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dma-mapping fix for Linux 6.11

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- avoid a deadlock with dma-debug and netconsole (Rik van Riel)
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Merge tag 'dma-mapping-6.11-2024-08-10' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping fix from Christoph Hellwig:

 - avoid a deadlock with dma-debug and netconsole (Rik van Riel)

* tag 'dma-mapping-6.11-2024-08-10' of git://git.infradead.org/users/hch/dma-mapping:
  dma-debug: avoid deadlock between dma debug vs printk and netconsole
This commit is contained in:
Linus Torvalds 2024-08-10 10:19:05 -07:00
commit 0409cc53c4
1 changed files with 4 additions and 1 deletions
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5
kernel/dma/debug.c
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@ -416,8 +416,11 @@ static unsigned long long phys_addr(struct dma_debug_entry *entry)
* dma_active_cacheline entry to track per event. dma_map_sg(), on the
* other hand, consumes a single dma_debug_entry, but inserts 'nents'
* entries into the tree.
*
* Use __GFP_NOWARN because the printk from an OOM, to netconsole, could end
* up right back in the DMA debugging code, leading to a deadlock.
*/
static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC);
static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC | __GFP_NOWARN);
static DEFINE_SPINLOCK(radix_lock);
#define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1)
#define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT)