syzbot

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BUG: KCSAN: data-race in __htab_map_lookup_elem / bpf_lru_pop_free

write to 0xffff88811b031d68 of 4 bytes by task 3599 on cpu 0:
 __local_list_add_pending kernel/bpf/bpf_lru_list.c:350 [inline]
 bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:449 [inline]
 bpf_lru_pop_free+0xbea/0xcc0 kernel/bpf/bpf_lru_list.c:496
 prealloc_lru_pop kernel/bpf/hashtab.c:299 [inline]
 __htab_lru_percpu_map_update_elem+0xea/0x690 kernel/bpf/hashtab.c:1346
 bpf_percpu_hash_update+0x61/0xa0 kernel/bpf/hashtab.c:2400
 bpf_map_update_value+0x36b/0x570 kernel/bpf/syscall.c:270
 generic_map_update_batch+0x3eb/0x540 kernel/bpf/syscall.c:2038
 bpf_map_do_batch+0x25c/0x380 kernel/bpf/syscall.c:5647
 __sys_bpf+0x5f8/0x7c0 kernel/bpf/syscall.c:-1
 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
 x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b031d68 of 4 bytes by task 3594 on cpu 1:
 lookup_nulls_elem_raw kernel/bpf/hashtab.c:639 [inline]
 __htab_map_lookup_elem+0xab/0x150 kernel/bpf/hashtab.c:668
 htab_lru_percpu_map_lookup_elem+0x20/0xb0 kernel/bpf/hashtab.c:2334
 bpf_prog_1908f35e458ae2da+0x48/0x50
 bpf_dispatcher_nop_func include/linux/bpf.h:1376 [inline]
 __bpf_prog_run include/linux/filter.h:723 [inline]
 bpf_prog_run include/linux/filter.h:730 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
 bpf_trace_run2+0x107/0x1d0 kernel/trace/bpf_trace.c:2116
 __traceiter_kfree+0x2e/0x50 include/trace/events/kmem.h:97
 __do_trace_kfree include/trace/events/kmem.h:97 [inline]
 trace_kfree include/trace/events/kmem.h:97 [inline]
 kfree+0x353/0x3c0 mm/slub.c:6863
 __import_iovec+0x46b/0x540 lib/iov_iter.c:1394
 io_import_vec io_uring/rw.c:99 [inline]
 __io_import_rw_buffer io_uring/rw.c:120 [inline]
 io_import_rw_buffer+0x245/0x380 io_uring/rw.c:139
 io_rw_do_import io_uring/rw.c:313 [inline]
 io_prep_rw io_uring/rw.c:325 [inline]
 io_prep_rwv+0xae/0x250 io_uring/rw.c:343
 io_prep_writev+0x22/0x30 io_uring/rw.c:363
 io_init_req io_uring/io_uring.c:2234 [inline]
 io_submit_sqe io_uring/io_uring.c:2281 [inline]
 io_submit_sqes+0x70f/0x11b0 io_uring/io_uring.c:2434
 __do_sys_io_uring_enter io_uring/io_uring.c:3280 [inline]
 __se_sys_io_uring_enter+0x1bd/0x1a30 io_uring/io_uring.c:3219
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3219
 x64_sys_call+0x27e4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xed14c2bb -> 0xe441e0ed

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3594 Comm: syz.2.36 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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