KCSAN: data-race in bpf_lru_pop_free / htab_lru_map_update_elem (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 407ab579 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d4714a500000
kernel config: https://syzkaller.appspot.com/x/.config?x=671e27f23e60a67b
dashboard link: https://syzkaller.appspot.com/bug?extid=11b79051c3362faa4ea0
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [and...@kernel.org a...@kernel.org b...@vger.kernel.org dan...@iogearbox.net john.fa...@gmail.com ka...@fb.com kps...@chromium.org linux-...@vger.kernel.org net...@vger.kernel.org songliu...@fb.com y...@fb.com]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+11b790...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in bpf_lru_pop_free / htab_lru_map_update_elem

write to 0xffff888021a7b8cb of 1 bytes by task 23435 on cpu 0:
bpf_lru_node_set_ref kernel/bpf/bpf_lru_list.h:70 [inline]
htab_lru_map_update_elem+0x370/0x430 kernel/bpf/hashtab.c:1067
bpf_map_update_value+0x1bc/0x330 kernel/bpf/syscall.c:201
generic_map_update_batch+0x344/0x450 kernel/bpf/syscall.c:1347
bpf_map_do_batch+0x2a8/0x310 kernel/bpf/syscall.c:4007
__do_sys_bpf+0x8a3/0x9aa0 kernel/bpf/syscall.c:4463
__se_sys_bpf kernel/bpf/syscall.c:4357 [inline]
__x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4357
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888021a7b8cb of 1 bytes by task 23436 on cpu 1:
bpf_lru_node_is_ref kernel/bpf/bpf_lru_list.c:44 [inline]
__local_list_pop_pending kernel/bpf/bpf_lru_list.c:384 [inline]
bpf_common_lru_pop_free kernel/bpf/bpf_lru_list.c:476 [inline]
bpf_lru_pop_free+0xb49/0xea0 kernel/bpf/bpf_lru_list.c:499
prealloc_lru_pop kernel/bpf/hashtab.c:238 [inline]
htab_lru_map_update_elem+0xb1/0x430 kernel/bpf/hashtab.c:1049
bpf_map_update_value+0x1bc/0x330 kernel/bpf/syscall.c:201
generic_map_update_batch+0x344/0x450 kernel/bpf/syscall.c:1347
bpf_map_do_batch+0x2a8/0x310 kernel/bpf/syscall.c:4007
__do_sys_bpf+0x8a3/0x9aa0 kernel/bpf/syscall.c:4463
__se_sys_bpf kernel/bpf/syscall.c:4357 [inline]
__x64_sys_bpf+0x3d/0x50 kernel/bpf/syscall.c:4357
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23436 Comm: syz-executor.2 Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.