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

write to 0xffffea0004827e58 of 8 bytes by task 7134 on cpu 0:
 page_cache_delete mm/filemap.c:145 [inline]
 __filemap_remove_folio+0x201/0x2e0 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+0x26d/0xb10 mm/shmem.c:1145
 shmem_fallocate+0x881/0x920 mm/shmem.c:3798
 vfs_fallocate+0x3b6/0x400 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+0x298e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffea0004827e58 of 8 bytes by task 7153 on cpu 1:
 folio_mapping+0xa1/0xe0 mm/util.c:703
 folio_evictable mm/internal.h:568 [inline]
 lru_add+0x8d/0x460 mm/swap.c:136
 folio_batch_move_lru+0x1c5/0x270 mm/swap.c:172
 __folio_batch_add_and_move mm/swap.c:196 [inline]
 folio_add_lru+0x149/0x1e0 mm/swap.c:511
 folio_add_lru_vma+0x49/0x70 mm/swap.c:530
 do_anonymous_page mm/memory.c:5313 [inline]
 do_pte_missing mm/memory.c:4475 [inline]
 handle_pte_fault mm/memory.c:6317 [inline]
 __handle_mm_fault mm/memory.c:6455 [inline]
 handle_mm_fault+0x2c31/0x3020 mm/memory.c:6624
 do_user_addr_fault+0x62f/0x1050 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0xffff88811b703a50 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7153 Comm: syz.2.1077 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
==================================================================
loop2: detected capacity change from 0 to 1024
EXT4-fs (loop2): ext4_check_descriptors: Inode bitmap for group 0 overlaps block group descriptors
EXT4-fs (loop2): ext4_check_descriptors: Checksum for group 0 failed (30349!=20869)
EXT4-fs error (device loop2): ext4_get_journal_inode:5890: comm syz.2.1077: inode #1: comm syz.2.1077: iget: illegal inode #
loop2: lost filesystem error report for type 5 error -117
EXT4-fs (loop2): no journal found
EXT4-fs (loop2): can't get journal size
EXT4-fs (loop2): failed to initialize system zone (-22)
EXT4-fs (loop2): mount failed