Gregory Price <gregory.price@memverge.com> Co-developed-by: Rakie Kim <rakie.kim@sk.com> Signed-off-by: Rakie Kim <rakie.kim@sk.com> Co-developed-by: Honggyu Kim <honggyu.kim@sk.com> Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Co-developed-by: Hyeongtak Ji <hyeongtak.ji@sk.com> Signed-off-by: Hyeongtak Ji <hyeongtak.ji@sk.com> Co-developed-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> Signed-off-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com> Co-developed-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@micron.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-05block: update cached timestamp post schedule/preemptionJens Axboe
Mark the task as having a cached timestamp when set assign it, so we can efficiently check if it needs updating post being scheduled back in. This covers both the actual schedule out case, which would've flushed the plug, and the preemption case which doesn't touch the plugged requests (for many reasons, one of them being then we'd need to have preemption disabled around plug state manipulation). Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-24exec: Distinguish in_execve from in_execKees Cook
Just to help distinguish the fs->in_exec flag from the current->in_execve flag, add comments in check_unsafe_exec() and copy_fs() for more context. Also note that in_execve is only used by TOMOYO now. Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Kees Cook <keescook@chromium.org>
2024-01-18Merge tag 'iommu-updates-v6.8' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu Pull iommu updates from Joerg Roedel: "Core changes: - Fix race conditions in device probe path - Retire IOMMU bus_ops - Support for passing custom allocators to page table drivers - Clean up Kconfig around IOMMU_SVA - Support for sharing SVA domains with all devices bound to a mm - Firmware data parsing cleanup - Tracing improvements for iommu-dma code - Some smaller fixes and cleanups ARM-SMMU drivers: - Device-tree binding updates: - Add additional compatible strings for Qualcomm SoCs - Document Adreno clocks for Qualcomm's SM8350 SoC - SMMUv2: - Implement support for the ->domain_alloc_paging() callback - Ensure Secure context is restored following suspend of Qualcomm SMMU implementation - SMMUv3: - Disable stalling mode for the "quiet" context descriptor - Minor refactoring and driver cleanups Intel VT-d driver: - Cleanup and refactoring AMD IOMMU driver: - Improve IO TLB invalidation logic - Small cleanups and improvements Rockchip IOMMU driver: - DT binding update to add Rockchip RK3588 Apple DART driver: - Apple M1 USB4/Thunderbolt DART support - Cleanups Virtio IOMMU driver: - Add support for iotlb_sync_map - Enable deferred IO TLB flushes" * tag 'iommu-updates-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (66 commits) iommu: Don't reserve 0-length IOVA region iommu/vt-d: Move inline helpers to header files iommu/vt-d: Remove unused vcmd interfaces iommu/vt-d: Remove unused parameter of intel_pasid_setup_pass_through() iommu/vt-d: Refactor device_to_iommu() to retrieve iommu directly iommu/sva: Fix memory leak in iommu_sva_bind_device() dt-bindings: iommu: rockchip: Add Rockchip RK3588 iommu/dma: Trace bounce buffer usage when mapping buffers iommu/arm-smmu: Convert to domain_alloc_paging() iommu/arm-smmu: Pass arm_smmu_domain to internal functions iommu/arm-smmu: Implement IOMMU_DOMAIN_BLOCKED iommu/arm-smmu: Convert to a global static identity domain iommu/arm-smmu: Reorganize arm_smmu_domain_add_master() iommu/arm-smmu-v3: Remove ARM_SMMU_DOMAIN_NESTED iommu/arm-smmu-v3: Master cannot be NULL in arm_smmu_write_strtab_ent() iommu/arm-smmu-v3: Add a type for the STE iommu/arm-smmu-v3: disable stall for quiet_cd iommu/qcom: restore IOMMU state if needed iommu/arm-smmu-qcom: Add QCM2290 MDSS compatible iommu/arm-smmu-qcom: Add missing GMU entry to match table ...
2024-01-10Merge tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefsLinus Torvalds
Pull header cleanups from Kent Overstreet: "The goal is to get sched.h down to a type only header, so the main thing happening in this patchset is splitting out various _types.h headers and dependency fixups, as well as moving some things out of sched.h to better locations. This is prep work for the memory allocation profiling patchset which adds new sched.h interdepencencies" * tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs: (51 commits) Kill sched.h dependency on rcupdate.h kill unnecessary thread_info.h include Kill unnecessary kernel.h include preempt.h: Kill dependency on list.h rseq: Split out rseq.h from sched.h LoongArch: signal.c: add header file to fix build error restart_block: Trim includes lockdep: move held_lock to lockdep_types.h sem: Split out sem_types.h uidgid: Split out uidgid_types.h seccomp: Split out seccomp_types.h refcount: Split out refcount_types.h uapi/linux/resource.h: fix include x86/signal: kill dependency on time.h syscall_user_dispatch.h: split out *_types.h mm_types_task.h: Trim dependencies Split out irqflags_types.h ipc: Kill bogus dependency on spinlock.h shm: Slim down dependencies workqueue: Split out workqueue_types.h ...
