On 23.12.21 10:44, Baoquan He wrote:
> Currently three dma atomic pools are initialized as long as the relevant
> kernel codes are built in. While in kdump kernel of x86_64, this is not
> right when trying to create atomic_pool_dma, because there's no managed
> pages in DMA zone. In the case, DMA zone only has low 1M memory presented
> and locked down by memblock allocator. So no pages are added into buddy
> of DMA zone. Please check commit f1d4d47c5851 ("x86/setup: Always reserve
> the first 1M of RAM").
>
> Then in kdump kernel of x86_64, it always prints below failure message:
>
> DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
> swapper/0: page allocation failure: order:5, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-0.rc5.20210611git929d931f2b40.42.fc35.x86_64 #1
> Hardware name: Dell Inc. PowerEdge R910/0P658H, BIOS 2.12.0 06/04/2018
> Call Trace:
> dump_stack+0x7f/0xa1
> warn_alloc.cold+0x72/0xd6
> ? _raw_spin_unlock_irq+0x24/0x40
> ? __alloc_pages_direct_compact+0x90/0x1b0
> __alloc_pages_slowpath.constprop.0+0xf29/0xf50
> ? __cond_resched+0x16/0x50
> ? prepare_alloc_pages.constprop.0+0x19d/0x1b0
> __alloc_pages+0x24d/0x2c0
> ? __dma_atomic_pool_init+0x93/0x93
> alloc_page_interleave+0x13/0xb0
> atomic_pool_expand+0x118/0x210
> ? __dma_atomic_pool_init+0x93/0x93
> __dma_atomic_pool_init+0x45/0x93
> dma_atomic_pool_init+0xdb/0x176
> do_one_initcall+0x67/0x320
> ? rcu_read_lock_sched_held+0x3f/0x80
> kernel_init_freeable+0x290/0x2dc
> ? rest_init+0x24f/0x24f
> kernel_init+0xa/0x111
> ret_from_fork+0x22/0x30
> Mem-Info:
> ......
> DMA: failed to allocate 128 KiB GFP_KERNEL|GFP_DMA pool for atomic allocation
> DMA: preallocated 128 KiB GFP_KERNEL|GFP_DMA32 pool for atomic allocations
>
> Here, let's check if DMA zone has managed pages, then create atomic_pool_dma
> if yes. Otherwise just skip it.
>
> Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Cc: Robin Murphy <robin.murphy@xxxxxxx>
> Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> ---
> kernel/dma/pool.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index 5a85804b5beb..00df3edd6c5d 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -206,7 +206,7 @@ static int __init dma_atomic_pool_init(void)
> GFP_KERNEL);
> if (!atomic_pool_kernel)
> ret = -ENOMEM;
> - if (IS_ENABLED(CONFIG_ZONE_DMA)) {
> + if (has_managed_dma()) {
> atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
> GFP_KERNEL | GFP_DMA);
> if (!atomic_pool_dma)
> @@ -229,7 +229,7 @@ static inline struct gen_pool *dma_guess_pool(struct gen_pool *prev, gfp_t gfp)
> if (prev == NULL) {
> if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32))
> return atomic_pool_dma32;
> - if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA))
> + if (atomic_pool_dma && (gfp & GFP_DMA))
> return atomic_pool_dma;
> return atomic_pool_kernel;
> }
I thought for a second that we might have to tweak
atomic_pool_work_fn(), but atomic_pool_resize() handles it properly already.
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
--
Thanks,
David / dhildenb
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