syzbot


KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (9)

Status: moderation: reported on 2025/09/10 13:57
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+bfcd49223b48fbfc8e5f@syzkaller.appspotmail.com
First crash: 1d19h, last: 1d19h
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (7) mm 6 10 389d 370d 0/29 auto-obsoleted due to no activity on 2024/09/23 07:15
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (8) mm ext4 6 3 68d 137d 0/29 auto-obsoleted due to no activity on 2025/08/30 17:27
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (5) mm 6 8 711d 807d 0/29 auto-obsoleted due to no activity on 2023/11/06 01:09
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (3) mm fs 6 3 905d 922d 0/29 auto-obsoleted due to no activity on 2023/04/29 19:41
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead fs 6 7 1325d 1399d 0/29 auto-closed as invalid on 2022/03/01 21:22
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (2) fs 6 1 1110d 1110d 0/29 auto-closed as invalid on 2022/10/02 20:33
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (6) fs mm 6 5 526d 621d 0/29 auto-obsoleted due to no activity on 2024/05/08 09:54
upstream KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (4) fs 6 1 864d 864d 0/29 auto-obsoleted due to no activity on 2023/06/06 03:32

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

write to 0xffff8881040f7150 of 8 bytes by task 20334 on cpu 0:
 do_sync_mmap_readahead+0x2ba/0x320 mm/filemap.c:-1
 filemap_fault+0x313/0xb40 mm/filemap.c:3445
 __do_fault+0xb9/0x200 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
 __get_user_pages_locked mm/gup.c:1712 [inline]
 get_dump_page+0xb5/0x250 mm/gup.c:2212
 dump_user_range+0x145/0x8f0 fs/coredump.c:1364
 elf_core_dump+0x1e00/0x1f90 fs/binfmt_elf.c:2085
 coredump_write+0xb0a/0xe30 fs/coredump.c:1049
 vfs_coredump+0x142f/0x20c0 fs/coredump.c:1168
 get_signal+0xd85/0xf70 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:73
 irqentry_exit+0x12/0x50 kernel/entry/common.c:177
 exc_general_protection+0x15b/0x1f0 arch/x86/kernel/traps.c:792
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

read to 0xffff8881040f7150 of 8 bytes by task 20315 on cpu 1:
 do_sync_mmap_readahead+0x2fc/0x320 mm/filemap.c:3303
 filemap_fault+0x313/0xb40 mm/filemap.c:3445
 __do_fault+0xb9/0x200 mm/memory.c:5152
 do_read_fault mm/memory.c:5573 [inline]
 do_fault mm/memory.c:5707 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault mm/memory.c:6195 [inline]
 handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
 faultin_page mm/gup.c:1144 [inline]
 __get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
 __get_user_pages_locked mm/gup.c:1712 [inline]
 get_dump_page+0xb5/0x250 mm/gup.c:2212
 dump_user_range+0x145/0x8f0 fs/coredump.c:1364
 elf_core_dump+0x1e00/0x1f90 fs/binfmt_elf.c:2085
 coredump_write+0xb0a/0xe30 fs/coredump.c:1049
 vfs_coredump+0x142f/0x20c0 fs/coredump.c:1168
 get_signal+0xd85/0xf70 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:73
 irqentry_exit+0x12/0x50 kernel/entry/common.c:177
 exc_general_protection+0x15b/0x1f0 arch/x86/kernel/traps.c:792
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

value changed: 0x0000000000000f0f -> 0x0000000000000687

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 20315 Comm: syz.4.5981 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/10 13:56 upstream 9dd1835ecda5 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead
* Struck through repros no longer work on HEAD.