syzbot


KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (6)

Status: fixed on 2023/07/01 16:05
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+4a03518df1e31b537066@syzkaller.appspotmail.com
Fix commit: 492888df0c7b ext4: fix data races when using cached status extents
First crash: 440d, last: 378d
Discussions (3)
Title Replies (including bot) Last reply
[PATCH v2] ext4: Fix data races when using cached status extents 2 (2) 2023/05/13 04:59
[PATCH] ext4: Fix data races when using cached status extents 3 (3) 2023/05/04 10:50
[syzbot] [ext4?] KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (6) 2 (3) 2023/05/03 17:42
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __es_find_extent_range / __es_find_extent_range ext4 2 1100d 1105d 0/26 auto-closed as invalid on 2021/05/27 20:25
upstream KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (4) ext4 1 538d 538d 0/26 auto-obsoleted due to no activity on 2022/12/10 23:58
upstream KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (5) ext4 1 501d 501d 0/26 auto-obsoleted due to no activity on 2023/01/17 15:46
upstream KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (3) ext4 1 893d 893d 0/26 auto-closed as invalid on 2021/12/20 16:23
upstream KCSAN: data-race in __es_find_extent_range / __es_find_extent_range (2) ext4 4 973d 1042d 0/26 auto-closed as invalid on 2021/10/01 16:26

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

write to 0xffff88810a5a98a8 of 8 bytes by task 10666 on cpu 0:
 __es_find_extent_range+0x212/0x300 fs/ext4/extents_status.c:296
 ext4_es_find_extent_range+0x91/0x260 fs/ext4/extents_status.c:318
 ext4_ext_put_gap_in_cache fs/ext4/extents.c:2284 [inline]
 ext4_ext_map_blocks+0x120d/0x36c0 fs/ext4/extents.c:4191
 ext4_map_blocks+0x2a0/0x1050 fs/ext4/inode.c:576
 ext4_mpage_readpages+0x699/0x1440 fs/ext4/readpage.c:300
 ext4_read_folio+0xc5/0x1a0 fs/ext4/inode.c:3308
 filemap_read_folio+0x2c/0x100 mm/filemap.c:2424
 filemap_fault+0x66f/0xb20 mm/filemap.c:3367
 __do_fault mm/memory.c:4155 [inline]
 do_read_fault mm/memory.c:4506 [inline]
 do_fault mm/memory.c:4635 [inline]
 handle_pte_fault mm/memory.c:4923 [inline]
 __handle_mm_fault mm/memory.c:5065 [inline]
 handle_mm_fault+0x115d/0x21d0 mm/memory.c:5211
 faultin_page mm/gup.c:925 [inline]
 __get_user_pages+0x363/0xc30 mm/gup.c:1147
 populate_vma_page_range mm/gup.c:1543 [inline]
 __mm_populate+0x23a/0x360 mm/gup.c:1652
 mm_populate include/linux/mm.h:3026 [inline]
 vm_mmap_pgoff+0x174/0x210 mm/util.c:547
 ksys_mmap_pgoff+0x2ac/0x320 mm/mmap.c:1410
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810a5a98a8 of 8 bytes by task 10630 on cpu 1:
 __es_find_extent_range+0x79/0x300 fs/ext4/extents_status.c:270
 __es_scan_range fs/ext4/extents_status.c:345 [inline]
 __es_scan_clu fs/ext4/extents_status.c:399 [inline]
 ext4_es_scan_clu+0xe4/0x190 fs/ext4/extents_status.c:415
 ext4_insert_delayed_block fs/ext4/inode.c:1694 [inline]
 ext4_da_map_blocks fs/ext4/inode.c:1806 [inline]
 ext4_da_get_block_prep+0x575/0xa70 fs/ext4/inode.c:1870
 __block_write_begin_int+0x349/0xe50 fs/buffer.c:2034
 __block_write_begin+0x5e/0x110 fs/buffer.c:2084
 ext4_da_write_begin+0x2fa/0x610 fs/ext4/inode.c:3084
 generic_perform_write+0x1c3/0x3d0 mm/filemap.c:3926
 ext4_buffered_write_iter+0x234/0x3e0 fs/ext4/file.c:289
 ext4_file_write_iter+0xd7/0x10e0
 call_write_iter include/linux/fs.h:1851 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x463/0x760 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffff88810a653dc0 -> 0xffff8881067334d8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10630 Comm: syz-executor.0 Not tainted 6.3.0-rc6-syzkaller-00138-g44149752e998 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/04/14 17:58 upstream 44149752e998 ec410564 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __es_find_extent_range / __es_find_extent_range
2023/03/07 17:15 upstream 8ca09d5fa354 d7ea8bc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __es_find_extent_range / __es_find_extent_range
2023/03/03 12:49 upstream 2eb29d59ddf0 f8902b57 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __es_find_extent_range / __es_find_extent_range
2023/02/11 22:38 upstream 47e9aa14ce5a 93e26d60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __es_find_extent_range / __es_find_extent_range
* Struck through repros no longer work on HEAD.