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BUG: KCSAN: data-race in shmem_fallocate / shmem_writeout

read-write to 0xffffc90006bbfe30 of 8 bytes by task 5633 on cpu 1:
 shmem_writeout+0x2eb/0x8f0 mm/shmem.c:1684
 pageout mm/vmscan.c:658 [inline]
 shrink_folio_list+0x1a81/0x26f0 mm/vmscan.c:1397
 evict_folios+0x1c6e/0x2830 mm/vmscan.c:4910
 try_to_shrink_lruvec+0x8fd/0xb30 mm/vmscan.c:5076
 lru_gen_shrink_lruvec mm/vmscan.c:5221 [inline]
 shrink_lruvec+0x252/0x1d40 mm/vmscan.c:5981
 shrink_node_memcgs mm/vmscan.c:6220 [inline]
 shrink_node+0x67c/0x2000 mm/vmscan.c:6264
 shrink_zones mm/vmscan.c:6503 [inline]
 do_try_to_free_pages+0x408/0xca0 mm/vmscan.c:6565
 try_to_free_mem_cgroup_pages+0x201/0x420 mm/vmscan.c:6887
 try_charge_memcg+0x422/0xae0 mm/memcontrol.c:2718
 obj_cgroup_charge_pages mm/memcontrol.c:3161 [inline]
 __memcg_kmem_charge_page+0x19a/0x3a0 mm/memcontrol.c:3205
 __alloc_frozen_pages_noprof+0x21d/0x400 mm/page_alloc.c:5453
 alloc_pages_mpol+0xaf/0x1d0 mm/mempolicy.c:2486
 alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
 alloc_pages_noprof+0x94/0x140 mm/mempolicy.c:2577
 vm_area_alloc_pages mm/vmalloc.c:3764 [inline]
 __vmalloc_area_node mm/vmalloc.c:3914 [inline]
 __vmalloc_node_range_noprof+0x96f/0x1000 mm/vmalloc.c:4104
 __kvmalloc_node_noprof+0x3be/0x5c0 mm/slub.c:7033
 futex_hash_allocate+0x163/0x890 kernel/futex/core.c:1877
 futex_hash_prctl+0xd8/0xf0 kernel/futex/core.c:2073
 __do_sys_prctl kernel/sys.c:2885 [inline]
 __se_sys_prctl+0x4f4/0x13b0 kernel/sys.c:2534
 __x64_sys_prctl+0x67/0x80 kernel/sys.c:2534
 x64_sys_call+0x2421/0x2550 arch/x86/include/generated/asm/syscalls_64.h:158
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc90006bbfe30 of 8 bytes by task 5614 on cpu 0:
 shmem_fallocate+0x5cb/0x8d0 mm/shmem.c:3733
 vfs_fallocate+0x3ac/0x400 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x7a/0xd0 fs/open.c:365
 x64_sys_call+0x1e1d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000446 -> 0x000000000000045c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5614 Comm: syz.2.9098 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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