2024-01-09Merge tag 'mm-nonmm-stable-2024-01-09-10-33' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull non-MM updates from Andrew Morton: "Quite a lot of kexec work this time around. Many singleton patches in many places. The notable patch series are: - nilfs2 folio conversion from Matthew Wilcox in 'nilfs2: Folio conversions for file paths'. - Additional nilfs2 folio conversion from Ryusuke Konishi in 'nilfs2: Folio conversions for directory paths'. - IA64 remnant removal in Heiko Carstens's 'Remove unused code after IA-64 removal'. - Arnd Bergmann has enabled the -Wmissing-prototypes warning everywhere in 'Treewide: enable -Wmissing-prototypes'. This had some followup fixes: - Nathan Chancellor has cleaned up the hexagon build in the series 'hexagon: Fix up instances of -Wmissing-prototypes'. - Nathan also addressed some s390 warnings in 's390: A couple of fixes for -Wmissing-prototypes'. - Arnd Bergmann addresses the same warnings for MIPS in his series 'mips: address -Wmissing-prototypes warnings'. - Baoquan He has made kexec_file operate in a top-down-fitting manner similar to kexec_load in the series 'kexec_file: Load kernel at top of system RAM if required' - Baoquan He has also added the self-explanatory 'kexec_file: print out debugging message if required'. - Some checkstack maintenance work from Tiezhu Yang in the series 'Modify some code about checkstack'. - Douglas Anderson has disentangled the watchdog code's logging when multiple reports are occurring simultaneously. The series is 'watchdog: Better handling of concurrent lockups'. - Yuntao Wang has contributed some maintenance work on the crash code in 'crash: Some cleanups and fixes'" * tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (157 commits) crash_core: fix and simplify the logic of crash_exclude_mem_range() x86/crash: use SZ_1M macro instead of hardcoded value x86/crash: remove the unused image parameter from prepare_elf_headers() kdump: remove redundant DEFAULT_CRASH_KERNEL_LOW_SIZE scripts/decode_stacktrace.sh: strip unexpected CR from lines watchdog: if panicking and we dumped everything, don't re-enable dumping watchdog/hardlockup: use printk_cpu_sync_get_irqsave() to serialize reporting watchdog/softlockup: use printk_cpu_sync_get_irqsave() to serialize reporting watchdog/hardlockup: adopt softlockup logic avoiding double-dumps kexec_core: fix the assignment to kimage->control_page x86/kexec: fix incorrect end address passed to kernel_ident_mapping_init() lib/trace_readwrite.c:: replace asm-generic/io with linux/io nilfs2: cpfile: fix some kernel-doc warnings stacktrace: fix kernel-doc typo scripts/checkstack.pl: fix no space expression between sp and offset x86/kexec: fix incorrect argument passed to kexec_dprintk() x86/kexec: use pr_err() instead of kexec_dprintk() when an error occurs nilfs2: add missing set_freezable() for freezable kthread kernel: relay: remove relay_file_splice_read dead code, doesn't work docs: submit-checklist: remove all of "make namespacecheck" ...
2023-12-27Kill sched.h dependency on rcupdate.hKent Overstreet
by moving cond_resched_rcu() to rcupdate_wait.h, we can kill another big sched.h dependency. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27rseq: Split out rseq.h from sched.hKent Overstreet
We're trying to get sched.h down to more or less just types only, not code - rseq can live in its own header. This helps us kill the dependency on preempt.h in sched.h. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-23sched/fair: Simplify util_estVincent Guittot
With UTIL_EST_FASTUP now being permanent, we can take advantage of the fact that the ewma jumps directly to a higher utilization at dequeue to simplify util_est and remove the enqueued field. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Lukasz Luba <lukasz.luba@arm.com> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com> Reviewed-by: Alex Shi <alexs@kernel.org> Link: https://lore.kernel.org/r/20231201161652.1241695-3-vincent.guittot@linaro.org
2023-12-20restart_block: Trim includesKent Overstreet
We don't actually use any timekeeping types, no need to pull in time64.h. Also, sched.h uses restart_block; add it as a direct dependency. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20sem: Split out sem_types.hKent Overstreet
More sched.h dependency pruning. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20uidgid: Split out uidgid_types.hKent Overstreet
More sched.h dependency pruning. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Reviewed-by: Christian Brauner <brauner@kernel.org>
2023-12-20seccomp: Split out seccomp_types.hKent Overstreet
More pruning of sched.h dependencies. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20refcount: Split out refcount_types.hKent Overstreet
More trimming of sched.h dependencies. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20syscall_user_dispatch.h: split out *_types.hKent Overstreet
thread_info.h pulls in a lot of junk that sched.h that we don't need; in particular, this helps to kill the printk.h dependency. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20Split out irqflags_types.hKent Overstreet
