On 07/23, Linus Torvalds wrote:
>
> But I'll walk over my patch mentally one more time. Here's the current
> version, anyway.
Both patches look correct to me, feel free to add
Reviewed-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> @@ -1013,18 +1014,40 @@ static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync,
> if (wait_page->bit_nr != key->bit_nr)
> return 0;
>
> + /* Stop walking if it's locked */
> + if (wait->flags & WQ_FLAG_EXCLUSIVE) {
> + if (test_and_set_bit(key->bit_nr, &key->page->flags))
> + return -1;
> + } else {
> + if (test_bit(key->bit_nr, &key->page->flags))
> + return -1;
> + }
not sure this makes any sense, but this looks like another user of
trylock_page_bit_common(), see the patch below on top of 1/2.
Oleg.
--- mm/filemap.c~ 2020-07-24 17:09:34.728133846 +0200
+++ mm/filemap.c 2020-07-24 17:23:52.279185374 +0200
@@ -1000,6 +1000,14 @@
wait_queue_entry_t wait;
};
+static int trylock_page_bit_common(struct page *page, int bit_nr,
+ struct wait_queue_entry *wait)
+{
+ return wait->flags & WQ_FLAG_EXCLUSIVE ?
+ !test_and_set_bit(bit_nr, &page->flags) :
+ !test_bit(bit_nr, &page->flags);
+}
+
static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
{
int ret;
@@ -1015,13 +1023,8 @@
return 0;
/* Stop walking if it's locked */
- if (wait->flags & WQ_FLAG_EXCLUSIVE) {
- if (test_and_set_bit(key->bit_nr, &key->page->flags))
- return -1;
- } else {
- if (test_bit(key->bit_nr, &key->page->flags))
- return -1;
- }
+ if (!trylock_page_bit_common(key->page, key->bit_nr, wait))
+ return -1;
/*
* Let the waiter know we have done the page flag
@@ -1126,14 +1129,6 @@
*/
};
-static inline int trylock_page_bit_common(struct page *page, int bit_nr,
- enum behavior behavior)
-{
- return behavior == EXCLUSIVE ?
- !test_and_set_bit(bit_nr, &page->flags) :
- !test_bit(bit_nr, &page->flags);
-}
-
static inline int wait_on_page_bit_common(wait_queue_head_t *q,
struct page *page, int bit_nr, int state, enum behavior behavior)
{
@@ -1170,7 +1165,7 @@
*/
spin_lock_irq(&q->lock);
SetPageWaiters(page);
- if (!trylock_page_bit_common(page, bit_nr, behavior))
+ if (!trylock_page_bit_common(page, bit_nr, wait))
__add_wait_queue_entry_tail(q, wait);
spin_unlock_irq(&q->lock);
