On 11/5/2025 9:04 PM, Heiko Carstens wrote:
On Tue, Oct 14, 2025 at 08:49:10AM +0200, Thomas Weißschuh wrote:
Allocating the datapages as part of the kernel image does not work on SPARC. It is also problematic with regards to dcache aliasing as there is no guarantee that the virtual addresses used by the kernel are compatible with those used by userspace.
Allocate the data pages through the page allocator instead. Unused pages in the vDSO VMA are still allocated to keep the virtual addresses aligned.
These pages are used by both the timekeeping, random pool and architecture initialization code. Introduce a new early initialization step, to make sure they are available when needed.
Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Tested-by: Andreas Larsson andreas@gaisler.com Reviewed-by: Andreas Larsson andreas@gaisler.com
include/linux/vdso_datastore.h | 6 ++++++ init/main.c | 2 ++ lib/vdso/datastore.c | 44 ++++++++++++++++++++++-------------------- 3 files changed, 31 insertions(+), 21 deletions(-)
...
+void __init vdso_setup_data_pages(void) +{
- unsigned int order = get_order(VDSO_NR_PAGES * PAGE_SIZE);
- struct folio *folio = folio_alloc(GFP_KERNEL, order);
I'm seeing random hangs on s390 too with our CI, but unfortunately I cannot reproduce it manually. But looking at one of the dumps it looks to me like the vdso time page contains (more or less) random junk at the end. Or in other words, shouldn't this be:
struct folio *folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, order);
? At least that is a difference to before as far as I can tell.
I was also hitting random hangs with an x86 KVM guest boot on an AMD64 platform. The bisection landed on this commit as the culprit. I see that v5 has been posted. I am in the process of testing that version and will reply to the v5 thread with the results.
Thank you Srikanth Aithal sraithal@amd.com