[PATCH 04/11] x86/mm/hotplug: Simplify sync_global_pgds()

Ingo Molnar
2015-09-22T06:24:34Z

Now that the memory hotplug code does not remove PGD entries anymore,
the only users of sync_global_pgds() use it after extending the
PGD.

So remove the 'removed' parameter and simplify the call sites.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: linux-mm@kvack.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/pgtable_64.h | 3 +--
arch/x86/mm/fault.c | 2 +-
arch/x86/mm/init_64.c | 27 ++++++++-------------------
3 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 2ee781114d34..f405fc3bb719 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -116,8 +116,7 @@ static inline void native_pgd_clear(pgd_t *pgd)
native_set_pgd(pgd, native_make_pgd(0));
}

-extern void sync_global_pgds(unsigned long start, unsigned long end,
- int removed);
+extern void sync_global_pgds(unsigned long start, unsigned long end);

/*
* Conversion functions: convert a page and protection to a page entry,
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index eef44d9a3f77..f890f5463ac1 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -353,7 +353,7 @@ static void dump_pagetable(unsigned long address)

void vmalloc_sync_all(void)
{
- sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END, 0);
+ sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
}

/*
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 60b0cc3f2819..467c4f66ded9 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -161,10 +161,10 @@ static int __init nonx32_setup(char *str)
__setup("noexec32=", nonx32_setup);

/*
- * When memory was added/removed make sure all the process MMs have
+ * When memory was added make sure all the process MMs have
* matching PGD entries in the local PGD level page as well.
*/
-void sync_global_pgds(unsigned long start, unsigned long end, int removed)
+void sync_global_pgds(unsigned long start, unsigned long end)
{
unsigned long address;

@@ -172,14 +172,8 @@ void sync_global_pgds(unsigned long start, unsigned long end, int removed)
const pgd_t *pgd_ref = pgd_offset_k(address);
struct task_struct *g;

- /*
- * When this function is called after memory hot remove,
- * pgd_none() already returns true, but only the reference
- * kernel PGD has been cleared, not the process PGDs.
- *
- * So clear the affected entries in every process PGD as well:
- */
- if (pgd_none(*pgd_ref) && !removed)
+ /* Only sync (potentially) newly added PGD entries: */
+ if (pgd_none(*pgd_ref))
continue;

rcu_read_lock(); /* Task list walk */
@@ -205,13 +199,8 @@ void sync_global_pgds(unsigned long start, unsigned long end, int removed)
if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));

- if (removed) {
- if (pgd_none(*pgd_ref) && !pgd_none(*pgd))
- pgd_clear(pgd);
- } else {
- if (pgd_none(*pgd))
- set_pgd(pgd, *pgd_ref);
- }
+ if (pgd_none(*pgd))
+ set_pgd(pgd, *pgd_ref);

spin_unlock(pgt_lock);
task_unlock(p);
@@ -646,7 +635,7 @@ kernel_physical_mapping_init(unsigned long start,
}

if (pgd_changed)
- sync_global_pgds(addr, end - 1, 0);
+ sync_global_pgds(addr, end - 1);

__flush_tlb_all();

@@ -1286,7 +1275,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
else
err = vmemmap_populate_basepages(start, end, node);
if (!err)
- sync_global_pgds(start, end - 1, 0);
+ sync_global_pgds(start, end - 1);
return err;
}

--
2.1.4