soft-dirty: call mmu notifiers when write-protecting ptes

As noticed by Xiao, since soft-dirty clear command modifies page tables we
have to flush tlbs and call mmu notifiers.  While the former is done by
the clear_refs engine itself, the latter is to be done.

One thing to note about this -- in order not to call per-page invalidate
notifier (_all_ address space is about to be changed), the
_invalidate_range_start and _end are used.  But for those start and end
are not known exactly.  To address this, the same trick as in exit_mmap()
is used -- start is 0 and end is (unsigned long)-1.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 9238acbc0a100e728c7bc0f5d8b4b6518f281635..a18e065c1c3e6c3b6ae9f4db8fb2d39c98eaa5b2 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -11,6 +11,7 @@
 #include <linux/rmap.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
 
 #include <asm/elf.h>
 #include <asm/uaccess.h>
@@ -791,6 +792,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                        .private = &cp,
                };
                down_read(&mm->mmap_sem);
+               if (type == CLEAR_REFS_SOFT_DIRTY)
+                       mmu_notifier_invalidate_range_start(mm, 0, -1);
                for (vma = mm->mmap; vma; vma = vma->vm_next) {
                        cp.vma = vma;
                        if (is_vm_hugetlb_page(vma))
@@ -811,6 +814,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                        walk_page_range(vma->vm_start, vma->vm_end,
                                        &clear_refs_walk);
                }
+               if (type == CLEAR_REFS_SOFT_DIRTY)
+                       mmu_notifier_invalidate_range_end(mm, 0, -1);
                flush_tlb_mm(mm);
                up_read(&mm->mmap_sem);
                mmput(mm);