KCSAN: data-race in ext4_file_write_iter / ext4_handle_inode

KCSAN: data-race in ext4_file_write_iter / ext4_handle_inode_extension (2)
Status: auto-closed as invalid on 2020/09/18 14:01
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 347d, last: 344d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ext4_file_write_iter / ext4_handle_inode_extension				1	516d	516d	0/22	auto-closed as invalid on 2020/05/04 10:14

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ext4_file_write_iter / ext4_handle_inode_extension

write to 0xffff888120757178 of 8 bytes by task 3766 on cpu 0:
 i_size_write include/linux/fs.h:876 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3109 [inline]
 ext4_handle_inode_extension+0x214/0x530 fs/ext4/file.c:331
 ext4_dio_write_iter fs/ext4/file.c:551 [inline]
 ext4_file_write_iter+0xdb3/0x1000 fs/ext4/file.c:655
 call_write_iter include/linux/fs.h:1882 [inline]
 do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:713
 do_iter_write+0x112/0x4b0 fs/read_write.c:1018
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x56a/0xba0 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1587
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120757178 of 8 bytes by task 3757 on cpu 1:
 i_size_read include/linux/fs.h:854 [inline]
 ext4_dio_write_iter fs/ext4/file.c:474 [inline]
 ext4_file_write_iter+0x1a1/0x1000 fs/ext4/file.c:655
 call_write_iter include/linux/fs.h:1882 [inline]
 do_iter_readv_writev+0x32e/0x3d0 fs/read_write.c:713
 do_iter_write+0x112/0x4b0 fs/read_write.c:1018
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1059
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x56a/0xba0 fs/read_write.c:1540
 __do_sys_sendfile64 fs/read_write.c:1601 [inline]
 __se_sys_sendfile64 fs/read_write.c:1587 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1587
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3757 Comm: syz-executor.5 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/08/14 14:00	upstream	a1d21081a60d	5ce13532	.config	log	report
ci2-upstream-kcsan-gce	2020/08/10 21:39	upstream	fc80c51fd4b2	7adc7b65	.config	log	report