diff mbox series

[v3] mm/z3fold.c: Lock z3fold page before __SetPageMovable()

Message ID 20190702233538.52793-1-henryburns@google.com (mailing list archive)
State New, archived
Headers show
Series [v3] mm/z3fold.c: Lock z3fold page before __SetPageMovable() | expand

Commit Message

Henry Burns July 2, 2019, 11:35 p.m. UTC 
Following zsmalloc.c's example we call trylock_page() and unlock_page(). 
Also make z3fold_page_migrate() assert that newpage is passed in locked,
as per the documentation.

Link: http://lkml.kernel.org/r/20190702005122.41036-1-henryburns@google.com
Signed-off-by: Henry Burns <henryburns@google.com>
Suggested-by: Vitaly Wool <vitalywool@gmail.com>
Acked-by: Vitaly Wool <vitalywool@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Vitaly Vul <vitaly.vul@sony.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Xidong Wang <wangxidong_97@163.com>
Cc: Jonathan Adams <jwadams@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 Changelog since v2:
 - Removed the WARN_ON entirely, as it is an expected code path.

 Changelog since v1:
 - Added an if statement around WARN_ON(trylock_page(page)) to avoid
   unlocking a page locked by a someone else.

 mm/z3fold.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Comments

Shakeel Butt July 3, 2019, 12:59 a.m. UTC | #1 
On Tue, Jul 2, 2019 at 4:35 PM Henry Burns <henryburns@google.com> wrote:
>
> Following zsmalloc.c's example we call trylock_page() and unlock_page().
> Also make z3fold_page_migrate() assert that newpage is passed in locked,
> as per the documentation.
>
> Link: http://lkml.kernel.org/r/20190702005122.41036-1-henryburns@google.com
> Signed-off-by: Henry Burns <henryburns@google.com>
> Suggested-by: Vitaly Wool <vitalywool@gmail.com>
> Acked-by: Vitaly Wool <vitalywool@gmail.com>
> Acked-by: David Rientjes <rientjes@google.com>
> Cc: Shakeel Butt <shakeelb@google.com>
> Cc: Vitaly Vul <vitaly.vul@sony.com>
> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
> Cc: Xidong Wang <wangxidong_97@163.com>
> Cc: Jonathan Adams <jwadams@google.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We need a "Fixes" tag.

Reviewed-by: Shakeel Butt <shakeelb@google.com>
diff mbox series

Patch

diff --git a/mm/z3fold.c b/mm/z3fold.c
index e174d1549734..eeb3fe7f5ca3 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -918,7 +918,16 @@  static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
 		set_bit(PAGE_HEADLESS, &page->private);
 		goto headless;
 	}
-	__SetPageMovable(page, pool->inode->i_mapping);
+	if (can_sleep) {
+		lock_page(page);
+		__SetPageMovable(page, pool->inode->i_mapping);
+		unlock_page(page);
+	} else {
+		if (!trylock_page(page)) {
+			__SetPageMovable(page, pool->inode->i_mapping);
+			unlock_page(page);
+		}
+	}
 	z3fold_page_lock(zhdr);
 
 found:
@@ -1325,6 +1334,7 @@  static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa
 
 	VM_BUG_ON_PAGE(!PageMovable(page), page);
 	VM_BUG_ON_PAGE(!PageIsolated(page), page);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
 
 	zhdr = page_address(page);
 	pool = zhdr_to_pool(zhdr);