Re: [PATCH] firmware, memmap: fix firmware_map_entry leak

[Yasuaki Ishimatsu]

2013/04/15 16:04, Wanpeng Li wrote:
> On Mon, Apr 15, 2013 at 02:48:17PM +0900, Yasuaki Ishimatsu wrote:
> > When hot removing a memory, a firmware_map_entry which has memory range
> > of the memory is released by release_firmware_map_entry(). If the entry
> > is allocated by bootmem, release_firmware_map_entry() adds the entry to
> > map_entires_bootmem list when firmware_map_find_entry() finds the entry
> > from map_entries list. But firmware_map_find_entry never find the entry
> > sicne map_entires list does not have the entry. So the entry just leaks.
> >
> > Here are steps of leaking firmware_map_entry:
> > firmware_map_remove()
> > -> firmware_map_find_entry()
> >    Find released entry from map_entries list
> > -> firmware_map_remove_entry()
> >    Delete the entry from map_entries list
> > -> remove_sysfs_fw_map_entry()
> >    ...
> >    -> release_firmware_map_entry()
> >       -> firmware_map_find_entry()
> >          Find the entry from map_entries list but the entry has been
> >          deleted from map_entries list. So the entry is not added
> >          to map_entries_bootmem. Thus the entry leaks
> >
> > release_firmware_map_entry() should not call firmware_map_find_entry()
> > since releaed entry has been deleted from map_entries list.
> > So the patch delete firmware_map_find_entry() from releae_firmware_map_entry()
>
> Reviewed-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>

Thank you for your review.

Thanks,
Yasuaki Ishimatsu

> > Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
> > ---
> > drivers/firmware/memmap.c |    9 +++------
> > 1 files changed, 3 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
> > index 0b5b5f6..e2e04b0 100644
> > --- a/drivers/firmware/memmap.c
> > +++ b/drivers/firmware/memmap.c
> > @@ -114,12 +114,9 @@ static void __meminit release_firmware_map_entry(struct kobject *kobj)
> > 		 * map_entries_bootmem here, and deleted from &map_entries in
> > 		 * firmware_map_remove_entry().
> > 		 */
> > -		if (firmware_map_find_entry(entry->start, entry->end,
> > -		    entry->type)) {
> > -			spin_lock(&map_entries_bootmem_lock);
> > -			list_add(&entry->list, &map_entries_bootmem);
> > -			spin_unlock(&map_entries_bootmem_lock);
> > -		}
> > +		spin_lock(&map_entries_bootmem_lock);
> > +		list_add(&entry->list, &map_entries_bootmem);
> > +		spin_unlock(&map_entries_bootmem_lock);
> >
> > 		return;
> > 	}
> >
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