On Fri, Dec 06, 2024 at 09:28:46PM +0000, Lorenzo Stoakes wrote:
> We no longer actually need to perform these checks in the f_op->mmap() hook
> any longer.
>
> We already moved the operation which clears VM_MAYWRITE on a read-only
> mapping of a write-sealed memfd in order to work around the restrictions
> imposed by commit 5de195060b2e ("mm: resolve faulty mmap_region() error
> path behaviour").
>
> There is no reason for us not to simply go ahead and additionally check to
> see if any pre-existing seals are in place here rather than defer this to
> the f_op->mmap() hook.
>
> By doing this we remove more logic from shmem_mmap() which doesn't belong
> there, as well as doing the same for hugetlbfs_file_mmap(). We also remove
> dubious shared logic in mm.h which simply does not belong there either.
>
> It makes sense to do these checks at the earliest opportunity, we know
> these are shmem (or hugetlbfs) mappings whose relevant VMA flags will not
> change from the invoking do_mmap() so there is simply no need to wait.
>
> This also means the implementation of further memfd seal flags can be done
> within mm/memfd.c and also have the opportunity to modify VMA flags as
> necessary early in the mapping logic.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Hi Andrew,
I made a rather silly typo in this patch which resulted in me failing to
mark a static inline as such and therefore, the build bots got very cross
with me :)
Apologies to all for the noise!
Could you apply the enclosed fix-patch to resolve this?
Thanks, Lorenzo
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