As described, gup_pgd_range is a lockless pagetable walk. So, in order to
monitor against THP split/collapse with the counting method, it's necessary
to bound it with {begin,end}_lockless_pgtbl_walk.
local_irq_{save,restore} is already inside {begin,end}_lockless_pgtbl_walk,
so there is no need to repeat it here.
Signed-off-by: Leonardo Bras <leonardo@xxxxxxxxxxxxx>
---
mm/gup.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index 23a9f9c9d377..52e53b4f39d8 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2319,7 +2319,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
{
unsigned long len, end;
- unsigned long flags;
+ unsigned long irq_mask;
int nr = 0;
start = untagged_addr(start) & PAGE_MASK;
@@ -2345,9 +2345,9 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
gup_fast_permitted(start, end)) {
- local_irq_save(flags);
+ irq_mask = begin_lockless_pgtbl_walk(current->mm);
gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
- local_irq_restore(flags);
+ end_lockless_pgtbl_walk(current->mm, irq_mask);
}
return nr;
@@ -2414,9 +2414,9 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) &&
gup_fast_permitted(start, end)) {
- local_irq_disable();
+ begin_lockless_pgtbl_walk(current->mm);
gup_pgd_range(addr, end, gup_flags, pages, &nr);
- local_irq_enable();
+ end_lockless_pgtbl_walk(current->mm, IRQS_ENABLED);
ret = nr;
}
--
2.20.1
