syzbot


KCSAN: data-race in __writeback_single_inode / xas_clear_mark (8)

Status: moderation: reported on 2025/09/27 02:34
Subsystems: fs mm
[Documentation on labels]
Reported-by: syzbot+68fb935b4a2bf2f83ce0@syzkaller.appspotmail.com
First crash: 153d, last: 16d
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
c4042d6b-3672-4ef0-9fd0-ad5a0537e243 assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in __writeback_single_inode / xas_clear_mark (8) 2026/02/24 20:05 2026/02/24 20:05 2026/02/24 20:16 305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9
4e0ef306-0841-4353-9443-7e10d777fab3 assessment-kcsan 💥 KCSAN: data-race in __writeback_single_inode / xas_clear_mark (8) 2026/01/10 02:17 2026/01/10 02:17 2026/01/10 02:34 7519916073b761ced56a7b15fdeeb4674e8dc125 Error 429, Message: You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. * Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0, Status: RESOURCE_EXHAUSTED, Details: [map[@type:type.googleapis.com/google.rpc.Help links:[map[description:Learn more about Gemini API quotas url:https://ai.google.dev/gemini-api/docs/rate-limits]]] map[@type:type.googleapis.com/google.rpc.QuotaFailure violations:[map[quotaId:GenerateRequestsPerDayPerProjectPerModel quotaMetric:generativelanguage.googleapis.com/generate_requests_per_model_per_day]]] map[@type:type.googleapis.com/google.rpc.DebugInfo detail:[ORIGINAL ERROR] generic::resource_exhausted: You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. * Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0 [google.rpc.error_details_ext] { message: "You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit. \n* Quota exceeded for metric: generativelanguage.googleapis.com/generate_requests_per_model_per_day, limit: 0" details { type_url: "type.googleapis.com/language_labs.genai.debug.GeminiApiDebugInfo" value: "RM\nK\nEgenerativelanguage.googleapis.com/generate_requests_per_model_per_day\030\000\"\000" } details { [type.googleapis.com/google.rpc.Help] { links { description: "Learn more about Gemini API quotas" url: "https://ai.google.dev/gemini-api/docs/rate-limits" } } } details { [type.googleapis.com/google.rpc.QuotaFailure] { violations { quota_metric: "generativelanguage.googleapis.com/generate_requests_per_model_per_day" quota_id: "GenerateRequestsPerDayPerProjectPerModel" } } } }]]
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (4) fs mm 6 1 1978d 1978d 0/29 auto-closed as invalid on 2020/11/02 04:03
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (6) mm fs 6 4 358d 450d 0/29 auto-obsoleted due to no activity on 2025/05/01 12:25
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (7) mm fs 6 5 248d 278d 0/29 auto-obsoleted due to no activity on 2025/08/19 20:24
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (2) ext4 6 5 2219d 2284d 0/29 auto-closed as invalid on 2020/04/10 19:48
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (5) fs mm 6 1 568d 568d 0/29 auto-obsoleted due to no activity on 2024/09/12 03:14
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark (3) mm fs 6 1 2013d 2013d 0/29 auto-closed as invalid on 2020/09/27 22:17
upstream KCSAN: data-race in __writeback_single_inode / xas_clear_mark ext4 6 3 2308d 2319d 0/29 closed as invalid on 2019/11/19 13:24

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

write to 0xffff88811a619cfc of 4 bytes by task 12538 on cpu 0:
 xa_mark_clear lib/xarray.c:77 [inline]
 xas_clear_mark+0x16b/0x180 lib/xarray.c:932
 __folio_start_writeback+0x257/0x370 mm/page-writeback.c:3053
 ext4_bio_write_folio+0x5ad/0x9f0 fs/ext4/page-io.c:584
 mpage_submit_folio fs/ext4/inode.c:2087 [inline]
 mpage_process_page_bufs+0x4a1/0x620 fs/ext4/inode.c:2198
 mpage_prepare_extent_to_map+0x7d4/0xc50 fs/ext4/inode.c:2737
 ext4_do_writepages+0x9f6/0x2800 fs/ext4/inode.c:2930
 ext4_writepages+0x18f/0x320 fs/ext4/inode.c:3026
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2598
 filemap_writeback mm/filemap.c:387 [inline]
 filemap_fdatawrite_range mm/filemap.c:412 [inline]
 file_write_and_wait_range+0x178/0x2f0 mm/filemap.c:786
 generic_buffers_fsync_noflush+0x45/0x130 fs/buffer.c:610
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1aa/0x680 fs/ext4/fsync.c:147
 vfs_fsync_range+0xc5/0xe0 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2640 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:306
 ext4_file_write_iter+0x380/0xf70 fs/ext4/file.c:-1
 iter_file_splice_write+0x6bc/0xa80 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x311/0x670 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1230
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a619cfc of 4 bytes by task 12533 on cpu 1:
 xa_marked include/linux/xarray.h:424 [inline]
 mapping_tagged include/linux/fs.h:507 [inline]
 __writeback_single_inode+0x1f2/0x6e0 fs/fs-writeback.c:1799
 writeback_single_inode+0x16d/0x3f0 fs/fs-writeback.c:1869
 sync_inode_metadata+0x6e/0xa0 fs/fs-writeback.c:2974
 generic_buffers_fsync_noflush+0xee/0x130 fs/buffer.c:620
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1aa/0x680 fs/ext4/fsync.c:147
 vfs_fsync_range+0xc5/0xe0 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2640 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:306
 ext4_file_write_iter+0x380/0xf70 fs/ext4/file.c:-1
 iter_file_splice_write+0x6bc/0xa80 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x311/0x670 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1230
 do_sendfile+0x382/0x650 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64 fs/read_write.c:1419 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1419
 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0e000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12533 Comm: syz.3.1821 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================
EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/10 20:44 upstream 72c395024dac 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2026/01/21 20:05 upstream cf38b2340c0e 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2026/01/16 03:14 upstream 603c05a1639f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2025/12/19 04:54 upstream 516471569089 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2025/12/02 15:26 upstream 4a26e7032d7d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2025/11/05 10:00 upstream 17d85f33a83b a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2025/10/02 17:27 upstream 7f7072574127 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
2025/09/27 02:33 upstream 083fc6d7fa0d 001c9061 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __writeback_single_inode / xas_clear_mark
* Struck through repros no longer work on HEAD.