lkml.org 
[lkml]   [2019]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 2/2] x86/xen: dont add memory above max allowed allocation
From
Date
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 <jgross@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

\
 
 \ /
  Last update: 2019-02-07 07:33    [W:0.066 / U:0.144 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site