The patch titled mmc: at91_mci: don't use coherent dma buffers has been added to the -mm tree. Its filename is at91_mci-dont-use-coherent-dma-buffers.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mmc: at91_mci: don't use coherent dma buffers From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> At91_mci is abusing dma_free_coherent(), which may not be called with IRQs disabled. I saw "mkfs.ext3" on an MMC card objecting voluminously as each write completed: WARNING: at arch/arm/mm/consistent.c:368 dma_free_coherent+0x2c/0x224() [<c002726c>] (dump_stack+0x0/0x14) from [<c00387d4>] (warn_on_slowpath+0x4c/0x68) [<c0038788>] (warn_on_slowpath+0x0/0x68) from [<c0028768>] (dma_free_coherent+0x2c/0x224) r6:00008008 r5:ffc06000 r4:00000000 [<c002873c>] (dma_free_coherent+0x0/0x224) from [<c01918ac>] (at91_mci_irq+0x374/0x420) [<c0191538>] (at91_mci_irq+0x0/0x420) from [<c0065d9c>] (handle_IRQ_event+0x2c/0x6c) ... This bug has been around for a LONG time. The MM warning is from late 2005, but the driver merged a year later ... so I'm puzzled why nobody noticed this before now. The fix involves noting that this buffer shouldn't be DMA-coherent; it's just used for normal DMA writes. So replace it with standard kmalloc() buffering and DMA mapping calls. This is the quickie fix. A better one would not rely on allocating large bounce buffers. (Note that dma_alloc_coherent could have failed too, but that case was ignored... kmalloc is a bit more likely to fail though.) Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> Cc: Pierre Ossman <drzeus-mmc@xxxxxxxxx> Cc: Andrew Victor <linux@xxxxxxxxxxxx> Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> Cc: Russell King <rmk@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/mmc/host/at91_mci.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff -puN drivers/mmc/host/at91_mci.c~at91_mci-dont-use-coherent-dma-buffers drivers/mmc/host/at91_mci.c --- a/drivers/mmc/host/at91_mci.c~at91_mci-dont-use-coherent-dma-buffers +++ a/drivers/mmc/host/at91_mci.c @@ -621,12 +621,21 @@ static void at91_mci_send_command(struct if (cpu_is_at91sam9260 () || cpu_is_at91sam9263()) if (host->total_length < 12) host->total_length = 12; - host->buffer = dma_alloc_coherent(NULL, - host->total_length, - &host->physical_address, GFP_KERNEL); + + host->buffer = kmalloc(host->total_length, GFP_KERNEL); + if (!host->buffer) { + pr_debug("Can't alloc tx buffer\n"); + cmd->error = -ENOMEM; + mmc_request_done(host->mmc, host->request); + return; + } at91_mci_sg_to_dma(host, data); + host->physical_address = dma_map_single(NULL, + host->buffer, host->total_length, + DMA_TO_DEVICE); + pr_debug("Transmitting %d bytes\n", host->total_length); at91_mci_write(host, ATMEL_PDC_TPR, host->physical_address); @@ -694,7 +703,10 @@ static void at91_mci_completed_command(s cmd->resp[3] = at91_mci_read(host, AT91_MCI_RSPR(3)); if (host->buffer) { - dma_free_coherent(NULL, host->total_length, host->buffer, host->physical_address); + dma_unmap_single(NULL, + host->physical_address, host->total_length, + DMA_TO_DEVICE); + kfree(host->buffer); host->buffer = NULL; } _ Patches currently in -mm which might be from dbrownell@xxxxxxxxxxxxxxxxxxxxx are linux-next.patch at91_mci-dont-use-coherent-dma-buffers.patch rtc-ds1307-alarm-support-for-ds1337-ds1339.patch rtc-remove-some-nop-open-release-methods.patch legacy-rtc-remove-needless-confusing-hpet_rtc_irq-option.patch rtc-file-close-consistently-disables-repeating-irqs.patch rtc-cmos-strongly-avoid-hpet-emulation.patch make-gpiochip-label-const.patch irq-warn-about-irqf_disabledirqf_shared.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html