On Tue, 04 May 2010 18:54:02 +0800 Miao Xie <miaox@xxxxxxxxxxxxxx> wrote: > Before applying this patch, cpuset updates task->mems_allowed and mempolicy by > setting all new bits in the nodemask first, and clearing all old unallowed bits > later. But in the way, the allocator may find that there is no node to alloc > memory. > > The reason is that cpuset rebinds the task's mempolicy, it cleans the nodes which > the allocater can alloc pages on, for example: > (mpol: mempolicy) > task1 task1's mpol task2 > alloc page 1 > alloc on node0? NO 1 > 1 change mems from 1 to 0 > 1 rebind task1's mpol > 0-1 set new bits > 0 clear disallowed bits > alloc on node1? NO 0 > ... > can't alloc page > goto oom > > This patch fixes this problem by expanding the nodes range first(set newly > allowed bits) and shrink it lazily(clear newly disallowed bits). So we use a > variable to tell the write-side task that read-side task is reading nodemask, > and the write-side task clears newly disallowed nodes after read-side task ends > the current memory allocation. > > > ... > > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -16,6 +16,7 @@ > #include <linux/key.h> > #include <linux/security.h> > #include <linux/cpu.h> > +#include <linux/cpuset.h> > #include <linux/acct.h> > #include <linux/tsacct_kern.h> > #include <linux/file.h> > @@ -1003,8 +1004,10 @@ NORET_TYPE void do_exit(long code) > > exit_notify(tsk, group_dead); > #ifdef CONFIG_NUMA > + task_lock(tsk); > mpol_put(tsk->mempolicy); > tsk->mempolicy = NULL; > + task_unlock(tsk); > #endif > #ifdef CONFIG_FUTEX > if (unlikely(current->pi_state_cache)) Given that this function is already holding task_lock(tsk), this didn't work very well. Also, why was the inclusion of cpuset.h added? Nothing which this patch adds appears to need it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>