The patch titled
Subject: mm: call invalidate_range_end in do_wp_page even for zero pages
has been added to the -mm tree. Its filename is
mm-wrap-calls-to-set_pte_at_notify-with-invalidate_range_start-and-invalidate_range_end-fix.patch
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From: Haggai Eran <haggaie@xxxxxxxxxxxx>
Subject: mm: call invalidate_range_end in do_wp_page even for zero pages
The previous patch "mm: wrap calls to set_pte_at_notify with
invalidate_range_start and invalidate_range_end" only called the
invalidate_range_end mmu notifier function in do_wp_page when the new_page
variable wasn't NULL. This was done in order to only call
invalidate_range_end after invalidate_range_start was called.
Unfortunately, there are situations where new_page is NULL and
invalidate_range_start is called. This caused invalidate_range_start to
be called without a matching invalidate_range_end, causing kvm to loop
indefinitely on the first page fault.
This patch adds a flag variable to do_wp_page that marks whether the
invalidate_range_start notifier was called. invalidate_range_end is then
called if the flag is true.
Reported-by: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Haggai Eran <haggaie@xxxxxxxxxxxx>
Cc: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Cc: Haggai Eran <haggaie@xxxxxxxxxxxx>
Cc: Shachar Raindel <raindel@xxxxxxxxxxxx>
Cc: Liran Liss <liranl@xxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN mm/memory.c~mm-wrap-calls-to-set_pte_at_notify-with-invalidate_range_start-and-invalidate_range_end-fix mm/memory.c
--- a/mm/memory.c~mm-wrap-calls-to-set_pte_at_notify-with-invalidate_range_start-and-invalidate_range_end-fix
+++ a/mm/memory.c
@@ -2529,6 +2529,7 @@ static int do_wp_page(struct mm_struct *
struct page *dirty_page = NULL;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
+ bool mmun_called = false; /* For mmu_notifiers */
old_page = vm_normal_page(vma, address, orig_pte);
if (!old_page) {
@@ -2706,8 +2707,9 @@ gotten:
if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
goto oom_free_new;
- mmun_start = address & PAGE_MASK;
- mmun_end = (address & PAGE_MASK) + PAGE_SIZE;
+ mmun_start = address & PAGE_MASK;
+ mmun_end = (address & PAGE_MASK) + PAGE_SIZE;
+ mmun_called = true;
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
/*
@@ -2776,8 +2778,7 @@ gotten:
page_cache_release(new_page);
unlock:
pte_unmap_unlock(page_table, ptl);
- if (new_page)
- /* Only call the end notifier if the begin was called. */
+ if (mmun_called)
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
if (old_page) {
/*
_
Patches currently in -mm which might be from haggaie@xxxxxxxxxxxx are
linux-next.patch
mm-mmu_notifier-have-mmu_notifiers-use-a-global-srcu-so-they-may-safely-schedule.patch
mm-mmu_notifier-init-notifier-if-necessary.patch
mm-mmu_notifier-make-the-mmu_notifier-srcu-static.patch
mm-move-all-mmu-notifier-invocations-to-be-done-outside-the-pt-lock.patch
mm-wrap-calls-to-set_pte_at_notify-with-invalidate_range_start-and-invalidate_range_end.patch
mm-wrap-calls-to-set_pte_at_notify-with-invalidate_range_start-and-invalidate_range_end-fix.patch
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