Messages in this thread | | | Date | Sat, 20 Mar 2004 16:06:21 +0100 | From | Andrea Arcangeli <> | Subject | Re: can device drivers return non-ram via vm_ops->nopage? |
| |
On Sat, Mar 20, 2004 at 06:40:22AM -0800, William Lee Irwin III wrote: > On Sat, Mar 20, 2004 at 02:30:25PM +0100, Andrea Arcangeli wrote: > > Anyways returning to the non-ram returned by ->nopage see the below > > email exchange with Jens. the bug triggering of course is the > > BUG_ON(!pfn_valid(page_to_pfn(new_page))). > > If we want to return non-ram, we could, but I believe we should change > > the API to return a pfn not a page_t * if we want to. > > This would be very helpful for other reasons also. There's a general > API issue with drivers that want or need to do this. The one I've
I'm afraid I'll have to teach ->nopage how to deal with non-ram with this page_t API too (changing it to pfn sounds too intrusive in the short term), it seems to me that alsa can return non-ram (in the nopage callback there's a virt_to_page on some iomm region), and changing alsa to use remap_file_pages sounds too intrusive too.
So in short I believe alsa can corrupt memory randomly starting with 2.6.5-rc1, and it could only generate machine check crashes in previous kernels.
So for the short term (i.e. next few weeks) we'll have to deal with page_t still there... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |