kernel/linux.git/include/linux/sched/task.h, branch v6.19.11

Merge tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:44:54+00:00

Pull non-MM updates from Andrew Morton: - "ida: Remove the ida_simple_xxx() API" from Christophe Jaillet completes the removal of this legacy IDR API - "panic: introduce panic status function family" from Jinchao Wang provides a number of cleanups to the panic code and its various helpers, which were rather ad-hoc and scattered all over the place - "tools/delaytop: implement real-time keyboard interaction support" from Fan Yu adds a few nice user-facing usability changes to the delaytop monitoring tool - "efi: Fix EFI boot with kexec handover (KHO)" from Evangelos Petrongonas fixes a panic which was happening with the combination of EFI and KHO - "Squashfs: performance improvement and a sanity check" from Phillip Lougher teaches squashfs's lseek() about SEEK_DATA/SEEK_HOLE. A mere 150x speedup was measured for a well-chosen microbenchmark - plus another 50-odd singleton patches all over the place * tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (75 commits) Squashfs: reject negative file sizes in squashfs_read_inode() kallsyms: use kmalloc_array() instead of kmalloc() MAINTAINERS: update Sibi Sankar's email address Squashfs: add SEEK_DATA/SEEK_HOLE support Squashfs: add additional inode sanity checking lib/genalloc: fix device leak in of_gen_pool_get() panic: remove CONFIG_PANIC_ON_OOPS_VALUE ocfs2: fix double free in user_cluster_connect() checkpatch: suppress strscpy warnings for userspace tools cramfs: fix incorrect physical page address calculation kernel: prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit Squashfs: fix uninit-value in squashfs_get_parent kho: only fill kimage if KHO is finalized ocfs2: avoid extra calls to strlen() after ocfs2_sprintf_system_inode_name() kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock coccinelle: platform_no_drv_owner: handle also built-in drivers coccinelle: of_table: handle SPI device ID tables lib/decompress: use designated initializers for struct compress_format efi: support booting with kexec handover (KHO) ...

sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock

2025-09-23T03:10:59+00:00

The ancient comment above task_lock() states that it can be nested outside of read_lock(&tasklist_lock), but this is no longer true: CPU_0 CPU_1 CPU_2 task_lock() read_lock(tasklist) write_lock_irq(tasklist) read_lock(tasklist) task_lock() Unless CPU_0 calls read_lock() in IRQ context, queued_read_lock_slowpath() won't get the lock immediately, it will spin waiting for the pending writer on CPU_2, resulting in a deadlock. Link: https://lkml.kernel.org/r/20250914110908.GA18769@redhat.com Signed-off-by: Oleg Nesterov Cc: Christian Brauner Cc: Jiri Slaby Cc: Mateusz Guzik Signed-off-by: Andrew Morton

copy_process: pass clone_flags as u64 across calltree

2025-09-01T13:31:34+00:00

With the introduction of clone3 in commit 7f192e3cd316 ("fork: add clone3") the effective bit width of clone_flags on all architectures was increased from 32-bit to 64-bit, with a new type of u64 for the flags. However, for most consumers of clone_flags the interface was not changed from the previous type of unsigned long. While this works fine as long as none of the new 64-bit flag bits (CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still undesirable in terms of the principle of least surprise. Thus, this commit fixes all relevant interfaces of callees to sys_clone3/copy_process (excluding the architecture-specific copy_thread) to consistently pass clone_flags as u64, so that no truncation to 32-bit integers occurs on 32-bit architectures. Signed-off-by: Simon Schuster Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com Acked-by: David Hildenbrand Reviewed-by: Lorenzo Stoakes Reviewed-by: Arnd Bergmann Signed-off-by: Christian Brauner

sched: Do not call __put_task_struct() on rt if pi_blocked_on is set

2025-07-14T15:16:33+00:00

With PREEMPT_RT enabled, some of the calls to put_task_struct() coming from rt_mutex_adjust_prio_chain() could happen in preemptible context and with a mutex enqueued. That could lead to this sequence: rt_mutex_adjust_prio_chain() put_task_struct() __put_task_struct() sched_ext_free() spin_lock_irqsave() rtlock_lock() ---> TRIGGERS lockdep_assert(!current->pi_blocked_on); This is not a SCHED_EXT bug. The first cleanup function called by __put_task_struct() is sched_ext_free() and it happens to take a (RT) spin_lock, which in the scenario described above, would trigger the lockdep assertion of "!current->pi_blocked_on". Crystal Wood was able to identify the problem as __put_task_struct() being called during rt_mutex_adjust_prio_chain(), in the context of a process with a mutex enqueued. Instead of adding more complex conditions to decide when to directly call __put_task_struct() and when to defer the call, unconditionally resort to the deferred call on PREEMPT_RT to simplify the code. Fixes: 893cdaaa3977 ("sched: avoid false lockdep splat in put_task_struct()") Suggested-by: Crystal Wood Signed-off-by: Luis Claudio R. Goncalves Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Wander Lairson Costa Reviewed-by: Valentin Schneider Reviewed-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/aGvTz5VaPFyj0pBV@uudg.org

sched/smp: Use the SMP version of sched_exec()

2025-06-13T06:47:20+00:00

Simplify the scheduler making CONFIG_SMP=y sched_exec() code unconditional. Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Cc: Dietmar Eggemann Cc: Juri Lelli Cc: Linus Torvalds Cc: Mel Gorman Cc: Sebastian Andrzej Siewior Cc: Shrikanth Hegde Cc: Steven Rostedt Cc: Valentin Schneider Cc: Vincent Guittot Link: https://lore.kernel.org/r/20250528080924.2273858-27-mingo@kernel.org

cgroup: fix race between fork and cgroup.kill

2025-02-02T16:54:51+00:00

Tejun reported the following race between fork() and cgroup.kill at [1]. Tejun: I was looking at cgroup.kill implementation and wondering whether there could be a race window. So, __cgroup_kill() does the following: k1. Set CGRP_KILL. k2. Iterate tasks and deliver SIGKILL. k3. Clear CGRP_KILL. The copy_process() does the following: c1. Copy a bunch of stuff. c2. Grab siglock. c3. Check fatal_signal_pending(). c4. Commit to forking. c5. Release siglock. c6. Call cgroup_post_fork() which puts the task on the css_set and tests CGRP_KILL. The intention seems to be that either a forking task gets SIGKILL and terminates on c3 or it sees CGRP_KILL on c6 and kills the child. However, I don't see what guarantees that k3 can't happen before c6. ie. After a forking task passes c5, k2 can take place and then before the forking task reaches c6, k3 can happen. Then, nobody would send SIGKILL to the child. What am I missing? This is indeed a race. One way to fix this race is by taking cgroup_threadgroup_rwsem in write mode in __cgroup_kill() as the fork() side takes cgroup_threadgroup_rwsem in read mode from cgroup_can_fork() to cgroup_post_fork(). However that would be heavy handed as this adds one more potential stall scenario for cgroup.kill which is usually called under extreme situation like memory pressure. To fix this race, let's maintain a sequence number per cgroup which gets incremented on __cgroup_kill() call. On the fork() side, the cgroup_can_fork() will cache the sequence number locally and recheck it against the cgroup's sequence number at cgroup_post_fork() site. If the sequence numbers mismatch, it means __cgroup_kill() can been called and we should send SIGKILL to the newly created task. Reported-by: Tejun Heo Closes: https://lore.kernel.org/all/Z5QHE2Qn-QZ6M-KW@slm.duckdns.org/ [1] Fixes: 661ee6280931 ("cgroup: introduce cgroup.kill") Cc: stable@vger.kernel.org # v5.14+ Signed-off-by: Shakeel Butt Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo

sched_ext: TASK_DEAD tasks must be switched into SCX on ops_enable

2024-09-04T20:23:32+00:00

During scx_ops_enable(), SCX needs to invoke the sleepable ops.init_task() on every task. To do this, it does get_task_struct() on each iterated task, drop the lock and then call ops.init_task(). However, a TASK_DEAD task may already have lost all its usage count and be waiting for RCU grace period to be freed. If get_task_struct() is called on such task, use-after-free can happen. To avoid such situations, scx_ops_enable() skips initialization of TASK_DEAD tasks, which seems safe as they are never going to be scheduled again. Unfortunately, a racing sched_setscheduler(2) can grab the task before the task is unhashed and then continue to e.g. move the task from RT to SCX after TASK_DEAD is set and ops_enable skipped the task. As the task hasn't gone through scx_ops_init_task(), scx_ops_enable_task() called from switching_to_scx() triggers the following warning: sched_ext: Invalid task state transition 0 -> 3 for stress-ng-race-[2872] WARNING: CPU: 6 PID: 2367 at kernel/sched/ext.c:3327 scx_ops_enable_task+0x18f/0x1f0 ... RIP: 0010:scx_ops_enable_task+0x18f/0x1f0 ... switching_to_scx+0x13/0xa0 __sched_setscheduler+0x84e/0xa50 do_sched_setscheduler+0x104/0x1c0 __x64_sys_sched_setscheduler+0x18/0x30 do_syscall_64+0x7b/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e As in the ops_disable path, it just doesn't seem like a good idea to leave any task in an inconsistent state, even when the task is dead. The root cause is ops_enable not being able to tell reliably whether a task is truly dead (no one else is looking at it and it's about to be freed) and was testing TASK_DEAD instead. Fix it by testing the task's usage count directly. - ops_init no longer ignores TASK_DEAD tasks. As now all users iterate all tasks, @include_dead is removed from scx_task_iter_next_locked() along with dead task filtering. - tryget_task_struct() is added. Tasks are skipped iff tryget_task_struct() fails. Signed-off-by: Tejun Heo Cc: David Vernet Cc: Peter Zijlstra

sched: Allow sched_cgroup_fork() to fail and introduce sched_cancel_fork()

2024-06-18T20:09:16+00:00

A new BPF extensible sched_class will need more control over the forking process. It wants to be able to fail from sched_cgroup_fork() after the new task's sched_task_group is initialized so that the loaded BPF program can prepare the task with its cgroup association is established and reject fork if e.g. allocation fails. Allow sched_cgroup_fork() to fail by making it return int instead of void and adding sched_cancel_fork() to undo sched_fork() in the error path. sched_cgroup_fork() doesn't fail yet and this patch shouldn't cause any behavior changes. v2: Patch description updated to detail the expected use. Signed-off-by: Tejun Heo Reviewed-by: David Vernet Acked-by: Josh Don Acked-by: Hao Luo Acked-by: Barret Rhoden

Merge tag 'header_cleanup-2024-01-10' of https://evilpiepirate.org/git/bcachefs

2024-01-11T00:43:55+00:00

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 ...

Kill sched.h dependency on rcupdate.h

2023-12-27T16:50:20+00:00

by moving cond_resched_rcu() to rcupdate_wait.h, we can kill another big sched.h dependency. Signed-off-by: Kent Overstreet