[Issue]
Current erst driver is kicked in panic case.
On the other hand, a dynamic memory allocation seems to run in it
with a following code path.
erst_writer -> erst_write -> __erst_write_to_storage -> many of apei_exec_run ->
ctx->ins_table[entry->instruction].run()
which are functions defined in erst_ins_type table i.e:
apei_exec_read_register -> apei_read -> acpi_os_read_memory64 -> acpi_os_ioremap -> ioremap_cache
which possibly involve IOMMU allocator.
I may cause a failure of an erst driver if the panic happens in an interrupt context.
[Idea]
If we can remove ioremap_cache() from acpi_os_read_memory() as follows,
It is easy to fix this issue.
But I'm not sure if it is feasible because I can't see the reason of tying acpi_os_ioremap() from a git log...
Any comment?
<snip>
@@ -918,10 +918,7 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u64 *value, u32 width)
virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
if (!virt_addr) {
rcu_read_unlock();
- virt_addr = acpi_os_ioremap(phys_addr, size);
- if (!virt_addr)
- return AE_BAD_ADDRESS;
- unmap = true;
+ return AE_BAD_ADDRESS;
}
if (!value)
<snip>
Seiji
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