On 14/12/13 08:32, Andrew Morton wrote: > On Thu, 12 Dec 2013 12:50:47 +0000 David Vrabel <[email protected]> > wrote: > >>> each time. But that would require difficult tuning of N. >>> >>> I suppose we could just do >>> >>> if (!in_interrupt()) >>> cond_resched(); >>> >>> in vunmap_pmd_range(), but that's pretty specific to ghes.c and doesn't >>> permit unmap-inside-spinlock. >>> >>> So I can't immediately think of a suitable fix apart from adding a new >>> unmap_kernel_range_atomic(). Then add a `bool atomic' arg to >>> vunmap_page_range() and pass that all the way down. >> >> That would work for the unmap, but looking at the GHES driver some more >> and it looks like it's call to ioremap_page_range() is already unsafe -- >> it may need to allocate a new PTE page with a non-atomic alloc in >> pte_alloc_one_kernel(). >> >> Perhaps what's needed here is a pair of ioremap_page_atomic() and >> iounmap_page_atomic() calls? With some prep function to sure the PTE >> pages (etc.) are preallocated. > > Is ghes.c the only problem source here? If so then a suitable solution > would be to declare that driver hopelessly busted and proceed as if it > didn't exist :(
All the other callers do so from non-atomic context. ghes.c is the only broken caller. Shall I resend or are you happy to take the patch off the first email in this thread? David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
