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-rw-r--r--mm/memory.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/mm/memory.c b/mm/memory.c
index ba5189e..1358012 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2431,7 +2431,8 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
lock_page(page);
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
- if (mem_cgroup_try_charge(mm, GFP_HIGHUSER_MOVABLE, &ptr) == -ENOMEM) {
+ if (mem_cgroup_try_charge_swapin(mm, page,
+ GFP_HIGHUSER_MOVABLE, &ptr) == -ENOMEM) {
ret = VM_FAULT_OOM;
unlock_page(page);
goto out;
@@ -2449,8 +2450,20 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
goto out_nomap;
}
- /* The page isn't present yet, go ahead with the fault. */
+ /*
+ * The page isn't present yet, go ahead with the fault.
+ *
+ * Be careful about the sequence of operations here.
+ * To get its accounting right, reuse_swap_page() must be called
+ * while the page is counted on swap but not yet in mapcount i.e.
+ * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
+ * must be called after the swap_free(), or it will never succeed.
+ * And mem_cgroup_commit_charge_swapin(), which uses the swp_entry
+ * in page->private, must be called before reuse_swap_page(),
+ * which may delete_from_swap_cache().
+ */
+ mem_cgroup_commit_charge_swapin(page, ptr);
inc_mm_counter(mm, anon_rss);
pte = mk_pte(page, vma->vm_page_prot);
if (write_access && reuse_swap_page(page)) {
@@ -2461,7 +2474,6 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
flush_icache_page(vma, page);
set_pte_at(mm, address, page_table, pte);
page_add_anon_rmap(page, vma, address);
- mem_cgroup_commit_charge_swapin(page, ptr);
swap_free(entry);
if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
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