On 29.09.21 12:10, Will Deacon wrote:
On Thu, Sep 23, 2021 at 03:54:48PM -0700, Chris Goldsworthy wrote:From: Sudarshan Rajagopalan <quic_sudaraja@xxxxxxxxxxx> After new memory blocks have been hotplugged, max_pfn and max_low_pfn needs updating to reflect on new PFNs being hot added to system. Signed-off-by: Sudarshan Rajagopalan <quic_sudaraja@xxxxxxxxxxx> Signed-off-by: Chris Goldsworthy <quic_cgoldswo@xxxxxxxxxxx> --- arch/arm64/mm/mmu.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index cfd9deb..fd85b51 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1499,6 +1499,11 @@ int arch_add_memory(int nid, u64 start, u64 size, if (ret) __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); + else { + max_pfn = PFN_UP(start + size); + max_low_pfn = max_pfn; + }We use 'max_pfn' as part of the argument to set_max_mapnr(). Does that need updating as well? Do we have sufficient locking to ensure nobody is looking at max_pfn or max_low_pfn while we update them?
Only the write side is protected by memory hotplug locking. The read side is lockless -- just like all of the other pfn_to_online_page() machinery.
Will
-- Thanks, David / dhildenb
