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BUG: KCSAN: data-race in __filemap_remove_folio / folio_mapping

write to 0xffffea000425fb18 of 8 bytes by task 14771 on cpu 0:
 page_cache_delete mm/filemap.c:145 [inline]
 __filemap_remove_folio+0x1a5/0x2a0 mm/filemap.c:228
 filemap_remove_folio+0x6d/0x1d0 mm/filemap.c:257
 truncate_inode_folio+0x42/0x50 mm/truncate.c:176
 shmem_undo_range+0x244/0xa80 mm/shmem.c:1133
 shmem_truncate_range mm/shmem.c:1249 [inline]
 shmem_evict_inode+0x12e/0x510 mm/shmem.c:1379
 evict+0x2af/0x510 fs/inode.c:837
 iput_final fs/inode.c:1954 [inline]
 iput+0x4bd/0x650 fs/inode.c:2006
 do_unlinkat+0x20a/0x4b0 fs/namei.c:5452
 __do_sys_unlink fs/namei.c:5483 [inline]
 __se_sys_unlink fs/namei.c:5481 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:5481
 x64_sys_call+0x2f48/0x3000 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffea000425fb18 of 8 bytes by task 15885 on cpu 1:
 folio_mapping+0xa1/0xe0 mm/util.c:703
 folio_evictable mm/internal.h:499 [inline]
 lru_add+0x8d/0x480 mm/swap.c:136
 folio_batch_move_lru+0x1c5/0x280 mm/swap.c:172
 __folio_batch_add_and_move mm/swap.c:196 [inline]
 folio_add_lru+0x14a/0x1f0 mm/swap.c:511
 shmem_alloc_and_add_folio mm/shmem.c:1991 [inline]
 shmem_get_folio_gfp+0x7a5/0xd50 mm/shmem.c:2556
 shmem_fault+0xf6/0x250 mm/shmem.c:2757
 __do_fault+0xbc/0x200 mm/memory.c:5320
 do_read_fault mm/memory.c:5755 [inline]
 do_fault mm/memory.c:5889 [inline]
 do_pte_missing mm/memory.c:4401 [inline]
 handle_pte_fault mm/memory.c:6273 [inline]
 __handle_mm_fault mm/memory.c:6411 [inline]
 handle_mm_fault+0xfab/0x2c60 mm/memory.c:6580
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1024/0x1ed0 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x243/0x3a0 mm/gup.c:1963
 mm_populate include/linux/mm.h:3701 [inline]
 vm_mmap_pgoff+0x232/0x2e0 mm/util.c:586
 ksys_mmap_pgoff+0xc2/0x310 mm/mmap.c:604
 x64_sys_call+0x16bb/0x3000 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811bde24d0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15885 Comm: syz.9.15828 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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