BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

[Mirsad Todorovac]

Hi,

The usual setup: vanilla torvalds tree kernel 6.6-rc2, Ubuntu 22.04 LTS.

KCSAN had found a number of data-races in the btrfs implementation.

It is not clear whether this can lead to the corruption of data on the storage media.

Please find the complete KCSAN dmesg report attached.

Best regards,
Mirsad Todorovac

 2149.512903] ==================================================================
[ 2149.512933] BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

[ 2149.512967] write to 0xffff8881ab9d2468 of 8 bytes by interrupt on cpu 27:
[ 2149.512984] xas_clear_mark (/home/marvin/linux/kernel/torvalds2/./arch/x86/include/asm/bitops.h:178 /home/marvin/linux/kernel/torvalds2/./include/asm-generic/bitops/instrumented-non-atomic.h:115 /home/marvin/linux/kernel/torvalds2/lib/xarray.c:102 /home/marvin/linux/kernel/torvalds2/lib/xarray.c:914)
[ 2149.513002] __xa_clear_mark (/home/marvin/linux/kernel/torvalds2/lib/xarray.c:1929)
[ 2149.513019] __folio_end_writeback (/home/marvin/linux/kernel/torvalds2/mm/page-writeback.c:2960)
[ 2149.513039] folio_end_writeback (/home/marvin/linux/kernel/torvalds2/mm/filemap.c:1613)
[ 2149.513053] end_page_writeback (/home/marvin/linux/kernel/torvalds2/mm/folio-compat.c:28)
[ 2149.513073] btrfs_page_clear_writeback (/home/marvin/linux/kernel/torvalds2/fs/btrfs/subpage.c:646) btrfs
[ 2149.513829] end_bio_extent_writepage (/home/marvin/linux/kernel/torvalds2/./include/linux/bio.h:84 /home/marvin/linux/kernel/torvalds2/fs/btrfs/extent_io.c:468) btrfs
[ 2149.514481] __btrfs_bio_end_io (/home/marvin/linux/kernel/torvalds2/fs/btrfs/bio.c:117 /home/marvin/linux/kernel/torvalds2/fs/btrfs/bio.c:112) btrfs
[ 2149.515130] btrfs_orig_bbio_end_io (/home/marvin/linux/kernel/torvalds2/fs/btrfs/bio.c:164) btrfs
[ 2149.515777] btrfs_simple_end_io (/home/marvin/linux/kernel/torvalds2/fs/btrfs/bio.c:380) btrfs
[ 2149.516425] bio_endio (/home/marvin/linux/kernel/torvalds2/block/bio.c:1603)
[ 2149.516436] blk_mq_end_request_batch (/home/marvin/linux/kernel/torvalds2/block/blk-mq.c:851 /home/marvin/linux/kernel/torvalds2/block/blk-mq.c:1089)
[ 2149.516449] nvme_pci_complete_batch (/home/marvin/linux/kernel/torvalds2/drivers/nvme/host/pci.c:986) nvme
[ 2149.516494] nvme_irq (/home/marvin/linux/kernel/torvalds2/drivers/nvme/host/pci.c:1086) nvme
[ 2149.516538] __handle_irq_event_percpu (/home/marvin/linux/kernel/torvalds2/kernel/irq/handle.c:158)
[ 2149.516553] handle_irq_event (/home/marvin/linux/kernel/torvalds2/kernel/irq/handle.c:195 /home/marvin/linux/kernel/torvalds2/kernel/irq/handle.c:210)
[ 2149.516566] handle_edge_irq (/home/marvin/linux/kernel/torvalds2/kernel/irq/chip.c:833)
[ 2149.516578] __common_interrupt (/home/marvin/linux/kernel/torvalds2/./include/linux/irqdesc.h:161 /home/marvin/linux/kernel/torvalds2/arch/x86/kernel/irq.c:238 /home/marvin/linux/kernel/torvalds2/arch/x86/kernel/irq.c:257)
[ 2149.516589] common_interrupt (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/irq.c:247 (discriminator 14))
[ 2149.516601] asm_common_interrupt (/home/marvin/linux/kernel/torvalds2/./arch/x86/include/asm/idtentry.h:636)
[ 2149.516612] cpuidle_enter_state (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:291)
[ 2149.516623] cpuidle_enter (/home/marvin/linux/kernel/torvalds2/drivers/cpuidle/cpuidle.c:390)
[ 2149.516633] call_cpuidle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:135)
[ 2149.516646] do_idle (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:219 /home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:282)
[ 2149.516655] cpu_startup_entry (/home/marvin/linux/kernel/torvalds2/kernel/sched/idle.c:378 (discriminator 1))
[ 2149.516664] start_secondary (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:210 /home/marvin/linux/kernel/torvalds2/arch/x86/kernel/smpboot.c:294)
[ 2149.516677] secondary_startup_64_no_verify (/home/marvin/linux/kernel/torvalds2/arch/x86/kernel/head_64.S:433)

[ 2149.516697] read to 0xffff8881ab9d2468 of 8 bytes by task 4603 on cpu 25:
[ 2149.516708] xas_find_marked (/home/marvin/linux/kernel/torvalds2/./include/linux/find.h:63 /home/marvin/linux/kernel/torvalds2/./include/linux/xarray.h:1722 /home/marvin/linux/kernel/torvalds2/lib/xarray.c:1354)
[ 2149.516719] filemap_get_folios_tag (/home/marvin/linux/kernel/torvalds2/mm/filemap.c:1978 /home/marvin/linux/kernel/torvalds2/mm/filemap.c:2266)
[ 2149.516729] __filemap_fdatawait_range (/home/marvin/linux/kernel/torvalds2/mm/filemap.c:516)
[ 2149.516739] filemap_fdatawait_range (/home/marvin/linux/kernel/torvalds2/mm/filemap.c:553)
[ 2149.516749] btrfs_wait_ordered_range (/home/marvin/linux/kernel/torvalds2/fs/btrfs/ordered-data.c:841) btrfs
[ 2149.517405] btrfs_sync_file (/home/marvin/linux/kernel/torvalds2/fs/btrfs/file.c:1844) btrfs
[ 2149.518059] vfs_fsync_range (/home/marvin/linux/kernel/torvalds2/fs/sync.c:188)
[ 2149.518071] __x64_sys_fsync (/home/marvin/linux/kernel/torvalds2/./include/linux/file.h:45 /home/marvin/linux/kernel/torvalds2/fs/sync.c:213 /home/marvin/linux/kernel/torvalds2/fs/sync.c:220 /home/marvin/linux/kernel/torvalds2/fs/sync.c:218 /home/marvin/linux/kernel/torvalds2/fs/sync.c:218)
[ 2149.518081] do_syscall_64 (/home/marvin/linux/kernel/torvalds2/arch/x86/entry/common.c:50 /home/marvin/linux/kernel/torvalds2/arch/x86/entry/common.c:80)
[ 2149.518095] entry_SYSCALL_64_after_hwframe (/home/marvin/linux/kernel/torvalds2/arch/x86/entry/entry_64.S:120)

[ 2149.518111] value changed: 0xffffff8000000000 -> 0x0000000000000000

[ 2149.518126] Reported by Kernel Concurrency Sanitizer on:
[ 2149.518133] CPU: 25 PID: 4603 Comm: mozStorage #1 Tainted: G             L     6.6.0-rc2-kcsan-00003-g16819584c239-dirty #21
[ 2149.518146] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
[ 2149.518153] ==================================================================

Attachment: xas_clear_mark.log.xz
Description: application/xz