[PATCH] mm: remove PageMovable export

[PATCH] mm: remove PageMovable export

[Greg Kroah-Hartman]

The only in-kernel users that need PageMovable() to be exported are
z3fold and zsmalloc and they are only using it for dubious debugging
functionality.  So remove those usages and the export so that no driver
code accidentally thinks that they are allowed to use this symbol.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/compaction.c | 1 -
 mm/z3fold.c     | 2 --
 mm/zsmalloc.c   | 3 ---
 3 files changed, 6 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index ca1603524bbe..62a61de44658 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -122,7 +122,6 @@ bool PageMovable(struct page *page)
 
 	return false;
 }
-EXPORT_SYMBOL(PageMovable);
 
 void __SetPageMovable(struct page *page, const struct movable_operations *mops)
 {
diff --git a/mm/z3fold.c b/mm/z3fold.c
index a4de0c317ac7..0cef845d397b 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1450,7 +1450,6 @@ static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
 	struct z3fold_header *zhdr;
 	struct z3fold_pool *pool;
 
-	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(PageIsolated(page), page);
 
 	if (test_bit(PAGE_HEADLESS, &page->private))
@@ -1490,7 +1489,6 @@ static int z3fold_page_migrate(struct page *newpage, struct page *page,
 	struct z3fold_header *zhdr, *new_zhdr;
 	struct z3fold_pool *pool;
 
-	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
 	VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
 	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 9445bee6b014..6aafacd664fc 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1973,7 +1973,6 @@ static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
 	 * Page is locked so zspage couldn't be destroyed. For detail, look at
 	 * lock_zspage in free_zspage.
 	 */
-	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(PageIsolated(page), page);
 
 	zspage = get_zspage(page);
@@ -2005,7 +2004,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	if (mode == MIGRATE_SYNC_NO_COPY)
 		return -EINVAL;
 
-	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
 
 	/* The page is locked, so this pointer must remain valid */
@@ -2070,7 +2068,6 @@ static void zs_page_putback(struct page *page)
 {
 	struct zspage *zspage;
 
-	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
 
 	zspage = get_zspage(page);
-- 
2.39.0

Re: [PATCH] mm: remove PageMovable export

[Miaohe Lin]

On 2023/1/6 21:59, Greg Kroah-Hartman wrote:
> The only in-kernel users that need PageMovable() to be exported are
> z3fold and zsmalloc and they are only using it for dubious debugging
> functionality.  So remove those usages and the export so that no driver
> code accidentally thinks that they are allowed to use this symbol.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Vitaly Wool <vitaly.wool@konsulko.com>
> Cc: Miaohe Lin <linmiaohe@huawei.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

LGTM. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks,
Miaohe Lin

Re: [PATCH] mm: remove PageMovable export

[David Hildenbrand]

On 06.01.23 14:59, Greg Kroah-Hartman wrote:
> The only in-kernel users that need PageMovable() to be exported are
> z3fold and zsmalloc and they are only using it for dubious debugging
> functionality.  So remove those usages and the export so that no driver
> code accidentally thinks that they are allowed to use this symbol.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Vitaly Wool <vitaly.wool@konsulko.com>
> Cc: Miaohe Lin <linmiaohe@huawei.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

Re: [PATCH] mm: remove PageMovable export

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] mm: remove PageMovable export

[Minchan Kim]

On Fri, Jan 06, 2023 at 02:59:00PM +0100, Greg Kroah-Hartman wrote:
> The only in-kernel users that need PageMovable() to be exported are
> z3fold and zsmalloc and they are only using it for dubious debugging
> functionality.  So remove those usages and the export so that no driver
> code accidentally thinks that they are allowed to use this symbol.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Vitaly Wool <vitaly.wool@konsulko.com>
> Cc: Miaohe Lin <linmiaohe@huawei.com>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>