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From: "pedro at palves dot net" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug threads/28065] FAIL:
 gdb.threads/access-mem-running-thread-exit.exp: all-stop: access mem (print
 global_var after writing again, inf=1, iter=354)
Date: Thu, 08 Jul 2021 13:34:46 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D28065

--- Comment #9 from Pedro Alves <pedro at palves dot net> ---
I'm looking at the kernel sources, and AFAICT, the only way pread64 could
return 0 is if the address space is gone.  See here:

 https://github.com/torvalds/linux/blob/master/fs/proc/base.c#L834

For reads, mem_read -> mem_rw.

We either reach the !mm path:

        if (!mm)
                return 0;

or, here:

        copied =3D 0;
        if (!mmget_not_zero(mm))
                goto free;
...
  free:
        free_page((unsigned long) page);
        return copied;

'mm' is cleared by mem_release.

Could this be something like an OOM kill?

Maybe by tweaking the testcase to not exit immediately on first FAIL we wou=
ld
see the process exit.

--=20
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