Am Dienstag, 27. November 2018, 17:06:34 CET schrieb Richard Genoud:
The leak was found when opening/closing a serial port a great number of time, increasing kmalloc-32 in slabinfo.
Each time the port was opened, dma_request_slave_channel() was called. Then, in at_dma_xlate(), atslave was allocated with devm_kzalloc() and never freed. (Well, it was free at module unload, but that's not what we want). So, here, kzalloc is more suited for the job since it has to be freed in atc_free_chan_resources().
Cc: stable@vger.kernel.org Fixes: bbe89c8e3d59 ("at_hdmac: move to generic DMA binding") Reported-by: Mario Forner m.forner@be4energy.com Suggested-by: Alexandre Belloni alexandre.belloni@bootlin.com Acked-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Richard Genoud richard.genoud@gmail.com
After testing I installed an updated kernel on a production machine, which worked fine. The memory leak has been repaired successfully. There have been no adverse side-effects.
Thank you for providing the patch.
drivers/dma/at_hdmac.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index 7cbac6e8c113..1b7f0ca0d5cd 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -1641,6 +1641,12 @@ static void atc_free_chan_resources(struct dma_chan *chan) atchan->descs_allocated = 0; atchan->status = 0;
- /*
* Free atslave allocated in at_dma_xlate()*/- kfree(chan->private);
- chan->private = NULL;
- dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
} @@ -1675,7 +1681,7 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec, dma_cap_zero(mask); dma_cap_set(DMA_SLAVE, mask);
- atslave = devm_kzalloc(&dmac_pdev->dev, sizeof(*atslave), GFP_KERNEL);
- atslave = kzalloc(sizeof(*atslave), GFP_KERNEL); if (!atslave) return NULL;