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BUG: KCSAN: data-race in page_pool_put_unrefed_netmem / page_pool_refill_alloc_cache

write to 0xffff8881508a2680 of 8 bytes by task 10807 on cpu 0:
 __ptr_ring_zero_tail include/linux/ptr_ring.h:259 [inline]
 __ptr_ring_discard_one include/linux/ptr_ring.h:291 [inline]
 __ptr_ring_consume include/linux/ptr_ring.h:311 [inline]
 page_pool_refill_alloc_cache+0x2a5/0x3c0 net/core/page_pool.c:398
 __page_pool_get_cached net/core/page_pool.c:437 [inline]
 page_pool_alloc_netmems net/core/page_pool.c:655 [inline]
 page_pool_alloc_pages+0xd0/0x130 net/core/page_pool.c:671
 page_pool_dev_alloc_pages include/net/page_pool/helpers.h:96 [inline]
 xdp_test_run_batch net/bpf/test_run.c:295 [inline]
 bpf_test_run_xdp_live+0x54d/0x11c0 net/bpf/test_run.c:379
 bpf_prog_test_run_xdp+0x525/0x970 net/bpf/test_run.c:1320
 bpf_prog_test_run+0x22a/0x390 kernel/bpf/syscall.c:4688
 __sys_bpf+0x4c0/0x7c0 kernel/bpf/syscall.c:6167
 __do_sys_bpf kernel/bpf/syscall.c:6259 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6257 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6257
 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+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881508a2680 of 8 bytes by task 10808 on cpu 1:
 __ptr_ring_produce include/linux/ptr_ring.h:106 [inline]
 page_pool_recycle_in_ring net/core/page_pool.c:782 [inline]
 page_pool_put_unrefed_netmem+0x38b/0x4b0 net/core/page_pool.c:903
 page_pool_put_netmem include/net/page_pool/helpers.h:343 [inline]
 page_pool_put_full_netmem include/net/page_pool/helpers.h:373 [inline]
 napi_pp_put_page+0xe9/0x200 net/core/skbuff.c:998
 skb_pp_recycle net/core/skbuff.c:1009 [inline]
 skb_free_head+0x12c/0x150 net/core/skbuff.c:1056
 skb_release_data+0x33b/0x370 net/core/skbuff.c:1087
 skb_release_all net/core/skbuff.c:1152 [inline]
 __kfree_skb+0x44/0x150 net/core/skbuff.c:1166
 sk_skb_reason_drop+0xbd/0x270 net/core/skbuff.c:1204
 kfree_skb_reason include/linux/skbuff.h:1322 [inline]
 udp_recvmsg+0x11a/0xb90 net/ipv4/udp.c:2154
 inet_recvmsg+0x143/0x290 net/ipv4/af_inet.c:885
 sock_recvmsg_nosec net/socket.c:1069 [inline]
 sock_recvmsg+0xf6/0x170 net/socket.c:1091
 ____sys_recvmsg+0xf5/0x280 net/socket.c:2828
 ___sys_recvmsg+0x11f/0x370 net/socket.c:2870
 do_recvmmsg+0x1ef/0x540 net/socket.c:2965
 __sys_recvmmsg net/socket.c:3039 [inline]
 __do_sys_recvmmsg net/socket.c:3062 [inline]
 __se_sys_recvmmsg net/socket.c:3055 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3055
 x64_sys_call+0x2b75/0x3000 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffea0006c4b500 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10808 Comm: syz.3.14118 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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