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Mike Galbraith e776981391 cpuset: Convert callback_lock to raw_spinlock_t 
The two commits below add up to a cpuset might_sleep() splat for RT:

8447a0fee9 cpuset: convert callback_mutex to a spinlock
344736f29b cpuset: simplify cpuset_node_allowed API

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:995
in_atomic(): 0, irqs_disabled(): 1, pid: 11718, name: cset
CPU: 135 PID: 11718 Comm: cset Tainted: G            E   4.10.0-rt1-rt #4
Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRHSXSD1.86B.0056.R01.1409242327 09/24/2014
Call Trace:
 ? dump_stack+0x5c/0x81
 ? ___might_sleep+0xf4/0x170
 ? rt_spin_lock+0x1c/0x50
 ? __cpuset_node_allowed+0x66/0xc0
 ? ___slab_alloc+0x390/0x570 <disables IRQs>
 ? anon_vma_fork+0x8f/0x140
 ? copy_page_range+0x6cf/0xb00
 ? anon_vma_fork+0x8f/0x140
 ? __slab_alloc.isra.74+0x5a/0x81
 ? anon_vma_fork+0x8f/0x140
 ? kmem_cache_alloc+0x1b5/0x1f0
 ? anon_vma_fork+0x8f/0x140
 ? copy_process.part.35+0x1670/0x1ee0
 ? _do_fork+0xdd/0x3f0
 ? _do_fork+0xdd/0x3f0
 ? do_syscall_64+0x61/0x170
 ? entry_SYSCALL64_slow_path+0x25/0x25

The later ensured that a NUMA box WILL take callback_lock in atomic
context by removing the allocator and reclaim path __GFP_HARDWALL
usage which prevented such contexts from taking callback_mutex.

One option would be to reinstate __GFP_HARDWALL protections for
RT, however, as the 8447a0fee9 changelog states:

The callback_mutex is only used to synchronize reads/updates of cpusets'
flags and cpu/node masks. These operations should always proceed fast so
there's no reason why we can't use a spinlock instead of the mutex.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 		2023-03-25 04:21:30 +03:00
..
Makefile
…
cgroup-internal.h cgroup: Use open-time cgroup namespace for process migration perm checks 2022-04-15 14:18:41 +02:00
cgroup-v1.c cgroup: Allocate cgroup_file_ctx for kernfs_open_file->priv 2022-04-15 14:18:41 +02:00
cgroup.c cgroup: Remove ->css_rstat_flush() 2023-03-25 04:21:19 +03:00
cpuset.c cpuset: Convert callback_lock to raw_spinlock_t 2023-03-25 04:21:30 +03:00
debug.c
…
freezer.c cgroup: freezer: don't change task and cgroups status unnecessarily 2019-12-31 16:45:06 +01:00
legacy_freezer.c
…
namespace.c
…
pids.c cgroup: pids: use atomic64_t for pids->limit 2019-12-17 19:56:15 +01:00
rdma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 451 2019-06-19 17:09:08 +02:00
rstat.c cgroup: Acquire cgroup_rstat_lock with enabled interrupts 2023-03-25 04:21:19 +03:00