On Wed, 13 Aug 2025 15:04:54 +0900, Dominique Martinet wrote:
So we've had this regression in 9p for.. almost a year, which is way too long, but there was no "easy" reproducer until yesterday (thank you again!!)
It turned out to be a bug with iov_iter on folios, iov_iter_get_pages_alloc2() would advance the iov_iter correctly up to the end edge of a folio and the later copy_to_iter() fails on the iterate_folioq() bug.
[...]
Applied to the vfs.fixes branch of the vfs/vfs.git tree. Patches in the vfs.fixes branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs.fixes
[1/2] iov_iter: iterate_folioq: fix handling of offset >= folio size https://git.kernel.org/vfs/vfs/c/546a40359fd2 [2/2] iov_iter: iov_folioq_get_pages: don't leave empty slot behind https://git.kernel.org/vfs/vfs/c/334430b2d585