ChangeSet 1.2231.1.153, 2005/03/28 19:59:00-08:00, [EMAIL PROTECTED]
[PATCH] cpusets: alloc GFP_WAIT sleep fix
The cpuset mems_allowed update code in alloc_pages_current could (in
theory) put a task to sleep that didn't allow sleeping (did not have
__GFP_WAIT flag set). In the rare circumstance that the current tasks
mems_generation is outofdate compared to the tasks cpuset
mems_generation,
this mems_allowed update code needs to grap cpuset_sem, which can sleep.
We avoid this by not trying to update mems_allowed here if we can't
sleep
(__GFP_WAIT not set).
Thanks to Ray Bryant <[EMAIL PROTECTED]> for noticing this.
Signed-off-by: Paul Jackson <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
mempolicy.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletion(-)
diff -Nru a/mm/mempolicy.c b/mm/mempolicy.c
--- a/mm/mempolicy.c 2005-03-28 21:40:06 -08:00
+++ b/mm/mempolicy.c 2005-03-28 21:40:06 -08:00
@@ -788,12 +788,16 @@
* Allocate a page from the kernel page pool. When not in
* interrupt context and apply the current process NUMA policy.
* Returns NULL when no page can be allocated.
+ *
+ * Don't call cpuset_update_current_mems_allowed() unless
+ * 1) it's ok to take cpuset_sem (can WAIT), and
+ * 2) allocating for current task (not interrupt).
*/
struct page *alloc_pages_current(unsigned gfp, unsigned order)
{
struct mempolicy *pol = current->mempolicy;
- if (!in_interrupt())
+ if ((gfp & __GFP_WAIT) && !in_interrupt())
cpuset_update_current_mems_allowed();
if (!pol || in_interrupt())
pol = &default_policy;
-
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