From: Hugh Dickins <hughd@xxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 887843961c4b4681ee993c36d4997bf4b4aa8253 upstream.
Fix some "Bad rss-counter state" reports on exit, arising from the
interaction between page migration and remap_file_pages(): zap_pte()
must count a migration entry when zapping it.
And yes, it is possible (though very unusual) to find an anon page or
swap entry in a VM_SHARED nonlinear mapping: coming from that horrid
get_user_pages(write, force) case which COWs even in a shared mapping.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Tested-by: Sasha Levin sasha.levin@xxxxxxxxxx>
Tested-by: Dave Jones davej@xxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
mm/fremap.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/mm/fremap.c b/mm/fremap.c
index bbc4d660221a..34feba60a17e 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -23,28 +23,44 @@
#include "internal.h"
+static int mm_counter(struct page *page)
+{
+ return PageAnon(page) ? MM_ANONPAGES : MM_FILEPAGES;
+}
+
static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
pte_t pte = *ptep;
+ struct page *page;
+ swp_entry_t entry;
if (pte_present(pte)) {
- struct page *page;
-
flush_cache_page(vma, addr, pte_pfn(pte));
pte = ptep_clear_flush(vma, addr, ptep);
page = vm_normal_page(vma, addr, pte);
if (page) {
if (pte_dirty(pte))
set_page_dirty(page);
+ update_hiwater_rss(mm);
+ dec_mm_counter(mm, mm_counter(page));
page_remove_rmap(page);
page_cache_release(page);
+ }
+ } else { /* zap_pte() is not called when pte_none() */
+ if (!pte_file(pte)) {
update_hiwater_rss(mm);
- dec_mm_counter(mm, MM_FILEPAGES);
+ entry = pte_to_swp_entry(pte);
+ if (non_swap_entry(entry)) {
+ if (is_migration_entry(entry)) {
+ page = migration_entry_to_page(entry);
+ dec_mm_counter(mm, mm_counter(page));
+ }
+ } else {
+ free_swap_and_cache(entry);
+ dec_mm_counter(mm, MM_SWAPENTS);
+ }
}
- } else {
- if (!pte_file(pte))
- free_swap_and_cache(pte_to_swp_entry(pte));
pte_clear_not_present_full(mm, addr, ptep, 0);
}
}
--
2.1.0
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