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dma-mapping: warn when coherent pool is depleted

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When a DMA coherent pool is depleted, allocation failures may or may not
get reported in the kernel log depending on the allocator.

The admin does have a workaround, however, by using coherent_pool= on the
kernel command line.

Provide some guidance on the failure and a recommended minimum size for
the pools (double the size).

Signed-off-by: David Rientjes <rientjes@google.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
David Rientjes 2020-06-21 13:43:02 -07:00 committed by Christoph Hellwig
parent 9ebcfadb06
commit 71cdec4fab
1 changed files with 5 additions and 1 deletions
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6
kernel/dma/pool.c
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@ -239,12 +239,16 @@ void *dma_alloc_from_pool(struct device *dev, size_t size,
}
val = gen_pool_alloc(pool, size);
if (val) {
if (likely(val)) {
phys_addr_t phys = gen_pool_virt_to_phys(pool, val);
*ret_page = pfn_to_page(__phys_to_pfn(phys));
ptr = (void *)val;
memset(ptr, 0, size);
} else {
WARN_ONCE(1, "DMA coherent pool depleted, increase size "
"(recommended min coherent_pool=%zuK)\n",
gen_pool_size(pool) >> 9);
}
if (gen_pool_avail(pool) < atomic_pool_size)
schedule_work(&atomic_pool_work);