mm/zsmalloc: convert reset_page to reset_zpdesc

zpdesc.zspage matches with page.private, zpdesc.next matches with
page.index.  They will be reset in reset_page() which is called prior to
free base pages of a zspage.

Since the fields that need to be initialized are independent of the order
in struct zpdesc, Keep it to use struct page to ensure robustness against
potential rearrangements of struct zpdesc fields in the future.

[42.hyeyoo@gmail.com: reset zpdesc fields in reset_zpdesc()]
Link: https://lkml.kernel.org/r/Z4Uw136VdG7vlKCL@localhost.localdomain
[42.hyeyoo@gmail.com: keep reset_zpdesc() to use struct page fields]
Link: https://lkml.kernel.org/r/20241216150450.1228021-12-42.hyeyoo@gmail.com
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 432e78e61d2e3c6080d284c31f9e8b89d7b5b4ba..98b152a0b264388b9399d6a6484134eace3aafd0 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -843,12 +843,14 @@ static inline bool obj_allocated(struct zpdesc *zpdesc, void *obj,
        return true;
 }
 
-static void reset_page(struct page *page)
+static void reset_zpdesc(struct zpdesc *zpdesc)
 {
+       struct page *page = zpdesc_page(zpdesc);
+
        __ClearPageMovable(page);
        ClearPagePrivate(page);
-       set_page_private(page, 0);
-       page->index = 0;
+       zpdesc->zspage = NULL;
+       zpdesc->next = NULL;
        __ClearPageZsmalloc(page);
 }
 
@@ -887,7 +889,7 @@ static void __free_zspage(struct zs_pool *pool, struct size_class *class,
        do {
                VM_BUG_ON_PAGE(!PageLocked(page), page);
                next = get_next_page(page);
-               reset_page(page);
+               reset_zpdesc(page_zpdesc(page));
                unlock_page(page);
                dec_zone_page_state(page, NR_ZSPAGES);
                put_page(page);
@@ -1865,7 +1867,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
                zpdesc_inc_zone_page_state(newzpdesc);
        }
 
-       reset_page(page);
+       reset_zpdesc(zpdesc);
        zpdesc_put(zpdesc);
 
        return MIGRATEPAGE_SUCCESS;