Re: [PATCH v2 01/40] mm/vma: fix mmap_prepare file handling, remove file_doesnt_need_get
From: sashiko-bot@kernel.org
Date: 2026-09-14 15:40:22
Also in:
bpf, dri-devel, kvm, kvmarm, linux-perf-users, linux-rdma, linux-s390, linux-scsi, selinux
The map->file_doesnt_need_get flag is confusing and the existing implementation has holes. Drivers are permitted to change the owning file of a mapping. If they do so, they are required to take a reference on that file. The mmap() operation which ultimately invokes __mmap_region() is guaranteed to drop the refcount for the original file the mapping was made under, but this is not true for the replaced file. This has been addressed so far by tracking map->file_doesnt_need_get, which is rather poorly named and unfortunately fails to correctly track whether or not an additional put were needed in a number of cases. Make life easier by removing this flag, and instead drop the reference for [ ... ] No in-tree driver is impacted by the incorrect implementation of this currently (no driver that does this is mergeable for one), so this does not need to be a fix. Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review · https://sashiko.dev/#/patchset/20260914-b4-mmap-prepare-vma-flag-sanify-v2-0-7d9781ed5361@kernel.org?part=1