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BUG: KCSAN: data-race in __bpf_get_stackid / __bpf_get_stackid

write to 0xffff888109eeb67c of 4 bytes by task 7488 on cpu 0:
 __bpf_get_stackid+0x77a/0x800 kernel/bpf/stackmap.c:292
 ____bpf_get_stackid kernel/bpf/stackmap.c:324 [inline]
 bpf_get_stackid+0xee/0x120 kernel/bpf/stackmap.c:300
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1810 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1799
 bpf_prog_e6fc920cfeff8120+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 bpf_trace_run2+0x107/0x1c0 kernel/trace/bpf_trace.c:2298
 __do_trace_kfree include/trace/events/kmem.h:94 [inline]
 trace_kfree include/trace/events/kmem.h:94 [inline]
 kfree+0x27b/0x320 mm/slub.c:4881
 free_func_state kernel/bpf/verifier.c:1666 [inline]
 prepare_func_exit kernel/bpf/verifier.c:11038 [inline]
 process_bpf_exit_full+0x2da/0x780 kernel/bpf/verifier.c:19820
 do_check_insn kernel/bpf/verifier.c:19958 [inline]
 do_check+0x484a/0x7a10 kernel/bpf/verifier.c:20097
 do_check_common+0xc3a/0x12a0 kernel/bpf/verifier.c:23264
 do_check_main kernel/bpf/verifier.c:23347 [inline]
 bpf_check+0x942b/0xd9e0 kernel/bpf/verifier.c:24707
 bpf_prog_load+0xedd/0x1070 kernel/bpf/syscall.c:2979
 __sys_bpf+0x462/0x7b0 kernel/bpf/syscall.c:6029
 __do_sys_bpf kernel/bpf/syscall.c:6139 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6137 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6137
 x64_sys_call+0x2aea/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888109eeb67c of 4 bytes by task 4570 on cpu 1:
 __bpf_get_stackid+0x33a/0x800 kernel/bpf/stackmap.c:278
 ____bpf_get_stackid kernel/bpf/stackmap.c:324 [inline]
 bpf_get_stackid+0xee/0x120 kernel/bpf/stackmap.c:300
 ____bpf_get_stackid_raw_tp kernel/trace/bpf_trace.c:1810 [inline]
 bpf_get_stackid_raw_tp+0xf6/0x120 kernel/trace/bpf_trace.c:1799
 bpf_prog_e6fc920cfeff8120+0x2a/0x32
 bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 bpf_trace_run2+0x107/0x1c0 kernel/trace/bpf_trace.c:2298
 __do_trace_kfree include/trace/events/kmem.h:94 [inline]
 trace_kfree include/trace/events/kmem.h:94 [inline]
 kfree+0x27b/0x320 mm/slub.c:4881
 free_one kernel/bpf/memalloc.c:260 [inline]
 free_all kernel/bpf/memalloc.c:269 [inline]
 drain_mem_cache+0x12f/0x300 kernel/bpf/memalloc.c:640
 bpf_mem_alloc_destroy+0xe5/0x860 kernel/bpf/memalloc.c:754
 trie_free+0xb8/0xd0 kernel/bpf/lpm_trie.c:652
 bpf_map_free kernel/bpf/syscall.c:864 [inline]
 bpf_map_free_deferred+0xcc/0x160 kernel/bpf/syscall.c:891
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000d -> 0x0000000e

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4570 Comm: kworker/u8:20 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound bpf_map_free_deferred
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