On Sun, Sep 03, 2023 at 10:33:57AM +0200, Mateusz Guzik wrote: > On Sun, Sep 03, 2023 at 03:25:28PM +1000, Dave Chinner wrote: > > On Sat, Sep 02, 2023 at 09:11:34PM -0700, syzbot wrote: > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: b97d64c72259 Merge tag '6.6-rc-smb3-client-fixes-part1' of.. > > > git tree: upstream > > > console output: https://syzkaller.appspot.com/x/log.txt?x=14136d8fa80000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=958c1fdc38118172 > > > dashboard link: https://syzkaller.appspot.com/bug?extid=e245f0516ee625aaa412 > > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Been happening for months, apparently, yet for some reason it now > > thinks a locking hang in __fdget_pos() is an XFS issue? > > > > #syz set subsystems: fs > > > > The report does not have info necessary to figure this out -- no > backtrace for whichever thread which holds f_pos_lock. I clicked on a > bunch of other reports and it is the same story. > > Can the kernel be configured to dump backtraces from *all* threads? > > If there is no feature like that I can hack it up. <break>t over serial console, or echo t >/proc/sysrq-trigger would do it... "Locking hang in __fdget_pos()" would mean either something stuck inside ->read/->write/->read_iter/->write_iter/->llseek instance, making any further syscalls in that bunch on the same open file to block, or a lost fdput_pos() somewhere; AFAICS, we don't have anything of the latter variety, but the former is too wide to tell anything useful.
