On 12/18/2013 04:43 PM, Andrew Morton wrote:
On Wed, 18 Dec 2013 17:23:03 +0800 Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> wrote:
diff --git a/mm/rmap.c b/mm/rmap.c
index 55c8b8d..1e24813 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1347,6 +1347,7 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
unsigned long end;
int ret = SWAP_AGAIN;
int locked_vma = 0;
+ int we_locked = 0;
address = (vma->vm_start + cursor) & CLUSTER_MASK;
end = address + CLUSTER_SIZE;
@@ -1385,9 +1386,15 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
BUG_ON(!page || PageAnon(page));
if (locked_vma) {
- mlock_vma_page(page); /* no-op if already mlocked */
- if (page == check_page)
+ if (page != check_page) {
+ we_locked = trylock_page(page);
If it's not us who has the page already locked, but somebody else, he
might unlock it at this point and then the BUG_ON in mlock_vma_page()
will trigger again.
yes, this patch is pretty weak.
Any better idea is appreciated. ;-)
Remove the BUG_ON() from mlock_vma_page()? Why was it added?
isolate_lru_page() and putback_lru_page() and *might* require
the page be locked, but I don't immediately see issues?
Ping? This BUG() is triggerable in 3.13-rc6 right now.
Thanks,
Sasha
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