KCSAN: data-race in __filemap_add_folio / sync

ID	Workflow	Result	Correct	Bug	Created	Started	Finished	Revision	Error
4edf0f64-7c2a-4a05-b990-97ac854e3bf3	assessment-security	DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌	❓	KCSAN: data-race in __filemap_add_folio / sync_bdevs (3)	2026/05/31 22:03	2026/05/31 22:03	2026/05/31 22:47	6b4a844333e83556da95d61d7f207e7ef5cd4bc6
82d37d86-f554-42b6-b214-f676466263b6	assessment-security		💥	KCSAN: data-race in __filemap_add_folio / sync_bdevs (3)	2026/05/15 07:12	2026/05/15 07:12	2026/05/15 07:13	6ccb967e465e832a7bfd7a116ad00d52a0923a5d	failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128 From /app/workdir/repo/linux * branch HEAD -> FETCH_HEAD Updating files: ... truncated to first 200 bytes; open job for full error
af7922ee-8483-4d3c-aa57-4bcef35f1887	assessment-kcsan	Benign: ✅ Confident: ✅	❓	KCSAN: data-race in __filemap_add_folio / sync_bdevs (3)	2026/02/23 21:13	2026/02/23 21:13	2026/02/23 21:22	305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __filemap_add_folio / sync_bdevs fs mm	6				1	1238d	1238d	0/29	auto-obsoleted due to no activity on 2023/04/05 16:41
upstream	KCSAN: data-race in __filemap_add_folio / sync_bdevs (2) ext4	6				1	634d	634d	0/29	auto-obsoleted due to no activity on 2024/10/26 07:57

Kernel

Title

Rank 🛈

upstream

KCSAN: data-race in __filemap_add_folio / sync_bdevs fs mm

1238d

0/29

auto-obsoleted due to no activity on 2023/04/05 16:41

upstream

KCSAN: data-race in __filemap_add_folio / sync_bdevs (2) ext4

634d

0/29

auto-obsoleted due to no activity on 2024/10/26 07:57

================================================================== BUG: KCSAN: data-race in __filemap_add_folio / sync_bdevs read-write to 0xffff888100492b08 of 8 bytes by task 2963 on cpu 0: __filemap_add_folio+0x671/0x8b0 mm/filemap.c:919 filemap_add_folio+0x1d3/0x350 mm/filemap.c:966 __filemap_get_folio_mpol+0x326/0x680 mm/filemap.c:2021 __filemap_get_folio include/linux/pagemap.h:763 [inline] grow_dev_folio fs/buffer.c:1047 [inline] grow_buffers fs/buffer.c:1113 [inline] __getblk_slow fs/buffer.c:1131 [inline] bdev_getblk+0x173/0x3f0 fs/buffer.c:1458 __getblk include/linux/buffer_head.h:380 [inline] jbd2_journal_get_descriptor_buffer+0xce/0x210 fs/jbd2/journal.c:976 jbd2_journal_commit_transaction+0xcc8/0x3420 fs/jbd2/commit.c:610 kjournald2+0x22e/0x3e0 fs/jbd2/journal.c:201 kthread+0x22a/0x280 kernel/kthread.c:436 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 read to 0xffff888100492b08 of 8 bytes by task 19578 on cpu 1: sync_bdevs+0xd3/0x260 block/bdev.c:1285 ksys_sync fs/sync.c:105 [inline] __ia32_sys_sync+0x81/0xb0 fs/sync.c:111 x64_sys_call+0x2f3a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:163 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: 0x000000000000033d -> 0x000000000000033e Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 19578 Comm: syz.0.4667 Tainted: G W syzkaller #0 PREEMPT(full) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 ================================================================== loop0: detected capacity change from 0 to 256 FAT-fs (loop0): utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive! FAT-fs (loop0): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

Crashes (2):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2026/04/06 01:24	upstream	1791c390149f	4440e7c2	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __filemap_add_folio / sync_bdevs
2026/02/23 21:13	upstream	7dff99b35460	6beca497	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __filemap_add_folio / sync_bdevs

Crashes (2):

Assets (help?)