==================================================================
BUG: KCSAN: data-race in __delete_from_swap_cache / folio_mapping

write to 0xffffea0004b3a7e8 of 8 bytes by task 7779 on cpu 0:
 __delete_from_swap_cache+0x1e8/0x280 mm/swap_state.c:161
 delete_from_swap_cache+0x73/0xe0 mm/swap_state.c:180
 shmem_swapin_folio+0xf3e/0x13e0 mm/shmem.c:2461
 shmem_get_folio_gfp+0x26c/0xd60 mm/shmem.c:2530
 shmem_fault+0xf6/0x250 mm/shmem.c:2798
 __do_fault+0xbc/0x200 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
 populate_vma_page_range mm/gup.c:1880 [inline]
 __mm_populate+0x243/0x3a0 mm/gup.c:1983
 mm_populate include/linux/mm.h:3367 [inline]
 __do_sys_remap_file_pages mm/mmap.c:1200 [inline]
 __se_sys_remap_file_pages+0x39b/0x600 mm/mmap.c:1087
 __x64_sys_remap_file_pages+0x67/0x80 mm/mmap.c:1087
 x64_sys_call+0x23b3/0x3000 arch/x86/include/generated/asm/syscalls_64.h:217
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffea0004b3a7e8 of 8 bytes by task 7778 on cpu 1:
 folio_mapping+0xdd/0x120 mm/util.c:700
 folio_evictable mm/internal.h:499 [inline]
 lru_add+0x80/0x430 mm/swap.c:136
 folio_batch_move_lru+0x1c5/0x280 mm/swap.c:172
 lru_add_drain_cpu+0x77/0x250 mm/swap.c:648
 lru_add_drain+0x25/0x70 mm/swap.c:737
 swap_cluster_readahead+0x35a/0x3e0 mm/swap_state.c:629
 shmem_swapin_cluster mm/shmem.c:1763 [inline]
 shmem_swapin_folio+0xa2f/0x13e0 mm/shmem.c:2371
 shmem_get_folio_gfp+0x26c/0xd60 mm/shmem.c:2530
 shmem_fault+0xf6/0x250 mm/shmem.c:2798
 __do_fault+0xbc/0x200 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
 do_user_addr_fault+0x3fe/0x1080 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
 fault_in_readable+0xad/0x170 mm/gup.c:-1
 fault_in_iov_iter_readable+0x129/0x210 lib/iov_iter.c:94
 generic_perform_write+0x3cf/0x490 mm/filemap.c:4224
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3528
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x527/0x960 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2802/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000042b2 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7778 Comm: syz.1.1706 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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syz.1.1706 (7778) used greatest stack depth: 10320 bytes left