On 01/02/2019 19:46, Boris Ostrovsky wrote: > On 1/30/19 3:22 AM, Juergen Gross wrote: >> Don't allow memory to be added above the allowed maximum allocation >> limit set by Xen. >> >> Trying to do so would result in cases like the following: >> >> [ 584.559652] ------------[ cut here ]------------ >> [ 584.564897] WARNING: CPU: 2 PID: 1 at ../arch/x86/xen/multicalls.c:129 >> xen_alloc_pte+0x1c7/0x390() >> [ 584.575151] Modules linked in: >> [ 584.578643] Supported: Yes >> [ 584.581750] CPU: 2 PID: 1 Comm: swapper/0 Not tainted >> 4.4.120-92.70-default #1 >> [ 584.590000] Hardware name: Cisco Systems Inc UCSC-C460-M4/UCSC-C460-M4, >> BIOS C460M4.4.0.1b.0.0629181419 06/29/2018 >> [ 584.601862] 0000000000000000 ffffffff813175a0 0000000000000000 >> ffffffff8184777c >> [ 584.610200] ffffffff8107f4e1 ffff880487eb7000 ffff8801862b79c0 >> ffff88048608d290 >> [ 584.618537] 0000000000487eb7 ffffea0000000201 ffffffff81009de7 >> ffffffff81068561 >> [ 584.626876] Call Trace: >> [ 584.629699] [<ffffffff81019ad9>] dump_trace+0x59/0x340 >> [ 584.635645] [<ffffffff81019eaa>] show_stack_log_lvl+0xea/0x170 >> [ 584.642391] [<ffffffff8101ac51>] show_stack+0x21/0x40 >> [ 584.648238] [<ffffffff813175a0>] dump_stack+0x5c/0x7c >> [ 584.654085] [<ffffffff8107f4e1>] warn_slowpath_common+0x81/0xb0 >> [ 584.660932] [<ffffffff81009de7>] xen_alloc_pte+0x1c7/0x390 >> [ 584.667289] [<ffffffff810647f0>] >> pmd_populate_kernel.constprop.6+0x40/0x80 >> [ 584.675241] [<ffffffff815ecfe8>] phys_pmd_init+0x210/0x255 >> [ 584.681587] [<ffffffff815ed207>] phys_pud_init+0x1da/0x247 >> [ 584.687931] [<ffffffff815edb3b>] kernel_physical_mapping_init+0xf5/0x1d4 >> [ 584.695682] [<ffffffff815e9bdd>] init_memory_mapping+0x18d/0x380 >> [ 584.702631] [<ffffffff81064699>] arch_add_memory+0x59/0xf0 >> >> Signed-off-by: Juergen Gross <jgr...@suse.com> >> --- >> arch/x86/xen/setup.c | 10 ++++++++++ >> drivers/xen/xen-balloon.c | 6 ++++++ >> 2 files changed, 16 insertions(+) >> >> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c >> index d5f303c0e656..fdb184cadaf5 100644 >> --- a/arch/x86/xen/setup.c >> +++ b/arch/x86/xen/setup.c >> @@ -12,6 +12,7 @@ >> #include <linux/memblock.h> >> #include <linux/cpuidle.h> >> #include <linux/cpufreq.h> >> +#include <linux/memory_hotplug.h> >> >> #include <asm/elf.h> >> #include <asm/vdso.h> >> @@ -825,6 +826,15 @@ char * __init xen_memory_setup(void) >> xen_max_p2m_pfn = pfn_s + n_pfns; >> } else >> discard = true; >> +#ifdef CONFIG_MEMORY_HOTPLUG >> + /* >> + * Don't allow adding memory not in E820 map while >> + * booting the system. Once the balloon driver is up >> + * it will remove that restriction again. >> + */ >> + max_mem_size = xen_e820_table.entries[i].addr + >> + xen_e820_table.entries[i].size; >> +#endif >> } >> >> if (!discard) >> diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c >> index 2acbfe104e46..2a960fcc812e 100644 >> --- a/drivers/xen/xen-balloon.c >> +++ b/drivers/xen/xen-balloon.c >> @@ -37,6 +37,7 @@ >> #include <linux/mm_types.h> >> #include <linux/init.h> >> #include <linux/capability.h> >> +#include <linux/memory_hotplug.h> >> >> #include <xen/xen.h> >> #include <xen/interface/xen.h> >> @@ -63,6 +64,11 @@ static void watch_target(struct xenbus_watch *watch, >> static bool watch_fired; >> static long target_diff; >> >> +#ifdef CONFIG_MEMORY_HOTPLUG >> + /* The balloon driver will take care of adding memory now. */ >> + max_mem_size = U64_MAX; >> +#endif > > > I don't think I understand this. Are you saying the guest should ignore > 'mem' boot option?
No, I just managed to forget thinking about that possibility. I need to save the old max_mem_size setting in setup.c and restore it here. Juergen
