On 1/10/2025 1:43 PM, Matthew Wilcox wrote:
On Tue, Dec 17, 2024 at 12:04:42AM +0900, Hyeonggon Yoo wrote:
From: Alex Shi <alexs@xxxxxxxxxx>
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: keep reset_zpdesc() to use struct page fields]
Ummm ... why did you make this change? Now page->index still has a user
in zsmalloc ;-(
Ohhh.., my bad :/
I was thinking of a situation when someone re-arranges zpdesc fields
and forgets to reset the field that overlaps page->index now.
And when writing it did not consider that we're going to remove usages
of page->index anyway...
Let me fix this - will send an updated version of this patch or series
(whatever way that is convenient for You and Andrew)
---
Hyeonggon
Signed-off-by: Alex Shi <alexs@xxxxxxxxxx>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
---
mm/zsmalloc.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 432e78e61d2e..dded6d1f3b7a 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -843,8 +843,10 @@ 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);
@@ -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;
--
2.43.5
