[PATCH RESEND v2 5/5] mm/slub: do not create dma-kmalloc if no managed pages in DMA zone

Baoquan He
2021-12-07T03:08:41Z

Dma-kmalloc will be created as long as CONFIG_ZONE_DMA is enabled.
However, it will fail if DMA zone has no managed pages. The failure
can be seen in kdump kernel of x86_64 as below:

kworker/u2:2: page allocation failure: order:0, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 0 PID: 36 Comm: kworker/u2:2 Not tainted 5.16.0-rc3+ #6
Hardware name: Dell Inc. PowerEdge R815/06JC9T, BIOS 3.2.2 09/15/2014
Workqueue: events_unbound async_run_entry_fn
Call Trace:
dump_stack_lvl+0x57/0x72
warn_alloc.cold+0x72/0xd6
__alloc_pages_slowpath.constprop.0+0xf56/0xf70
__alloc_pages+0x23b/0x2b0
allocate_slab+0x406/0x630
___slab_alloc+0x4b1/0x7e0
? sr_probe+0x200/0x600
? lock_acquire+0xc4/0x2e0
? fs_reclaim_acquire+0x4d/0xe0
? lock_is_held_type+0xa7/0x120
? sr_probe+0x200/0x600
? __slab_alloc+0x67/0x90
__slab_alloc+0x67/0x90
? sr_probe+0x200/0x600
? sr_probe+0x200/0x600
kmem_cache_alloc_trace+0x259/0x270
sr_probe+0x200/0x600
......
bus_probe_device+0x9f/0xb0
device_add+0x3d2/0x970
......
__scsi_add_device+0xea/0x100
ata_scsi_scan_host+0x97/0x1d0
async_run_entry_fn+0x30/0x130
process_one_work+0x2b0/0x5c0
worker_thread+0x55/0x3c0
? process_one_work+0x5c0/0x5c0
kthread+0x149/0x170
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
Mem-Info:
......

The above failure happened when calling kmalloc() to allocate buffer with
GFP_DMA. It requests to allocate slab page from DMA zone while no managed
pages in there.
sr_probe()
--> get_capabilities()
--> buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);

The DMA zone should be checked if it has managed pages, then try to create
dma-kmalloc.

Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
---
mm/slab_common.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index e5d080a93009..ae4ef0f8903a 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -878,6 +878,9 @@ void __init create_kmalloc_caches(slab_flags_t flags)
{
int i;
enum kmalloc_cache_type type;
+#ifdef CONFIG_ZONE_DMA
+ bool managed_dma;
+#endif

/*
* Including KMALLOC_CGROUP if CONFIG_MEMCG_KMEM defined
@@ -905,10 +908,16 @@ void __init create_kmalloc_caches(slab_flags_t flags)
slab_state = UP;

#ifdef CONFIG_ZONE_DMA
+ managed_dma = has_managed_dma();
+
for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[KMALLOC_NORMAL][i];

if (s) {
+ if (!managed_dma) {
+ kmalloc_caches[KMALLOC_DMA][i] = kmalloc_caches[KMALLOC_NORMAL][i];
+ continue;
+ }
kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(
kmalloc_info[i].name[KMALLOC_DMA],
kmalloc_info[i].size,
--
2.17.2