Re: [PATCH v4 2/9] mm: add atomic VMA flags and set VM_MAYBE_GUARD as such

On 18.11.25 11:17, Lorenzo Stoakes wrote:

This patch adds the ability to atomically set VMA flags with only the mmap read/VMA read lock held.

As this could be hugely problematic for VMA flags in general given that all other accesses are non-atomic and serialised by the mmap/VMA locks, we implement this with a strict allow-list - that is, only designated flags are allowed to do this.

We make VM_MAYBE_GUARD one of these flags.

Signed-off-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Pedro Falcato pfalcato@suse.de Reviewed-by: Vlastimil Babka vbabka@suse.cz

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IIUC all other flag modifications need a write lock, so this should just work.

Acked-by: David Hildenbrand (Red Hat) david@kernel.org