Re: [PATCH mmotm/next] mm: memcontrol: rewrite charge API: fix shmem_unuse
From: Hugh Dickins
Date: Mon Jun 30 2014 - 21:08:05 EST
On Mon, 30 Jun 2014, Andrew Morton wrote:
> On Mon, 30 Jun 2014 17:10:54 -0700 (PDT) Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> > On Mon, 30 Jun 2014, Andrew Morton wrote:
> > > On Mon, 30 Jun 2014 15:48:39 -0700 (PDT) Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> > > > - return 0;
> > > > + return -EAGAIN;
> > >
> > > Maybe it's time to document the shmem_unuse_inode() return values.
> >
> > Oh dear. I had hoped they would look after themselves. This one is a
> > private matter between shmem_unuse_inode and its one caller, just below.
>
> Well, readers of shmem_unuse_inode() won't know that unless we tell them.
Add comments on the private use of -EAGAIN.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
mm/shmem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- 3.16-rc2-mm1+/mm/shmem.c 2014-06-30 15:05:50.736335600 -0700
+++ linux/mm/shmem.c 2014-06-30 18:00:02.820584009 -0700
@@ -611,7 +611,7 @@ static int shmem_unuse_inode(struct shme
radswap = swp_to_radix_entry(swap);
index = radix_tree_locate_item(&mapping->page_tree, radswap);
if (index == -1)
- return -EAGAIN;
+ return -EAGAIN; /* tell shmem_unuse we found nothing */
/*
* Move _head_ to start search for next from here.
@@ -712,6 +712,7 @@ int shmem_unuse(swp_entry_t swap, struct
cond_resched();
if (error != -EAGAIN)
break;
+ /* found nothing in this: move on to search the next */
}
mutex_unlock(&shmem_swaplist_mutex);
--
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