On 3/21/25 06:43, Ye Liu wrote:
> From: Ye Liu <liuye@xxxxxxxxxx>
>
> This patch consolidates the handling of unlikely conditions in the
> page_expected_state function, reducing code duplication and improving
> readability.
>
> Previously, the check_new_page_bad function contained logic to handle
> __PG_HWPOISON flags, which was called from check_new_page. This patch
> moves the handling of __PG_HWPOISON flags into the page_expected_state
> function and removes the check_new_page_bad function. The check_new_page
> function now directly calls bad_page if the page has unexpected flags.
>
> This change simplifies the code by reducing the number of functions and
> centralizing the unlikely condition handling in one place.
>
> Signed-off-by: Ye Liu <liuye@xxxxxxxxxx>
> ---
> mm/page_alloc.c | 26 ++++++++++----------------
> 1 file changed, 10 insertions(+), 16 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2842da893eea..d8d04ac1d709 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -892,6 +892,13 @@ static inline bool page_expected_state(struct page *page,
> if (unlikely(atomic_read(&page->_mapcount) != -1))
> return false;
>
> + if (unlikely(PageHWPoison(page))) {
> + /* Don't complain about hwpoisoned pages */
> + if (PageBuddy(page))
> + __ClearPageBuddy(page);
> + return false;
Should this be return 'true' instead ?
Let's consider a scenario where PageHWPoison(page) is true.
Previously bad_page() was not getting called as check_new_page_bad() will
return earlier before reaching bad_page().
But now with the proposed change here page_expected_state() returns false
and hence bad_page() still gets called later on in check_new_page().
There is a change in behaviour - or am I missing something here ?
> + }
> +
> if (unlikely((unsigned long)page->mapping |
> page_ref_count(page) |
> #ifdef CONFIG_MEMCG
> @@ -1586,29 +1593,16 @@ static __always_inline void page_del_and_expand(struct zone *zone,
> account_freepages(zone, -nr_pages, migratetype);
> }
>
> -static void check_new_page_bad(struct page *page)
> -{
> - if (unlikely(PageHWPoison(page))) {
> - /* Don't complain about hwpoisoned pages */
> - if (PageBuddy(page))
> - __ClearPageBuddy(page);
> - return;
> - }
> -
> - bad_page(page,
> - page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
> -}
> -
> /*
> * This page is about to be returned from the page allocator
> */
> static bool check_new_page(struct page *page)
> {
> - if (likely(page_expected_state(page,
> - PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
> + if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_PREP)))
> return false;
>
> - check_new_page_bad(page);
> + bad_page(page,
> + page_bad_reason(page, PAGE_FLAGS_CHECK_AT_PREP));
> return true;
> }
>
