On Wed 26-08-20 19:48:16, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: c3d8f220 Merge tag 'kbuild-fixes-v5.9' of git://git.kernel.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=15f83cb6900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=bb68b9e8a8cc842f > dashboard link: https://syzkaller.appspot.com/bug?extid=3622cea378100f45d59f > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1287ac96900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11c7ac46900000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3622cea378100f45d59f@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > kernel BUG at fs/ext4/inode.c:2598! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 27612 Comm: syz-executor879 Not tainted 5.9.0-rc1-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:mpage_prepare_extent_to_map+0xd34/0xd40 fs/ext4/inode.c:2598 Doh, so this is: wait_on_page_writeback(page); >>> BUG_ON(PageWriteback(page)); in mpage_prepare_extent_to_map(). So we have PageWriteback() page after we have called wait_on_page_writeback() on a locked page. Not sure how this could ever happen even less how ext4 could cause this... Anyway, syzbot has found a reproducer so I'll try if it reproduces in my KVM... Honza > Code: 89 e8 a0 74 9f ff 0f 0b e8 59 81 70 ff 4c 89 e7 48 c7 c6 da a3 07 89 e8 8a 74 9f ff 0f 0b e8 43 81 70 ff 0f 0b e8 3c 81 70 ff <0f> 0b e8 c5 b3 25 06 0f 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 > RSP: 0018:ffffc9000a0974d8 EFLAGS: 00010293 > RAX: ffffffff820476e4 RBX: 00fffe000000a01f RCX: ffff88808ea5c340 > RDX: 0000000000000000 RSI: 000000000000a01f RDI: 000000000000ffff > RBP: ffffea00020d4f80 R08: ffffffff820471e4 R09: fffff9400041a9f1 > R10: fffff9400041a9f1 R11: 0000000000000000 R12: ffffea00020d4f80 > R13: ffffc9000a0977b0 R14: 1ffffd400041a9f1 R15: dffffc0000000000 > FS: 00007f5055f25700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000004ae4b0 CR3: 00000000a2d7f000 CR4: 00000000001506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ext4_writepages+0xa98/0x3750 fs/ext4/inode.c:2735 > do_writepages+0xda/0x1f0 mm/page-writeback.c:2352 > __filemap_fdatawrite_range+0x2a5/0x350 mm/filemap.c:422 > filemap_write_and_wait_range+0xca/0x160 mm/filemap.c:655 > iomap_dio_rw+0x5a7/0xeb0 fs/iomap/direct-io.c:478 > ext4_dio_read_iter fs/ext4/file.c:77 [inline] > ext4_file_read_iter+0x544/0x6d0 fs/ext4/file.c:129 > call_read_iter include/linux/fs.h:1876 [inline] > generic_file_splice_read+0x3c5/0x640 fs/splice.c:312 > do_splice_to fs/splice.c:870 [inline] > splice_direct_to_actor+0x3bd/0xb60 fs/splice.c:950 > do_splice_direct+0x201/0x340 fs/splice.c:1059 > do_sendfile+0x86d/0x1210 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+0x164/0x1a0 fs/read_write.c:1587 > do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x448bc9 > Code: e8 1c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f5055f24ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 > RAX: ffffffffffffffda RBX: 00000000006e4a28 RCX: 0000000000448bc9 > RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000004 > RBP: 00000000006e4a20 R08: 0000000000000000 R09: 0000000000000000 > R10: 00008400fffffffb R11: 0000000000000246 R12: 00000000006e4a2c > R13: 00007ffdc73a76df R14: 00007f5055f259c0 R15: 20c49ba5e353f7cf > Modules linked in: > ---[ end trace aba5fca59eda2183 ]--- > RIP: 0010:mpage_prepare_extent_to_map+0xd34/0xd40 fs/ext4/inode.c:2598 > Code: 89 e8 a0 74 9f ff 0f 0b e8 59 81 70 ff 4c 89 e7 48 c7 c6 da a3 07 89 e8 8a 74 9f ff 0f 0b e8 43 81 70 ff 0f 0b e8 3c 81 70 ff <0f> 0b e8 c5 b3 25 06 0f 1f 44 00 00 55 41 57 41 56 41 55 41 54 53 > RSP: 0018:ffffc9000a0974d8 EFLAGS: 00010293 > RAX: ffffffff820476e4 RBX: 00fffe000000a01f RCX: ffff88808ea5c340 > RDX: 0000000000000000 RSI: 000000000000a01f RDI: 000000000000ffff > RBP: ffffea00020d4f80 R08: ffffffff820471e4 R09: fffff9400041a9f1 > R10: fffff9400041a9f1 R11: 0000000000000000 R12: ffffea00020d4f80 > R13: ffffc9000a0977b0 R14: 1ffffd400041a9f1 R15: dffffc0000000000 > FS: 00007f5055f25700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000004ae4b0 CR3: 00000000a2d7f000 CR4: 00000000001506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
