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 Best regards, J. Neuschäfer