We're working on only pulling in type definitions to sched.h whenever possible. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20ipc: Kill bogus dependency on spinlock.hKent Overstreet
pruning sched.h dependencies, headers shouldn't pull in more than they need. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20plist: Split out plist_types.hKent Overstreet
Trimming down sched.h dependencies: we don't want to include more than the base types. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20sched.h: move pid helpers to pid.hKent Overstreet
This is needed for killing the sched.h dependency on rcupdate.h, and pid.h is a better place for this code anyways. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20pid: Split out pid_types.hKent Overstreet
Trimming down sched.h dependencies: we dont't want to include more than the base types. Cc: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Will Drewry <wad@chromium.org> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20locking/seqlock: Split out seqlock_types.hKent Overstreet
Trimming down sched.h dependencies: we don't want to include more than the base types. Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20posix-cpu-timers: Split out posix-timers_types.hKent Overstreet
Trimming down sched.h dependencies: we don't want to include more than the base types. Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20locking/mutex: split out mutex_types.hKent Overstreet
Trimming down sched.h dependencies: we don't want to include more than the base types. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20hrtimers: Split out hrtimer_types.hKent Overstreet
We need to reduce the scope of what's included in sched.h: task_struct includes a hrtimer, so split out the core types into their own header. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Cc: Thomas Gleixner <tglx@linutronix.de>
2023-12-20sched.h: Move (spin|rwlock)_needbreak() to spinlock.hKent Overstreet
This lets us kill the dependency on spinlock.h. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-20nodemask: Split out include/linux/nodemask_types.hKent Overstreet
sched.h, which defines task_struct, needs nodemask_t - but sched.h is a frequently used header and ideally shouldn't be pulling in any more code that it needs to. This splits out nodemask_types.h which has the definition sched.h needs, which will avoid a circular header dependency in the alloc tagging patch series, and as a bonus should speed up kernel build times. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2023-12-12iommu: Change kconfig around IOMMU_SVAJason Gunthorpe
Linus suggested that the kconfig here is confusing: https://lore.kernel.org/all/CAHk-=wgUiAtiszwseM1p2fCJ+sC4XWQ+YN4TanFhUgvUqjr9Xw@mail.gmail.com/ Let's break it into three kconfigs controlling distinct things: - CONFIG_IOMMU_MM_DATA controls if the mm_struct has the additional fields for the IOMMU. Currently only PASID, but later patches store a struct iommu_mm_data * - CONFIG_ARCH_HAS_CPU_PASID controls if the arch needs the scheduling bit for keeping track of the ENQCMD instruction. x86 will select this if IOMMU_SVA is enabled - IOMMU_SVA controls if the IOMMU core compiles in the SVA support code for iommu driver use and the IOMMU exported API This way ARM will not enable CONFIG_ARCH_HAS_CPU_PASID Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20231027000525.1278806-2-tina.zhang@intel.com Signed-off-by: Joerg Roedel <jroedel@suse.de>
2023-12-10arch: remove ARCH_TASK_STRUCT_ON_STACKHeiko Carstens
IA-64 was the only architecture which selected ARCH_TASK_STRUCT_ON_STACK. IA-64 was removed with commit cf8e8658100d ("arch: Remove Itanium (IA-64) architecture"). Therefore remove support for ARCH_TASK_STRUCT_ON_STACK as well. Note: this also reveals a potential bug in powerpc code, which makes use of __init_task_data without selecting ARCH_TASK_STRUCT_ON_STACK which makes __init_task_data a no-op. This is broken since commit d11ed3ab3166 ("Expand INIT_TASK() in init/init_task.c and remove") from 2018 and needs to be addressed separately. Link: https://lkml.kernel.org/r/20231116133638.1636277-4-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-11-15sched/deadline: Introduce deadline serversPeter Zijlstra
Low priority tasks (e.g., SCHED_OTHER) can suffer starvation if tasks with higher priority (e.g., SCHED_FIFO) monopolize CPU(s). RT Throttling has been introduced a while ago as a (mostly debug) countermeasure one can utilize to reserve some CPU time for low priority tasks (usually background type of work, e.g. workqueues, timers, etc.). It however has its own problems (see documentation) and the undesired effect of unconditionally throttling FIFO tasks even when no lower priority activity needs to run (there are mechanisms to fix this issue as well, but, again, with their own problems). Introduce deadline servers to service low priority tasks needs under starvation conditions. Deadline servers are built extending SCHED_DEADLINE implementation to allow 2-level scheduling (a sched_deadline entity becomes a container for lower priority scheduling entities). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/4968601859d920335cf85822eb573a5f179f04b8.1699095159.git.bristot@kernel.org