diff options
| author | Robin Murphy <robin.murphy@arm.com> | 2018-12-10 14:00:30 +0000 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2018-12-11 14:31:18 +0100 |
| commit | ceb51173b2b5bd7af0d99079f6bbacdcfc58fe08 (patch) | |
| tree | bc9245f7e98c8e07a1d203d143da808330c244fd /Documentation/DMA-API.txt | |
| parent | 2b9d9ac02b9d8d32c515c82bb17401c429f160ab (diff) | |
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 'Documentation/DMA-API.txt')
| -rw-r--r-- | Documentation/DMA-API.txt | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 0fcb7561af1e..7a7d8a415ce8 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -747,7 +747,11 @@ driver afterwards. This filter can be disabled or changed later using debugfs. When the code disables itself at runtime this is most likely because it ran out of dma_debug_entries and was unable to allocate more on-demand. 65536 entries are preallocated at boot - if this is too low for you boot with -'dma_debug_entries=<your_desired_number>' to overwrite the default. +'dma_debug_entries=<your_desired_number>' to overwrite the default. The +code will print to the kernel log each time it has dynamically allocated +as many entries as were initially preallocated. This is to indicate that a +larger preallocation size may be appropriate, or if it happens continually +that a driver may be leaking mappings. :: |