Hi Pavel, On Fri, Oct 13, 2017 at 11:09:41AM -0400, Pavel Tatashin wrote: > > It shouldn't be difficult to use section mappings with my patch, I just > > don't really see the need to try to optimise TLB pressure when you're > > running with KASAN enabled which already has something like a 3x slowdown > > afaik. If it ends up being a big deal, we can always do that later, but > > my main aim here is to divorce kasan from vmemmap because they should be > > completely unrelated. > > Yes, I understand that kasan makes system slow, but my point is why > make it even slower? However, I am OK adding your patch to the series, > BTW, symmetric changes will be needed for x86 as well sometime later. > > > > > This certainly doesn't sound right; mapping the shadow with pages shouldn't > > lead to problems. I also can't seem to reproduce this myself -- could you > > share your full .config and a pointer to the git tree that you're using, > > please? > > Config is attached. I am using my patch series + your patch + today's > clone from https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git Great, I hit the same problem with your .config. It might actually be CONFIG_DEBUG_MEMORY_INIT which does it. > Also, in a separate e-mail i sent out the qemu arguments. > > > > >> I feel, this patch requires more work, and I am troubled with using > >> base pages instead of large pages. > > > > I'm happy to try fixing this, because I think splitting up kasan and vmemmap > > is the right thing to do here. > > Thank you very much. Thanks for sharing the .config and tree. It looks like the problem is that kimg_shadow_start and kimg_shadow_end are not page-aligned. Whilst I fix them up in kasan_map_populate, they remain unaligned when passed to kasan_populate_zero_shadow, which confuses the loop termination conditions in e.g. zero_pte_populate and the shadow isn't configured properly. Fixup diff below; please merge in with my original patch. Will --->8 diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index b922826d9908..207b1acb823a 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -146,7 +146,7 @@ asmlinkage void __init kasan_early_init(void) static void __init kasan_map_populate(unsigned long start, unsigned long end, int node) { - kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false); + kasan_pgd_populate(start, end, node, false); } /* @@ -183,8 +183,8 @@ void __init kasan_init(void) struct memblock_region *reg; int i; - kimg_shadow_start = (u64)kasan_mem_to_shadow(_text); - kimg_shadow_end = (u64)kasan_mem_to_shadow(_end); + kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK; + kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end)); mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
