On Tue, 13 Sep 2022 14:10:45 +0800 "zhaoyang.huang" <zhaoyang.huang@xxxxxxxxxx> wrote:
> From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
>
> free_pages_check return 0 when result is ok while bulkfree_pcp_prepare
> treat it as false wrongly.
It's called check_free_page().
And that's a poor name because the name doesn't communicate what a
true/false return value means - was the page good or bad?
So I'd propose this renaming:
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc.c: rename check_free_page() to free_page_is_bad()
Date: Tue Sep 13 03:20:48 PM PDT 2022
The name "check_free_page()" provides no information regarding its return
value when the page is indeed found to be bad.
Renaming it to "free_page_is_bad()" makes it clear that a `true' return
value means the page was bad.
And make it return a bool, not an int.
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
--- a/mm/page_alloc.c~a
+++ a/mm/page_alloc.c
@@ -1290,20 +1290,20 @@ static const char *page_bad_reason(struc
return bad_reason;
}
-static void check_free_page_bad(struct page *page)
+static void free_page_bad_report(struct page *page)
{
bad_page(page,
page_bad_reason(page, PAGE_FLAGS_CHECK_AT_FREE));
}
-static inline int check_free_page(struct page *page)
+static inline bool free_page_bad(struct page *page)
{
if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
- return 0;
+ return false;
/* Something has gone sideways, find it */
- check_free_page_bad(page);
- return 1;
+ free_page_bad_report(page);
+ return true;
}
static int free_tail_pages_check(struct page *head_page, struct page *page)
@@ -1436,7 +1436,7 @@ static __always_inline bool free_pages_p
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
- if (unlikely(check_free_page(page + i))) {
+ if (unlikely(free_page_bad(page + i))) {
bad++;
continue;
}
@@ -1448,7 +1448,7 @@ static __always_inline bool free_pages_p
if (memcg_kmem_enabled() && PageMemcgKmem(page))
__memcg_kmem_uncharge_page(page, order);
if (check_free)
- bad += check_free_page(page);
+ bad += free_page_bad(page);
if (bad)
return false;
@@ -1510,7 +1510,7 @@ static bool free_pcp_prepare(struct page
static bool bulkfree_pcp_prepare(struct page *page)
{
if (debug_pagealloc_enabled_static())
- return check_free_page(page);
+ return free_page_bad(page);
else
return false;
}
@@ -1531,7 +1531,7 @@ static bool free_pcp_prepare(struct page
static bool bulkfree_pcp_prepare(struct page *page)
{
- return check_free_page(page);
+ return free_page_bad(page);
}
#endif /* CONFIG_DEBUG_VM */
_
And bulkfree_pcp_prepare() is pretty bad as well - how about we
document the dang return value?
--- a/mm/page_alloc.c~b
+++ a/mm/page_alloc.c
@@ -1507,6 +1507,7 @@ static bool free_pcp_prepare(struct page
return free_pages_prepare(page, order, true, FPI_NONE);
}
+/* return true if this page has an inappropriate state */
static bool bulkfree_pcp_prepare(struct page *page)
{
if (debug_pagealloc_enabled_static())
_
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1424,7 +1424,7 @@ static bool free_pcp_prepare(struct page *page, unsigned int order)
> static bool bulkfree_pcp_prepare(struct page *page)
> {
> if (debug_pagealloc_enabled_static())
> - return check_free_page(page);
> + return !check_free_page(page);
> else
> return false;
> }
> @@ -1445,7 +1445,7 @@ static bool free_pcp_prepare(struct page *page, unsigned int order)
>
> static bool bulkfree_pcp_prepare(struct page *page)
> {
> - return check_free_page(page);
> + return !check_free_page(page);
> }
> #endif /* CONFIG_DEBUG_VM */
And after clarifying these things, your patch seems incorrect.
free_pcppages_bulk() does
if (bulkfree_pcp_prepare(page))
continue;
in other words, it leaks the page if it was found to be messed up?
