user/sven/linux.git/kernel/padata.c, branch next/HEAD

padata: Put CPU offline callback in ONLINE section to allow failure

2026-03-22T02:17:59Z

syzbot reported the following warning: DEAD callback error for CPU1 WARNING: kernel/cpu.c:1463 at _cpu_down+0x759/0x1020 kernel/cpu.c:1463, CPU#0: syz.0.1960/14614 at commit 4ae12d8bd9a8 ("Merge tag 'kbuild-fixes-7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux") which tglx traced to padata_cpu_dead() given it's the only sub-CPUHP_TEARDOWN_CPU callback that returns an error. Failure isn't allowed in hotplug states before CPUHP_TEARDOWN_CPU so move the CPU offline callback to the ONLINE section where failure is possible. Fixes: 894c9ef9780c ("padata: validate cpumask without removed CPU during offline") Reported-by: syzbot+123e1b70473ce213f3af@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69af0a05.050a0220.310d8.002f.GAE@google.com/ Debugged-by: Thomas Gleixner Signed-off-by: Daniel Jordan Signed-off-by: Herbert Xu

padata: Remove cpu online check from cpu add and removal

2026-03-07T05:12:21Z

During the CPU offline process, the dying CPU is cleared from the cpu_online_mask in takedown_cpu(). After this step, various CPUHP_*_DEAD callbacks are executed to perform cleanup jobs for the dead CPU, so this cpu online check in padata_cpu_dead() is unnecessary. Similarly, when executing padata_cpu_online() during the CPUHP_AP_ONLINE_DYN phase, the CPU has already been set in the cpu_online_mask, the action even occurs earlier than the CPUHP_AP_ONLINE_IDLE stage. Remove this unnecessary cpu online check in __padata_add_cpu() and __padata_remove_cpu(). Signed-off-by: Chuyi Zhou Acked-by: Daniel Jordan Signed-off-by: Herbert Xu

Convert more 'alloc_obj' cases to default GFP_KERNEL arguments

2026-02-22T04:03:00Z

This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51Z

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28Z

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

padata: Constify padata_sysfs_entry structs

2026-01-23T05:48:44Z

These structs are never modified. To prevent malicious or accidental modifications due to bugs, mark them as const. Signed-off-by: Thomas Weißschuh Signed-off-by: Herbert Xu

padata: remove __padata_list_init()

2025-11-14T10:15:49Z

syzbot is reporting possibility of deadlock due to sharing lock_class_key between padata_init_squeues() and padata_init_reorder_list(). This is a false positive, for these callers initialize different object. Unshare lock_class_key by embedding __padata_list_init() into these callers. Reported-by: syzbot+bd936ccd4339cea66e6b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=bd936ccd4339cea66e6b Signed-off-by: Tetsuo Handa Signed-off-by: Herbert Xu

padata: WQ_PERCPU added to alloc_workqueue users

2025-09-13T04:11:06Z

Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. alloc_workqueue() treats all queues as per-CPU by default, while unbound workqueues must opt-in via WQ_UNBOUND. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they’re needed and reducing noise when CPUs are isolated. This default is suboptimal: most workloads benefit from unbound queues, allowing the scheduler to place worker threads where they’re needed and reducing noise when CPUs are isolated. This patch adds a new WQ_PERCPU flag to explicitly request the use of the per-CPU behavior. Both flags coexist for one release cycle to allow callers to transition their calls. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND must now use WQ_PERCPU. All existing users have been updated accordingly. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Signed-off-by: Herbert Xu

padata: replace use of system_unbound_wq with system_dfl_wq

2025-09-13T04:11:06Z

padata: Reset next CPU when reorder sequence wraps around

2025-08-22T09:28:44Z

When seq_nr wraps around, the next reorder job with seq 0 is hashed to the first CPU in padata_do_serial(). Correspondingly, need reset pd->cpu to the first one when pd->processed wraps around. Otherwise, if the number of used CPUs is not a power of 2, padata_find_next() will be checking a wrong list, hence deadlock. Fixes: 6fc4dbcf0276 ("padata: Replace delayed timer with immediate workqueue in padata_reorder") Cc: Signed-off-by: Xiao Liang Signed-off-by: Herbert Xu