Re: [PATCH v3] vmalloc: Fix accounting with i915

On Wed, Dec 11, 2024 at 08:25:37PM +0000, Matthew Wilcox (Oracle) wrote:

If the caller of vmap() specifies VM_MAP_PUT_PAGES (currently only the i915 driver), we will decrement nr_vmalloc_pages and MEMCG_VMALLOC in vfree(). These counters are incremented by vmalloc() but not by vmap() so this will cause an underflow. Check the VM_MAP_PUT_PAGES flag before decrementing either counter.

Fixes: b944afc9d64d (mm: add a VM_MAP_PUT_PAGES flag for vmap) Cc: stable@vger.kernel.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Acked-by: Johannes Weiner hannes@cmpxchg.org

Nice, thanks, looks good to me.