[PATCH] Swap Migration V5: PF_SWAPWRITE to allow writing to swap
Add PF_SWAPWRITE to control a processes permission to write to swap.
- Use PF_SWAPWRITE in may_write_to_queue() instead of checking for kswapd
and pdflush
- Set PF_SWAPWRITE flag for kswapd and pdflush
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7da3361..a746620 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -895,6 +895,7 @@
#define PF_SYNCWRITE 0x00200000 /* I am doing a sync write */
#define PF_BORROWED_MM 0x00400000 /* I am a kthread doing use_mm */
#define PF_RANDOMIZE 0x00800000 /* randomize virtual address space */
+#define PF_SWAPWRITE 0x01000000 /* Allowed to write to swap */
/*
* Only the _current_ task can read/write to tsk->flags, but other
diff --git a/mm/pdflush.c b/mm/pdflush.c
index 52822c9..c4b6d0a 100644
--- a/mm/pdflush.c
+++ b/mm/pdflush.c
@@ -90,7 +90,7 @@
static int __pdflush(struct pdflush_work *my_work)
{
- current->flags |= PF_FLUSHER;
+ current->flags |= PF_FLUSHER | PF_SWAPWRITE;
my_work->fn = NULL;
my_work->who = current;
INIT_LIST_HEAD(&my_work->list);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 261a56e..6c30a8c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -268,9 +268,7 @@
static int may_write_to_queue(struct backing_dev_info *bdi)
{
- if (current_is_kswapd())
- return 1;
- if (current_is_pdflush()) /* This is unlikely, but why not... */
+ if (current->flags & PF_SWAPWRITE)
return 1;
if (!bdi_write_congested(bdi))
return 1;
@@ -1299,7 +1297,7 @@
* us from recursively trying to free more memory as we're
* trying to free the first piece of memory in the first place).
*/
- tsk->flags |= PF_MEMALLOC|PF_KSWAPD;
+ tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
order = 0;
for ( ; ; ) {