x86: Cleanup highmap after brk is concluded

Now cleanup_highmap actually is in two steps: one is early in head64.c
and only clears above _end; a second one is in init_memory_mapping() and
tries to clean from _brk_end to _end.
It should check if those boundaries are PMD_SIZE aligned but currently
does not.
Also init_memory_mapping() is called several times for numa or memory
hotplug, so we really should not handle initial kernel mappings there.

This patch moves cleanup_highmap() down after _brk_end is settled so
we can do everything in one step.
Also we honor max_pfn_mapped in the implementation of cleanup_highmap.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@kaball-desktop>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 3 insertions, 25 deletions

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2d2673c28aff..5655c2272adb 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -77,9 +77,6 @@ void __init x86_64_start_kernel(char * real_mode_data)
         /* Make NULL pointers segfault */
         zap_identity_mappings();
 
-        /* Cleanup the over mapped high alias */
-        cleanup_highmap();
-
         max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
 
         for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b176f2b1f45d..4a52a5f9afcb 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -294,30 +294,11 @@ static void __init init_gbpages(void)
         else
                 direct_gbpages = 0;
 }
-
-static void __init cleanup_highmap_brk_end(void)
-{
-        pud_t *pud;
-        pmd_t *pmd;
-
-        mmu_cr4_features = read_cr4();
-
-        /*
-         * _brk_end cannot change anymore, but it and _end may be
-         * located on different 2M pages. cleanup_highmap(), however,
-         * can only consider _end when it runs, so destroy any
-         * mappings beyond _brk_end here.
-         */
-        pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);
-        pmd = pmd_offset(pud, _brk_end - 1);
-        while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))
-                pmd_clear(pmd);
-}
 #else
 static inline void init_gbpages(void)
 {
 }
-static inline void cleanup_highmap_brk_end(void)
+static void __init cleanup_highmap(void)
 {
 }
 #endif
@@ -330,8 +311,6 @@ static void __init reserve_brk(void)
         /* Mark brk area as locked down and no longer taking any
            new allocations */
         _brk_start = 0;
-
-        cleanup_highmap_brk_end();
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
@@ -950,6 +929,8 @@ void __init setup_arch(char **cmdline_p)
          */
         reserve_brk();
 
+        cleanup_highmap();
+
         memblock.current_limit = get_max_mapped();
         memblock_x86_fill();