syzbot

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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff888118109d88 of 8 bytes by task 40 on cpu 0:
 instrument_read_write include/linux/instrumented.h:55 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:84 [inline]
 ___test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
 node_clear_mark lib/xarray.c:102 [inline]
 xas_clear_mark+0x90/0x180 lib/xarray.c:915
 __folio_start_writeback+0x2e2/0x440 mm/page-writeback.c:3152
 __block_write_full_folio+0x506/0x8c0 fs/buffer.c:1905
 block_write_full_folio+0x293/0x2b0
 write_cache_pages+0x62/0x100 mm/page-writeback.c:2640
 blkdev_writepages+0x59/0x90 block/fops.c:433
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x274/0x640 fs/fs-writeback.c:2158
 wb_check_background_flush fs/fs-writeback.c:2228 [inline]
 wb_do_writeback fs/fs-writeback.c:2316 [inline]
 wb_workfn+0x67f/0x940 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff888118109d88 of 8 bytes by task 22559 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1733 [inline]
 xas_find_marked+0x216/0x660 lib/xarray.c:1370
 find_get_entry+0x54/0x390 mm/filemap.c:1994
 filemap_get_folios_tag+0x136/0x210 mm/filemap.c:2261
 writeback_get_folio mm/page-writeback.c:2489 [inline]
 writeback_iter+0x4b0/0x830 mm/page-writeback.c:2590
 write_cache_pages+0x4b/0x100 mm/page-writeback.c:2639
 blkdev_writepages+0x59/0x90 block/fops.c:433
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 filemap_fdatawrite_wbc mm/filemap.c:398 [inline]
 __filemap_fdatawrite_range mm/filemap.c:431 [inline]
 __filemap_fdatawrite mm/filemap.c:437 [inline]
 filemap_flush+0xe7/0x120 mm/filemap.c:464
 sync_blockdev_nowait+0x29/0x40 block/bdev.c:207
 sync_filesystem+0xe3/0x190 fs/sync.c:60
 fat_reconfigure+0x89/0x110 fs/fat/inode.c:812
 reconfigure_super+0x319/0x5b0 fs/super.c:1083
 do_remount fs/namespace.c:3047 [inline]
 path_mount+0x967/0xb30 fs/namespace.c:3826
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x27c/0x2d0 fs/namespace.c:4034
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4034
 x64_sys_call+0x2c84/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000110 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22559 Comm: syz.5.8708 Tainted: G        W          6.12.0-syzkaller-01892-g8f7c8b88bda4 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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