On Fri, Jul 13, 2018 at 8:04 PM Pavel Tatashin
<pasha.tatashin@xxxxxxxxxx> wrote:
>
> > You can't just memset() the 'struct page' to zero after it's been set up.
>
> That should not be happening, unless there is a bug.
Well, it does seem to happen. My memory stress-tester has been running
for about half an hour now with the revert I posted - it used to
trigger the problem in maybe ~5 minutes before.
So I do think that revert fixes it for me. No guarantees, but since I
figured out how to trigger it, it's been fairly reliable.
> We want to zero those struct pages so we do not have uninitialized
> data accessed by various parts of the code that rounds down large
> pages and access the first page in section without verifying that the
> page is valid. The example of this is described in commit that
> introduced zero_resv_unavail()
I'm attaching the relevant (?) parts of dmesg, which has the node
ranges, maybe you can see what the problem with the code is.
(NOTE! This dmesg is with that "mem=6G" command line option, which causes that
e820: remove [mem 0x180000000-0xfffffffffffffffe] usable
line - that's just because it's my stress-test boot. It happens with
or without it, but without the "mem=6G" it took days to trigger).
I'm more than willing to test patches (either for added information or
for testing fixes), although I think I'm getting off the computer for
today.
Linus
Attachment:
dmesg.out
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