On Mon, Jul 28, 2014 at 10:14 PM, Will Deacon <[email protected]> wrote: > On Tue, Jul 22, 2014 at 04:36:35PM +0100, Konstantin Khlebnikov wrote: >> idmap layout combines both phisical and virtual addresses. >> Everything works fine if ram physically lays below PAGE_OFFSET. >> Otherwise idmap starts punching huge holes in virtual memory layout. >> It maps ram by 2MiB sections, but when it allocates new pmd page it >> cuts 1GiB at once. >> >> This patch makes a copy of all affected pmds from init_mm. >> Only few (usually one) 2MiB sections will be lost. >> This is not eliminates problem but makes it 512 times less likely. > > I'm struggling to understand your commit message, but making a problem `512 > times less likely' does sound like a bit of a hack to me. Can't we fix this > properly instead?
Yep, my comment sucks. Usually idmap looks like this: |0x00000000 -- <chunk of physical memory in identical mapping > --- | TASK_SIZE -- <kernel space vm layoyt> --- 0xFFFFFFFF | But when that physical memory chunk starts from 0xE8000000 or even 0xF2000000 evenything becomes very complicated. > > Will > > _______________________________________________ > linux-arm-kernel mailing list > [email protected] > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- 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/
