Re: [locking/lockdep] 4051a81774: page_allocation_failure:order:#,mode:#(GFP_KERNEL),nodemask=(null)

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2022-06-21 17:27:22 [+0200], Jinpu Wang wrote:
> Hi, there
Hi,

> > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> > >
> > …
> > > [   17.451787][    T1] rtrs_server L2256: Loading module rtrs_server, proto 2.0: (max_chunk_size: 131072 (pure IO 126976, headers 4096) , sess_queue_depth: 512, always_invalidate: 1)
> > > [   17.470894][    T1] swapper: page allocation failure: order:5, mode:0xcc0(GFP_KERNEL), nodemask=(null)
> >
> > If I read this right, it allocates "512 * 10" chunks of order 5 / 128KiB
> > of memory (contiguous memory). And this appears to fail.
> > This is either a lot of memory or something that shouldn't be used on
> > i386.
> It allocates 512 * 128 KiB of memory, which is probably to big for
> this VM setup.

why 512 * 128KiB? It is:
|         chunk_pool = mempool_create_page_pool(sess_queue_depth * CHUNK_POOL_SZ,
|                                               get_order(max_chunk_size));
with
| static int __read_mostly max_chunk_size = DEFAULT_MAX_CHUNK_SIZE;
| static int __read_mostly sess_queue_depth = DEFAULT_SESS_QUEUE_DEPTH;
| #define CHUNK_POOL_SZ 10

so isn't it (512 * 10) * 128KiB?

> Thanks!

Sebastian