On Mon 04-01-21 16:43:49, David Hildenbrand wrote:
> On 04.01.21 16:33, Michal Hocko wrote:
> > On Mon 04-01-21 16:15:23, David Hildenbrand wrote:
> >> On 04.01.21 16:10, Michal Hocko wrote:
> > [...]
> >> Do the physical addresses you see fall into the same section as boot
> >> memory? Or what's around these addresses?
> >
> > Yes I am getting a garbage for the first struct page belonging to the
> > pmem section [1]
> > [ 0.020161] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x603fffffff]
> > [ 0.020163] ACPI: SRAT: Node 4 PXM 4 [mem 0x6060000000-0x11d5fffffff] non-volatile
> >
> > The pfn without the initialized struct page is 0x6060000. This is a
> > first pfn in a section.
>
> Okay, so we're not dealing with the "early section" mess I described,
> different story.
>
> Due to [1], is_mem_section_removable() called
> pfn_to_page(PHYS_PFN(0x6060000)). page_zone(page) made it crash, as not
> initialized.
Exactly!
> Let's assume this is indeed a reserved pfn in the altmap. What's the
> actual address of the memmap?
Not sure what exactly you are asking for but crash says
crash> kmem -p 6060000
PAGE PHYSICAL MAPPING INDEX CNT FLAGS
fffff8c600181800 6060000 0 0 0 fffffc0000000
> I do wonder what hosts pfn_to_page(PHYS_PFN(0x6060000)) - is it actually
> part of the actual altmap (i.e. > 0x6060000) or maybe even self-hosted?
I am not really familiar with the pmem so I would need more assistance
here. I've tried this (shot into the dark):
crash> struct page.pgmap fffff8c600181800
pgmap = 0xfffff8c600181808
crash> struct -x dev_pagemap 0xfffff8c600181808
struct dev_pagemap {
altmap = {
base_pfn = 0xfffff8c600181808,
end_pfn = 0xfffff8c600181808,
reserve = 0x0,
free = 0x0,
align = 0x0,
alloc = 0xffffffff
},
res = {
start = 0x0,
end = 0xfffffc0000000,
name = 0xfffff8c600181848 "H\030\030",
flags = 0xfffff8c600181848,
desc = 0x0,
parent = 0x0,
sibling = 0x0,
child = 0xffffffff
},
ref = 0x0,
internal_ref = {
count = {
counter = 0xfffffc0000000
},
percpu_count_ptr = 0xfffff8c600181888,
release = 0xfffff8c600181888,
confirm_switch = 0x0,
force_atomic = 0x0,
allow_reinit = 0x0,
rcu = {
next = 0x0,
func = 0xffffffff
}
},
done = {
done = 0x0,
wait = {
lock = {
{
rlock = {
raw_lock = {
{
val = {
counter = 0xc0000000
},
{
locked = 0x0,
pending = 0x0
},
{
locked_pending = 0x0,
tail = 0xc000
}
}
}
}
}
},
head = {
next = 0xfffff8c6001818c8,
prev = 0xfffff8c6001818c8
}
}
},
dev = 0x0,
type = 0,
flags = 0x0,
ops = 0x0
}
Not sure whether this is of any use.
> If it's not self-hosted, initializing the relevant memmaps should work
> just fine I guess. Otherwise things get more complicated.
--
Michal Hocko
SUSE Labs
