Re: [PATCH mm] mm: fix BUG with kvzalloc+GFP_ATOMIC

From: Michal Hocko
Date: Fri Sep 23 2022 - 09:29:36 EST


On Fri 23-09-22 12:38:58, Florian Westphal wrote:
> Martin Zaharinov reports BUG() in mm land for 5.19.10 kernel:
> kernel BUG at mm/vmalloc.c:2437!
> invalid opcode: 0000 [#1] SMP
> CPU: 28 PID: 0 Comm: swapper/28 Tainted: G W O 5.19.9 #1
> [..]
> RIP: 0010:__get_vm_area_node+0x120/0x130
> __vmalloc_node_range+0x96/0x1e0
> kvmalloc_node+0x92/0xb0
> bucket_table_alloc.isra.0+0x47/0x140
> rhashtable_try_insert+0x3a4/0x440
> rhashtable_insert_slow+0x1b/0x30
> [..]
>
> bucket_table_alloc uses kvzallocGPF_ATOMIC). If kmalloc fails, this now
> falls through to vmalloc and hits code paths that assume GFP_KERNEL.
>
> Revert the problematic change and stay with slab allocator.

Why don't you simply fix the caller?
--
Michal Hocko
SUSE Labs