Merge branch 'akpm' (updates from Andrew Morton)

Merge misc fixes from Andrew Morton:
 "Bunch of fixes and one little addition to math64.h"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (27 commits)
  include/linux/math64.h: add div64_ul()
  mm: memcontrol: fix lockless reclaim hierarchy iterator
  frontswap: fix incorrect zeroing and allocation size for frontswap_map
  kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()
  mm: migration: add migrate_entry_wait_huge()
  ocfs2: add missing lockres put in dlm_mig_lockres_handler
  mm/page_alloc.c: fix watermark check in __zone_watermark_ok()
  drivers/misc/sgi-gru/grufile.c: fix info leak in gru_get_config_info()
  aio: fix io_destroy() regression by using call_rcu()
  rtc-at91rm9200: use shadow IMR on at91sam9x5
  rtc-at91rm9200: add shadow interrupt mask
  rtc-at91rm9200: refactor interrupt-register handling
  rtc-at91rm9200: add configuration support
  rtc-at91rm9200: add match-table compile guard
  fs/ocfs2/namei.c: remove unecessary ERROR when removing non-empty directory
  swap: avoid read_swap_cache_async() race to deadlock while waiting on discard I/O completion
  drivers/rtc/rtc-twl.c: fix missing device_init_wakeup() when booted with device tree
  cciss: fix broken mutex usage in ioctl
  audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE
  drivers/rtc/rtc-cmos.c: fix accidentally enabling rtc channel
  ...

1 files changed, 16 insertions, 20 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 7fe5bdee163..2bbcacf74d0 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -141,9 +141,6 @@ static void aio_free_ring(struct kioctx *ctx)
 	for (i = 0; i < ctx->nr_pages; i++)
 		put_page(ctx->ring_pages[i]);
 
-	if (ctx->mmap_size)
-		vm_munmap(ctx->mmap_base, ctx->mmap_size);
-
 	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages)
 		kfree(ctx->ring_pages);
 }
@@ -322,11 +319,6 @@ static void free_ioctx(struct kioctx *ctx)
 
 	aio_free_ring(ctx);
 
-	spin_lock(&aio_nr_lock);
-	BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
-	aio_nr -= ctx->max_reqs;
-	spin_unlock(&aio_nr_lock);
-
 	pr_debug("freeing %p\n", ctx);
 
 	/*
@@ -435,17 +427,24 @@ static void kill_ioctx(struct kioctx *ctx)
 {
 	if (!atomic_xchg(&ctx->dead, 1)) {
 		hlist_del_rcu(&ctx->list);
-		/* Between hlist_del_rcu() and dropping the initial ref */
-		synchronize_rcu();
 
 		/*
-		 * We can't punt to workqueue here because put_ioctx() ->
-		 * free_ioctx() will unmap the ringbuffer, and that has to be
-		 * done in the original process's context. kill_ioctx_rcu/work()
-		 * exist for exit_aio(), as in that path free_ioctx() won't do
-		 * the unmap.
+		 * It'd be more correct to do this in free_ioctx(), after all
+		 * the outstanding kiocbs have finished - but by then io_destroy
+		 * has already returned, so io_setup() could potentially return
+		 * -EAGAIN with no ioctxs actually in use (as far as userspace
+		 *  could tell).
 		 */
-		kill_ioctx_work(&ctx->rcu_work);
+		spin_lock(&aio_nr_lock);
+		BUG_ON(aio_nr - ctx->max_reqs > aio_nr);
+		aio_nr -= ctx->max_reqs;
+		spin_unlock(&aio_nr_lock);
+
+		if (ctx->mmap_size)
+			vm_munmap(ctx->mmap_base, ctx->mmap_size);
+
+		/* Between hlist_del_rcu() and dropping the initial ref */
+		call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
 	}
 }
 
@@ -495,10 +494,7 @@ void exit_aio(struct mm_struct *mm)
 		 */
 		ctx->mmap_size = 0;
 
-		if (!atomic_xchg(&ctx->dead, 1)) {
-			hlist_del_rcu(&ctx->list);
-			call_rcu(&ctx->rcu_head, kill_ioctx_rcu);
-		}
+		kill_ioctx(ctx);
 	}
 }