syzbot


KCSAN: data-race in generic_fillattr / shmem_symlink (6)

Status: moderation: reported on 2026/02/12 05:33
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+67197a361277d25df493@syzkaller.appspotmail.com
First crash: 6d03h, last: 6h38m
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in generic_fillattr / shmem_symlink (2) mm 6 247 664d 803d 0/29 auto-obsoleted due to no activity on 2024/05/30 03:00
upstream KCSAN: data-race in generic_fillattr / shmem_symlink (5) mm 6 2 99d 127d 0/29 auto-obsoleted due to no activity on 2026/01/05 20:06
upstream KCSAN: data-race in generic_fillattr / shmem_symlink (3) mm 6 16 494d 600d 0/29 auto-obsoleted due to no activity on 2024/11/16 05:24
upstream KCSAN: data-race in generic_fillattr / shmem_symlink (4) mm 6 6 334d 435d 0/29 auto-obsoleted due to no activity on 2025/05/15 12:20
upstream KCSAN: data-race in generic_fillattr / shmem_symlink fs 6 30 2075d 2265d 0/29 closed as invalid on 2020/06/18 14:24

Sample crash report:
==================================================================
BUG: KCSAN: data-race in generic_fillattr / shmem_symlink

write to 0xffff8881052d20d8 of 8 bytes by task 3616 on cpu 0:
 inode_set_mtime_to_ts include/linux/fs.h:1658 [inline]
 shmem_symlink+0x37a/0x3b0 mm/shmem.c:4151
 vfs_symlink+0x106/0x220 fs/namei.c:5615
 filename_symlinkat+0xe8/0x2b0 fs/namei.c:5640
 __do_sys_symlink fs/namei.c:5667 [inline]
 __se_sys_symlink+0x42/0x1b0 fs/namei.c:5663
 __x64_sys_symlink+0x31/0x40 fs/namei.c:5663
 x64_sys_call+0x2465/0x3020 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881052d20d8 of 8 bytes by task 3743 on cpu 1:
 inode_get_mtime_sec include/linux/fs.h:1640 [inline]
 inode_get_mtime include/linux/fs.h:1650 [inline]
 generic_fillattr+0x201/0x340 fs/stat.c:102
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr+0x48/0x60 fs/stat.c:262
 vfs_statx_path+0x28/0x140 fs/stat.c:299
 vfs_statx+0xc4/0x170 fs/stat.c:356
 vfs_fstatat+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000699520a0 -> 0x00000000699520b5

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3743 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/18 02:15 upstream d295082ea672 06ec4f7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / shmem_symlink
2026/02/13 16:32 upstream 37a93dd5c49b 6a673c50 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / shmem_symlink
2026/02/12 05:32 upstream c22e26bd0906 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / shmem_symlink
* Struck through repros no longer work on HEAD.