tracing: Keep track of set_ftrace_filter position and allow lseek again

[pandora-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 9b3b73f..71b161b 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2623,7 +2623,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                unsigned int flags, pte_t orig_pte)
 {
        spinlock_t *ptl;
-       struct page *page;
+       struct page *page, *swapcache = NULL;
        swp_entry_t entry;
        pte_t pte;
        struct mem_cgroup *ptr = NULL;
@@ -2679,10 +2679,23 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
        lock_page(page);
        delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
 
-       page = ksm_might_need_to_copy(page, vma, address);
-       if (!page) {
-               ret = VM_FAULT_OOM;
-               goto out;
+       /*
+        * Make sure try_to_free_swap didn't release the swapcache
+        * from under us. The page pin isn't enough to prevent that.
+        */
+       if (unlikely(!PageSwapCache(page)))
+               goto out_page;
+
+       if (ksm_might_need_to_copy(page, vma, address)) {
+               swapcache = page;
+               page = ksm_does_need_to_copy(page, vma, address);
+
+               if (unlikely(!page)) {
+                       ret = VM_FAULT_OOM;
+                       page = swapcache;
+                       swapcache = NULL;
+                       goto out_page;
+               }
        }
 
        if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
@@ -2735,6 +2748,18 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
        if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
                try_to_free_swap(page);
        unlock_page(page);
+       if (swapcache) {
+               /*
+                * Hold the lock to avoid the swap entry to be reused
+                * until we take the PT lock for the pte_same() check
+                * (to avoid false positives from pte_same). For
+                * further safety release the lock after the swap_free
+                * so that the swap count won't change under a
+                * parallel locked swapcache.
+                */
+               unlock_page(swapcache);
+               page_cache_release(swapcache);
+       }
 
        if (flags & FAULT_FLAG_WRITE) {
                ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
@@ -2756,25 +2781,43 @@ out_page:
        unlock_page(page);
 out_release:
        page_cache_release(page);
+       if (swapcache) {
+               unlock_page(swapcache);
+               page_cache_release(swapcache);
+       }
        return ret;
 }
 
 /*
- * This is like a special single-page "expand_downwards()",
- * except we must first make sure that 'address-PAGE_SIZE'
+ * This is like a special single-page "expand_{down|up}wards()",
+ * except we must first make sure that 'address{-|+}PAGE_SIZE'
  * doesn't hit another vma.
- *
- * The "find_vma()" will do the right thing even if we wrap
  */
 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
 {
        address &= PAGE_MASK;
        if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
-               address -= PAGE_SIZE;
-               if (find_vma(vma->vm_mm, address) != vma)
-                       return -ENOMEM;
+               struct vm_area_struct *prev = vma->vm_prev;
+
+               /*
+                * Is there a mapping abutting this one below?
+                *
+                * That's only ok if it's the same stack mapping
+                * that has gotten split..
+                */
+               if (prev && prev->vm_end == address)
+                       return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
 
-               expand_stack(vma, address);
+               expand_stack(vma, address - PAGE_SIZE);
+       }
+       if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
+               struct vm_area_struct *next = vma->vm_next;
+
+               /* As VM_GROWSDOWN but s/below/above/ */
+               if (next && next->vm_start == address + PAGE_SIZE)
+                       return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
+
+               expand_upwards(vma, address + PAGE_SIZE);
        }
        return 0;
 }
@@ -2792,24 +2835,23 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
        spinlock_t *ptl;
        pte_t entry;
 
-       if (check_stack_guard_page(vma, address) < 0) {
-               pte_unmap(page_table);
+       pte_unmap(page_table);
+
+       /* Check if we need to add a guard page to the stack */
+       if (check_stack_guard_page(vma, address) < 0)
                return VM_FAULT_SIGBUS;
-       }
 
+       /* Use the zero-page for reads */
        if (!(flags & FAULT_FLAG_WRITE)) {
                entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
                                                vma->vm_page_prot));
-               ptl = pte_lockptr(mm, pmd);
-               spin_lock(ptl);
+               page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
                if (!pte_none(*page_table))
                        goto unlock;
                goto setpte;
        }
 
        /* Allocate our own private page. */
-       pte_unmap(page_table);
-
        if (unlikely(anon_vma_prepare(vma)))
                goto oom;
        page = alloc_zeroed_user_highpage_movable(vma, address);