CVE-2026-89986mm/mempolicy: fix sleeping allocation in alloc_pages_bulk_weighted_interleave()

Official description

In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: fix sleeping allocation in alloc_pages_bulk_weighted_interleave() syzbot reported a sleeping function called from invalid context splat in bucket_table_alloc(). When rhashtable_insert_slow() rehashes the table under rcu_read_lock(), it calls bucket_table_alloc(..., GFP_ATOMIC | __GFP_NOWARN). If the bucket table allocation uses vmalloc, __vmalloc_node_range_noprof() invokes vm_area_alloc_pages() -> alloc_pages_bulk_mempolicy_noprof() with the passed GFP_ATOMIC flags. If the current task has an MPOL_WEIGHTED_INTERLEAVE mempolicy, alloc_pages_bulk_weighted_interleave() is called and currently hardcodes GFP_KERNEL when allocating the temporary weights array, triggering a might_alloc() splat in atomic/RCU contexts. Pass the gfp flags (masked with GFP_RECLAIM_MASK to strip page-allocator zone modifiers like __GFP_HIGHMEM) received by alloc_pages_bulk_weighted_interleave() to kmalloc() instead of hardcoding GFP_KERNEL. Since the weights buffer is immediately initialized in full, kmalloc() is sufficient.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/bcb3d0c867ee40dc48e9c085bf328fbc679b6656
• https://git.kernel.org/stable/c/0ceda28f371df9e0bbdaa29214f71fe8298f23d8
• https://git.kernel.org/stable/c/2943f1f4b7f2816177060eb9f551f2e6d8b629ba
• https://git.kernel.org/stable/c/540e583b66d6402bf556fde5e53c817a54c1afe5