syzbot

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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff888119638908 of 8 bytes by interrupt 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 lib/xarray.c:922 [inline]
 __xa_clear_mark+0xf5/0x1e0 lib/xarray.c:2100
 __folio_end_writeback+0xf7/0x3b0 mm/page-writeback.c:2998
 folio_end_writeback_no_dropbehind+0x6d/0x1b0 mm/filemap.c:1668
 folio_end_writeback+0x1c/0x70 mm/filemap.c:1694
 end_buffer_async_write+0x156/0x1f0 fs/buffer.c:419
 end_bio_bh_io_sync+0x79/0xa0 fs/buffer.c:2776
 bio_endio+0x37e/0x420 block/bio.c:1672
 blk_update_request+0x336/0x730 block/blk-mq.c:998
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1160
 lo_complete_rq+0x98/0x140 drivers/block/loop.c:314
 blk_complete_reqs block/blk-mq.c:1235 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1240
 handle_softirqs+0xba/0x290 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x3a/0xc0 kernel/softirq.c:723
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1052
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 kcsan_setup_watchpoint+0x415/0x430 kernel/kcsan/core.c:705
 io_init_req io_uring/io_uring.c:2169 [inline]
 io_submit_sqe io_uring/io_uring.c:2295 [inline]
 io_submit_sqes+0x316/0x1060 io_uring/io_uring.c:2447
 __do_sys_io_uring_enter io_uring/io_uring.c:3514 [inline]
 __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3453
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3453
 x64_sys_call+0x2df0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
 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 0xffff888119638908 of 8 bytes by task 13379 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x218/0x620 lib/xarray.c:1510
 find_get_entry+0x5d/0x380 mm/filemap.c:2070
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2338
 __filemap_fdatawait_range mm/filemap.c:533 [inline]
 filemap_write_and_wait_range+0x1d3/0x340 mm/filemap.c:703
 filemap_write_and_wait include/linux/pagemap.h:68 [inline]
 sync_blockdev+0x35/0x50 block/bdev.c:260
 bdev_disk_changed+0xdb/0xcb0 block/partitions/core.c:656
 blkdev_get_whole+0x1f5/0x2d0 block/bdev.c:748
 bdev_open+0x280/0x7e0 block/bdev.c:957
 blkdev_open+0x259/0x290 block/fops.c:701
 do_dentry_open+0x649/0xa20 fs/open.c:965
 vfs_open+0x37/0x1e0 fs/open.c:1097
 do_open fs/namei.c:3975 [inline]
 path_openat+0x1c5e/0x2170 fs/namei.c:4134
 do_filp_open+0x109/0x230 fs/namei.c:4161
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x2eab/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 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: 0xfffffffffffffff8 -> 0xfffffffffffff000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13379 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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