Hi Joanne, On Mon, Dec 15, 2025 at 06:37:42AM +0800, Joanne Koong wrote: > On Sun, Dec 14, 2025 at 10:27 PM Salvatore Bonaccorso <[email protected]> > wrote: > > > > Hi Joanne, > > > > In Debian J. Neuschäfer reported an issue where after 0c58a97f919c > > ("fuse: remove tmp folio for writebacks and internal rb tree") a > > specific, but admittely not very minimal workload, involving podman > > contains, x2goserver and a openjdk application restults in > > suspend-to-ram hang. > > > > The report is at https://bugs.debian.org/1120058 and information on > > bisection and the test setup follows: > > > > On Sun, Nov 30, 2025 at 02:11:13PM +0100, J. Neuschäfer wrote: > > > On Fri, Nov 28, 2025 at 09:10:25PM +0100, Salvatore Bonaccorso wrote: > > > > Control: found -1 6.17.8-1 > > > > > > > > Hi, > > > > > > > > On Fri, Nov 28, 2025 at 11:50:48AM +0100, J. Neuschäfer wrote: > > > > > On Wed, Nov 05, 2025 at 06:09:43AM +0100, Salvatore Bonaccorso wrote: > > > [...] > > > > > I can reproduce the bug fairly reliably on 6.16/17 by running a > > > > > specific > > > > > podman container plus x2go (not entirely sure which parts of this is > > > > > necessary). > > > > > > > > Okay if you have a very reliable way to reproduce it, would you be > > > > open to make "your hands bit dirty" and do some bisecting on the > > > > issue? > > > > > > Thank you for your detailed instructions! I've already started and > > > completed > > > the git bisect run in the meantime. I had to restart a few times due to > > > mistakes, but I was able to identify the following upstream commit as the > > > commit that introduced the issue: > > > > > > https://git.kernel.org/linus/0c58a97f919c24fe4245015f4375a39ff05665b6 > > > > > > fuse: remove tmp folio for writebacks and internal rb tree > > > > > > The relevant commit history is as follows: > > > > > > * 2619a6d413f4c3 Merge tag 'fuse-update-6.16' of > > > git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse <-- bad > > > |\ > > > | * dabb9039102879 fuse: increase readdir buffer size > > > | * 467e245d47e666 readdir: supply dir_context.count as readdir buffer > > > size hint > > > | * c31f91c6af96a5 fuse: don't allow signals to interrupt getdents > > > copying > > > | * f3cb8bd908c72e fuse: support large folios for writeback > > > | * 906354c87f4917 fuse: support large folios for readahead > > > | * ff7c3ee4842d87 fuse: support large folios for queued writes > > > | * c91440c89fbd9d fuse: support large folios for stores > > > | * cacc0645bcad3e fuse: support large folios for symlinks > > > | * 351a24eb48209b fuse: support large folios for folio reads > > > | * d60a6015e1a284 fuse: support large folios for writethrough writes > > > | * 63c69ad3d18a80 fuse: refactor fuse_fill_write_pages() > > > | * 3568a956932621 fuse: support large folios for retrieves > > > | * 394244b24fdd09 fuse: support copying large folios > > > | * f09222980d7751 fs: fuse: add dev id to /dev/fuse fdinfo > > > | * 18ee43c398af0b docs: filesystems: add fuse-passthrough.rst > > > | * 767c4b82715ad3 MAINTAINERS: update filter of FUSE documentation > > > | * 69efbff69f89c9 fuse: fix race between concurrent setattrs from > > > multiple nodes > > > | * 0c58a97f919c24 fuse: remove tmp folio for writebacks and internal > > > rb tree <-- first bad commit > > > | * 0c4f8ed498cea1 mm: skip folio reclaim in legacy memcg contexts for > > > deadlockable mappings > > > | * 4fea593e625cd5 fuse: optimize over-io-uring request expiration check > > > | * 03a3617f92c2a7 fuse: use boolean bit-fields in struct > > > fuse_copy_state > > > | * a5c4983bb90759 fuse: Convert 'write' to a bit-field in struct > > > fuse_copy_state > > > | * 2396356a945bb0 fuse: add more control over cache invalidation > > > behaviour > > > | * faa794dd2e17e7 fuse: Move prefaulting out of hot write path > > > | * 0486b1832dc386 fuse: change 'unsigned' to 'unsigned int' > > > * 0fb34422b5c223 Merge tag 'vfs-6.16-rc1.netfs' of > > > git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs <-- good > > > > > > The first and last commits shown are merge commits done by Linus > > > Torvalds. The > > > fuse-update branch was based on v6.15-rc1, under which I can't run my > > > test due > > > to an unrelated bug, so I ended up merging in 0fb34422b5c223 to test the > > > commits within the fuse-update branch. e.g.: > > > > > > git reset --hard 394244b24fdd09 && git merge 0fb34422b5c223 && make > > > clean && make > > > > > > > > > I have also verified that the issue still happens on v6.18-rc7 but I > > > wasn't > > > able to revert 0c58a97f919 on top of this release, because a trivial > > > revert > > > is not possible. > > > > > > My test case consists of a few parts: > > > > > > - A podman container based on the "debian:13" image (which points to > > > docker.io/library/debian via > > > /etc/containers/registries.conf.d/shortnames.conf), > > > where I installed x2goserver and a openjdk-21-based application; It > > > runs the > > > OpenSSH server and port 22 is exposed as localhost:2001 > > > - x2goclient to start a desktop session in the container > > > > > > Source code: https://codeberg.org/neuschaefer/re-workspace > > > > > > I suspect, but haven't verified, that the X server in the container > > > somehow > > > uses the FUSE-emulated filesystem in the container to create a file that > > > is > > > used with mmap (perhaps to create shared pages as frame buffers). > > > > > > > > > Raw bisect notes: > > > > > > good: > > > - v6.12.48+deb13-amd64 > > > - v6.12.59 > > > - v6.12 > > > - v6.14 > > > - v6.15-1304-g14418ddcc2c205 > > > - v6.15-10380-gec71f661a572 > > > - v6.15-10888-gb509c16e1d7cba > > > - v6.15-rc7-357-g8e86e73626527e > > > - v6.15-10933-g4c3b7df7844340 > > > - v6.15-10954-gd00a83477e7a8f > > > - v6.15-rc7-366-g438e22801b1958 (CONFIG_X86_5LEVEL=y) > > > - v6.15-rc4-126-g07212d16adc7a0 > > > - v6.15-10958-gdf7b9b4f6bfeb1 <-- first parent, 5LEVEL doesn't exist > > > - v6.15-rc4-00127-g4d62121ce9b5 > > > - v6.15-rc7-375-g61374cc145f4a5 <-- second parent, `X86_5LEVEL=y` > > > - v6.15-rc7-375-g61374cc145f4a5 <-- second parent, `X86_5LEVEL=n` > > > - v6.15-11061-g7f9039c524a351: "first bad", actually good. merge of > > > df7b9b4f6bfeb1 61374cc145f4a5 > > > - v6.15-11093-g0fb34422b5c223 > > > - v6.15-rc1-7-g0c4f8ed498cea1 + merge = v6.15-11101-gaec20ffad33068 > > > > > > testing: > > > - v6.18-rc7 + revert: doesn't apply > > > > > > weird (ssh doesn't work): > > > - v6.15-rc1-1-g0486b1832dc386 > > > - v6.15-rc1-10-g767c4b82715ad3 > > > - v6.15-rc1-13-g394244b24fdd09: folio stuff > > > - v6.15-rc1-22-gf3cb8bd908c72e > > > - v6.15-rc1-23-gc31f91c6af96a5 > > > - next-20251128 > > > > > > bad: > > > - v6.15-rc1-8-g0c58a97f919c24 + merge = v6.15-11102-gdfc4869c8ef1f0 > > > first bad commit > > > - v6.15-rc1-9-g69efbff69f89c9 + merge = v6.15-11103-ga7b103c57680ce > > > - v6.15-rc1-11-g18ee43c398af0b + merge = v6.15-11105-g4ad0d4fa61974c > > > - v6.15-rc1-13-g394244b24fdd09 + merge = v6.15-11107-g37da056b3b873b > > > - v6.15-11119-g2619a6d413f4c3: merge of 0fb34422b5c223 (last good) > > > dabb9039102879 (fuse branch) > > > - v6.15-11165-gfd1f8473503e5b: confirmed bad > > > - v6.15-11401-g69352bd52b2667 > > > - v6.15-12422-g2c7e4a2663a1ab > > > - regulator-fix-v6.16-rc2-372-g5c00eca95a9a20 > > > - v6.16.12 > > > - v6.16.12 again > > > - v6.16.12+deb14+1-amd64 > > > - v6.18-rc7 > > > > Would that ring some bells to you which make this tackable? > > Hi Salvatore, > > This looks like the same issue reported in this thread [1]. The lockup > occurs when there's a faulty fuse server on the system that doesn't > complete a write request. Prior to commit 0c58a97f919c24 ("fuse: > remove tmp folio for writebacks and internal rb tree"), syncs on fuse > filesystems were effectively no-ops. This patch upstream [2] reverts > the behavior back to that. I'll send v2 of that patch and work on > getting it merged as soon as possible.
Do you know did that felt trough the cracks or is it just delayed because of vacation/holiday times? Regards, Salvatore
