Folks, the LKP robot reported an issue with Paolo's recent bug fix
that syncs the identity mapping in 'initial_page_table'. Turns out
that KERNEL_PGD_PTRS is not the correct constant to use when copying
to the lower region because that's every PGD from PAGE_OFFSET to the
end of the addressable memory.
Crucially, KERNEL_PGD_PTRS > KERNEL_PGD_BOUNDARY and so the patch ends
up trashing some of the kernel mappings in 'initial_page'table,
leading to boot crashes on 32-bit SMP when bringing APs online.
The following changes since commit 9ee870feaa9e0c6abef95a3b1fc518d88adfa2d3:
Merge branch 'x86/cpufeature' into x86/urgent, to pick up pending Intel MID change (2015-11-03 12:00:40 +0100)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi.git tags/efi-urgent
for you to fetch changes up to 5965d1bbeba70fe3626e4537f4729283cb0e75f7:
x86/setup: Fix recent boot crash on 32-bit SMP machines (2015-11-04 09:26:24 +0000)
----------------------------------------------------------------
* Avoid trashing the kernel mappings in 'initial_page_table' when
copying the identity mapping from 'swapper_pg_dir'. This bug was
introduced by a bug fix in v4.3 which erroneously copies too many
entries from 'swapper_pg_dir'.
----------------------------------------------------------------
Matt Fleming (1):
x86/setup: Fix recent boot crash on 32-bit SMP machines
arch/x86/kernel/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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