KCSAN: data-race in xas_create / xas_find (10)

Status: upstream: reported on 2026/10/22 10:01
Subsystems: fs mm
Labels: race:harmful
[Documentation on labels]
Reported-by: syzbot+73641b60a3bc11dfca8c@syzkaller.appspotmail.com
First crash: 6h10m, last: 6h10m
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ID Workflow Result Correct Bug Created Started Finished Revision
0d21abff assessment-kcsan Benign: ❌ ❓ KCSAN: data-race in xas_create / xas_find (10) 2026/10/22 09:11 2026/10/22 09:11 2026/10/22 10:00 4ba27f85
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Title Replies (including bot) Last reply
[syzbot] [fs?] [mm?] KCSAN: data-race in xas_create / xas_find (10) 0 (1) 2026/10/22 10:01
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in xas_create / xas_find (4) fs mm 6 3 1630d 1669d 0/29 auto-closed as invalid on 2022/06/09 16:26
upstream KCSAN: data-race in xas_create / xas_find (2) fs mm 6 5 1890d 1963d 0/29 auto-closed as invalid on 2021/09/22 15:56
upstream KCSAN: data-race in xas_create / xas_find (6) fs mm 6 4 962d 1026d 0/29 auto-obsoleted due to no activity on 2024/04/08 00:15
upstream KCSAN: data-race in xas_create / xas_find (5) fs mm 6 1 1589d 1589d 0/29 auto-closed as invalid on 2022/07/21 09:43
upstream KCSAN: data-race in xas_create / xas_find (3) fs mm 6 11 1739d 1855d 0/29 auto-closed as invalid on 2022/02/20 21:56
upstream KCSAN: data-race in xas_create / xas_find fs mm 6 2 2001d 2015d 0/29 auto-closed as invalid on 2021/06/03 16:29
upstream KCSAN: data-race in xas_create / xas_find (7) fs mm 6 1 789d 789d 0/29 auto-obsoleted due to no activity on 2024/09/28 12:31
upstream KCSAN: data-race in xas_create / xas_find (9) fs mm 6 2 604d 616d 0/29 auto-obsoleted due to no activity on 2025/04/22 10:38
upstream KCSAN: data-race in xas_create / xas_find (8) fs mm 6 4 710d 738d 0/29 auto-obsoleted due to no activity on 2025/01/05 23:56

Sample crash report:
loop6: detected capacity change from 0 to 1024
EXT4-fs: Ignoring removed i_version option
EXT4-fs (loop6): Unsupported encryption level 6
==================================================================
BUG: KCSAN: data-race in xas_create / xas_find

write to 0xffff88811a8efda9 of 1 bytes by task 6715 on cpu 1:
 xas_expand lib/xarray.c:620 [inline]
 xas_create+0x685/0xbf0 lib/xarray.c:661
 xas_store+0x6f/0xce0 lib/xarray.c:795
 __filemap_add_folio+0x647/0x910 mm/filemap.c:915
 filemap_add_folio+0x1cd/0x380 mm/filemap.c:972
 page_cache_ra_unbounded+0x1a4/0x3a0 mm/readahead.c:293
 do_page_cache_ra mm/readahead.c:348 [inline]
 force_page_cache_ra+0x190/0x1d0 mm/readahead.c:378
 page_cache_sync_ra+0x11d/0x560 mm/readahead.c:602
 filemap_get_pages+0x2f2/0x1360 mm/filemap.c:2714
 filemap_read+0x21c/0xad0 mm/filemap.c:2824
 blkdev_read_iter+0x21e/0x2d0 block/fops.c:838
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a8efda9 of 1 bytes by task 6813 on cpu 0:
 xas_find+0x360/0x3e0 lib/xarray.c:1421
 find_get_entry mm/filemap.c:2085 [inline]
 find_lock_entries+0xd4/0x6b0 mm/filemap.c:2189
 mapping_try_invalidate+0xc7/0x430 mm/truncate.c:545
 invalidate_mapping_pages+0x27/0x40 mm/truncate.c:602
 invalidate_bdev+0x58/0x70 block/bdev.c:101
 __ext4_fill_super fs/ext4/super.c:5840 [inline]
 ext4_fill_super+0x2cd3/0x37c0 fs/ext4/super.c:5865
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1883
 get_tree_bdev+0x1f/0x30 fs/super.c:1906
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5897
 vfs_get_tree+0x57/0x1d0 fs/super.c:1943
 fc_mount fs/namespace.c:1282 [inline]
 do_new_mount_fc fs/namespace.c:3910 [inline]
 do_new_mount+0x288/0x730 fs/namespace.c:3986
 path_mount+0x4ad/0xb90 fs/namespace.c:4337
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4542
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4542
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x03 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6813 Comm: syz.6.569 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/22 09:11 upstream a804c5742bff 4ba27f85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in xas_create / xas_find
* Struck through repros no longer work on HEAD.