On Thu, 19 Jan 2023 at 08:05, YoungJun.Park <her0gyugyu@xxxxxxxxx> wrote: > > On Wed, Aug 31, 2022 at 11:58:50AM +0200, Miklos Szeredi wrote: > > On Tue, 30 Aug 2022 at 03:58, 박영준 <her0gyugyu@xxxxxxxxx> wrote: > > > > > > I found fuse livelock situation and report it for possibility of problem. > > > > > > [Environment] > > > 22.04 5.15.0-43-generic ubuntu kernel. > > > ntfs-3g version ntfs-3g 2021.8.22 integrated FUSE 28 - Third > > > Generation NTFS Driver > > > > > > [Problem] > > > I bumped on livelock and analyze it. and concluded that it is needed > > > to be fixed. > > > it happends when 3 operation concurrently progressing. > > > > > > 1) usb detach by user. and kernel detect it. > > > 2) mount.ntfs umount request & device release operation > > > 3) pool-udisksd umount operation. > > > > > > [Conclusion] > > > 1. mounted target device file must be released after /dev/fuse > > > release. it makes deadlocky scenario. > > > > Shouldn't this be reported to ntfs-3g developers then? > > > > Thanks, > > Miklos > > I reported it ntfs-3g and ubuntu bug report channel. > ntfs-3g does not respond and ubuntu bug report channel response it like below. > (If you want a detail scenario flow picture, calltack etc check the link > https://github.com/tuxera/ntfs-3g/issues/56) > > > Hi > > > Thanks for reporting this issue - in general it is better to report bugs > > via launchpad than email (e.g. by running the following command (without > > the quotation marks) in a terminal: "ubuntu-bug ntfs-3g" or by > > https://bugs.launchpad.net/ubuntu/+source/ntfs-3g/+filebug) > > > I notice you also appear to have reported this to the upstream nfts-3g > > project at https://github.com/tuxera/ntfs-3g/issues/56 but have had no > > response. > > > However, my initial thoughts when looking at this is that it appears you > > can trigger a livelock within the kernel from an unprivileged user in > > userspace - as such I wonder if this is a bug in the FUSE subsystem > > within the Linux kernel and hence whether it should be reported to the > > upstream kernel developers as well? As per > > https://www.kernel.org/doc/html/v4.15/admin-guide/reporting-bugs.html it > > would appear that this should be reported to the following email > > addresses (assuming this is a real kernel bug rather than a bug within > > the ntfs-3g userspace project): > > > $ ./scripts/get_maintainer.pl fs/fuse/fuse_i.h > > Miklos Szeredi <miklos@xxxxxxxxxx> (maintainer:FUSE: FILESYSTEM IN USERSPACE) > > linux-fsdevel@xxxxxxxxxxxxxxx (open list:FUSE: FILESYSTEM IN USERSPACE) > > linux-kernel@xxxxxxxxxxxxxxx (open list) > > > Thanks, > > Alex > > Could you explan why it shoulde be fixed in userspace? > then I try to fix this issue and to report it one more based on your comment. If the block device close is blocked, then ntfs-3g should reply to the DESTROY request before it tries to close the block device. Thanks, Miklos
