Hi Sasha,
On 20.04.22 17:49, Sasha Levin wrote:
On Wed, Apr 20, 2022 at 05:43:41AM -0700, Georgi Djakov wrote:
From: Anshuman Khandual anshuman.khandual@arm.com
[ Upstream commit 3de360c3fdb34fbdbaf6da3af94367d3fded95d3 ]
CONFIG_SPARSEMEM_VMEMMAP is now the only available memory model on arm64 platforms and free_unused_memmap() would just return without creating any holes in the memmap mapping. There is no need for any special handling in pfn_valid() and HAVE_ARCH_PFN_VALID can just be dropped. This also moves the pfn upper bits sanity check into generic pfn_valid().
It's not clear why we need this patch in stable.
I added a Link: tag, pointing to the discussion where the problem is explained in details and the suggestion to backport these patches to 5.15. But probably this is not enough and i should have mentioned it in the commit message too.
So in short: This is fixing a crash on systems where the RAM base address is not aligned to the pageblock size. Only v5.15 is affected.
Fixes: 859a85ddf90e ("mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE") Link: https://lore.kernel.org/r/Yl0IZWT2nsiYtqBT@linux.ibm.com
Thanks, Georgi