On Tue, Mar 12, 2019 at 08:50:04AM +0800, Baoquan He wrote: > Restrict kdump to only reserve crashkernel below 64TB. Since the kdump > jumping may be from 5-level to 4-level, and the kdump kernel is put > above 64TB in 5-level kernel, then the jumping will fail. And the > crashkernel reservation is done during the 1st kernel bootup, there's > no way to detect the paging mode of kdump kernel at that time. > > Hence change the upper limit of crashkernel reservation to 64TB > on x86_64. > > Signed-off-by: Baoquan He <b...@redhat.com> > --- > arch/x86/kernel/setup.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 3d872a527cd9..d4d1366738a4 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -451,16 +451,26 @@ static void __init > memblock_x86_reserve_range_setup_data(void) > #define CRASH_ALIGN (16 << 20) > > /* > - * Keep the crash kernel below this limit. On 32 bits earlier kernels > - * would limit the kernel to the low 512 MiB due to mapping restrictions. > - * On 64bit, old kexec-tools need to under 896MiB. > + * Keep the crash kernel below this limit. > + * > + * On 32 bits earlier kernels would limit the kernel to the low > + * 512 MiB due to mapping restrictions. > + * > + * On 64bit, old kexec-tools need to be under 896MiB. The later > + * supports to put kernel above 4G, up to system RAM top. Here > + * kdump kernel need be restricted to be under 64TB, which is > + * the upper limit of system RAM in 4-level paing mode. Since > + * the kdump jumping could be from 5-level to 4-level, the jumping > + * will fail if kernel is put above 64TB, and there's no way to > + * detect the paging mode of the kernel which will be loaded for > + * dumping during the 1st kernel bootup. > */ > #ifdef CONFIG_X86_32 > # define CRASH_ADDR_LOW_MAX (512 << 20) > # define CRASH_ADDR_HIGH_MAX (512 << 20) > #else > # define CRASH_ADDR_LOW_MAX (896UL << 20) > -# define CRASH_ADDR_HIGH_MAX MAXMEM > +# define CRASH_ADDR_HIGH_MAX (1ULL < 46)
Maybe # define CRASH_ADDR_HIGH_MAX (64UL << 40) to match the notation for the rest of defines? Otherwise the patchset look good to me. You can use my ack for all of them: Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com> > #endif > > static int __init reserve_crashkernel_low(void) > -- > 2.17.2 > -- Kirill A. Shutemov
