KCSAN: data-race in ext4_write_end / mpage_process_page

KCSAN: data-race in ext4_write_end / mpage_process_page_bufs (2)
Status: closed as invalid on 2020/06/18 14:24
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 672d, last: 601d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ext4_write_end / mpage_process_page_bufs				1	762d	762d	0/22	auto-closed as invalid on 2020/03/01 21:02
upstream	KCSAN: data-race in ext4_write_end / mpage_process_page_bufs (3)				150	46d	413d	0/22	auto-closed as invalid on 2022/01/12 03:52

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ext4_write_end / mpage_process_page_bufs

write to 0xffff888120fed278 of 8 bytes by task 22795 on cpu 1:
 i_size_write include/linux/fs.h:894 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3083 [inline]
 ext4_write_end+0x30d/0x920 fs/ext4/inode.c:1286
 generic_perform_write+0x1d7/0x320 mm/filemap.c:3313
 ext4_buffered_write_iter+0x14e/0x280 fs/ext4/file.c:270
 ext4_file_write_iter+0xf4/0xd30 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x303/0x400 fs/read_write.c:484
 __vfs_write+0x9e/0xb0 fs/read_write.c:497
 vfs_write fs/read_write.c:559 [inline]
 vfs_write+0x189/0x380 fs/read_write.c:543
 ksys_write+0xc5/0x1a0 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x49/0x60 fs/read_write.c:621
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120fed278 of 8 bytes by task 22798 on cpu 0:
 mpage_process_page_bufs+0x3f/0x400 fs/ext4/inode.c:2165
 mpage_prepare_extent_to_map+0x43b/0x6e0 fs/ext4/inode.c:2595
 ext4_writepages+0x5a1/0x1e10 fs/ext4/inode.c:2723
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1bb/0x220 mm/filemap.c:421
 filemap_write_and_wait_range mm/filemap.c:654 [inline]
 filemap_write_and_wait_range+0xad/0x140 mm/filemap.c:648
 filemap_write_and_wait include/linux/fs.h:2767 [inline]
 iomap_bmap+0x67/0x100 fs/iomap/fiemap.c:138
 ext4_bmap+0x12b/0x230 fs/ext4/inode.c:3213
 bmap+0x5d/0x90 fs/inode.c:1623
 ioctl_fibmap fs/ioctl.c:72 [inline]
 file_ioctl fs/ioctl.c:541 [inline]
 do_vfs_ioctl+0xbce/0xd00 fs/ioctl.c:742
 ksys_ioctl+0xb2/0x150 fs/ioctl.c:761
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x47/0x60 fs/ioctl.c:770
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 22798 Comm: syz-executor.0 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report
ci2-upstream-kcsan-gce	2020/06/01 00:23	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	a0331e89	.config	log	report
ci2-upstream-kcsan-gce	2020/05/02 12:05	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	58da4c35	.config	log	report
ci2-upstream-kcsan-gce	2020/04/28 08:40	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	0ce7569e	.config	log	report
ci2-upstream-kcsan-gce	2020/04/07 06:04	https://github.com/google/ktsan.git kcsan	40959e34d670	99a96044	.config	log	report
ci2-upstream-kcsan-gce	2020/04/02 06:17	https://github.com/google/ktsan.git kcsan	40959e34d670	a34e2c33	.config	log	report
ci2-upstream-kcsan-gce	2020/03/22 11:58	https://github.com/google/ktsan.git kcsan	40959e34d670	78267cec	.config	log	report