SynIC has to be switched off when we unload the module, otherwise registered
memory pages can get corrupted after (as Hyper-V host still writes there) and
we see the following crashes for random processes:
[ 89.116774] BUG: Bad page map in process sh pte:4989c716 pmd:36f81067
[ 89.159454] addr:0000000000437000 vm_flags:00000875 anon_vma: (null) mapping:ffff88007bba55a0 index:37
[ 89.226146] vma->vm_ops->fault: filemap_fault+0x0/0x410
[ 89.257776] vma->vm_file->f_op->mmap: generic_file_mmap+0x0/0x60
[ 89.297570] CPU: 0 PID: 215 Comm: sh Tainted: G B 3.19.0-rc5_bug923184+ #488
[ 89.353738] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090006 05/23/2012
[ 89.409138] 0000000000000000 000000004e083d7b ffff880036e9fa18 ffffffff81a68d31
[ 89.468724] 0000000000000000 0000000000437000 ffff880036e9fa68 ffffffff811a1e3a
[ 89.519233] 000000004989c716 0000000000000037 ffffea0001edc340 0000000000437000
[ 89.575751] Call Trace:
[ 89.591060] [<ffffffff81a68d31>] dump_stack+0x45/0x57
[ 89.625164] [<ffffffff811a1e3a>] print_bad_pte+0x1aa/0x250
[ 89.667234] [<ffffffff811a2c95>] vm_normal_page+0x55/0xa0
[ 89.703818] [<ffffffff811a3105>] unmap_page_range+0x425/0x8a0
[ 89.737982] [<ffffffff811a3601>] unmap_single_vma+0x81/0xf0
[ 89.780385] [<ffffffff81184320>] ? lru_deactivate_fn+0x190/0x190
[ 89.820130] [<ffffffff811a4131>] unmap_vmas+0x51/0xa0
[ 89.860168] [<ffffffff811ad12c>] exit_mmap+0xac/0x1a0
[ 89.890588] [<ffffffff810763c3>] mmput+0x63/0x100
[ 89.919205] [<ffffffff811eba48>] flush_old_exec+0x3f8/0x8b0
[ 89.962135] [<ffffffff8123b5bb>] load_elf_binary+0x32b/0x1260
[ 89.998581] [<ffffffff811a14f2>] ? get_user_pages+0x52/0x60
hv_synic_cleanup() function exists but noone calls it now. Do the following:
- call hv_synic_cleanup() on each cpu from vmbus_exit();
- write global disable bit through MSR;
- use hv_synic_free_cpu() to avoid memory leask and code duplication.
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/hv/hv.c | 9 +++++++--
drivers/hv/vmbus_drv.c | 4 ++++
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 50e51a5..39531dc 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -477,6 +477,7 @@ void hv_synic_cleanup(void *arg)
union hv_synic_sint shared_sint;
union hv_synic_simp simp;
union hv_synic_siefp siefp;
+ union hv_synic_scontrol sctrl;
int cpu = smp_processor_id();
if (!hv_context.synic_initialized)
@@ -502,6 +503,10 @@ void hv_synic_cleanup(void *arg)
wrmsrl(HV_X64_MSR_SIEFP, siefp.as_uint64);
- free_page((unsigned long)hv_context.synic_message_page[cpu]);
- free_page((unsigned long)hv_context.synic_event_page[cpu]);
+ /* Disable the global synic bit */
+ rdmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+ sctrl.enable = 0;
+ wrmsrl(HV_X64_MSR_SCONTROL, sctrl.as_uint64);
+
+ hv_synic_free_cpu(cpu);
}
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index d5cd2fb..f7e2c9e 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -996,11 +996,15 @@ cleanup:
static void __exit vmbus_exit(void)
{
+ int cpu;
+
vmbus_connection.conn_state = DISCONNECTED;
hv_remove_vmbus_irq();
vmbus_free_channels();
bus_unregister(&hv_bus);
hv_cleanup();
+ for_each_online_cpu(cpu)
+ smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
acpi_bus_unregister_driver(&vmbus_acpi_driver);
vmbus_disconnect();
}
--
1.9.3
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