> For ordinary files the only way the VMA_MAYWRITE_BIT flag is cleared is if > the underlying file is itself read-only. > > This means that mprotect() cannot mark a shared mapping of a read-only file > as read/write, as doing so would violate the read only attribute, and > permit writes. > > In general, we do not want file systems to be able to do this for > read/write files. > > Doing so would violate fundamental user expectation of file attributes and > likely break userspace. > > However, drivers pose a tricky problem here - the /dev/xxx file may be > read/write but provide access to a resource which is fundamentally > [ ... ] > As no driver which clears VMA_MAYWRITE_BIT establishes an mm-managed > mapping, no functional change is intended. > > Acked-by: Zi Yan <[email protected]> > Signed-off-by: Lorenzo Stoakes (ARM) <[email protected]>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review ยท https://sashiko.dev/#/patchset/20261003-b4-mmap-prepare-vma-flag-sanify-v4-0-a1f052500...@kernel.org?part=15
