On Fri, 5 Dec 2014, Sebastian Andrzej Siewior wrote: > the following error pops up during "testusb -a -t 10" > | musb-hdrc musb-hdrc.1.auto: dma_pool_free buffer-128, f134e000/be842000 (bad dma) > hcd_buffer_create() creates a few buffers, the smallest has 32 bytes of > size. ARCH_KMALLOC_MINALIGN is set to 64 bytes. This combo results in > hcd_buffer_alloc() returning memory which is 32 bytes aligned and it > might by identified by buffer_offset() as another buffer. This means the > buffer which is on a 32 byte boundary will not get freed, instead it > tries to free another buffer with the error message. > > This patch fixes the issue by creating the smallest DMA buffer with the > size of ARCH_KMALLOC_MINALIGN (or 32 in case ARCH_KMALLOC_MINALIGN is > smaller). This might be 32, 64 or even 128 bytes. The next three pools > will have the size 128, 512 and 2048. > In case the smallest pool is 128 bytes then we have only three pools > instead of four (and zero the first entry in the array). > The last pool size is always 2048 bytes which is the assumed PAGE_SIZE / > 2 of 4096. I doubt it makes sense to continue using PAGE_SIZE / 2 where > we would end up with 8KiB buffer in case we have 16KiB pages. > Instead I think it makes sense to have a common size(s) and extend them > if there is need to. > There is a BUILD_BUG_ON() now in case someone has a minalign of more than > 128 bytes. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > --- > v3…v4: rewrite as suggested per Alan Stern so it is less confusing. Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
