ARM: 8685/1: ensure memblock-limit is pmd-aligned

BugLink: http://bugs.launchpad.net/bugs/1702863
commit 9e25ebfe56ece7541cd10a20d715cbdd148a2e06 upstream.

The pmd containing memblock_limit is cleared by prepare_page_table()
which creates the opportunity for early_alloc() to allocate unmapped
memory if memblock_limit is not pmd aligned causing a boot-time hang.

Commit 965278dcb8ab ("ARM: 8356/1: mm: handle non-pmd-aligned end of RAM")
attempted to resolve this problem, but there is a path through the
adjust_lowmem_bounds() routine where if all memory regions start and
end on pmd-aligned addresses the memblock_limit will be set to
arm_lowmem_limit.

Since arm_lowmem_limit can be affected by the vmalloc early parameter,
the value of arm_lowmem_limit may not be pmd-aligned. This commit
corrects this oversight such that memblock_limit is always rounded
down to pmd-alignment.

Fixes: 965278dcb8ab ("ARM: 8356/1: mm: handle non-pmd-aligned end of RAM")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4867f5daf82c99bdf4ee64ebb6b61613cd792a3e..e47cffd25c6cfd3c0edee465ac01a454d22cc116 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1184,15 +1184,15 @@ void __init sanity_check_meminfo(void)
 
        high_memory = __va(arm_lowmem_limit - 1) + 1;
 
+       if (!memblock_limit)
+               memblock_limit = arm_lowmem_limit;
+
        /*
         * Round the memblock limit down to a pmd size.  This
         * helps to ensure that we will allocate memory from the
         * last full pmd, which should be mapped.
         */
-       if (memblock_limit)
-               memblock_limit = round_down(memblock_limit, PMD_SIZE);
-       if (!memblock_limit)
-               memblock_limit = arm_lowmem_limit;
+       memblock_limit = round_down(memblock_limit, PMD_SIZE);
 
        memblock_set_current_limit(memblock_limit);
 }