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authorRobin Murphy <robin.murphy@arm.com>2018-12-10 14:00:30 +0000
committerChristoph Hellwig <hch@lst.de>2018-12-11 14:31:18 +0100
commitceb51173b2b5bd7af0d99079f6bbacdcfc58fe08 (patch)
treebc9245f7e98c8e07a1d203d143da808330c244fd /kernel/dma
parent2b9d9ac02b9d8d32c515c82bb17401c429f160ab (diff)
downloadlinux-ceb51173b2b5bd7af0d99079f6bbacdcfc58fe08.tar.bz2
dma-debug: Make leak-like behaviour apparent
Now that we can dynamically allocate DMA debug entries to cope with drivers maintaining excessively large numbers of live mappings, a driver which *does* actually have a bug leaking mappings (and is not unloaded) will no longer trigger the "DMA-API: debugging out of memory - disabling" message until it gets to actual kernel OOM conditions, which means it could go unnoticed for a while. To that end, let's inform the user each time the pool has grown to a multiple of its initial size, which should make it apparent that they either have a leak or might want to increase the preallocation size. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Tested-by: Qian Cai <cai@lca.pw> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'kernel/dma')
-rw-r--r--kernel/dma/debug.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index ef7c90b7a346..912c23f4c177 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -691,6 +691,18 @@ static struct dma_debug_entry *__dma_entry_alloc(void)
return entry;
}
+void __dma_entry_alloc_check_leak(void)
+{
+ u32 tmp = nr_total_entries % nr_prealloc_entries;
+
+ /* Shout each time we tick over some multiple of the initial pool */
+ if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) {
+ pr_info("dma_debug_entry pool grown to %u (%u00%%)\n",
+ nr_total_entries,
+ (nr_total_entries / nr_prealloc_entries));
+ }
+}
+
/* struct dma_entry allocator
*
* The next two functions implement the allocator for
@@ -710,6 +722,7 @@ static struct dma_debug_entry *dma_entry_alloc(void)
pr_err("debugging out of memory - disabling\n");
return NULL;
}
+ __dma_entry_alloc_check_leak();
}
entry = __dma_entry_alloc();