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dma/pool: distinguish between missing and exhausted atomic pools

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Currently, dma_alloc_from_pool() unconditionally warns and dumps a stack
trace when an allocation fails, with the message "Failed to get suitable
pool".

This conflates two distinct failure modes:
1. Configuration error: No atomic pool is available for the requested
   DMA mask (a fundamental system setup issue)
2. Resource Exhaustion: A suitable pool exists but is currently full (a
   recoverable runtime state)

This lack of distinction prevents drivers from using __GFP_NOWARN to
suppress error messages during temporary pressure spikes, such as when
awaiting synchronous reclaim of descriptors.

Refactor the error handling to distinguish these cases:
- If no suitable pool is found, keep the unconditional WARN regarding
  the missing pool.
- If a pool was found but is exhausted, respect __GFP_NOWARN and update
  the warning message to explicitly state "DMA pool exhausted".

Fixes: 9420139f51 ("dma-pool: fix coherent pool allocations for IOMMU mappings")
Signed-off-by: Sai Sree Kartheek Adivi <s-adivi@ti.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20260128133554.3056582-1-s-adivi@ti.com
This commit is contained in:
Sai Sree Kartheek Adivi 2026-01-28 19:05:54 +05:30 • committed by Marek Szyprowski
parent 0fd17e5983
commit 56c430c7f0
1 changed files with 6 additions and 1 deletions
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7
kernel/dma/pool.c
View file

@ -277,15 +277,20 @@ struct page *dma_alloc_from_pool(struct device *dev, size_t size,
{
struct gen_pool *pool = NULL;
struct page *page;
bool pool_found = false;
while ((pool = dma_guess_pool(pool, gfp))) {
pool_found = true;
page = __dma_alloc_from_pool(dev, size, pool, cpu_addr,
phys_addr_ok);
if (page)
return page;
}
WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
if (pool_found)
WARN(!(gfp & __GFP_NOWARN), "DMA pool exhausted for %s\n", dev_name(dev));
else
WARN(1, "Failed to get suitable pool for %s\n", dev_name(dev));
return NULL;
}